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CSI # 16xxx – Mission Critical (MC11)
CYBEREX
Mission Critical (MC11)
PDM Mark II/SS3
Dual Input PDM With Input-positioned Digital Static Transfer Switch
GUIDE SPECIFICATIONS
1
1.1
GENERAL
SUMMARY (PDM/STS)
This specification covers the electrical characteristics and general
requirements for a combination of a power distribution module (PDM) and
digital static transfer switch (DSTS). This combination shall consist of a
digital static transfer switch (DSTS) at the input of a PDM plus output
distribution. The output distribution shall be configurable with panel boards
or sub feed breakers. The equipment so combined shall hereafter be
referred to as a “Mission Critical PDM (Model MC11)” or “PDM/DSTS”. The
system shall be designed primarily for distribution of electrical power
beneath a raised floor and shall provide a redundant power path from input
to output in order to increase reliability, serviceability and availability. The
system shall be designed primarily for distribution of electrical power in
computer (IT) rooms, but its design shall also permit its adaptation for use
in electrical rooms, industrial plants and other applications. The system
shall be an integrated device which provides isolation, distribution, control
and monitoring of AC power; and shall properly interface redundant AC
power sources with sensitive electronic loads.
The Mission Critical PDM defined in this specification is comprised of
separate cabinets containing either the PDM or DSTS components. The
following sections in this specification are classified according to their
applicability to the PDM, DSTS or both and are labeled accordingly.
1.2
SYSTEM RATING SUMMARY (PDM/DSTS)
The Mission Critical PDM system described in this specification shall have
the following characteristics:

Input: 480VAC, 3 phase, 3 wire (dual sources)

Output: 208/120VAC, 3 phase, 4 wire, 60 Hz

PDM rating: [75] [100] [125] [150] [200] [225] [300] kVA

DSTS rating: [200] [400] amperes, 480VAC, 3 phase, 3 wire, 60 Hz,
short circuit withstand 100 kAIC
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CSI # 16xxx – Mission Critical (MC11)
The above equipment definition is based on the following table:
MC11 Available Configurations
Transformer
kVA
DSTS Voltage
Rating
DSTS
Ampere
Rating
Effective
PDM/DSTS
kVA Through-put
75
100
125
150
200
225
300
480VAC
480VAC
480VAC
480VAC
480VAC
480VAC
480VAC
200
200
200
200
400
400
400
75
100
125
150
200
225
300
(Note: Other input and output voltages and frequencies available by special
order)
1.3
ACCESS FOR INSTALLATION AND MAINTENANCE (PDM/DSTS)
[Each PDM/DSTS shall consist of two (2) 34” cabinets – one for the DSTS
and one for the transformer cabinet plus distribution. Total equipment lineup shall be 68 inches.]
(Note: Some 300 kVA transformers with low inrush, high K rating and/or low
temperature rise may require a 46” cabinet. Total equipment width: 80
inches.)
(Additional PDM side cars may be included in the PDM/DSTS line-up as
required for distribution space beyond that which is provided on the front of
the transformer cabinet.)
The DSTS shall be placed at either end of the line-up in order to provide
side access to the DSTS circuit breakers for installation and maintenance
unless rear access to the DSTS is provided.
Rear access shall be provided for access to the transformer if its side
access is blocked by an end-placed distribution side car.
Front access shall be required for operation and maintenance.
Cable entrance for the two sources shall be top or bottom of the DSTS
cabinet; cable exit from distribution shall be top and bottom for PDM
cabinets that do not have a transformer; cable exit shall be bottom only
from PDM cabinets with a transformer.
Rear distribution shall not be allowed in side cars unless they are placed at
the end of the line-up.
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1.4
STANDARDS (PDM)
The PDM shall be designed, tested (or certified) and manufactured to the
following standards:
1.5

Underwriters Laboratories Standard, UL 60950

Underwriters Laboratories Standard, UL 891
STANDARDS (DSTS)
The DSTS equipment and components shall be manufactured in
compliance with the applicable requirements of the following standards:
1.6

Underwriters Laboratories (UL). The DSTS shall be ETL Listed to
UL 1008. Submit documentation with the bid indicating listing
agency and file number.

ANSI/IEEE C 62.41 Surge/Noise suppression
STANDARDS (PDM/DSTS)
All component of the Mission Critical (PDM/DSTS) shall be designed and
manufactured the following standards:
1.7

ANSI/NFPA 70 (2008)

National Electrical Code (2008)

NEMA (All applicable standards)
DEFINITIONS (PDM/DSTS)
The following definitions shall apply throughout this specification:

DSTS - a complete automatic digital static transfer switch and
associated accessories.

PDM – a complete power distribution module consisting of a main
input breaker, step-down isolation transformer, and output
distribution in the form of panel boards, sub feed breakers or both.

Bypass - direct power flow from one source to the critical load as
required for maintenance of the DSTS without disruption of the load.

Redundant - inclusion of one more device than is required to achieve
continuous operation without disruption of the load.

Owner, User or Buyer - owner (or its designated representatives).

Manufacturer - the firm or corporation who will manufacture and deliver
the DSTS equipment specified herein.

Specifications - technical instructions described or portions of
standards referenced herein, and any addenda thereto.
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1.8
SYSTEM DESCRIPTION (PDM)
1.8.1 Environmental Requirements
The PDM shall be capable of withstanding any combinations of the
following environmental conditions without mechanical or electrical damage
or degradation of operation:
 Operating temperature: 0C to 40C (300kva 0C to +37C)
 Storage: 0C to +60C
 Relative humidity: 10% to 95% non-condensing
 Maximum operating altitude without de-rating: 2,500 meters
 Non-operating altitude: 15,000 meters
 Audible noise: 55 db maximum
1.8.2 Electrical Requirements
The PDM shall have a full load continuous capacity of [50] [75] [100]
[125] [150] [200] [225] [300] kVA.
The input voltage to the PDM shall be 480 VAC, three (3) phase,
three (3) wire plus ground @ 60 Hz.
The output voltage from the PDM shall be 208/120 VAC wye, three
(3) phase, four (4) wire plus ground @ 60 Hz.
1.9
SYSTEM DESCRIPTION (DSTS)
1.9.1 Environmental Requirements
The DSTS shall be capable of withstanding any combinations of the
following environmental conditions without mechanical or electrical
damage or degradation of operation.







Operating ambient temperature: 0 to 40°C.
Non-operating storage temperature: 0 to 80°C.
Relative humidity: 10% to 95% non-condensing.
Noise Level: <65dba at six feet from the DSTS.
Maximum operating altitude without de-rating: 6000 feet
above sea level.
Equipment shall be designated for indoor use in a clean (dustfree) temperature and humidity controlled environment.
AC to AC efficiency defined as the ratio (expressed as a
percentage) of AC output kW to AC input kW at full nominal
rating at 0.8 power factor load shall not be less than 99%.
Provide proposed efficiency data in specification compliance
form in the proposal, if other than this figure.
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1.9.2 Electrical Characteristics

Nominal Source Voltages: 480 volts AC plus ± 10%, 3 phase,
3 or 4 wire + ground (neutral is not switched, nor is it utilized
in the MC11).
 Source Frequencies: [60 Hz] ± 5%.
 Continuous Current Rating: [200] [400] Amps.
 Load Power Factor: Unity to .50 lagging or leading.
 Overload Rating:
o 125% for 30 minutes
o 150% for 1 minute
o 200% for 10 seconds
o 1000% for 3 cycles
o 1500% for 1 cycle
 Harmonic Current fed back from the load: Unlimited
 Source Voltage THD in the line feeding the load:
o Maximum 5% total harmonics or as
acceptable to the load.
o Maximum 3% single harmonic or as
acceptable to the load.
 Voltage Transient Withstand without failure or mis-operation,
present on the line: Up to 20,000-volt spike, per IEEE C62.41
Category C3 Standards. Such transient levels shall not effect
the operation of the DSTS except to cause a transfer due to
over-voltage beyond pre-set limits.
 Over-current Protection: The non-automatic internal breakers
shall be rated at a continuous [200] [400] AF/NA current rating
(frame rating should be higher if the breaker is de-rated 80%),
with magnetic trips set at their highest setting to allow
coordination with up-stream protective devices.
 Short circuit and overload rating shall be such that the unit
does not drop the load while such conditions are being
protected or acted on by properly rated thermal-magnetic
circuit breakers in the owner’s distribution system.
1.9.3 Construction, Enclosure and Access
The DSTS assembly shall be constructed in modular configuration
for maximum ease of maintenance, installed in NEMA Type-1 metal
enclosures made of 11 gauge steel frame and 16 gauge steel sides,
with provisions for computer room installation (with casters and
leveling feet). Sheet metal parts shall be either electroplated or
primed and painted. Color shall be manufacturer’s standard.

Individual enclosures shall require front access for equipment
operation and removal of serviceable parts such as pc boards,
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SCR assemblies and plug-in breakers. Front doors shall be
lockable to provide access only by authorized personal.
Deadfronts shall be provided behind the lockable front doors
to allow safe operation of breakers and to cover all energized
parts.
 Individual enclosures shall also require rear access or one
side access for installing, torquing or IR scanning of customer
connections. Left or right side access, dictated by operational
position, must be specified at the time of order. Side and rear
access doors shall be lockable.
 All circuit breakers shall be plug-in or rack-out/draw-out.
 The enclosure shall have all normal operating controls,
instrumentation, display and lights mounted on the front door.
All control setting adjustments for voltage level sensing shall
be via a menu driven software on a color LCD panel on the
front of the unit. Adjustments options of the menu shall
require the knowledge of a security access code so as to not
allow unauthorized staff to make such adjustments. The doormounted controls shall be for human interaction with the
DSTS’ internal logic only. In the absence of or malfunction of
the door-mounted controls (e.g. if they are disconnected or
not operational) the DSTS shall enable an internal set of PCBmounted auxiliary operators that allow basic control functions
to be effected from inside the DSTS by qualified service
personnel.
 All wiring, terminal boards, logic assemblies shall be
accessible with ease from the front or side with doors open,
without having to remove any other assemblies first. SCR
assemblies shall be pull-out type for ease of replacement of
the entire phase assembly.
1.9.4 Modularity of Construction
Sub-assemblies shall be constructed for ease of access and
replacement of parts. Circuit boards shall use industry-accepted
connectors. Connectors shall be chosen such that erroneous
connections are not possible. SCR assemblies shall be pullout style
for ease of replacement and minimal down time.
1.9.5 Bracketing and Wiring
Brackets and securing hardware shall be electroplated with corrosion
resistant material. Internal wiring conductors shall be combined into
cables or bundles and tied securely together. All wiring shall be
clearly marked. All logic and control connections shall be routed
away from any power runs for noise suppression.
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1.9.6 Conducting Material
All internal bus work shall be fabricated of custom-formed copper.
All bus work shall be rated for 1000 amperes per square inch cross
section or to not exceed a temperature rise of 50 degrees Centigrade
in free air. Aluminum is not acceptable for the referenced
requirements. If the owner or their representatives discover
noncompliance in this area during or after completion of installation
(regardless of signed acceptance tests), the DSTS manufacturer is
responsible for replacing all areas of such noncompliance at its own
expense including materials, freight, and site labor expenses.
1.9.7 Material and Workmanship
All materials and parts comprising the DSTS shall be new, of current
manufacture, high grade, and free from all defects or imperfections,
and shall not have been in prior service, except as required during
factory testing. Workmanship shall be of the highest quality.
1.9.8 Short Circuit Bracing

Unit construction and component selections shall incorporate
ratings, support, and bracing methods to allow for the
specified short circuit withstand rating of the unit (including all
electro-mechanical and power electronic devices,
interconnections, cable and bus work).
1.9.9 EMI Susceptability
Radiated and conducted EMI generated within the units shall be
suppressed to prevent excessive interference with associated nearby
electronic equipment. Units shall also not be susceptible to misoperation due to EMI or RFI generated by a hand held VHF or UHF
transceiver from a distance of 24 inches in front of a unit, with the
doors closed.
1.9.10 Surge/Noise Suppression
Power SCRs used in the system shall be conservatively rated for
dv/dt of at least 800v/u-Sec. The design of the unit and component
selections shall provide capability to withstand noise spikes per
ANSI/IEEE C 62.41 standards (2kv impulse) without malfunction or
any device breakdowns or sporadic transfers. All power supplies
shall incorporate noise immunity circuits.
1.10 WARRANTY (PDM/DSTS)
The PDM/DSTS manufacturer shall guarantee the entire system against
defective material and workmanship for a period of one (1) year from date
of shipment.
With purchase of Factory Start-up Services and used in the continental
United States, the manufacturer shall include labor and expenses for a
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period of one (1) year from date of Factory Start-up, not to exceed eighteen
(18) months from date of factory shipment.
1.11 RELIABILITY (DSTS)
1.11.1 Overview
As the intended use of the DSTS is to achieve the ultimate reliability
of availability of power to critical loads, using two available power
paths, it is required that this device not introduce additional failure
contributions that would interfere with maintenance of power to the
load, as long as one or the other of the connected sources are
available and within tolerance of the load. The following critical
reliability parameters are therefore required.
1.11.2 Experience and Actual Accumulated Service History
The manufacturer shall have a minimum of 30 years of experience in
the design and manufacture of stand alone digital static transfer
switches and a minimum of 6000 installed locations with a proven
history of reliable operation. Provide a list of minimum 10 sites with
a description of the switch, rating and the names and phone
numbers of the contacts, and the number of years in operation, for
the purposes of checking references of the bidder. Prior experience
with UPS bypass switches is not acceptable for this project. It is the
owner’s intent to purchase products only from qualified bidders with
a well-established history of DSTS products.
1.11.3 High Reliability Logic Components
The DSTS logic shall be Fault Tolerant in that no single point of
failure on the communications bus, internal wiring or any board can
cause a disturbance of power to critical loads, as long as two
sources of power are available.
1.11.4 Eliminate Single Point Failures
A conservative approach shall be taken in all aspects of the design
to eliminate single point failures as follows:

Redundant logic power supplies for the system and all
critical logic boards - The digital static switch system shall
employ redundant internal power distribution for all critical
circuits. Two independently derived control power buses shall
feed each critical function, such as the Main Logic Board.
Each control power bus shall be derived from three power
sources: one connected to the normal input source, a second
to the alternate input source, and the third to the output load
bus. The loss of a power source and the failure of any of the
redundant supplies shall not prevent the functioning of any
critical circuit.
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

Separate SCR drives for the two sources - Gating and
control logic of the two sources shall be segmented such that
each source has complete gate control and firing logic.
Failure of any component on one source gate drive shall not
prevent transfer to the other source. Exception: If the gate
drive board experiencing the failure is driving its SCRs to
conduction and the failure is in the communications path, the
gate drive board shall lock itself into a continuous SCR
conduction mode until communications are restored. Upon
failure, the condition shall cause an audible and visual
annunciation.
Two load isolation non-automatic breakers in parallel with each other, each rated at full load and full fault withstand
capacity, to share the load current from the SCR switch.
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2.1
PRODUCT (PDM/DSTS)
COMPONENTS (PDM)
2.1.1 Cabinet Construction: Main Transformer
The PDM’s primary element is the main transformer cabinet intended
to house the main input connection, main input breaker, the
transformer and basic metering and communications electronics.
The main transformer cabinet may also include power distribution
devices such as panel boards and sub feed circuit breakers which
will be covered in other sections of this specification.

The PDM main transformer cabinet enclosure shall be
designed for placement on the computer room raised floor.
The system shall be aesthetically pleasing and shall not
exceed [34] "W, 34"D, and 77.4"H. (46”W enclosure is
required for certain 300kVA transformers depending on
transformer options selected – e.g low temp rise, low inrush,
high K rating)
 The main transformer cabinet enclosure shall be a single bay
vertical cabinet using natural convection for cooling purposes.
Forced air (fan) cooling is expressly forbidden via this
specification.
 The main transformer enclosure shall be designed to allow all
routine service, including compensation tap changes, to be
made requiring FRONT ACCESS. This feature is a strict
requirement of this specification, due to the valuable nature of
computer room raised floor space on this project.
2.1.2 Cabinet Construction: Distribution Side Cars
The PDM shall be provided with [1] [2] [3] distribution side cars for
additional distribution devices as follows:
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CSI # 16xxx – Mission Critical (MC11)
 [quantity] 10” Side-facing side car
 [quantity] 24” Front-facing [and Rear-facing] side car
 [quantity] 34” Front-facing [and Rear-facing] side car
The side cars shall be affixed to the left and/or right sides of main
transformer cabinet to form a continuous equipment line-up of
uniform height and depth (except for ventilation top hat on the main
transformer cabinet which does not extend to the edges). The 34”
and 24” front-facing (but not the 10” side-facing) side cars shall be
provided with swivel casters and stabilizing feet (see Cabinet
Construction: General).
2.1.3 Cabinet Construction: General

The PDM cabinet enclosures shall be mobile and contain four
(4) 360o swivel casters and four (4) stabilizing feet for stability
purposes.
 The PDM cabinet enclosures shall be painted standard
Cyberex black to complement the data processing equipment
in this facility. The paint shall be applied using powder
coating methods and shall be heat treated and matte finished
to help protect the surface of the PDM.
2.1.4 Cabinet Access
Cabinet access shall be as follows:


Front Access required for operation.
Side access required for operation of the Side-facing Side
Car.
 Rear access required for operation of Rear-Facing side car.
 Left, Right, or Rear Access required for servicing the Main
Transformer cabinet. If side cars are placed on both sides of
the main transformer cabinet, then rear access is required for
service.
 Bottom cable entrance/exit for main transformer cabinet
 Top or bottom exit for distribution side cars
2.1.5 Input Main Circuit Breaker
The PDM shall include an input main circuit breaker to provide both
system protection and a means of disconnecting power from the
system.
The system's input main circuit breaker shall be a line voltage rated,
3-pole thermal magnetic molded case circuit breaker sized for 125%
of the PDM full load input current rating.
The system's input main circuit breaker shall contain a 24 VDC shunt
trip mechanism which shall be interfaced to the local Emergency
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CSI # 16xxx – Mission Critical (MC11)
Power-Off (EPO) pushbutton on the PDM as well as remote EPO
pushbutton connections for all remote needs.
The system's input main circuit breaker shall have a standard
interrupt rating of 65kAIC@480V for all kVA offerings. Lower kAIC
ratings shall also be available.
2.1.6 High Isolation Transformer
The PDM shall contain a high isolation electro-statically shielded
transformer for both voltage step-down and isolation purposes. The
transformer shall be constructed using all copper windings and shall
employ six (6), 2 1/2% full load compensation taps (two [2] above
and four [4] below nominal).
The PDM high isolation transformer shall have the following electrical
and construction characteristics:



Rated kVA
Primary Voltage
Secondary Voltage
kVA
480 VAC, 3 PH, 3 W + Ground
208/120 VAC, 3 PH, 4 W +
Ground
 Input/Output Frequency
60 Hz
 Percent Impedance
3.0 – 5.2%
 Percent Reactance
2.0 – 4.2%
 Voltage THD (added)
1% max.
 Full Load Efficiency
97.5%
 Insulation Class
Class 220
 Temperature Rise
150oC, optional 115°C
 Audible Noise
55 db maximum
 K-Rating
20 standard, optional 4, 9 & 13
The neutral of the high isolation transformer shall be rated 2 times
the system full load amps rating. This is a strict requirement of the
specification due to the anticipated high nonlinear loads associated
with this project.
[50,75,100,125,150,200,225,300]
The transformer shall contain two (2) overload protection devices per
coil to monitor core temperature. The first thermal device shall be
calibrated at 190oC. The second thermal device shall be calibrated
at 220oC. In the event of a 220oC core temperature condition, the
thermal overload protection device shall close a set of contacts and
initiate an automatic shutdown event.
The transformer shall be cooled by natural convection.
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2.1.7 Output Distribution Options
The PDM shall be provided with the following complement of
distribution options to be placed in the side cars as defined in section
2.1.2. of this specification
10” Side-facing side car with the following distribution devices:
[choose any 2]

225A Square D standard panel board with [10kAIC] [25kAIC]
225A mains
 225A GE panel board with [10kAIC] [25kAIC] 225A mains
 Grouping of up to (4) [100] [150] [225] amp, [10kAIC] [25kAIC]
Square D sub feed breakers
 400 amp, 42 kAIC Square D sub feed breaker
 800 amp Square D I-line panel board (one per side car)
24” Front/rear-facing side car with the following distribution
devices: [choose any 2 for front or any 2 for rear (rear distribution
allowed only if side car is at end of lineup)]


225A Square D column width panel board with [10kAIC]
[25kAIC] 225A mains
Grouping of up to (2) [100] [150] [225] amp, [10kAIC] [25kAIC]
Square D sub feed breakers
OR

225A Square D standard panel board with [10kAIC] [25kAIC]
225A mains
 225A GE panel board with [10kAIC] [25kAIC] 225A mains
 Grouping of up to (4) [100] [150] [225] amp, [10kAIC] [25kAIC]
Square D sub feed breakers
 400 amp, 42 kAIC Square D sub feed breaker
34” Front/rear-facing side car with the following distribution
devices: [choose any 2 for front or any 2 for rear (rear distribution
allowed only if side car is at end of lineup)]

225A Square D standard panel board with [10kAIC] [25kAIC]
225A mains
 225A GE panel board with [10kAIC] [25kAIC] 225A mains
 Grouping of up to (4) [100] [150] [225] amp, [10kAIC] [25kAIC]
Square D sub feed breakers
 400 amp, 42 kAIC Square D sub feed breaker
 800 amp Square D I-line panel board (one per side car)
Main Transformer Cabinet Distribution (34”) with the following
distribution devices: [choose and 2 (front only)]
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CSI # 16xxx – Mission Critical (MC11)

225A Square D standard panel board with [10kAIC] [25kAIC]
225A mains
 225A GE panel board with [10kAIC] [25kAIC] 225A mains
 Grouping of up to (4) [100] [150] [225] amp, [10kAIC] [25kAIC]
Square D sub feed breakers
 400 amp, 42 kAIC Square D sub feed breaker
Main Transformer Cabinet Distribution (46”) with the following
distribution devices: [choose and 2 (front only)]

225A Square D standard panel board with [10kAIC] [25kAIC]
225A mains
 225A GE panel board with [10kAIC] [25kAIC] 225A mains
 Grouping of up to (4) [100] [150] [225] amp, [10kAIC] [25kAIC]
Square D sub feed breakers
 400 amp, 42 kAIC Square D sub feed breaker
 400A Square D standard panel board with [25kAIC] 400A
mains
2.1.8 Panel Boards General:
The PDM distribution panel boards shall be 42-pole, [225] [400] amp,
240V, three (3) phase with a short circuit rating of 22, kAIC.
Each distribution panel board shall employ copper buss bars and
shall be capable of accepting 1-pole, 2-pole, and 3-pole circuit
breakers rated up to 100 amps.
Each distribution panel board shall be capable of accepting [bolt-on]
[snap-on] [both bolt-on or snap-on (Square D only)] branch circuit
breakers into the panel board interior.
Each distribution panel board shall feature a 42-position neutral bus
assembly and a 42-position ground bus kit to provide sufficient
output ground and neutral termination space. The ground and
neutral bus kits shall be mounted parallel to its distribution panel
board to facilitate optimum spacing for ease of installation and
expansion purposes.
Each neutral bus kit associated with each 42-pole distribution panel
board shall be fed by [two (2) 1/0 THHN/THWN] [two (2) 250kcmil
THHN/THWN] copper conductors. This will provide [450] [*800]
amps of conductor to each neutral bus kit to accommodate the
anticipated high nonlinear loads associated with this project.
(*applies to 400 amp panel boards only)
2.1.9 Panel Board Main Breakers
Each 42-pole distribution panel board shall be protected by a 225
amp, 240V, 3-pole main circuit breaker protective device.
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2.1.10 Branch Circuit Breakers
Each output branch circuit shall be protected by a separate branch
circuit breaker.
Each branch circuit breaker protective device shall have three (3)
toggle positions: ON, OFF, and TRIPPED.
Branch circuit breakers shall be [bolt-on] [snap-on] [both bolt-on or
snap-on] with a [10] [22] kAIC rating and sized in compliance with the
National Electric Code.
2.1.11 Sub Feed Circuit Breakers
Each sub feed breaker shall be fixed-mounted and rated at 240 VAC,
3 phase, [100] [150] [225] amp and [10] [25] kAIC. Four hundred
(400) amp breakers shall be rated at 240 VAC, 3 phase, 42 kAIC.
2.2
COMPONENTS (DSTS)
2.2.1 DSTS Circuit Breakers




All non-automatic switches shall be plug-in for ease of
removal for replacement, calibration, or testing, without
interruption of service to the critical load. Six (6) non-auto
breaker/switches shall be provided for the DSTS. All
breakers/switches shall be plug-in or draw-out/rack-out.
There shall be two breaker/switches for load bypass to each
input, two for SCR input source isolation, one to each source,
and two for SCR load isolation. There shall be visible
annunciation if one of the output breakers is left open in error
(or if it opens inadvertently).
Electrical and mechanical interlocks shall be provided for the
breakers to prevent operators from closing both bypass CB’s
at the same time or from closing the bypass CB on the nonconducting side of the DSTS. A mechanical interlock (Kirk
Key) as well as an electrical interlock are provided for
maximum protection against cross connection.
In addition, there shall be software guided, lighted LED
indicators by each breaker to aid the operator in placing the
unit into, and taking the DSTS out of, bypass. The software
shall be designed to guide the user through the proper stepby-step operation for each source.
Logic circuits that cause a SCR transfer to the side of an
inadvertently closed breaker of the opposite source are not
allowed, due to the fact that this design approach A) Does not
prevent cross connection from occurring in the first place, and
B) A momentary cross connection between the sources will be
disruptive if one or both sources are connected to a UPS
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(UPS’s are very sensitive to cross connections without
automated tie circuitry and load sharing networks).
 All DSTS breakers, with the exception of the master Output
Circuit Breaker, shall be equipped with shunt trip and auxiliary
contacts for logic interfaces with the digital static switch
controls and indicating circuits, as required. The Output
Circuit Breaker(s) shall have auxiliary contacts only. The
slave Output Circuit Breaker shall be equipped with a shunt
trip mechanism.
 Under no circumstances shall the bypass breakers be
motorized for automatic closure, so as to avert cross
connections caused by logic malfunctions (such as motorized
closure of the wrong side), or to avoid circumventing the
interlocking scheme specified above, because of the inherent
demonstrated unreliability of such mechanisms.
 All non-automatic switches shall be rated to carry the 100%
rating of the digital static transfer switch at the ambient
temperature specified. If 80% rated devices are used, then
the 80% times the frame rating shall not be less than the
specified rating (so that the DSTS rating is not de-rated by
80%). If 80% times the frame rating is less than the DSTS
rating specified, then a frame of next higher rating shall be
utilized.
 There shall be provisions to test the system and logic while in
maintenance bypass, without load disruption (this means,
while in maintenance bypass, both the load as well as the
SCRs are energized by both sources, however the SCR
outputs are isolated from the load so they can perform test
transfers). Testing the system means use of the SCRs in
making actual transfers. Simulation of transfer by using logic
annunciations is not acceptable.
2.2.2 Active Devices and Semiconductors
All active electronic devices shall be solid-state. All SCR’s shall be
hockey puck type, oversized to allow the use of circuit breakers as
the means of protection for these devices. All relays shall be sealed
with covers. All capacitors shall be non-PCB type and internally
protected in accordance to applicable UL standards. All circuit
boards and relays (if any) shall have mechanical restraints designed
to prevent loosening of these devices while in transit, while being relocated, or while in service.
The design shall allow a minimum of 25° C operating margin from
the maximum allowable junction temperature of all solid-state
semiconductor devices while operating in a 40°C ambient. SCR's
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CSI # 16xxx – Mission Critical (MC11)
shall have a rupture rating or be protected in a manner compatible
with the specified fault current availability.
2.2.3 Circuit Boards
For highest reliability, all internal logic circuit boards shall employ
connectors with gold flashed pins for all low-level signals.

Major circuit boards shall have LED indicators to annunciate
critical board functions for ease of troubleshooting and
maintenance.
 All circuit cards shall use high quality commercial grade
components for critical functions per the design of the
manufacturer, and shall have reference designations silkscreened on to the surface of the board.
 The circuit boards shall have no single points of failure that
could cause a loss of power to connected loads, when two
power sources are available.
 Circuit boards will minimize the use of through-hole
components and shall use surface mount technology for the
majority of board level components.
2.2.4 Ventilation and Cooling

Enclosure design shall provide adequate ventilation to insure
that all components are operated within their thermal ratings
for units rated 200-400A. The SCRs shall be oversized to a
degree that the unit has capability to operate at full capacity
(including overload rating) to allow overload clearing by an
upstream thermal magnetic trip circuit breaker without
damage to any components.
 The design of the unit ventilation shall take into account
continuous operation in an ambient temperature of 40°C, 095% non-condensing humidity, and an under-voltage
condition of -10% (or a simultaneous combination of these
elements). Provide a grill to ensure against falling of external
objects into the unit. Grill pattern shall not allow entry of
objects larger than 0.25 inches in diameter.
2.2.5 DSTS Control Panel
The DSTS control panel shall be mounted on the door of cabinet and
viewable from the front of the unit and contain the normal operating
controls, metering, and status indications on a high resolution bit
mapped graphic LCD with an easy-to-use graphical user interface
(GUI). All metering and alarms shall be displayed on the LCD
display. Additionally, a mimic bus with discreet LED graphics shall
depict the overall DSTS power flow. All device status indications
shall utilize LED’s for long life. The manufacturer shall provide the
minimum controls and audible/visual alarms required in these
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specifications as detailed in sections that follow (see “METERING,
ALARM AND MONITORING SYSTEM”).
2.3
METERING, ALARM AND MONITORING SYSTEM (PDM)
The PDM shall employ a microprocessor based monitor panel and shall
monitor all power points within the system.
The monitoring panel shall employ an audible alarm to annunciate fault
conditions that require acknowledgment. Such alarms shall include
transformer over-temperature and TVSS failure. The alarm shall be
silenced by acknowledging the condition on the display panel.
The PDM shall continuously monitor the core temperature of the main
isolation transformer. The transformer shall be equipped with two (2)
thermal sensors per coil, one (1) to annunciate a "High Temperature"
condition and the other to automatically shut down the PDM upon a
hazardous temperature condition (220°C).
The PDM shall log the “Excess Temperature Warning Threshold” event in
the event log as an alarm as well as sound the audible alarm.
The PDM monitoring panel shall contain a fully-guarded, red illuminated
Emergency Power Off pushbutton assembly. This control circuit shall be
interconnected to the 24 VDC shunt trip mechanism and shall allow the
user to completely remove the PDM from the line.
The PDM shall contain a user interface board which is to be located behind
the top left dead front, on the surface of the left panel. This board shall
allow the local installing electrical contractor to interconnect remote
emergency power off pushbutton stations to the EPO control circuit, as well
as any other customer monitoring connections.
The display panel shall also contain a 320 x 240 high resolution LCD
display with graphical user interface (GUI) to display both alarm and time
and date of the event.
The display panel shall feature a custom keypad to allow the user to custom
configure the system's alarm limits, ratings, time, date, and other
parameters.
2.3.1 Monitored Parameters
The display panel shall become an integral part of the PDM and shall
indicate the following system information:






Serial Number
Software Version
Modbus ID
Board Temperature
Date of Last Upgrade
Date of Last Service
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 Date of Initial Installation
The monitor panel shall continuously measure the following
alarm/warning conditions in the PDM system:
 Output Under/Over Voltages (L-N)
 Output Over Currents (3-phase)
 Output Over Neutral and Ground Currents (Amps)
 Input Under/Over Voltage (L-L)
 Under/Over Frequency
The following shall be metered:
 True RMS Output Voltages (3-phase, L-L, and L-N)
 True RMS Input Voltages (3-phase, L-L)
 True RMS Output Currents (3-phase)
 True RMS Neutral Current
 True RMS Ground Current
 Real Power (KW)
 Apparent Power (kVA)
 Energy Consumption (KWh)
 Frequency
 Power Demand (KW max)
 Percentage Load
 Voltage THD in %
 Current THD in %
 Crest Factor for Load
 Output Power Factor
Upon any alarm condition the system shall produce an event in the
event log describing the alarm/warning condition, for example:
12:13:26 A* PDM id 2 Phase AB Input Low Voltage
The system has the ability to output up to four (4) SPDT (Form C)
relay contacts. The function of these relays is given below:
 Relay 1: Summary Alarm
 Relay 2: Unacknowledged Events
 Relay 3: Factory-Programmable Alarm Output
 Relay 4: Factory-Programmable Alarm Output
In addition to the above monitoring features, the system shall have
the ability to accept normally open contacts from up to four (4)
building interface points. The PDM monitor panel shall provide
authorized field service personnel the ability to program whether the
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interface point is an alarm or warning as well as the ability to assign
a twenty (20) character name to the building interface point. The
PDM monitor panel shall also allow those points to be configured as
latching or non-latching (i.e. to change status back to “normal” when
the normal condition returns).
2.3.2 Monitoring Options


2.4
Branch Circuit Monitoring for Panel boards
Sub feed Monitoring for Sub feeds
METERING, ALARM AND MONITORING SYSTEM (DSTS)
The DSTS shall provide the following minimum metering, alarm and
monitoring functions.
2.4.1 Alarms – System (Audible and Visual):
 Output Available
 Load Breaker Open
 Fan Failure
 Cabinet Over-temperature
 Logic Power Supply Failure
 Communications Failure
 Heatsink Over-temperature
 EPO
2.4.2 Alarms – Preferred and Alternate Sources (Audible and Visual):
 Input Fail
 Overload
 CB Open
 Over Voltage (Amber and Red) – Fast/Slow
 Under Voltage (Amber and Red) – Fast/Slow
 Over Frequency
 Under Frequency
 Shorted SCR
 Open SCR
 Blown TVSS Fuse
 Gate Drive Power Supply Failure
 Gate Drive Communication Error
 Snubber Board Failure
2.4.3 Alarm – Event Logging

The DSTS shall display a chronology of the last 2500 events
including alarms and warnings date and time stamped by local
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real time clock in the order of occurrence. The date and time
stamp shall provide 10 millisecond resolution. Data shall be
displayed on the LCD display along with a text description of
the alarm or warning event. Data shall be retrievable via an
Ethernet port for customer collection. The Data logger shall
function in a first-in first- out mode and shall be provided with
an internal battery backup to protect data in the event both
power sources fail. Data shall remain in the log indefinitely for
future review or evaluation, and shall be filtered and/or sorted
by date, time & type of event.
2.4.4 Metering:

Voltmeter (on display LCD) with output, preferred, and
alternate sources for each phase; line to line A-B, B-C, and AC, all displayed simultaneously for instant comparison by
operator.
 Ammeter (on display LCD) with preferred and alternate
sources, for each phase; A, B, and C, all displayed
simultaneously for instant comparison by operator (for instant
detection of an open phase).
 Frequency Meter – both sources.
 Phase Angle Meter – between sources.
 Harmonic Voltage Distortion of the load (Voltage and Current)
in THD as well as individual frequencies up to 13th harmonic
in % of total.
 Transfer counter from last date reset (display count).
Resetting shall require passwords.
 Source Power Factor
 Output Power (KW)
 Maximum Peak Current (Amps Peak) since last reset
2.4.5 Mimic Indicators



One LED lighted symbol per breaker, lit when closed.
One LED lighted symbol per six SCR set, lit when closed.
Source Available; one LED lighted text field for each source,
lit when source is available and source breaker is closed.
 Alarm; one LED lighted text field.
 In Sync; one LED
 Output; one LED lighted text field, lit when output is available
2.4.6 Annunciation Points
The DSTS shall provide the following eight (8) isolated Form C
contacts to indicate the status of alarms:
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CSI # 16xxx – Mission Critical (MC11)
 Summary alarm
 Status of source 1
 Status of source 2
 Source 1 available
 Source 2 available
 Summary warning
 User-defined #1
 User-defined #2
2.4.7 Interface Points
The DSTS shall provide isolated inputs to accept user’s contact
closures to indicate the following:



Preferred source selection
Transfer inhibit
Six additional relays contact inputs are available for user
defined functions.
2.4.8 Monitoring Options

2.5
Waveform Capture – The DSTS shall provide the means to
capture the voltage and current waveforms of each source
and the output during each transfer. The Waveform Capture
function shall continuously digitize a “rolling window” that
includes 3 cycles before and 3 cycles after each transfer
event. All three phases shall be recorded. The function shall
capture the last 3 transfer events in a first-in-first-out nonvolatile memory queue. All 3 phases of the captured
waveforms shall be displayed in color so that the individual
phases can be differentiated. The captured waveforms shall
be capable of being recalled locally to the DSTS LCD display
or uploaded via Ethernet to a PC. The manufacturer shall
provide a PC Windows-based application for uploading,
managing, storing and displaying the waveform data on the
PC. The application shall provide the means to export the
numerical waveform data as a delimited text file for
manipulation in other applications such as a spreadsheet.
COMMUNICATIONS AND CONNECTIVITY (PDM)
The PDM shall provide industry standard communications connectivity and
protocols to interface with the user’s Building Management System (BMS),
local network and portable devices using the following methods. The
manufacturer shall provide comprehensive documentation (e.g. Modbus
register maps) to facilitate the interface with the user’s systems. All
communications connections shall incorporate industry standard connectors
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and well-marked terminal strips for user’s connections located at a central
user demarcation point in the PDM.
All remote communications with the PDM using Internet, Modbus or serial
protocols shall be strictly limited to monitoring and or changing alarm
thresholds. There shall be no provision that allows the PDM to be remotely
operated in such a way that load drop could occur.
The following communications connections shall be provided:

Modbus RTU (RS 485): The PDM shall provide serial (2 wire or 4
wire) standard Modbus connectivity over RS 485. The PDM and/or
any of its internally mounted Modbus devices shall be designated as
“slave” and assigned a Modbus IDs.

Modbus TCP (Ethernet)

Serial Service Port (RS 232): The PDM shall provide a dedicated
RS 232 service port for use by authorized field service personnel for
the purposes of performing maintenance tasks including diagnostics
and software upgrades.

Internet (Intranet) Functions: The PDM shall provide the following
functions for communicating its status via the Internet or Intranet:
o Web Server – The PDM shall provide its complete status via a
webpage-like interface and be accessible via any PC using a
standard web browser and connected the same network universe as
the PDM. The data displayable via the browser shall include the
input voltages, output voltages, output currents and their statuses
relative to user-defined thresholds demarked by “normal”, “warning”
and “alarm”. The data displayed in the browser shall include the
event log.
o FTP and TFTP – The PDM shall provide means for authorized field
service personnel to perform certain maintenance tasks including
diagnostics and software upgrades via an Internet connection.
2.6
COMMUNICATIONS AND CONNECTIVITY (DSTS)
The DSTS shall provide industry standard communications connectivity and
protocols to interface with the user’s Building Management System (BMS),
local network and portable devices using the following methods. The
manufacturer shall provide comprehensive documentation (e.g. Modbus
register maps) to facilitate the interface with the user’s systems. All
communications connections shall incorporate industry standard connectors
and well-marked terminal strips for user’s connections located at a central
user demarcation point in the DSTS.
All remote communications with the DSTS using Internet, Modbus or serial
protocols shall be strictly limited to monitoring. There shall be no provision
that allows the DSTS to be remotely controlled (e.g. command a transfer or
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shunt trip a breaker) or remotely perform any function that could cause a
load drop.
2.6.1 Modbus RTU (RS 485)
The DSTS shall provide serial (2 wire or 4 wire) standard Modbus
connectivity over RS 485. The DSTS shall be designated as “slave”
and assigned a single Modbus I.D.
2.6.2 Modbus TCP (Ethernet)
The DSTS shall provide Modbus TCP over Ethernet.
2.6.3 Serial Service Port (RS 232)
The DSTS shall provide a dedicated RS 232 service port for use by
authorized field service personnel for the purposes of performing
maintenance tasks including diagnostics and software upgrades.
The service port shall support standard terminal type
communications protocols including FTP and TFTP.
2.6.4 Internet (Intranet) Functions
The DSTS shall provide the following functions for communicating*
its status via the Internet or Intranet:



2.7
Web Server – The DSTS shall provide its complete status via
a webpage-like interface and be accessible via any PC using
a standard web browser and connected the same network
universe as the DSTS. The data displayable via the browser
shall include the mimic graphic showing the DSTS status, the
thermal status of the DSTS and the complete event log.
E-mail Alerts – The DSTS shall be configurable to transmit
email alerts annunciating selected events including warnings
and alarms to user email devices such as PCs and PDAs.
FTP and TFTP – The DSTS shall provide means for
authorized field service personnel to performing certain
maintenance tasks including diagnostics and software
upgrades via an Internet connection.
FUNCTIONAL AND OPERATIONAL REQUIREMENTS (DSTS)
2.7.1 Overview
The Digital Static Transfer Switch (DSTS) is a solid state three phase
dual position switch designed to connect a critical three phase load
to one of two separate sources of three phase power. The source to
which the load is normally connected is designated the Preferred
Source, and the other, the Alternate Source. Either can be
designated as preferred source by owner selection and as specified
hereafter.
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CSI # 16xxx – Mission Critical (MC11)




The Digital Static Transfer Switch consists of six pairs of
Silicon Controlled Rectifiers (SCRs) connected in an AC
switch configuration. These SCRs shall be hockey puck type
and rated to carry the full 100% load (continuous rated) while
operated as stipulated herein and at the maximum ambient
design temperature specified. Product using SCRs only rated
for 80% of the continuous rating of the DSTS shall be
devalued to 80% of the switch rating, i.e. 400 amps times 80
% = 320 amps continuous. Use of “brick” or “gel filled” type
SCRs are not allowed for all switch applications with available
fault levels that may cause an SCR rupture phase to ground
of such devices if not properly fused. Use of fuses integral to
the DSTS for protection of the DSTS and/or its components is
not acceptable due to possible fuse clearing, out of phase
transfers, and due to possible hazard, damage or injury if an
incorrect type of fuse is installed that may not remove the
brick type SCR fast enough to avoid catastrophic rupture. As
these type SCRs have a failure rate higher than those of
hockey pucks with a high potential failure mode of grounding
(which would force a UPS source to transfer to bypass), they
are not suitable for this critical application.
Momentary rated SCR's or SCR legs dependent on wrap
around breakers for continuous or overload rating capability
are not acceptable.
Three pairs of continuous rated SCR's (one pair per phase)
are connected to the preferred source while the other three
pairs are connected to the alternate power source. The load
sides of the SCR's are connected together with their
respective phases to form the critical AC load output
terminals.
Software-guided and manually operated maintenance bypass
switching arrangements shall be included to permit
transferring the loads to either source and to isolate the SCRs
for servicing without disrupting power to the critical loads.
This guided breaker bypass procedure shall be invoked from
a menu command and present step-by-step instructions with
pictorial prompts and LED indication of which breaker needs
to be manually operated and when. Certain breaker
operations which must take place to ensure the safety and
success of the bypass operation shall be invoked
automatically by shunt tripping. (e.g. opening the inactive
source breaker at the beginning of the bypass sequence and
opening the second output breaker after the operator has
manually opened the first output breaker)
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CSI # 16xxx – Mission Critical (MC11)
2.7.2 DSTS and Fault Coordination

In the event of a load side fault, the user’s protective device
(outside the DSTS) closest to the fault and upstream of it
should interrupt the fault. Therefore, in the event of a
downstream fault, the DSTS shall continue to conduct to allow
the appropriate downstream protective device to clear. This
will permit a root-cause analysis of the fault and minimizes the
impact on other parts of the distribution system. The system
let-through of the DSTS system shall be significantly higher
than that of all downstream protection devices so that the
presence of the DSTS is transparent to the coordination of
both the upstream and downstream protective devices in a
system with an available fault current of [65kA] [100kA].
2.7.3 Normal Mode

The DSTS is fed from two sources. The sources are referred
to as “Preferred”, and “Alternate”. The output of the DSTS is
connected to the critical load. The DSTS shall operate with
inputs from two synchronized AC sources 3 phase, 3 or 4
wire, 60 hertz, power sources (within +/- 10% of the DSTS’
rated voltage) from a grounded neutral wye system (DSTS
design shall also allow operation between two high
impedance ground systems. In high impedance ground
applications the manufacturer shall specify requirements for
proper operation of its DSTS to ensure safety). The DSTS
shall provide voltage to its output terminals for any load from 0
to 100% of rating, at any power factor or degree of nonlinearity. One power source shall be the normal source, and
when it is within normal limits, it shall supply AC power to the
critical loads. The other shall be the alternate source and
shall be immediately available for use in the event the normal
source exceeds its pre-set limits so that the critical load does
not have an operational interruption. Voltage and phase
angle adjustments to define the acceptable range shall be
user-defined through the user interface located outside the
equipment without special equipment.
2.7.4 Sensing Time

Digital Signal Process (DSP) technology shall be used to
provide real-time voltage sensing for both sources in order to
meet a maximum 2 ms sensing requirement. Peak and
averaging methods prone to slower detection time and fault
detection are not acceptable.
2.7.5 Transfer Operation

Upon loss of the primary source the DSTS shall automatically
transfer the load to the alternate source by turning off the
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CSI # 16xxx – Mission Critical (MC11)
primary source SCR's and turning on the alternate source
SCR's in a sequence and timing that allows a total combined
sense and transfer time of less than one quarter cycle
(4.17ms) during normal conditions where the two sources are
in phase.

The DSTS shall only perform a break-before-make or “open
transition” between sources. Under no circumstances shall
the DSTS perform a make-before-break or “closed transition”
that would momentarily connect the two sources together. A
closed transition under upstream fault conditions will allow
large amounts of current to flow from the good source to fault
and cause a load drop. Additionally, a closed transition could
cause load sharing problems between two source UPSs.

The alternate power source shall be monitored continuously
to inhibit transfer to a failing or out-of-spec source before
turning on the alternate side SCR's. If the alternate power
source is outside the pre-set power quality limits then it is
disqualified and the transfer is inhibited. The control panel
shall indicate when a transfer has been inhibited due to a
disqualified source. The control panel shall separately
indicate an out-of-synch condition.
2.7.6 Symmetrical Operation

The DSTS shall allow the preferred source to be selected at
the operator’s discretion. There shall be no difference in the
operation or performance of the DSTS because of which
source is selected as “preferred” or “alternate”. The operator
must have administrative password access to change the
source preference from the DSTS’s local user interface.
2.7.7 Automatic Retransfer Operation

After a transfer event the DSTS shall be capable of
automatically re-transferring the load back to the preferred
source. This operation shall be user-selectable by selecting
"Auto-retransfer On", or "Auto-retransfer Off". The "On"
selection allows re-transfer to occur after a user-selected time
delay of 0 to 120 seconds. The "Off" selection requites that
re-transfer be manually initiated. Shall require administrative
password access from the control interface. Re-transfer shall
not occur if the two sources are not within the phase and
voltage tolerance limits pre-set by the user unless the
alternate source is entirely lost.
2.7.8 Manual Transfer Operation

The digital static transfer switch shall be capable of operating
as a manual switch by disabling the transfer feature which is
normally “enabled”. The DSTS shall stay in either transfer
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mode until it is deliberately changed back. When the DSTS is
in the “disabled” mode the operator shall manually command
it to transfer to a qualified source by evoking the “Manual
transfer” command. If the incoming source is “rolling” in and
out of synchronization the DSTS shall wait for the
synchronized state then perform the transfer. It shall then be
up to the user to place the DSTS back into the (transfer)
“enabled” state so that it will perform automatic transfers.
The “transfer disabled” mode shall also prevent the operator
from transferring the switch inadvertently to a disqualified
source.
2.7.9 Load Uninterrupted Transfer

Transfer from one source to the other, regardless of direction,
shall appear uninterrupted to the load in-spite of the DSTS’
intrinsic break-before-make transfer. There shall be no direct
flow of current from one source to the other under any
conditions.
2.7.10 Pre-set Limits, Sensing and Adjustments
All settings shall be adjustable by the user. No setting shall be
“purchased pre-set from factory” requiring replacement of parts, pot
adjustments or component replacements by the supplier’s
technicians chargeable to the user. Adjustable parameters are:


Voltage and Frequency Limit Settings: Acceptable voltage
and frequency limits on both the primary and the reserve
sources shall be individually adjustable by an operator with
the ability to set the “over voltage” and “under voltage”
settings above or below nominal. There shall be three levels
of user-definable voltage set-points - “good, “marginal”, and
“unacceptable”. These adjustments shall be for the full range
of 0 to +100% of nominal for over voltage and under voltage
and made possible through the menu selection on the control
panel display. The same applies to settings of “under
frequency” and “over frequency” which are 57 and 63 Hertz
respectively. Administrative password access shall be
required to ensure only authorized staff can make these
adjustments (no internal pot adjustments shall be possible).
The unit shall immediately and automatically transfer to the
alternate source if the above limits are exceeded on the active
source, and stay in that position until such time that the
preferred source returns to normal. This event shall be
annunciated audibly and visually on the control panel.
Sensing Methods: Preferred and alternate voltage sensing
shall be via real-time digital signal processing (DSP)
techniques on both sources for immediate sensing of out-of27
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CSI # 16xxx – Mission Critical (MC11)
limit conditions. Use of analog averaging or peak sensing is
not acceptable.
 Retransfer Time Delay: The DSTS shall provide an
adjustable retransfer delay from one to 120 seconds through
menu options.
 Phase Angle Adjustments: The DSTS shall only permit a
transfer when the active and inactive sources are within a
user-defined phase angle window defined by single number of
degrees leading (plus) or lagging (minus) the active source.
No internal pot adjustments, scopes, or test meters shall be
required for this adjustment which is set from the control
panel. The DSTS shall be able to do an emergency transfer
within a phase difference window of any number of degrees
between the sources whose phase difference is between 0 to
180 degrees.
2.7.11 Short Circuit or Overload Operation
Under short circuit or overload conditions in the load, transfer shall
be inhibited until the fault or overload is cleared by downstream
protective devices.
2.7.12 Shorted or Open SCR Detection and Protection
The DSTS shall include sensing circuits to annunciate a shorted or
open SCR in either of its source legs. Sensing circuits shall detect a
failed SCR in any of the phases in the switch and shall initiate
audible and visual alarms, which indicates the location of the failed
SCR.



In the event of an open SCR in the active side powering the
load, the unit shall alarm and immediately make a transfer to
the inactive side. The isolation breaker on the previously
active side shall be shunt tripped. Retransfer shall be
automatically prohibited under such conditions until the repair
is made and the alarm is acknowledged and reset.
If an SCR in the active side shorts while that source is
powering the load, then this condition shall be sensed, and an
alarm indicator shall be actuated. The SCR isolation breaker
on the inactive side shall be shunt tripped. Automatic transfer
to inactive side shall be prohibited until repair is made and the
alarm is acknowledged and reset.
In an SCR in the inactive side shorts while the active side is
powering the load, this condition shall be sensed and an
alarm activated. The DSTS shall immediately transfer to the
inactive side. The isolation breaker on the active side shall be
shunt tripped. Retransfer shall be prohibited until repair is
made and the alarm is acknowledged and reset.
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2.8
EQUIPMENT OPTIONS (PDM)
Available as options, the PDM shall contain following:
2.9

Sub feed Breakers

Lightning Arrestor

Surge Suppressor

Transient Voltage Surge Suppression (80KA or 40KA)

Input Terminal Block

Branch Circuit Monitoring

Branch Circuit Monitoring with Energy Metering

Local EPO Pushbutton Assembly

REPO Expansion Module

Custom Paint

Floorstand (Seismic)

Distribution Side Cars

Isolated Ground

Kick Plate

Sub feed Monitoring

Sub feed Monitoring with Energy Metering

I-Line panel boards

Square-D and GE STD 225A, Square-D Column Width 225A

400A 42P panel boards
EQUIPMENT OPTIONS (DSTS)
2.9.1 Dynamic Inrush Restraint

The DSTS shall be available with optional “Dynamic Inrush Restraint
(DIR) for all DSTSs located on the primary (delta) side of distribution
transformers. DIR, when installed and enabled shall limit the peak
inrush current between two out-of-phase sources to 150% of the
transformer’s full load current (measured in RMS amps). In the
event that an emergency transfer between out-of-phase sources is
attempted, DIR feature shall examine the volt-second integral at the
primary of the downstream transformer, the phase difference
between the sources and the instantaneous values of the sources;
and calculate an optimum time delay to be inserted during the
transfer. The time delay shall ensure that the transformer flux has
been equalized and the inrush will be minimized. The delay shall be
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limited to always be less than the waveform gap allowed by the ITIC
standard. Settings shall permit the DIR function to always be
enabled; or to be disabled when phase angle difference between the
sources is within a user-defined “transfer enabled” window and
enabled when the phase difference between the sources is outside
the “transfer enabled” window.
3
3.1
EXECUTION (PDM/DSTS)
OVERVIEW
Factory start-up and user training, preventive maintenance service, and full
service for the above specified system shall be included upon request. The
manufacturer shall nationally employ service organizations of factorytrained field service personnel dedicated to the start-up, maintenance, and
repair of the manufacturer’s power equipment.
The manufacturer shall maintain (24 hours per day, 365 days per year) an
answering service to facilitate in providing technical support and emergency
service dispatching.
3.1.1 INSTALLATION, INSPECTION, AND FACTORY AUTHORIZED
STARTUP
Installation and start up shall include the following:




Ensure removal of temporary shipping bracing.
Verify all electrical connections for tightness as specified.
Review the field assembly and connection of components.
Inspect accessible components for cleanliness, for
mechanical and electrical integrity, and for evidence of
damage or deterioration.
 Pretest and adjust all transfer, monitoring and/or control
parameters as required.
 Correct all deficiencies before proceeding with tests. Correct
deficiencies identified by tests and retests.
 If applicable, adjust transformer taps to provide optimum
voltage conditions at utilization equipment throughout the
normal operation cycle of the facility.
 Record circuit monitors set-ups, if applicable.
 Measure output voltage of branch circuit panelboard, if
applicable. Verify proper operation of equipment, including
circuit monitor and input and output control circuits.
 Submit test reports.
3.1.2 TRAINING (Optional)
Concurrent with factory authorized system startup the manufacturer’s
field service engineer shall train the owner’s operating personnel in
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the proper operation of the system. Training shall last a minimum of
two hours and shall include:






Safety precautions
Features and construction of project equipment
Voltage adjustment procedures, if applicable
Routine inspection and test procedures
Routine cleaning
Interpretation of reading of warnings and alarms
END OF SPECIFICATION
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