Download Transformer Rectifier Manual Table of Contents

Transformer Rectifier Manual
Table of Contents
SECTION 1
Introduction
SECTION 2 Product Description
SECTION 3
Installation
SECTION 4 System Checkout and Startup
SECTION 5 Safety Precautions
SECTION 6 Maintenance
Section 1-Introduction
This Operation and Maintenance Manual describes the proper procedures for
successful installation and operation of Transformer/Rectifier Set.
A Note About Safety:
The most important issue governing the content of the procedures described
in this manual is the safety of the equipment installers and operators. It is
critically important that these procedures be carefully followed. T/R sets
contains dangerous and potentially lethal voltages. The following general
instructions must be followed:
Do not attempt to service the device while it is powered up or operating.
Turn off power to unit. Carefully follow the grounding procedures described
within this manual before doing any physical or electrical work on the unit.
Take precautions against shock or electrocution
Do not stand in water or on damp surfaces while working on the unit.
DANGER! - To reduce the risk of Electrical Shock, Carefully follow the
instructions within this manual. Only authorized and trained personnel are to
open, operate, or maintain this equipment.
Load current monitoring network: The low potential end of the rectifier bridge
is connected to a metering feedback terminal in the low voltage junction box.
A surge suppressor connected in parallel with an appropriate resistor will
provide a load current signal to monitor. Current metering resistors may or
may not be provided. If a resistor is not supplied; a shorting link will be
installed in its place. Remove the shorting link after the resistor has been
installed.
Accessories:
The following items may be provided with each transformer-rectifier power
supply. Refer to the electrical schematic and parts identifier drawing.
Surge suppressors: Surge suppressors are mounted in the junction box and
are connected between ground, the low potential terminal of the rectifier
bridge, and the KV metering terminal of the voltage divider network. They
prevent voltage on the metering terminals from exceeding a safe value if the
metering circuits were to open.
Temperature gauge: A dial type temperature gauge indicated top liquid
temperature. It includes an independent well for easy field replacement.
Liquid level gauge: The liquid level gauge indicates coolant level whether Hi
or Low.
Alarm contacts: Alarm contacts may be supplied with any of the above
gauge. If contacts are supplied, terminal connections will be located in the
low voltage junction box. (Only temperature gauge has alarm contactors)
Pressure relief valve: A pressure relief valve located on the handhole cover
will release excess pressure in the tank.
Fluid drain: A valve with plug is provided for draining and sampling coolant.
Ground boss: A threaded boss with thread protecting plug is provided on the
side of the tank for grounding purposes and additional ground boss is located
diagonal corner.
Current limiting reactor: A current limiting reactor (CLR) must be connected
in series with the primary of the transformer to limit the short circuit current
during sparking. A CLR is included main transformer. If the unit is operated
without a CLR being installed in the system circuit, serious damage to the
equipment will occur.
Radiator: Radiators are mounted on the tank side for cooling of insulation oil.
Quantity of radiator and mounted location are decided as design.
Section 3- Installation
The transformer-rectifier set is shipped completely assembled and full of
dielectric fluid. It is ready for mounting and electrical connection. Make
sure that the fluid level registers between the limits indicated on the liquid
level gauge.
If any of the feedback resistors are to be customer supplied, install them in
the low voltage junction box. As the resistors are installed, remove the
shorting links that were shipped with the unit. DO NOT OPERATE THE UNIT
WITHOUT EITHER SHORTING LINKS OR APPROPRIATE RESISTORS
INSTALLED.
Verify the rating
The maximum fault capability of the power system at the point of installation
should be verified and must not exceed the short-circuit rating of the unit.
All system accessories such as surge suppressor, lightning arrestors, etc.
should be checked to also verify their ratings capacity.
Do not exceed the ratings specified on the unit nameplate or system
accessories.
Check Area Conditions
The equipment should not be exposed to corrosive or explosive fumes, dusts,
vapors, dripping or standing water, abnormal vibration, shock, tilting, or other
abnormal operating conditions.
The temperature of the ambient air surrounding the power supply should be
between the limits of -40℃ (-40F) and +40℃ (104F).
NOTE: Temperature or altitude conditions outside of the usual limits may
require derating the unit or additional special equipment, such as heating,
cooling or ventilation.
Prepare the site
The floor beneath the unit must be level so that the tank is not distorted when
bolted in place.
Ensure the equipment adequately clears any underground raceways or cables.
Mount the unit
This is heavy equipment and must be securely anchored to prevent tipping
over. The recommended size for anchor bolts is M13.
The unit should be leveled and firmly secured to its supporting foundation.
Making Connections
Before making any connections, perform the megger test to confirm the
integrity of the unit internal connections. Then proceed with the following
steps.
The first step is to route cable and wire bundles that enter the enclosure to
avoid interference with moving parts. Observe minimum bending radius for
the type of cable used.
Then power cables should be braced and/or laced to withstand short circuit
forces wherever such cables are unsupported.
Cables should be dressed and terminated as appropriate to the voltage class
and cable manufacturer recommendations.
Connect the primary input terminals in series with a current limiting reactor,
and then to an appropriate control system. For proper primary voltage
metering, be sure the polarity is correct.
WHEN CONNECTING TO THE LOW VOLTAGE INPUT TERMINALS, BE SURE
TO TIGHTEN THE TWO NUTS AGAINST EACH OTHER TO PREVENT OVERTORQUEING THE STUD. FAILURE TO OBSERVE THIS PRECAUTION COULD
CAUSE THE EPOXY BUSHING TO BREAK AND ALLOW OIL TO LEAK FROM
THE TANK. FAILURE TO OBSERVE THIS METHOD WILL VOID THE
WARRANTY.
Connect the load to the HV bushing. Special precaution must be taken when
terminating, handling, and rout ing high voltage leads to ensure sufficient
voltage clearances. The electrical connection to a high voltage bushing
should be designed to cause minimal stress, otherwise small cracks may
develop in the porcelain. Flexible connections are best. If the electrical
conductor is rigid, its design should be such that it provides for ease of
adjustment, and accounts for expansion due to the high temperatures that will
be encountered.
WHENEVER SCREWED CONNECTIONS ARE MADE TO HIGH VOLTAGE
BUSHINGS, A RESTRAINING DEVICE SUCH AS A SPANNER WRENCH MUST
BE USED TO AVOID DAMAGING THE BUSHING AND INTERNALS OF THE T/R
SET.
If the unit is to be operated outdoors, the high voltage bushing must be
enclosed within a bus duct. Sufficient clearance must be allowed for the
rated DC kilovolt output level. Grounding straps must be used across all
bolted flange connections to provide adequate ground continuity.
Connect low impedance ground to the Power Supply, as per the GROUNDING
section.
Check to see that no components in the junction box have sustained any
transportation damage (resistors, lightning arrestors, etc.)
Section 4- System Checkout and Startup
The system check out and startup process consists of four steps:
Megger Test Verify connections integrity.
Switch Continuity Test
Verify high voltage switch operation.
Control System Setup
Setup current limit and overload trip features on
control system.
Start Up T/R Set
Energize unit & verify proper operation.
MEGGER TEST
Use a megohmmeter (megger) of 500-1000 VDC.
If the high voltage bushing is connected to the precipitator, it is best to
disconnect it.
The feedback terminals in the low voltage junction box must have a path to
ground for this test. Temporarily jumper all KV and mADC feedback terminals
to ground.
Place the high voltage switch in the HV position. If unit has a splitter switch,
place both arms of the switch in the ground position.
Connect the megger between the high voltage bushing and tank ground.
With the bushing positive and ground negative, the megger should read less
than three mega-ohms. Reverse the leads and take another measurement.
With reverse polarity, the megger should read the value of the voltage divider.
The divider is connected between the bushing and the KV metering terminal.
Refer to the electrical schematic for the value. Typical values are 80 or 120
MΩ. Divider value of Taichung project is 165MΩ .
A high mega-ohm reading in both directions indicates an open connection.
A low reading in both directions indicates a defective rectifier bridge. In
either case, an internal inspection is required.
SWITCH CONTINUITY TEST (Ohmmeter required).
Interlocks should be installed for this test.
Place the switch in its HV position. The ohmmeter should read infinity.
Place the switch in the GND position. If the switch is an internal ground, an
internal disconnect, or an external ground type switch, measure the resistance
between the high voltage bushing and tank ground. If the switch is an
external disconnect, or a splitter type switch, measure the resistance between
the high voltage output connection, and tank ground.
CONTROL SYSTEM SETUP
Use the following procedure to set the current limit and overload trip features
in your control system.
Check that the wiring betwe en all components (incoming power, controller,
T/R set, and precipitator) is correct and secure.
Place a temporary ground on the high voltage bushing.
Interlock the switch in the HV position.
Set up the controller adjustments for zero volts output when energized.
Energize the controller.
Start with the current limit set at minimum, and increase until the unit has
reached 100% of rated current. Set the overload to trip at this point and
record how long it takes to trip the unit off line.
Lower the cur rent limit to 100% of rated current.
Set the under-voltage trip level at the desired point and record the time it
takes the controller to trip off line.
De-energize the controller and use the proper safety interlock procedure to
remove the temporary ground from the high voltage bushing.
START UP T/R SET
Proceed with the following steps to start up the unit.
Interlock the switch in the HV position.
With the controller set for zero volts output, energize the unit. Bring the T/R
primary voltage up slowly. When the output reaches approximately 25 KVDC,
(150 VAC if KV metering is not available), see that both primary and econdary
currents are registering on their respective meters. If either current does not
register, or if they are excessive, de -energize the system, then check for an
open or shorted condition within the precipitator. BE SURE TO USE PROPER
INTERLOCK PROCEDURES TO INSURE PERSONNEL SAFETY!
Set the under-voltage trip level at the desired point and record the time it
takes the controller to trip off line.
Let the unit run at 25 KVDC for thirty minutes.
After the T/R has run at the reduced voltage level for thirty minutes, increase
the input until the unit reaches rated voltage or current, whichever comes first.
DO NOT EXCEED EITHER THE RATED VOLTAGES OR RATED CURRENTS OF
THE T/R SET!
Section 5- Safety Precautions
Never switch the T/R set on or off with full rated input voltage unless a load is
connected.
Never run the T/R set open circuited except by a qualified technician for test
purposes only. Otherwise the warranty will be voided.
This equipment must be grounded externally using a grounding stick and
cables to provide adequate personnel protection during servicing and
inspection. Switches with grounding provisions are not fail safe devices and
are inadequate for personnel safety.
A current limiting reactor must be utilized in the primary circuit to limit
overload surges.