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InsulGard™
Product Focus
Maximize Your Uptime
For Medium Voltage
Motors, Generators,
Switchgear, Bus Duct,
Cable Terminations, and
Power Center Transformers
Why InsulGard™?
Eaton Corporation understands the pressures you
face trying to reduce costs while at the same
time maximize your electrical system’s uptime
and reliability. That’s why we invented the CutlerHammer InsulGard, a system that changes the
rules of power equipment maintenance. Until
now, there were only two options: 1. Wait for
equipment to break down and fix it, and/or 2.
Periodically take equipment out of service to
perform tests and maintenance – whether it’s
needed or not.
Now there is a third, revolutionary option.
InsulGard is the first continuous, online, medium
voltage, predictive maintenance system that can
be used in a variety of applications; including
switchgear, bus duct, power centers, generators,
and motors. Through monitoring, it can ascertain
the relative condition of insulation, the
deterioration of which is the leading cause of
electrical failures. And, it can monitor these
conditions better than alternative testing
methods. Further, you won’t have to take
equipment out of service or send personnel to
conduct tests. In effect, the InsulGard system is a
lower-cost alternative to forced outages and rigid,
and sometimes unnecessary, maintenance
schedules. We believe you will find the InsulGard
system the best planning tool available today.
How Does InsulGard Work?
The InsulGard system consists of sensors and a monitor. The
monitor can be used as a stand-alone unit, or it can be wired so
that it can remotely upload data to you or Cutler-Hammer
diagnostics personnel for analysis. While the sensors vary
according to application, they are all designed to detect partial
discharges — the foundation of the InsulGard technology and one
of the best predictors of insulation breakdown.
Surface tracking on bus duct
The term partial discharge is not a mystery. It is simply a common
name for small electrical discharges (arcs) that typically occur
within or between insulation materials – usually across a void in the
insulation. Partial discharge is also referred to as corona or surface
tracking. The visible evidence of corona presents itself as white,
powdery residue; typically found on the end windings of motors or
generators. Surface tracking damage appears as tree-like, jagged
lines; typically found on switchgear and bus ducts. Surface
tracking stems from a contaminated insulation surface, often
started by corona. The small arcing activity on the surface of the
insulation contributes to further burning, resulting in additional
stress points that promote further deterioration. Both corona and
surface tracking are the primary causes of insulation breakdown,
which can lead to full discharges and electrical failures. It is
important to note that traditional methods of detecting corona and
surface tracking damage require taking equipment off line. It also
requires disassembling the equipment — a costly procedure.
Moreover, corona and surface tracking damage have to be severe
to be visible. The InsulGard system allows you to detect partial
discharge while the electrical system is energized. It does so by
detecting and analyzing the radio signal frequencies emitted by the
partial discharges. More specifically, the InsulGard focuses on the 1
MHz to 20 MHz bandwidth range where the majority of partial
discharge activity can be detected. InsulGard allows predictive
analysis and maintenance as opposed to preventive analysis and
time-based maintenance.
The detection of partial discharge on equipment can tell you that a
problem exists. Even more useful is information that can correlate
the signal intensity (measured in milliwatts) associated with partial
discharges to various states of insulation degradation on similar
equipment. The Cutler-Hammer Predictive Diagnostics group has
studied numerous cases of partial discharge on rotating equipment
and switchgear. The knowledge base they have accumulated has
allowed them to develop guidelines and parameters to help you
determine the seriousness (failure-time windows) of the partial
discharge activity your equipment may be exhibiting. And, because
it is a continuous, online monitoring system, it is easy to monitor
conditions over time.
Corona damage on the motor windings
Where Can the InsulGard
System be Used?
At the heart of the system is the InsulGard monitor. Whether
you use it to monitor switchgear or rotating equipment, only
some internal circuitry changes. The variable part of the system
is the broad array of sensors we’ve developed to function with
key electrical assets. Yet, each sensor is specifically designed to
work with the InsulGard monitor to provide seamless and
accurate data. They are also designed to work with existing
Resistive Temperature Devices (RTDs) already present within the
windings of generators and motors. Design integrity is
important when it comes to protecting your investment. The
InsulGard system has it.
Generators & Motors
The InsulGard system is available with a variety of sensors
appropriate for motors and generators. One of these is
the RTD Module which connects to existing Resistive
Temperature Devices (RTDs) already embedded within
the windings of the generator or motor. Another
(above) Radio frequency current
transformer for Partial Discharge detection
sensor that checks for partial discharges is the
Coupling Capacitor which is used on the line side. A
third sensor, ideal for generators and motors, is the
(right) Resistive Temperature Device Sensor
for rotating equipment
Radio Frequency Current Transformer (RFCT). The
RFCT embraces cable shielding and is used in
the line part of the winding. Used alone or in
combination, the sensors connect to the InsulGard monitor
where partial discharges and other variables such as humidity,
load, and temperature are monitored and recorded for analysis.
Specifically, here are the issues that partial discharge analysis can
tell you about your rotating equipment:
Early stages of insulation deterioration
Sparks in voids and between windings
Corona on end windings
Switchgear
Available sensors for switchgear include Coupling
Capacitors or a combination of Radio Frequency Voltage
Sensors (RFVSs) and Radio Frequency Current Transformers
(RFCTs). Coupling Capacitors detect partial discharges in a
cubicle and/or adjacent cubicles and are typically installed
(above) Partial Discharge
sensor connection points
for switchgear
(right) 95kV BIL rated
Partial Discharge sensing
coupling capacitor
on the load side of the feeder breakers or on the main bus.
Radio Frequency Voltage Sensors (RFVSs) are also used to
detect discharges within the cubicle. They are typically
installed on the load side of the feeder breakers, or on the
main bus. They are connected to the current or potential
transformer’s secondary neutral terminal.
RFCTs identify partial discharges related to the feeder
cables and are placed around the common cable shield.
All sensors are connected to the InsulGard monitor, which
displays readings and records data. The same sensors and
monitor can be used for power center transformers, cable
terminations, and bus duct.
Specifically, here are the problems partial discharge
analysis can detect in your switchgear apparatus:
Discharges in air gaps (between bus and support window, etc.)
Surface tracking (on supporting isolator or bus insulation surface)
Minute sparks in insulation voids
Insulation problems in cable terminations and
Partial discharge sensors can be installed in
new or existing switchgear
connected equipment
Poor electrical connections (floating potentials)
Defective current transformers and potential transformers
Incoming bus ducts
Large Power Transformers
Cutler-Hammer InsulGard G is available for transformers that
contain a capacitive tap at the base of the bushing. This tap is
normally used for power-factor measurements. Transformers
with a primary voltage of 13.8 kV can be monitored using our
standard partial discharge sensors. For more information, visit
www.partial-discharge.com.
What Are the Alternatives
to InsulGard?
Two of the alternative online methods of detecting partial discharge
are acoustic and corona probe testing. While these methods can
determine the approximate location and nature of insulation
breakdown, the inherent metal shielding of most electrical
equipment limits the precision and, thereby, the value of the
acoustic and corona probe readings.
Some off line tests include insulation
resistance, polarization index, high potential,
power-factor tip-up, and visual inspection.
The alternatives are costly because they
require an outage as well as trained
personnel to conduct the tests. The testing
method puts unnecessary high stress on the
entire system which could decrease the
service life of your electrical assets. The
masking effect, associated with some of the
traditional testing methods, also limits the
ability to detect single, but very serious,
insulation defects.
The InsulGard G unit (below right) prevents
your power transformer from electrical
failures (below left)
Benefits of Installing the
InsulGard System
It’s Easy to Use and Understand
With InsulGard, you get a self-contained system. You can
complete the interpretation or analysis, or contract it out. Eaton’s
Cutler-Hammer Predictive Diagnostics is equipped to provide this
service and/or the training to do your own analysis. The monitor
What About Other
Forms of Electrical
System Protection?
can be used as a stand-alone field unit or it can be configured so
that you can upload information to a computer where more indepth analysis can be conducted with specially-designed
InsulGard software. If you already have competitive sensors (not
Cutler-Hammer brand) installed on your equipment, we can
enhance your protection using our unique technologies.
Protective relays provide fault protection.
Though they may limit catastrophic damage,
their operation is indicative of a major failure.
The most damage occurs in the first half-cycle.
The InsulGard system is the first predictive relay
system that can help you avoid a forced outage.
It represents a quantum jump in uptime and
reliability technology.
Prevents Costly Damage and Catastrophic Failure
By the time a protective relay device operates, you already have a
problem that will require immediate repair and downtime.
InsulGard helps you identify and monitor problems in the early
stages before more permanent (and costly) damage occurs. It
allows you to plan your maintenance and outages. Further, it
provides an increased level of safety for personnel that could be
injured during a catastrophic failure.
Software
InsulGard software is part of the InsulGard
Reduces General Maintenance Costs and
Maintenance-Related Outages
system. It allows you to view the dynamics
Routine, preventive maintenance is a must if you cannot
captured by the monitor and analyze the
determine the status of your equipment online. But why take
condition of insulation based on the guidelines
equipment out of service when maintenance may not be
and parameters provided by Cutler-Hammer
necessary? InsulGard allows you to monitor and track partial
Predictive Diagnostics specialists. The eventual
discharges and then implement appropriate maintenance on a
goal of Predictive Diagnostics is to create a
needed basis as opposed to a time basis. It saves maintenance
Web-based service whereby you can
costs in terms of equipment being off line and the costs
statistically compare the relative condition of
associated with trained personnel to conduct the maintenance.
your equipment to others who have similar
equipment in operation by: equipment type,
Increases Life of System Assets
manufacturer, voltage class, ratings, partial
InsulGard provides the best means of preventing damage before
discharge activity, longevity, etc. Users will
it’s too late. Having all of the integral parts of rotating equipment
benefit by comparing their own measured
or switchgear in optimum condition prevents unnecessary wear
partial discharge data with our extensive
and tear on other components. The predictive nature of InsulGard
database to predict outcomes and plan
can help you extend the working life of your electrical system by
maintenance. This database will not identify
avoiding the domino effect of one component affecting the
customer sites or locations in order to guard the
performance and longevity of another component.
privacy of our customers.
Allows Better Outage/Maintenance Planning
How can I get an
InsulGard System?
To learn more about the Cutler-Hammer
InsulGard system, visit our Web site at
www.partial-discharge.com.
There’s a growing trend toward using predictive maintenance
rather than preventive maintenance. InsulGard will allow you to be
more strategic in your maintenance and repair planning. It can
help you manage your assets more efficiently and effectively with
less disruption to productivity.
Technical Specifications
All of the following outputs are standard on the InsulGard Monitor:
Two dry contacts for alarms
One dry contact indicating system status
4-20 ma output indicating the percent of the channel with
RS-485 with MODBUS RTU protocol for networkability
as well as remote off-site communications
Digital display on the unit, which cycles through
each channel
highest partial discharge activity as it relates to
the alarm set point
Other features include:
The use of all types and brands of partial discharge
sensors: Coupling Capacitors, Radio Frequency Current
Transformers (RFCTs), Rogowski Coils, Radio Frequency
Voltage Sensors (RFVS), Slot Couplers and existing
Resistive Temperature Devices (RTDs)
Built-in noise rejection algorithms
Dedicated noise channel where identified noise
requires cancellation
Individually programmable channels. Low-level noise
levels are also programmable for each channel
Programmable, continuous high partial discharge
level monitor
Advanced and user-friendly communications. RS485 with
MODBUS RTU protocol. This allows for several devices to
use one modem or computer. Local PC communications
or remote communications with supplied industrial
modem. All programming and data collection is possible
through this link
Easily programmed and easy-to-use front keypad
and display
The ability to program the display to continuously cycle
current information, machine parameters, and last
partial discharge readings
Up to 2000 days of data storage, depending on frequency
of tests. Typical would be four times per day
Data collection at a fixed time or on a fixed-time base
A complete data matrix stored by fixed time
Channels with complete setting independence including
warning and alarm thresholds for each of two
partial discharge parameters
Three analog inputs (one dedicated to temperature)
to measure a choice of machine or switchgear operating
dynamics. These could be current, power factor, humidity,
or other environment changes critical to partial discharge
levels. These inputs also serve as relay shutdown devices
if selected. Shutdown occurs when the machine falls out
of pre-programmed upper and/or lower parameters.
This means that monitoring will cease until the input
returns within specified levels. This is important so data
can be trended properly and memory conserved. The
relay also comes with transducers for voltage and
current measurement
User-friendly installation requirements with complete
instruction manual. If line, partial discharge sensors
are already installed, the relay can usually be installed
with no outage
A standard 120V AC 60 Hz power supply requirement
A non-volatile memory
A small footprint (12"x12"x8") which is completely
self contained
The ability to be installed up to 150' from sensors without
substantial attenuation
A partial discharge matrix that is large and uses 24 phase
windows and 21 amplitude levels for data definition.
This matrix is larger than many competitors' field-test sets
currently in use. This provides for phase-resolved data
Inputs that are logarithmic, giving the relay a large
dynamic range - 4 millivolt to 10,000 millivolts. There is no
need to change scales. This follows the same philosophy
as our world-renown, Universal Partial Discharge Analyzer
field test set
A configuration allowing remote communications so
Cutler-Hammer experts can analyze data upon
request as well as provide periodic reports and
appropriate recommendations
Communications software as well as data
base/analysis tools
Self-diagnostics. The unit self calibrates before each
measurement using a built-in pulse generator. It verifies all
analog and digital components
Enclosures available in Both NEMA 4 and 4X
A frequency range of 25 to 100 Hz
A design which allows the unit to operate reliably under
extreme weather conditions: -50 °C to 80 °C
Eaton’s Cutler-Hammer business is a worldwide leader providing customerdriven solutions. From power distribution and electrical control products to
industrial automation, the Cutler-Hammer business utilizes advanced product
development, world-class manufacturing, and offers global engineering services
and support. To learn more about Eaton’s innovative Cutler-Hammer products and
solutions call 1-800-525-2000, for engineering services call 1-800-498-2678, or
visit www.cutler-hammer.eaton.com.
Eaton Corporation is a global $7.3 billion diversified industrial manufacturer that
is a leader in fluid power systems; electrical power quality, distribution and
control; automotive engine air management and fuel economy; and intelligent
truck systems for fuel economy and safety. Eaton has 49,000 employees and sells
products in more than 50 countries. For more information, visit www.eaton.com.
Eaton Corporation
Cutler-Hammer business unit
1000 Cherrington Parkway
Moon Township, PA 15108
United States
tel: 1-800-525-2000
www.cutler-hammer.eaton.com
© 2002 Eaton Corporation
All Rights Reserved
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