Eaton InsulGard User manual

ELECTRICAL
PREDICTIVE DIAGNOSTICS DIVISION
5421 Feltl Road, Ste 190, Minnetonka, MN 55343
Phone [phone] or -1358, Fax [phone]
Web-site: www.partial-discharge.com e-mail: [e-mail]
InsulGard
TM
USER’S MANUAL
© EEPD, 2002, 2003, 2004, 2005
Version 2-0X
Revision 1.1
(December 2005)

EATON ELECTRICAL 2Predictive Diagnostics
Table of Contents
1Description ............................................................................................................... 6
1.1 General....................................................................................................................... 6
1.2 Principles of Operation ............................................................................................... 7
1.3 Important Features and Options ................................................................................. 8
1.3.1 Specifications...................................................................................................... 8
1.3.2 Display, Keypad, and External Connections........................................................ 9
1.3.3 Data Structure....................................................................................................11
1.3.4 Alarms ...............................................................................................................12
1.3.5 Trend .................................................................................................................12
1.3.6 Continuous Watch Feature ................................................................................13
1.3.7 Phase Resolved Data and Phase Reference .....................................................13
1.3.8 Schedule............................................................................................................13
1.3.9 Device Address and Communication Options ....................................................14
1.3.10 Self-test and Self-calibration ..............................................................................14
1.3.11 PDI (Partial Discharge Intensity) and PPS (Pulse per Second PD pulse repetition
rate) Calculation ................................................................................................................14
1.3.12 Auxiliary Inputs ..................................................................................................14
1.3.13 Measurement Suspend......................................................................................15
1.3.14 External Interfaces.............................................................................................15
1.3.15 Software ............................................................................................................15
2Installation.............................................................................................................. 16
2.1 Application Issues......................................................................................................16
2.1.1 Type and specifics of equipment to monitor .......................................................16
2.1.2 Configuration of PD Sensors..............................................................................16
2.1.3 Noise Aspects....................................................................................................17
2.1.4 Device Location and Environmental Issues........................................................17
2.1.5 What Additional Parameters to Measure?..........................................................17
2.1.6 Networking and Communicating with InsulGard.................................................18
2.1.7 Application Specific for Motors and Small Generators........................................18
2.1.8 Application Specific for Large Generators ..........................................................19
2.1.9 Application Specific for MV Switchgear ..............................................................20
2.2 Installation .................................................................................................................20
2.2.1 Important Note on Sensor Installation in Rotating Machines ..............................21
2.2.2 InsulGard Kit Contents.......................................................................................22
2.2.3 Installation..........................................................................................................24
3Startup ................................................................................................................... 33
3.1 Setting InsulGard.......................................................................................................33
3.1.1 General..............................................................................................................33
3.1.2 Quick Start Up ...................................................................................................33
3.2 Working with Data Memory........................................................................................42
4Troubleshooting ..................................................................................................... 43
4.1 Error Messages .........................................................................................................43
4.2 Fuse Replacement ....................................................................................................43
5Appendix 1. Device Setup via Keypad ................................................................... 45
6Appendix 2. Synchronization and Phase Reference Shift ...................................... 55
6.1 Synchronization .........................................................................................................55
6.1.1 Pre-Revision 1 ...................................................................................................55

EATON ELECTRICAL 3Predictive Diagnostics
6.1.2 Revision 1..........................................................................................................56
6.2 Phase Reference Shift...............................................................................................57
6.2.1 Internal Synchronization.....................................................................................57
6.2.2 External synchronization ....................................................................................59
6.3 Auxiliary input configuration.......................................................................................60
7Appendix 3. Temperature Channel Calibration ...................................................... 61

EATON ELECTRICAL 4Predictive Diagnostics
What is new in InsulGard
ТМ
Firmware version 2.0X
Starting from July, 2004 new firmware version 2.0X is preloaded in InsulGard
TM
monitor.
This updated manual is applicable to old firmware version and states the difference
where necessary.
The following table describes major differences between the version 2.0X and all
previous versions.
Description Version 2.0 and newer Older versions
Modbus RTU Data access via
registers
Full support Supports data access without
phase-resolved matrices
Modbus RTU InsulGard Setup access
via registers
Full support NO
Modbus TCP Full support of data extracting
and InsulGard settings
NO
Firmware upgrade via RS-485/232
port
YES NO
Display version at InsulGard booting Displays --2.0X-- NO
Display Max. PD magnitude Displays XXA- XXXX [mV]
The first two digits – channel number
Displays XX0.-XXXX [mV]
The first two digits – channel number
Accuracy of maximum PD magnitude
measurement
0.75dB 3.2dB
Error message on set clock earlier
then preexisting data in InsulGard
memory
Displays CLOCKErr and turn
on RED alarm LED. Also
opens device status relay
contact
NO
Saving FULL (phase-resolved) data
any time an alarm set point by level (
Qmax or PDI) is exceeded only for a
parameter selected for Alarm
Starting from the version 2.03
stores full data on alarm on
LEVEL event. Does not apply
for an alarm on TREND.
NO
Display at Phase Reference Shift
measurement
Displays dashes at Phase
Reference Shift measurement
while the signal does not
present or has abnormal
characteristics
Displays close to zero
number. Signal presence
must be checked with AC
voltmeter. Signal magnitude
should exceed 100мVAC.
Important NOTE for version 2.07
ONLY!
Phase Shift detected in the
version 2.07 should be
corrected manually by
subtracting automatically
detected phase shift from 360
Deg.
The current manual is applicable to all InsulGard
TM
firmware versions. Pay attention to
some version’s differences noted in several locations of this manual.

EATON ELECTRICAL 5Predictive Diagnostics
Revision 1
Some changes are made to the sensor interface board in order to simplify start up
procedures eliminating temporal connections to IG during start up. All necessary
commutations are done with additional switch located at the bottom of sensor interface
board. InsulGard
TM
, revision 1 can be identified by the presence of described switch or
by a wiring diagram identification label located on power outlet panel. The label looks
like WD-2-X . X – identifies real wiring diagram, used for assembly on particular
InsulGard
TM
device.
Note: Changes reflecting new features will be labeled as Rev1 down in the
manual!

EATON ELECTRICAL 6Predictive Diagnostics
1 Description
1.1 General
Partial discharge (PD) is a small spark that commonly occurs within or on surface of
insulation in various types of medium and high voltage equipment. Over time, PD
destroys the insulation, eventually causing insulation breakdown (full discharge). In
general, it takes months or even years before PD will cause a failure of insulation.
Therefore, PD is a good indicator of insulation degradation and should prompt
maintenance or repair.
Cutler-Hammer InsulGard by Eaton Corporation is a standalone microprocessor-
controlled continuous PD monitoring device for a wide range of medium voltage power
equipment. It is designed to provide an alarm based on PD characteristics at an early
stage of insulation degradation. It measures partial discharges from up to 15 different
partial discharge sensors and stores the information in internal memory; alarming users
if any set points are exceeded. InsulGard can work with constant 50/60 Hz frequency
powered equipment as well as with variable frequency applications.
Various PD sensor types can be used, depending on the application.
InsulGard has three auxiliary inputs for PD data correlation to additional parameters.
One of the inputs is designated for temperature, where the other two are commonly
used for load, voltage, or humidity depending upon the application. InsulGard has
several interfaces that allow for easy implementation into any alarm or SCADA system:
Three C-form dry relay contacts provide Yellow or Red alarm indication, and the Device
Status relay indicates any device malfunction
4-20 mAmp optically isolated output can be configured to represent Partial Discharge
Intensity (PDI) or maximum discharge magnitude to any SCADA system
RS-485 optically isolated interface based on ModBus RTU protocol allows for remote
device configuration and data download. InsulGard can be networked with an existing
ModBus, allowing for up to 231 addressable devices
[Note: RS232 is also available on special order]
Communication protocol includes Modbus, proprietary binary and ASCII text options
allowing a software programmer to build InsulGard into a high-level software program
using simple text type commands. InsulGard is supplied with database software that
allows for automated communication to a device or several devices for data acquisition
and analysis. The software allows for either direct network or dial up connection to a
device by a regular telephone landline or a cellular connection.

EATON ELECTRICAL 7Predictive Diagnostics
1.2 Principles of Operation
InsulGard has 15 signal inputs (Ch1 - Ch15) for partial discharge measurement and a
noise input dedicated for noise suppression (Ch16). All sixteen inputs have identical
conditioning circuits (CC) providing signal isolation, transient suppression, and high-
pass filtering of the input signals. The frequency band of the InsulGard is from 1 MHz to
20 MHz.
InsulGard acquires PD data in the form of three dimensional phase-resolved pulse
height distribution (PRPHD) - PD pulse count as a function of pulse magnitude and
60(50) Hz phase. It has 24 (15
0
) phase windows and a magnitude dynamic range of
about 70dB, divided in 21 magnitude windows.
The data can be stored in the internal device memory in the form of three-dimensional
PRPHD matrixes and/or in the brief form of integral quantities derived from these
matrixes. Each record is accompanied by three additional correlation parameters.
Before each measurement, InsulGard performs self-calibration and self-test. If any
problem is detected, the status relay dry contacts will open and an appropriate message
will appear on the InsulGard display. Loss of power will be indicated in the same way
by opening status relay contacts.
InsulGard measures signals from signal inputs sequentially multiplexing them to a single
metering channel. Each pulse from each sensor is validated by the allowed pulse width.
In the case of non-compliance, InsulGard will not count the pulse.
After each measurement, data from all active signal channels will be compared to alarm
thresholds. If any of the Yellow threshold limits are exceeded, the Warning LED will be
turned on and the Warning relay dry contacts will close. In the case of a Red level
achieved, InsulGard will trigger additional measurement and, if confirmed, an Alarm
LED will be turned on and the Alarm relay dry contacts will close. If Red alarm is
detected, full measurement data will be stored in the memory.
PD measurements can be performed on a time schedule (up to 50 per day) or in
specified time intervals (from 1 minute to 23hours 59 minutes). Four measurements per
day are recommended.
Between scheduled measurements, the “High Alarm” feature is enabled. All signal
sensors are connected to a summation unit and further to a separate “High Alarm”
channel. InsulGard continuously searches for an appearance of high magnitude pulses
and pulse series. Magnitude threshold and repetition in series are configurable. If five
events of pulse series were detected between the scheduled measurements, InsulGard
will trigger a full PD measurement, and display an alarm, if any.

EATON ELECTRICAL 8Predictive Diagnostics
1.3 Important Features and Options
1.3.1 Specifications
Small Footprint 12”x12”x8” Flush-mounted
Enclosure NEMA 4 (4X) or Panel Mounted
Power Source 115V/230V AC +/-10%
60 (50) Hz
Power Consumption of device (max) 10 W
Power consumption from outlet for 120VAC application
(Amps max)
10A
Installation category II
Pollution Degree 2
Temperature Range -40
0
C - +70
0
C (+85
0
C without
NEMA 4 enclosure)
Relative humidity 15%RH – 90%RH
Maximum Altitude (m) 2000
Sensor Interface Board 1
Input Channels (PD), Isolated 15
Noise Channels (PD), Isolated 1
Continuous Watch (High PD activity) Channel 1
Auxiliary Temperature Input (10, 100, 1000 Ohms RTD,
specify while ordering)
1
Auxiliary Analog Inputs (specified to use for Voltage, Current
or Humidity)
2
Alarm C-form Dry Type Relay Contacts (Yellow and Red
alarms, fully configurable)
2
120VAC/ 5 Amps
28VDC/ 5 Amps
1
Device Status Dry Type, C-form Relay Contacts 1
120VAC/ 5 Amps
28VDC/ 5 Amps
2
4–20 mAmps Optically-isolated Interface Represents
Highest PDI or Max. Magnitude as % of the Red Alarm
Threshold
1mAmp per 10% slope
Interface Optically-isolated RS-485 or None-isolated RS-232
Communication Protocol ModBus RTU,
ModBus TCP-(version 2.0 and
higher)
Binary
Text commands
Addressablity (with RS-485 Interface) 231 addresses
Internal Data Memory (allows for up to 2000 days data
storage @ 2 measurements per day)
2 MB
Display 8-digit, Alphanumeric
Keypad 4 arrows and
4 functional keys
LEDs (Normal condition, Red and Yellow alarms, and
History and Setting modes)
5 LEDs
Setup Fully configurable from keypad
and PC
1
For another rating refer to the relay specification
2
For another rating refer to the relay specification

EATON ELECTRICAL 9Predictive Diagnostics
Applications MV equipment (motors,
switchgears, generators, bus
ducts, cable terminations)
Calculated Parameters for Each PD Channel Partial Discharge Intensity (PDI),
Pulse Repetition rate (pps), Max
Pulse magnitude (Q
02
)
Alarming Parameters PDI, Q
02
, trend
Data Record Types Full/Brief
Basic Type of Data Phase-Resolved PD Distribution
PD Channel Dynamic Range 68dB
Number of Magnitude Windows (3.23 dB each) 21
Number of Phase Windows (15
0
each) 24
Power Frequency at the Monitored Object 25–120 Hz
Maximum Measured Pulse Repetition Rate 367,300pps @60Hz
306,000pps @50Hz
Self-test and Self-calibration At powering up and before every
measurement
Allowed Coax Cable Length to a Sensor Up to 150ft (50m)
Cable Type for PD Sensors RG-58 or similar
1.3.2 Display, Keypad, and External Connections
InsulGard is shipped fully assembled in NEMA4 (4X) enclosure, mounted on aluminum
plate with selected communication options or in panel-mount version. These options
may include RS485/RS232 converter (Figure 2), landline (Figure 1 & 3) or cellular
modem, radio-modem (Figure 2).
Sensor Interface Board (on the left hand in Figure 2) handles all signal connections
including 15 PD channels, one noise channel and auxiliary signals. All outputs and AC
power are connected to the terminal board located on the right in Figure 2. Outputs
include 2 alarm relay contacts, device status relay contact, 4-20mAmp output and RS-
485 or RS-232 interface.
Five LEDs are placed on the front panel of the device, three for indication of alarm
status (Green, Yellow, and Red) and two for Memory and Setup operation modes.
(Figure 1)
A bright, 8-digit alphanumeric screen displays information at setup, memory mode
operation, normal operation, and all error messages. During normal operation the
display continuously scrolls the current data.
The membrane keypad has four navigation ARROW keys () and two function
keys (Esc and Enter), as well as two specific function keys (Set and Memory).

EATON ELECTRICAL 10 Predictive Diagnostics
LED:
3 – alarms
1 – Memory
mode
1 - Set
Display
Keypad
Figure 1
Figure 2
RS485/RS232
Converter
Radio-modem
InsulGard.
Back view
Sensor
Interface Board
PD signal
connection
Auxiliary signal
Flat ribbon cable
to sensor
interface board
Terminal board for
outputs and
power

EATON ELECTRICAL 11 Predictive Diagnostics
Figure 3
1.3.3 Data Structure
Full PD measurement by InsulGard involves a measurement of statistical Phase
Resolved Partial Discharge Distribution (PRPDD) for every active channel. After each
measurement for every active channel, InsulGard calculates PDI, Maximum PD
magnitude, PD pulse repetition rate, and trend parameters (rate of PD parameter
change). The calculated parameters are compared to alarm set points and alarm status
is determined. All calculated and alarm status parameters are stored in the internal
memory for each measurement. Additionally, three auxiliary parameters (temperature,
% of full load current and operating voltage or humidity) are assigned to the
measurement data. PRPDD can, optionally, be stored in the internal memory. There
are two modes of PD data storage “Brief” and “Full.”
Full – during this mode PRPDD is stored in the memory with the mentioned above
parameters for each active channel and every measurement.
Brief – in order to save a memory, PRPDD can be stored in the memory several times a
month. An operator should set a number of days and a measurement number at the
current day for storing PRPDD. During the remaining measurements InsulGard will
store the brief version of PD data.

EATON ELECTRICAL 12 Predictive Diagnostics
InsulGard has two Megabytes of internal flash memory for data storage allowing for its
standalone operation. When the memory is filled, the device starts replacing the oldest
data with the latest data. The rate of the memory consumption depends upon a number
of active channels, frequency of measurements, and frequency of PRPDD storage. As
an example, if all 15 channels are active for measurements four times a day and
PRPDD are stored twice a month, the device holds 17 months of the latest PD data in
its internal memory. All stored data and settings can be accessed from the keypad, or
remotely from a PC.
1.3.4 Alarms
InsulGard has two configurable alarms, Red and Yellow that connect to two C-form
relays. There are two groups of parameters that can generate an alarm. One is if an
alarm set point is exceeded (Partial Discharge Intensity (PDI) and its trend or PD pulse
magnitude and its trend). One of two, PDI or Magnitude, can be configured for alarm at
one time. The same parameter is configured for 4-20 mAmp interface output
automatically. 4-20 mAmp output provides a signal with the slope of 10% of Red Alarm
Threshold per 1mAmp. That means that Red alarm threshold corresponds to 14 mAmps
output.
Alarm set points for PDI are represented in terms of mW. Magnitude is represented in
terms of mV.
Trend is set in terms of times per year for both PDI and Magnitude. Alarm on trend is
enabled after a training period of 1/3 of the trend-sliding window.
Yellow and Red alarms operate differently. In the case of a Yellow alarm, it will appear
on the corresponding relay as received. In the case of a Red alarm, InsulGard will
initiate an additional measurement at the time of alarm, and only if confirmed, will
indicate the alarm by relay. If the Red alarm is not confirmed, the status of the alarm will
be set per the last measurement. If at any measurement the alarm status will be
reduced, InsulGard will indicate the reduced alarm status with both an alarm LED
reading and relay.
Alarm relays can operate in two modes (configurable). Relays lock in an alarm status
received at the last measurements, until the next measurement. Or a relay can operate
for a limited configurable time and then open the contacts. At the next measurement, if
an alarm status is detected, relays will hold the alarm contacts closed for the same time.
1.3.5 Trend
InsulGard calculates trend of a parameter enabled for alarm. Trend is normalized to the
value of the parameter change in times per year. Trend has two alarm thresholds,
Yellow and Red, connected to alarm relays and also to the alarm status LED at the front
panel of the device. Trend is calculated as a linear approximation of data over specified
time interval (default is 18 weeks). This 18-week time window is sliding over time while
device monitors partial discharges.

EATON ELECTRICAL 13 Predictive Diagnostics
1.3.6 Continuous Watch Feature
Between the scheduled measurements the Continuos Watch feature (“High Alarm”) is
initiated. At this time all signal sensors are summarized and connected to the separate
High Alarm channel. InsulGard is continuously watching for the events of high
magnitude pulses (configurable) and their series. If five series of such events are
detected, InsulGard starts full PD measurement and, in the case of Red alarm
confirmation, InsulGard indicates this alarm and stores full PD data in the internal
device memory.
1.3.7 Phase Resolved Data and Phase Reference
In order to provide a phase-resolved data, InsulGard should be synchronized with a
signal that is synchronous with the voltage at the object under monitoring and known
constant phase shift to that voltage.
There are two options of supplying the synchronization:
• In most of cases power source (120/230 VAC) powering up InsulGard is used as a
synchronization signal. The device has the internal connection of the power circuit
voltage to its synchronization circuitry. This option (default) always works on
monitored objects powered from a regular power system (60/50Hz) in the area. Be
cautious if power an Insulgard from UPS, unless UPS has constant phase shift to
the voltage in the monitored object in Standby mode. If not you get an
“asynchronous” situation (see below). Phase shift between power voltage and object
high voltage should be determined during InsulGard startup and can be used at all
times, while the same object is monitored and the same power circuit is used.
InsulGard allows for automated detection of a phase shift between its power circuit
and an external phase reference signal. (On automatic phase shift detection refer to
the Quick Start Up or Appendix 1. For more detailed information on synchronization
and phase reference options refer to Appendix 2.)
• External synchronization should be used if the InsulGard power supply voltage is not
synchronous with the voltage on the test object. Examples can be variable frequency
drives, 25 or 400 Hz systems, etc. This option can be used, of course, in the
synchronous situation as well. An external synchronization signal should be
continuously provided to the special synchronization input and appropriate jumpers
in the device should be configured. Low frequency component of a signal applied to
the channel #1 (coupling capacitor option) may be used also for external
synchronization. For more information on synchronization and device configuration
refer to Appendix 2.
1.3.8 Schedule
PD measurements can be performed at specified times during a day or time interval
basis (configurable). The device is shipped with “time basis” schedule enabled and set
to record measurements four times a day. This is sufficient for all common applications.
If necessary, InsulGard can be set to measure up to 50 times per day at scheduled
times or in specific time intervals varying from 1 minute to 23 hours 59 minutes.

EATON ELECTRICAL 14 Predictive Diagnostics
1.3.9 Device Address and Communication Options
InsulGard has isolated RS-485 interface using ModBus RTU communication protocol
(most commonly used in industry) and can be networked to any local device network
supporting the protocol. InsulGard is shipped with the device address #1, unless
otherwise specified. The address can be changed from the keypad and set to the value
from 1 to 231. In any case, the address must be unique at each particular local device
network.
There are two communication options to the device from a PC for set up or to download
data. Most preferable is using a landline or cellular modem equipped with RS-485
interface. Up to 231 devices can be connected to one modem. A modem allows a user
to remotely download data and get an expert opinion on a critical situation within few
hours. Another option is using RS-485/232 converter or a device equipped with RS-232
interface to connect the device to PC directly. In this case, it would require a periodic
(monthly) connection to a device, or group of devices, connected by one RS-485
network with the converter and downloading the data into the database. In an
emergency, data from database can be e-mailed to an expert for analysis.
1.3.10 Self-test and Self-calibration
While powering up, and before each PD measurement, InsulGard performs a self-test
and calibration of PD and noise channels. In the case of a fault, an error message will
be displayed and the status relay contacts will open. Error status can be remotely
requested though interface.
1.3.11 PDI (Partial Discharge Intensity) and PPS (Pulse per Second PD pulse
repetition rate) Calculation
PDI and pulse count (PPS) are calculated for each channel at every measurement
starting from some preset magnitude zone and up. This feature allows for rejecting
background noise from affecting PDI and pulse count calculations. The low magnitude
threshold to calculate parameters can be set for each channel independently, based on
its own background noise level, if any. There are options to set these values manually
or automatically. Automatic low magnitude threshold detection could be launched only
from the keypad (usually during device start up or during initial period of operation).
1.3.12 Auxiliary Inputs
It is well known that operation conditions of monitored equipment can significantly affect
PD behavior. Correlation of PD activity changes can be used as valuable diagnostic
information for further defect type identification. In general, insulation temperature,
mechanical vibration reflected by load current, voltage on the object, and humidity of air
are some of the most valuable parameters to correlate with PD characteristics.
InsulGard has three auxiliary inputs. One of the inputs is strictly designated for
temperature. 10, 100, and 1000 Ohms RTD can be used as a sensor. This setting is
factory configured and should be specified at the time of device ordering.

EATON ELECTRICAL 15 Predictive Diagnostics
Two other inputs can accept any AC or DC signals within a specified voltage range. As
factory default, they are configured for accessory sensors providing load current,
humidity, or voltage inputs and are supplied with the device. These parameters are
important to correlate with PD signals.
1.3.13 Measurement Suspend
Frequently, measurements need to be suspended for some time. Measurements can be
suspended in three different ways:
• Monitoring can be stopped. The operator is responsible for resuming monitoring.
• Monitoring can be paused. In this case, monitoring will resume automatically in three
hours.
Auto-suspend mode is controlled by any of three auxiliary parameters. The device
allows the user to set low and high thresholds for three additional parameters brought to
three auxiliary inputs and enables parameter checks to comply with the thresholds. The
check can be performed to any of the parameters (configurable) and suspend
measurements, if at least one of them extends beyond the allowed boundaries.
Measurement will be automatically resumed at the next scheduled time, if parameters
will comply to allowed boundaries.
This feature is widely used to suspend measurements while monitored equipment is out
of service (load current is 0 for example). Therefore, trend calculations are not affected
by zero readings. It also allows users to perform measurements under the same
operational conditions, if required.
1.3.14 External Interfaces
InsulGard has built-in isolated RS-485 interface (RS-232 is optional). Device supports
ASCII-type and binary command protocols. Most commands and settings are supported
in both command protocols and from the device keypad. Isolated 4-20 mAmp interface
provides PDI or Magnitude levels as a percentage to Red alarm threshold. Two C-type
dry relay contacts provide Yellow and Red alarm status. One C-type dry relay contact
provides device status.
1.3.15 Software
InsulGard comes with Database InsulGard software that allows it to communicate with a
PC via a local RS-485 network or a modem. It also provides automated or manual data
downloading and storage for several devices at different locations, device setting, data
analysis, and presentation.

EATON ELECTRICAL 16 Predictive Diagnostics
2 Installation
2.1 Application Issues
InsulGard is a versatile device that can be applied to most medium voltage equipment.
Specifics of a particular application (optional components and planning installation)
should be taken into account when ordering.
Issues that should be considered are:
• Type and specifics of equipment to monitor
• Configuration of PD sensors
• Noise aspects
• Device location and environmental issues
• What additional parameters to measure?
• Networking and Communicating to the device
You may wish to use a short Manual “InsulGard Guide: How to Choose Proper
Installation Options”, CHPD, 2003. For sensor installation use corresponding CHPD
Installation Manuals.
2.1.1 Type and specifics of equipment to monitor
In general, InsulGard was designed to monitor partial discharges in medium voltage
rotating machines, switchgear, cast transformers and associated connections. The
connections may include cable terminations and portions of cable and portions of bus
feeding an object. InsulGard can be used for additional variations of medium voltage
and high voltage equipment, but application of the technology will require special pre-
engineering and adaptation. Consideration should be given while attempting to use
InsulGard on high voltage equipment above 120kV. External noise in the form of corona
discharges should be addressed in this case.
The nature of PD indicates it will not occur in the equipment 2300 Volts and below.
Marginally, 2300V equipment can be considered, but the technology is inconclusive. It
may or may not detect a significant problem at 2300V. Ratings 4160V and higher are
considered reliable for PD diagnostic applications. In general, higher voltage provides
greater destructive power of partial discharges and problems can be detected and
predicted.
2.1.2 Configuration of PD Sensors
Configuration of PD sensors is really application specific. There are some general
guidelines below. We recommend discussing any sensor installations with a Cutler-
Hammer application engineer.

EATON ELECTRICAL 17 Predictive Diagnostics
2.1.3 Noise Aspects
Noise is a major issue in any type of partial discharge measurement. Noise is always
site specific. There is not an absolute solution for noise suppression in the modern
world. However, most noise issues can be overcome. InsulGard has been designed
with several noise suppressing algorithms and, along with recommended sensors, is
able to suppress most industrial noises. While planning InsulGard installation, keep in
mind most common noise sources:
• Power thyristor firing
• Switching power supplies in modern metering and protective electronics
• Arcing and sparking somewhere at the facility
• Aerial corona on overhead lines on high voltage substation
• Partial discharges in the adjacent equipment
• Pulse signals coming from incoming lines and feeders
2.1.4 Device Location and Environmental Issues
InsulGard can be shipped with or without an environmental enclosure. Without the
enclosure, it can be used indoors on switchgear lineups (given a relatively clean
environment).
In most applications, indoor and outdoor, InsulGard is contained in a NEMA-4 enclosure
protecting the device from direct rain, sun, and dust. If the application environment is a
chemically aggressive medium, or a company policy requires a stainless steel enclosure
(NEMA-4X), please, specify this while ordering InsulGard. Also you may use if specified
NEMA4X plastic enclosure with a clear window.
In a switchgear lineup InsulGard can be installed without an environmental enclosure.
When planning to install InsulGard, consider a non-vibrating location, conveniently
located in a centralized position between all sensors and possible communicating
means (phone jack, tray to control room for alarms, etc.). The length of PD signal
coaxial cables (RG58 or similar, 50 Ohm) can be up to 150ft. It is preferred to keep the
PD signal cables short and uniform in length.
2.1.5 What Additional Parameters to Measure?
Several factors can affect PD level: temperature, humidity, voltage, mechanical
vibration, etc. In North America voltage commonly is not an issue. It is stable and does
not commonly affect PD. If more than +/-5% voltage variation is expected, plan
correlating PD to voltage. Temperature is very important for rotating machine
monitoring. Temperature variations can change size of voids and surface conductivity
thus affecting PDs. Humidity is also a factor for line terminals in rotating machines,
especially in an outdoor installation.
Temperature and humidity are important factors in switchgear; often affecting
contaminated surface conductivity or condensing moisture on some surfaces and

EATON ELECTRICAL 18 Predictive Diagnostics
pulling. Therefore, a varying range of PD is expected. If insulation can vibrate against
support or core rotating machines, load current is a good parameter to correlate. Also
zero load currents could be used to suspend monitoring during equipment outage.
2.1.6 Networking and Communicating with InsulGard
InsulGard provides several interfaces for alarms, SCADA, and data retransmission
• Always wire alarm relays to an annunciation system. Use two relays for Red and
Yellow alarm and the third relay for device status. If necessary, all three relays can
be wired in series to the same enunciator.
• 20mAmps output is for SCADA systems. A SCADA system can trend the most
important parameters.
• RS-485/232 with database software allows for remote device setting, initiating
measurements, and downloading of data. If an expert opinion will occasionally be
needed, designate a permanent or temporary phone line and specify a modem.
Cellular modem subscriptions are available. If a Cellular modem is used, extra
conduits for RS-485 networking can be excluded.
2.1.7 Application Specific for Motors and Small Generators
PD sensors set for small generators and medium voltage motors typically include three
sensors located at the line terminal and six to twelve RTDs. A necessity of having too
many sensors comes from very strong high frequency signal attenuation in motor
winding. Therefore, sensors located at the line terminals will not produce valuable
information on a winding depth; likewise, a sensor embedded into a winding will not
sense discharges at the line terminal.
Two types of sensors can be used at line terminals.
• Radio Frequency Current Transformers (RFCT) placed on incoming feeders’ shield
grounding conductor (one per phase) or on single-phase surge capacitor grounding
conductor (one per phase). Using a single three-phase surge capacitor is not
recommended. In such a case, phase-to-phase PD signals are shorted inside the
capacitor and will not be detected by any of RFCT. An advantage of RFCT is that
they are non-invasive (no connection to a live part is required). A disadvantage of
using RFCT on a cable shield ground is, in some cases, a ground noise. This means
that RFCT measures all radio frequency signals coming through the cable shield.
Using RFCT on a single-phase surge capacitor ground is more noise immune.
• Coupling Capacitors (IPDS) commonly have an 80pF capacitance. They have
sufficient insulation and connect directly to motor line terminals. These sensors
exhibit the most noise-immune characteristics due to their low capacitance and,
therefore, can suppress most low frequency noise by themselves. Using IPDS is a
highly recommended option for line terminals. Note: Installation of line terminal
sensors always requires an outage.
As stated above, additional sensors embedded into winding sensors are required. RTD
outputs are commonly used for this purpose. RTD supplies DC temperature signal to a

EATON ELECTRICAL 19 Predictive Diagnostics
metering device. RTD and it’s wires also operate as a local RF antenna for PD. High
frequency signals can be filtered out and used to for PD representation. Common noise
disturbing PD signals from RTD comes from temperature metering system wires. A
possible source of noise can be the operation (switching pulses) of the temperature
metering system itself and/or pulses cross-coupled to wires from another wire at the
same tray.
CHPD produces RTD PD sensor board with embedded filters, suppressing external
noise. RTD PD sensors are designed as a single board replacing the existing RTD
terminal board at the motor frame. It does not affect temperature measurements, and
produces PD signals for InsulGard. RTD PD board is designed to handle six RTDs. If, in
a particular application, the number of RTDs is greater than 6, additional boards might
be needed. An RTD PD board can be installed online, disabling temporarily temperature
alarm or relay system.
Winding temperature, load current, and humidity in a terminal enclosure are the three
most important parameters to correlate. Use one of the winding RTDs for temperature.
It can be difficult to bring a load current signal to the InsulGard enclosure from some
distant CT (frequently in switchgear cubicle). In this case you can consider installing a
FlexCore CT around a cable of the phase A in the motor terminal enclosure. The
FlexCore CT is installed over the shielded part of a cable and, therefore, is under
ground potential and does not endanger insulation integrity. Cable shield should be
grounded through CT.
Note: One InsulGard device is required for a motor.
2.1.8 Application Specific for Large Generators
The application for large generators is, in general, similar to one on a motor or small
generator. Some specifics include:
• Coupling capacitor (IPDS) is commonly used as a sensor at line terminals.
Generator equipped with iso-phase bus duct might produce sparking in bus
supporting insulators. The later firmware versions (02-14-03 and higher) have built in software
filters. The older versions may require two sets of IPDS for noise suppression.
• Certain generators do not have RTDs embedded into a stator winding. For example,
large Westinghouse hydrogen cooled machines have RTDs near the hydrogen outlet
from the winding. These RTDs cannot be used as PD sensors. Check RTD location
in a winding.
• Large generators may have very long signal wires from RTD to the first RTD
terminal board. Frequently, these wires are also placed into a spiral armature. These
factors significantly affect high frequency signal propagation attenuating PD pulse.In
order to minimize signal attenuation; install the RTD PD board at the generator
gland, where the RTD wires come out of generator.

EATON ELECTRICAL 20 Predictive Diagnostics
2.1.9 Application Specific for MV Switchgear
Three types of PD sensors can be used for switchgear lineup: coupling capacitor
(IPDS), RFCT and RFVS. Preferred option is IPDS.
• Three IPDS sensors (one per phase) are installed, commonly in every third cubicle.
Therefore, each set of three IPDSs assess the cubicle, where it is installed, and on
each sides. Increasing a distance between IPDS sets might cause some distant PD
to be missed. Keep in mind that PD signals attenuate approximately twice from
cubicle to cubicle due to energy splitting in every T-connection. IPDS can be
installed on a bus side or load side of a breaker. In the case of a load side, the
sensor will not measure PD while the breaker is open. In general, one InsulGard can
handle up to 15 cubicles.
• An RFCT sensor is installed on incoming and outgoing feeder shield grounding
conductors; commonly, one per cubicle. Phase to phase signals can be missed in
such a configuration. Installing three RFCT sensors in every cubicle looks very
difficult. RFCT sensors on cable shields are susceptible to any ground noise. Noise
level should be checked before deciding to use an RFCT.
• An RFVS sensor is connected to C0 (common point) of a metering CT and to V0
(common point) of PT. Constructive capacitance of CT or PT to a bus is used as a
small coupling capacitor. This sensor is the easiest to install, however, it is
susceptible to many noises produced by modern metering and relaying electronics.
These sensors work very well on older lineups without modern electronics.
Two main factors, temperature and humidity, should be considered to correlate with PD.
Plan on installing temperature and humidity sensors with InsulGard. You may also
consider voltage signal, if expected voltage variation can exceed +/-5%.
In indoor installation InsulGard can be mounted without NEMA-4 enclosure in one of the
cubicles. Check for available space before ordering a device. In some cases, the bus
and breaker structure is very complicated. Consult with a Cutler-Hammer application
engineer before ordering sensors.
2.2 Installation
InsulGard
TM
is normally shipped in one of the following options:
• In NEMA-4 (4X) enclosure. In such a case, all ordered options (modem, cellular
modem, radio-modem and power supplies and so on) have already been installed
onto internal mounting panel. The enclosure has two entries for power and signal
cables in the bottom.
• On the mounting panel. This option is identical to the first one, except that mounting
panel is not mounted into enclosure.
• Flash mount option. This option is used for panel mount predominantly in switchgear
line up. InsulGard comes with Sensor Interface Board installed on it’s back cover.
Communication options (modems and their power supplies) are separate items.