EATON ELECTRICAL
6
Predictive 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.
