EATON ELECTRICAL
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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.
