Power Quality; Power Factor, Thd And Crest Factor; Alarms; Waveform Capture Feature - Eaton Cutler-Hammer Digitrip 1150 Instructions Manual

I.L. 70C1036H05
The Auxiliary ReLaY A can be assigned to a Pulse Initiator
function for either kVAh or kWh. When this feature is
selected, ReLaY A will be dedicated for Pulse Initiator and
no other relay function is possible for ReLaY A (See
Appendix D-15). The Pulse Initiator provides a contact
change of state to an external counter device whenever a
value is exceeded. This pulse value is based on an ANSI
document and is expressed as the general equation:
Pulse Value = .000717 x I
(kVA or kW)

4.8 Power Quality

The Digitrip 1150 in a Magnum Circuit Breaker can mea-
sure a variety of parameters relating to today's modern
Power System. This data can be viewed locally or via a
computer remotely in which case the data can be logged.
4.8.1 Power Factor, THD and Crest Factor (CF)
The System Power Factor is a real time measurement with
approximately a one second update rate. The tolerance is
the value ± 0.02. Max PF and Min PF values are historic
values that are held until Reset.
Total Harmonic Distortion (THD) of each phase and neutral
(if valid) and corresponding per harmonic data up to the
27th harmonic and Crest Factor are available via a wave-
form capture trigger. This waveform capture trigger can be
done locally by selecting HARMONIC in the Main Menu or
by exceeding a THD alarm threshold programmed by the
user. See section 4.8.2.

4.8.2 Alarms

Alarming on low power factor can be accomplished by
enabling this function in the ALARM programming screen.
Any System Power Factor seen by the Digitrip 1150 less
than the level programmed will initiate an alarm message
on the twenty four character display as well as illuminating
the yellow LED and communicating to a host computer.
The powerfactor calculation is valid for currents less than
the Long Delay Pickup level. The Auxiliary Relay A can be
also assigned to the THD alarm.
The THD alarm feature is an alarm setting with a range of
10% to 30% THD that when exceeded will initiate wave-
form capture and also set the front panel alarm LED. The
THD alarm has a 1 minute update rate. The Auxiliary Relay
A can also be assigned to a THD alarm.

4.9 Waveform Capture Feature

The Digitrip 1150 can respond to a command from a
remote master to perform a waveform capture of phase
currents IA, IB and IC, as well as waveform IN (on catalog
LSI ) or waveform IG (on catalog LSIG employing the
Effective 10/2004
Courtesy of NationalSwitchgear.com
source ground configuration). A total of 58 data points per
phase per cycle is captured and can be sent to a host
computer. From this data, parameters such as [THD],
individual harmonics content and waveform are fabricated.
There is a timer in the Digitrip unit that will limit the
acceptance of a "WAVEFORM CAPTURE" software
command to once per second. Three waveforms are held in
a first in, first out manner in the Digitrip's volatile memory.
n (plug amperes)

4.9.1 Six Cycle Waveform Capture on Trip

On Long Time, Short Time, Instantaneous or Ground Fault
tripping events, the Digitrip 1150 will capture the curve
waveforms to a buffer. The buffer as a waveform can be
displayed on the master computer using the PowerNet
software screen (Ref. I.L.17384 for protocol and software
commands). The six cycle waveform capture will typically
contain one cycle of pre-interruption data and five cycles of
interruption and post-interruption data for analysis of the
power system.
NOTE: The phase loss, phase unbalance, voltage and
frequency trips, reverse power trips and alarm events do
not produce a waveform capture.
NOTE: PowerNet communications will require hardware
and software specified in the Cutler-Hammer PowerNet
Operations Manual and also the Digitrip 1150 Firmware
must be DISPLAY VERsion 8B, REVision 02 or greater
and PROTECT VERsion 8A, REVision 02 or greater (See
Appendix Page D-5).

4.9.2 One Cycle Waveform Capture

There are two methods of obtaining a one cycle waveform
capture from the Digitrip 1150. One method is via the
PowerNet software to manually request a waveform
capture. The second way is to trigger a waveform capture
via an Alarm condition. This is accomplished by entering
the PROGRAM - ALARM screen. Enable the ALARM type
of interest as well as ALARM TO EventLOG.
The one cycle waveform capture of the currents IA, IB, IC
and IN, if applicable, can then be displayed on the master
computer for analysis. IG waveform is not displayed for
residual ground application (See Appendix D-16).
4.10 Health (applicable only to Digitrip 1150+ Rev. E
or higher)
The HEALTH menu on the Digitrip 1150 front panel will
provide information on the Magnum Circuit Breaker's
Health as well as a history of the circuit breaker and circuit
it is protecting. This data is useful for planning mainte-
nance and inspection schedules.
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