GE Power Break II Manual page 21

M ic roVersaTri p P l us™ a n d PM™ Tri p Un its
Metering
When the metering fu nction is selected, a n u m ber of
standard metering parameters can be viewed on the LCD
display. All of these values a re com m u nicated to the POWER
LEADER™ Power Management System. The accuracy of the
metering functions i s constrained by the physical size of the
current sensors. Consequently, all meteri ng functions a re
designed for load management decisions, and a re not a
su bstitute for utility revenue metering equipment.
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All trip units, including MicroVersaTrip Plus™, pro­
Current:
vide metering of individual p ha se cu rrents. The user can
select pha ses 1, 2, or 3. Cu rrent displays a utomatically shift
from amps to kiloamps a bove 999 a m ps. The minimum
current display reso lution is in tenths of a n a m p (e.g., 5 12
A I .
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The metering d isplay of fou r wire systems can
Voltage:
rea d both line-to-neutral and line-to-line voltage d isplay
for each phase. The smal lest resolution of the voltage
display is one volt (e.g. 2 77V, or 276V).
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The energy display indicates the a mount of rea l
Energy:
power that has passed through t h e breaker. T h e d isplay
has three-digit resolution, and automatical ly scales the
display from kWh to MWh to GWh. Normal power flow can
be selected as either load-line or line-load in the setu p
mode. Once normal flow is configures, energy values will
accumulate i n the positive direction. For certai n a pplica­
tions where power may flow i n either direction, such a s tie
breakers, energy m ay d isplay a negative value.
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Real power in u nits of kW or MW can be
Rea l power:
shown on command on the LCD display.
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Volt-amperes (or tota l power):
peres in units of kVA o r MVA can be viewed on command
on the LCD display.
Table 21.1 Trip U n it Metering Display Accuracy
Value Breaker Full Scale
Current. rms -A, kA
Voltage, rms -V
Phase-Phase, Phase-Neutral
Energy -kWh, MWh, GWh
Dema n d - kW. MW
Peak Demand- kW. MW
Real Power - kW, MW
Total Power - kVA, MVA
Frequency
Time Delay
CD Includes trip unit. breaker. current sensors and rating plug. Accuracy is based on
loading range of 20% to 100% of breaker current sensor rating.
@ Includes trip unit. breaker. current sensors. rating plug. plus Voltage Module [poten­
tial transformers. control power voltage conditioner[. Accuracy is based an loading
range of 20 % to 100 % of breaker current sensor rating.
"Total power " or vo lt-am­
System Full Scale
Accuracy @
AccuracyCD
±2.5% ±2.5%
N/A ± 1 . 5 %
N/A ±4 0%
N/A ±4.0%
N/A ±4 0%
N/A ±4.0%
N/A ±4.0%
N/A ± 1 Hz
N/A ±1 sec
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Demand in units of kW or MW can be d isplayed.
Demand:
The monitoring time period can be varied from 5 to 60
minutes, in increments of 5 m i nutes. The display provides a
rolling average of power over the scheduled time interva l.
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Pea k demand: Peak demands in un its of kW or MW can be
displayed. This value indicates the highest power demand
reached since the start of demand measureme nts, or since
reset. The peak demand value can be reset to the p resent
demand via the keypad.
Protective Relayi ng
When protective relaying functions a re selected, a ny combi­
nation of the following protective relays can be enab led. All
relay fu nctions combine both an adjustable setpoint and a n
a djustable d iscrete (not inverse) time delay. A l l t i m e delays
a re adjusta ble from 1 to 15 seconds in i ncrements of 1 sec­
ond. All tripping is performed through the trip unit. The user
can configure the trip u nit to activate the bell alarm o nly, the
bell alarm with lockout , or neither, in response to a p rotective
relay (or overcu rrent/ground-fault) trip.
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Undervoltage: U ndervoltage protection may be set from
50% to 90% of the true rms nominal voltage in i ncrements
of 1%.
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Overvoltage p rotectio n may be set from
Overvoltage:
1 10% to 150% of the true rms nominal voltage in i ncre­
ments of 1%.
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Voltage-unbala nce p rotection com­
Voltage unbalance:
pares the lowest or highest p hase voltage with the other
two, and initiates a trip if the d ifference exceeds the
setpoint. True rms voltages a re com puted for each phase.
The range of trip setti ngs varies from 10% to 50% in incre­
ments of 1%.
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Cu rrent unbalance: Current-u nbalance protection com­
p a res the true rms current in either the highest or lowest
phase with the true rms cu rrent in the other two phases. A
tri p is initiated if the d ifference exceeds the setpoint. The
range of trip settings varies from 10% to 50% i n incre­
ments of 1%.
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Power reversal: The Power Break® II b reaker may be set
so that "positive" power flow can be in either direction (i.e.,
from line to load, or vice versa). Reverse power protection
is set in u nits of kW. Reverse power setpoints vary from
10kW to 990kW in i ncrements of 10kW.
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To disable any of the protective
Ena ble/disa ble relays:
relay functions, set the time delay for that function to OFF.
Setting the time delay to any discrete value enables the
relay.
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