Table of Contents
Metering
When the metering function is selected, a number of stan-
dard metering parameters can be viewed on the LCD dis-
play. All of these values are communicated to the POWER
LEADER™ Power Management System. The accuracy of the
metering functions is constrained by the physical size of the
current sensors. Consequently, all metering functions are
designed for load management decisions, and are not a
substitute for utility revenue metering equipment.
• Current: MicroVersaTrip Plus™ and PM™, provide
metering of individual phase currents. The user can
view each phase current individually. Current displays
automatically shift from amps to kiloamps above 999
amps. The minimum current display resolution is in
tenths of an amp (e.g., 51.2 A).
• Voltage: The metering display of four wire systems can
read both line-to-neutral and line-to-line voltages for each
phase. The smallest resolution of the voltage display is
one volt (e.g., 277V, or 276V).
• Energy: The energy display indicates the amount of real
power that has passed through the breaker. The display
has three-digit resolution, and automatically scales the dis-
play from kWh to MWh to GWh. Normal power flow can
be selected as either line-load or load-line in the setup
mode. Once normal flow is configured, energy values will
accumulate in the positive direction. For certain applica-
tions where power may flow in either direction, such as tie
breakers, energy may display a negative value.
• Real power: Real power in units of kW or MW, can be
shown on command on the LCD display.
• Volt-amperes (or total power): "Total power" or volt-amperes
in units of kVA or MVA can be viewed on command on
the LCD display.
• Demand: Demand in units of kW or MW can be displayed.
The monitoring time period can be varied from 5 to 60
minutes, in increments of 5 minutes. The display provides
a rolling average of power over the scheduled time inter-
val.
• Peak demand: Peak demand in units of kW or MW can be
displayed. This value indicates the highest power demand
reached since the start of demand measurements, or
since reset. The peak demand value can be reset to the
present demand via the keypad.
Protective Relaying
When protective relaying functions are selected, any combi-
nation of the following protective relays can be enabled. All
relay functions combine both an adjustable setpoint and an
adjustable discrete (not inverse) time delay. All time delays
are adjustable from 1 to 15 seconds in increments of 1 sec-
ond. All tripping is performed through the trip unit. Any
protective relay trip will operate the bell alarm accessory if
the breaker is so equipped.
24
MicroVersaTrip PM™ Metering and Relaying
• Undervoltage: Undervoltage protection may be set from
50% to 90% of the true rms nominal voltage in incre-
ments of 1%.
• Overvoltage: Overvoltage protection may be set from 110%
to 150% of the true rms nominal voltage in increments of
1%.
• Voltage unbalance: Voltage-unbalance protection compares
the lowest or highest phase voltage with the other two,
and initiates a trip if the difference exceeds the setpoint.
True rms voltages are computed for each phase. The
range of trip settings varies from 10% to 50% in incre-
ments of 1%.
• Current unbalance: Current-unbalance protection com-
pares the true rms current in either the highest or lowest
phase with the true rms current in the other two phases.
A trip is initiated if the difference exceeds the setpoint.
The range of trip settings varies from 10% to 50% in
increments of 1%.
• Power reversal: WavePro™ breakers 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 units of kW. Reverse power setpoints vary from 10 kW
to 990 kW in increments of 10 kW.
• Enable/disable relays: To disable any of the protective relay
functions, set the time delay for that function to OFF.
Setting the time delay to any discrete value enables the
protective function.
Table 24.1 Trip Unit Metering Display Accuracy
Value
Current, rms-A, kA
Voltage, rms-V
Phase-Phase, Phase-Neutral
Energy-kWh, MWh, GWh
Demand-kW, MW
Peak demand-kW, MW
Real power-kW, MW
Total power-kVA, MVA
Frequency
Time delay
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 (potential transformer, voltage conditioner). Accuracy is
based on loading range of 20% to 100% of breaker current sensor
rating.
Breaker Full
System Full
Scale
Scale
Accuracy
Accuracy
±2.0%
±2.0%
N/A
±1.5%
N/A
±3.5%
N/A
±3.5%
N/A
±3.5%
N/A
±3.5%
N/A
±3.5%
N/A
±1Hz
N/A
±1 sec
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