GE EntelliGuard G Application Manual page 24

Section 3. EntelliGuard TU Trip Unit System
Relay Functions
The Entelliguard TU offers various protective and
alarm relay functions that may be displayed on
the LCD screen, assigned contact outputs or com-
municated serially. They are shown in Table 3.13.
Protective Relays
Protection relays may be set by the user to alarm,
trip the circuit breaker or both. Alarms and trips are
displayed on the local LCD trip and communicated
serially. Alarms may also be assigned to one of
two output contacts.
Voltage-Unbalance Relay
This function compares the highest or lowest phase
voltage with the average of all three phases and
initiates a trip if the difference exceeds the set point.
The true RMS voltage is computed for each phase.
Table 3.14
Voltage Unbalance Settings
Item Options
Voltage unbalance Adjustable from 10% to 50% in increments
pickup of 1%.
User adjustable from 1 second to 15 seconds
Voltage unbalance
in increments of 1S. Setting this value to
delay setting
zero (0) will disable the relay.
Current-Unbalance Relay
This function compares the true RMS current in
the highest or lowest phase with the average of all
three phases and initiates a trip if the difference
exceeds the set point.
Table 3.15
Current Unbalance Settings
Item Options
Current unbalance Adjustable from 10% to 50% in increments
pickup of 1%.
User adjustable from 1 second to 15 seconds
Current unbalance
in increments of 1S. Setting this value to
delay setting
zero (0) will disable the relay.
Under-Voltage Relay
This function measures the true RMS voltage in all
phases and initiates a trip if any phase voltage
drops below the set point.
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Under-Voltage Relay Zero-Volt Trip Enable
This function determines if the relay trips when all
three-phase voltages drop to zero volts. Uses the
same timing set for the Under-Voltage Relay.
Table 3.16
Under-Voltage Settings
Item Options
Under voltage Adjustable from 50% to 90% in increments
pickup of 1%.
User adjustable from 1 second to 15 seconds
Under voltage
in increments of 1S. Setting this value to
delay setting
zero (0) will disable the relay.
Over-Voltage Relay
This function measures the true RMS voltage in all
phases and initiates a trip if any phase voltage
exceeds the set point.
Table 3.17
Over-Voltage Settings
Item Options
Over-voltage User adjustable from 110% to 150% in
pickup increments of 1%.
User adjustable from 1 second to 15 seconds
Over-voltage
in increments of 1S. Setting this value to
delay setting
zero (0) will disable the relay.
Power-Reversal Relay
This function measures the direction of power flow
through the breaker and initiates a trip if a suffi-
cient magnitude of reverse power is detected.
Table 3.18
Power-Reversal Settings
Item Options
Power reversal User adjustable from 10 kW to 1990 kW in
pickup increments of 10 kW.
User adjustable from 1 second to 15 seconds
Power reversal
in increments of 1S. Setting this value to
delay setting
zero (0) will disable the relay.
Power-Direction Setup
This function selects the normal power flow direc-
tion for the breaker, either from line to load or
from load to line. This direction setup also affects
the sign of the normal power metering displays.