GE Industrial Solutions Entellisys System User Manual - Manual (Page 58)

Single point functions 58
5
Relay trips can be configured to use either the OPEN command (flux shifter open without bell
alarm activation) or the TRIP command (flux shifter open with bell alarm activation). The system
will not perform a relay function requiring voltage if there is no valid PT source for that
Messenger.
If a circuit breaker is opened (either through a OPEN or TRIP command) by a voltage relay, and
the circuit breaker is re-closed, Entellisys will re-open the circuit breaker within approximately
three seconds if the condition is still present.
5.2.0.1 Enabling Single Point Relay packages
Single Point Relay packages must be enabled for each circuit breaker before any relay can be
used individually on that circuit breaker. This is done by GE.
5.2.1 Undervoltage Relay
Entellisys executes the Undervoltage Relay function by comparing the voltage in each phase to
the nominal 1X value of the system voltage. For example, in a 120-V wye system, nominal 1X is
defined to be 120-V phase to neutral.
The relay can be in three states:
• Pickup – If the voltage in a set number of voltage phases (one, two or all three voltage
phases) is less than the pickup set point, the relay goes into pickup, and is said to enter
Pickup state
• Operate – If the relay stays in pickup state for a specified pick up delay time, the system
trips the appropriate circuit breaker or activates an alarm, and the relay is said to be in
Operate state
• Drop out – The relay drops out of pickup when the voltage exceeds 103% of the
programmed threshold. The relay is said to be in Drop out state.
For wye potential transformers, the Undervoltage Relay operates on line-to-neutral voltage. For
open delta potential transformers, the Undervoltage Relay operates on line-line voltage.
Entellisys uses RMS voltages in the calculations.
The Undervoltage Relay can function using both constant and inverse time curves.
Constant time function: If the constant time curve is selected, the system trips the appropriate
circuit breaker or activates an alarm if the phase voltage is less than the set point for the
specified time delay.
Trip time accuracy: Trip-time accuracy is ± 0.1 second.