GE Industrial Solutions Entellisys System User Manual - Manual (Page 79)

Synch Check relay 79
5
5.3 Synch Check relay
The Synch Check function is used as a permissive for closed-transition automatic throw-over
control schemes.
Entellisys performs the synch check relay function by comparing the amplitude, phase and
frequency of the voltages in each of the three phases of the two selected source circuit
breakers.
NOTE: The Synch Check Relay function is not a per node option, but a per line up option.
Entellisys provides up to six synch check functions.
The following thresholds are used by the Synch Check relay:
Dead Bus Threshold: This user-programmable value represents the voltage for source 1 below
which a phase is considered dead.
Live Bus Threshold: This user-programmable value represents the voltage for source 1 above
which a phase is considered live.
5.3.1 Synch check status
Each synch check function provides the following status information:
Synchronous Live: Set to true if all three phases at both sources are above the live bus
threshold and are in synch (i.e., all three phases satisfy the programmed voltage, frequency, and
phase differential criteria) and is set to false otherwise.
Dead Source: If one or both sources are de-energized, the dead source selection permits closing
of the circuit breaker to by-pass the synch check measurements. The following Dead Source
criteria selections are available:
• None – Dead source function is disabled
• LV1 and DV2 – Voltage source 1 live and voltage source 2 dead
• DV1 and LV2 – Voltage source 1 dead and voltage source 2 live
• DV1 or DV2 – Voltage source 1 dead or voltage source 2 dead
• DV1 xor DV2 – One voltage source is dead, the other is live
• DV1 and DV2 – Both sources are dead
The Dead Source status is shown as true if the programmed dead bus configuration condition is
true.
Close: This status is set to true if Synchronous Live is true or Dead Source is true.
Each synch check function verifies that the two sources have the same PT primary voltage and
configuration (delta or wye). If both parameters are not the same for both sources, the CPU logs
an event and disables the synch check function.