GE Industrial Solutions Entellisys 5.0 User Manual - Manual (Page 116)

Multi-point functions 116
7
The only setting that is not topology specific on the Topology Settings tab is the Trip/Open
setting that determines whether the Trip relay just opens the circuit breakers (either trip-targets
or backup-trip-targets) or opens the circuit breaker and activates the lockout too.
7.1.1.3 Setting Bus Differential pickups/delays
To configure pickup and delay settings
1. On the Main Menu, click User Settings.
2. Click Advanced Protection, and then click Bus Differential as shown in Figure 7-3.
3. Select the zone number and topology number, and then select the appropriate settings for
pickup setting 1, pickup setting 2, etc.
Pickup setting 1 must always be less than pickup setting 2. A similar constraint is enforced for
time delay settings; time delay setting 1 must always be greater than time delay setting 2. A
second constraint for pickup settings is that the pickup setting (1 or 2) cannot be less than the
minimum pickup of its bus differential zone. A bus differential zone's minimum pickup is
computed as 20% of the CT rating of the largest circuit breaker of that zone. So, although the
allowed pickup setting range for the Bus Differential Relay is 100 to 22,000 Amps, the actual
allowed range is only from “zone-minimum-pickup” to 22,000 Amps.
There are seven delay bands available:
For 60 Hz systems
Band 1: 0.025 sec < T < 0.092 sec (Note: The actual fault clearing time depends on the energy
content of the current at the circuit breaker.)
Band 2: 0.058 sec < T < 0.158 sec
Band 3: 0.100 sec < T < 0.200 sec
Band 4: 0.167 sec < T < 0.267 sec
Band 5: 0.217 sec < T < 0.317 sec
Band 6: 0.283 sec < T < 0.383 sec
Band 7: 0.400 sec < T < 0.500 sec
For 50 Hz systems
Band 1: 0.030 sec < T < 0.095 sec (Note: The actual fault clearing time depends on the energy
content of the current at the circuit breaker.)
Band 2: 0.060 sec < T < 0.160 sec
Band 3: 0.100 sec < T < 0.200 sec
Band 4: 0.170 sec < T < 0.270 sec
Band 5: 0.220 sec < T < 0.320 sec
Band 6: 0.280 sec < T < 0.380 sec
Band 7: 0.400 sec < T < 0.500 sec
The pickup default is 1200 Amps and the time delay default is BAND 3.
If Topology Settings is set to Topology 1 and Apply to all Topologies is selected, then the
settings of topology 1 are applied to all topologies from 1 to 2
(num of buses) – 1. To apply different
settings to different topologies, click Advanced Settings and select the desired topology and
settings as shown in Figure 7-3. For topology 0, settings are selected separately and these
settings are used when the Reduced Let-Thru Mode is enabled.