Table 3.57
Default inhibits
Controller type
Inhibit(s)
GENSET
•
Generator breaker open
•
ACM wire break
EMERGENCY genset
•
Generator breaker open
•
Tie breaker open
•
EDG handling blackout
SHAFT generator
•
Shaft breaker open
•
ACM wire break
SHORE connection
•
Shore breaker open
•
ACM wire break
BUS TIE breaker
•
ACM wire break
3.5.3 [Busbar] voltage unbalance (ANSI 47)
Protection
IEC symbol (IEC60617)
ANSI (IEEE C37.2)
IEC 61850
Operate time
Voltage unbalance (voltage asymmetry)
UUB>
47
-
< 200 ms*
*Note: This operate time includes the minimum user-defined delay of 100 ms.
The alarm response is based on the highest difference between any of the three busbar phase-
to-phase voltage or phase-to-neutral true RMS values and the average voltage, as measured
by the controller. The phase-to-phase voltage is the default.
If phase-to-phase voltages are used, the controller calculates the average phase-to-phase
voltage. The controller then calculates the difference between each phase-to-phase voltage
and the average voltage. Finally, the controller divides the maximum difference by the average
voltage to get the voltage unbalance. See the example.
For the BUS TIE breaker controller, these are the voltages measured on busbar B.
Set
point
Value
time
Delay
Configure the parameters under
Configure > Parameters > [Busbar] > Voltage protections > Voltage unbalance
.
Table 3.58
Default parameters
Parameter
Range
Busbar voltage unbalance
Set point
0 to 50 % of nominal voltage
10 %
Delay
0.1 s to 1 h
10.0 s
Enable
Not enabled, Enabled
Enabled
Action
Warning
Table 3.59
Default inhibits
Controller type
Inhibit(s)
GENSET
ACM wire break
EMERGENCY genset
EDG handling blackout
SHAFT generator
ACM wire break
DESIGNER'S HANDBOOK 4189340911K UK
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