no
The Protection stage is not blocked when a measuring-voltage failure
is detected.
Parameter: Blk. w. inrush curr. detect.
•
Default setting (_:13921:27) Blk. w. inrush curr. detect. = no
You use the Blk. w. inrush curr. detect. parameter to determine whether the operate delay and
operate signal are blocked during the detection of an inrush current.
Parameter: I> release threshold
•
Recommended setting value (_:13921:105) I> release threshold = 0.100 A
You use the I> release threshold parameter to define a precondition that the stage can pick up. The
default setting is at 10 % of the rated current. Siemens recommends using the default setting.
Parameter: V< threshold value
•
Recommended setting value (_:13921:103) V< threshold value = 85.000 V
You use the V< threshold value parameter to define one of the 2 pickup criteria. If all 3 phase-to-phase
voltages drop below the parameterized undervoltage threshold value, the pickup criterion is fulfilled.
The setting should be set below the lower value of the permissible voltage range, according to the national
transmission code. In Germany, the recommended undervoltage threshold is 85 % of the rated voltage. There-
fore Siemens recommends using the default setting.
Parameter: Q> threshold value
•
Default setting (_:13921:3) Q> threshold value = 5 %
You use the Q> threshold value parameter to define the second of the 2 pickup criteria. If the positive
reactive power exceeds the parameterized Q> threshold value, the pickup criterion is fulfilled.
In the following example, the pickup takes place if Q exceeds 5 % of the power-supply system rated power.
EXAMPLE
The following example is given for settings in secondary values.
Rated voltage: V
rated, sec
= 100 V
Rated current: I
rated, sec
= 1 A
Threshold value: 5 % of the power-supply system rated power
You can calculate the setting value as follows:
[foqvprot-110713-01.tif, 1, en_US]
Parameter: Operate delay
•
Default setting (_:13921:6) Operate delay grid CB = 1.50 s
•
Default setting (_:13921:108) Oper. delay generator CB = 0.50 s
You can set the Operate delay grid CB for the circuit breaker at the power-supply system connection
point, or set the Oper. delay generator CB for the circuit breaker of the facility, for example, the gener-
ator.
The time of the Operate delay grid CB should always be set longer than the time of the Oper. delay
generator CB.
Protection and Automation Functions
6.40 Undervoltage-Controlled Reactive-Power Protection
830 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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