Parameter: Time dial
•
Default setting (_:106) Time dial = 1.00
With the Time dial parameter, you displace the characteristic curve in the time direction.
As usually, there is no time grading for voltage protection and therefore no displacement of the characteristic
curve, Siemens recommends leaving the Time dial parameter at 1.00 (default setting).
Parameter: Reset time
•
Default setting (_:108) Reset time = 0.00 s
With the Reset time parameter, you define the reset time delay which is started when the voltage exceeds
the dropout value. Set the parameter Reset time to 0 s when instantaneous reset is desired.
Under network conditions of intermittent faults or faults which occur in rapid succession, Siemens recom-
mends setting the Reset time to an appropriate value > 0 s to ensure the operation. Otherwise, Siemens
recommends keeping the default value to ensure a fast reset of the function.
Parameter: Additional time delay
•
Default setting (_:107) Additional time delay = 0.00 s
With the Additional time delay parameter, you define a definite-time delay in addition to the inverse-
time delay.
If the setting is left on its default value of 0 s, only the inverse-time delay is operative.
Parameter: Blk. by meas.-volt. failure
•
Default setting (_:10) Blk. by meas.-volt. failure = yes
With the Blk. by meas.-volt. failure parameter, you control the behavior of the stage when a meas-
uring-voltage failure is detected.
A measuring-voltage failure can only be detected if one of the following two conditions is met:
•
The device-internal supervision function Measuring-voltage failure detection is configured and
switched on.
•
The binary input signal >Open of the function block VTCB is connected to the voltage-transformer circuit
breaker (see chapter 9.3.4.1 Overview of Functions).
Parameter Value
Description
yes
The protection stage is blocked (= default setting). Siemens recommends
using the default setting.
no
The protection stage is not blocked.
Parameter: Current-flow criterion
•
Recommended setting value (_:2311:104) Current-flow criterion = on
Depending on the system, the voltage transformers are arranged on either the supply side or the junction side.
These 2 possible voltage-transformer locations induce a different behavior of the function after tripping and
opening of the circuit breaker:
•
If they are located on the supply side, the voltage still exists.
•
If they are located on the junction side, the voltage does not exist.
Parameter Value
Description
on
If the voltage transformers are located on the junction side, you can use the
current-flow criterion to make the pickup drops out when the current falls
below a minimum value (parameter Threshold I>).
off
In the case of undervoltage, the pickup of the undervoltage protection
stage persists when the current-flow criterion is not used.
Protection and Automation Functions
6.29 Undervoltage Protection with 3-Phase Voltage
748 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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