Siemens 6MD85 Manual page 792

Protection and Automation Functions
7.13 Overvoltage Protection with 3-Phase Voltage
Parameter Value
phase-to-phase
phase-to-ground
Parameter: Threshold, Pickup factor
•
Default setting (_:3) Threshold = 110.000 V
•
Default setting (_:101) Pickup factor = 1.10
The stage picks up when the measured voltage value exceeds the pickup value Threshold × Pickup
factor.
Depending on the Measured value, the Threshold is set either as phase-to-phase quantity or as phase-to-
ground quantity.
With the Pickup factor parameter, you modify the pickup value. To avoid a long-time operate delay after
pickup when the measured value is slightly over the threshold, Siemens recommends using the default
setting.
Specify the Threshold (pickup threshold) and Pickup factor for the specific application.
Parameter: Pickup mode
•
Recommended setting value (_:182:101) Pickup mode = 1 out of 3
With the Pickup mode parameter, you define whether the protection stage picks up if all 3 measuring
elements detect the overvoltage condition (3 out of 3) or if only 1 measuring element detects the over-
voltage condition (1 out of 3).
Parameter Value
1 out of 3
3 out of 3
Parameter: Charact. constant k, Charact. constant α, Charact. constant c
•
Default setting (_:102) Charact. constant k = 1.00
•
Default setting (_:103) Charact. constant α = 1.000
•
Default setting (_:104) Charact. constant c = 0.000
With the parameters Charact. constant k, Charact. constant α, and Charact. constant c,
you define the required inverse-time characteristic curve.
Parameter: Time dial
•
Default setting (_:105) 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: Additional time delay
•
Default setting (_:106) Additional time delay = 0.00 s
792
Description
If you want to monitor the voltage range, keep phase-to-phase as the
default setting. In this case, the function will not pick up on ground faults.
Siemens recommends the measured value phase-to-phase as the
default setting.
Select the phase-to-ground setting if you want to detect voltage unbal-
ances and overvoltage conditions caused by ground faults.
Description
Select the setting for protection applications or for monitoring the voltage
range.
Siemens recommends 1 out of 3 as the default setting. This reflects how
the function behaved in previous generations (SIPROTEC 4, SIPROTEC 3).
Select this setting when using the stage to disconnect from the power
system (in the case of wind farms, for example).
SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017