Parameter Value Description
RMS value
Select this method of measurement if you want the stage to take harmonics
into account (for example, at capacitor banks). Consider that aperiodic DC
components present in the secondary circuit are measured and can cause
an overfunction.
For this method of measurement, do not set the threshold value of the
stage to less than 0.1 I
rated,sec
. If currents from more than one measuring
point are added up in the current interface of a function group, the setting
value should not be set lower than 0.1 I
rated,sec
multiplied by the number of
added currents.
Parameter: Type of character. curve
•
Default setting (_:691:130) Type of character. curve = IEC normal inverse
The device offers all the usual inverse-time characteristic curves according to IEC and ANSI. Select the Type
of character. curve required for your specific application. For more information about the parameter
Type of character. curve, refer to chapter 12.5.2 Stage with Inverse-Time Characteristic Curve.
Parameter: Min. time of the curve
•
Default setting (_:691:113) Min. time of the curve = 0.00 s
This parameter is only available in the advanced stage.
With the Min. time of the curve parameter, you define a minimum operate delay time. The operate
delay time of inverse-time characteristic curve never falls below the minimum operate delay time. If the
setting is left on its default value of 0 s, this parameter has no effect on the inverse-time characteristic curve.
This parameter is only required for time coordination in recloser schemes. For all other applications, Siemens
recommends keeping the default setting of 0 s.
NOTE
If the set value is smaller than the smallest possible time delay of the inverse-time characteristic curve, the
parameter has no influence on the delay time.
Parameter: Additional time delay
•
Default setting (_:691:115) 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, this parameter has no effect on the inverse-time characteristic
time.
This parameter is only required for time coordination in recloser schemes. For all other applications, Siemens
recommends keeping the default setting of 0 s.
Parameter: Threshold
•
Default setting (_:691:3) Threshold = 1.500 A
Set the Threshold and Type of character. curve parameters for the specific application.
The setting depends on the maximum occurring operating current. Pickup by overload must be excluded since
overcurrent protection operates with short tripping times as short-circuit protection and not as overload
protection. Set the Threshold parameter for lines to approx. 10 %, for transformers and motors to approx.
20 % above the maximum expected load.
Note that a safety margin is set between pickup value and threshold value. The stage only picks up at approx.
10 % above the Threshold.
Protection and Automation Functions
6.3 Overcurrent Protection, Phases
344 SIPROTEC 5, Overcurrent Protection, Manual
C53000-G5040-C017-8, Edition 07.2017
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