Application And Setting Notes - Siemens 6MD85 Manual

Protection and Automation Functions
7.4 Overcurrent Protection, Phases
Blocking of the Time Delay (Basic and Advanced Stage)
You can use the binary input signal >Block delay & op. to prevent the start of the time delay and thus
also the operate signal. A running time delay is reset. The pickup is indicated and the fault logging and
recording takes place.
Blocking of the Operate Delay and the Operate Signal via the Device-Internal Inrush-Current Detection Function
(Basic and Advanced Stage)
Blocking of the operate delay and the operate signal via the device-internal Inrush-current detection function
is described in chapter
Influence of Other Functions via Dynamic Settings (Advanced Stage)
If available in the device, the following functions can influence the overcurrent-protection stages:
•
Automatic reclosing
•
Cold-load pickup detection
•
Binary input signal
The influence of these functions via dynamic settings is described in chapter
7.4.4.2

Application and Setting Notes

Parameter: Method of measurement
•
Default setting (_:661:8) Method of measurement = fundamental comp.
With the Method of measurement parameter, you define whether the stage uses the fundamental
comp. (standard method) or the calculated RMS value.
Parameter Value
fundamental comp.
RMS value
Parameter: Threshold, Operate delay
•
Default setting (_:661:3) Threshold = 1.500 A (for the 1st stage)
•
Default setting (_:661:6) Operate delay = 0.30 s (for the 1st stage)
Set the Threshold and Operate delay parameters for the specific application.
The following details apply to a 2-stage characteristic curve (1st stage = definite-time overcurrent protection
stage and 2nd stage = high-current stage).
1st stage (overcurrent stage):
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. Therefore, set the Threshold parameter for lines to approx. 10 %, for transformers and motors to
approx. 20 % above the maximum load that is expected.
606
7.4.7.1 Description .
Description
Select this method of measurement if harmonics or transient current peaks
are to be suppressed.
Siemens recommends using this method as the standard method.
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
point are added up in the current interface of a function group, the setting
value should not be set lower than 0.1 I
added currents.
7.4.8.1 Description
. If currents from more than one measuring
rated,sec
multiplied by the number of
rated,sec
SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017
.