Siemens 6MD85, Manual

Page: 606 / 1256

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
7.4.7.1 Description .
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 7.4.8.1 Description .
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 Description
fundamental comp.
Select this method of measurement if harmonics or transient current peaks
are to be suppressed.
Siemens recommends using this method as the standard method.
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:
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.
7.4.4.2
Protection and Automation Functions
7.4 Overcurrent Protection, Phases
606 SIPROTEC 5, High-Voltage Bay Controller, Manual
C53000-G5040-C015-9, Edition 11.2017