ROVPTOV, START -output
TONGAPC: On delay time (ms)
TONGAPC, Q1 -output
MFADPSDE, OPERATE -output
MFADPSDE, START -output
MFADPSDE, BLOCK -input, inversed
Figure 332: Logic to release MFADPSDE at the time of resistor (re)connection
The logic enables exact operate time of MFADPSDE elapsed from time of resistor
(re)connection.
In the configuration, equal
Reset delay time
and
Voltage start value
must
be used for ROVPTOV and MFADPSDE.
The release delay should be based on known delays in resistor (re)connection:
• Logic OFF-ON-OFF:
Switch on delay
of the parallel resistor.
• Logic ON-OFF-ON:
Switch off delay
+
Time off
time of the parallel resistor.
The resulting total protection operate time is defined as follows:
• Logic OFF-ON-OFF:
Switch on delay
of the parallel resistor + set
Operate delay
time
of MFADPSDE.
• Logic ON-OFF-ON:
Switch off delay
+
Time off
time of the parallel resistor + set
Operate delay time
of MFADPSDE.
• Set
Operate delay time
of MFADPSDE smaller than the connection duration time
of the resistor.
If earth faults are only alarmed, the external logic is not needed.
When the proposed logic is used and indication of transient earth faults is needed,
the START output from INTRPTEF can be used.
Timer
If the detected fault direction is opposite to the set directional mode and GFC
release is active, BLK_EF output is activated once
Start delay time
has elapsed.
Reset timer is activated at the falling edge of GFC release, that is, when zero-
sequence voltage falls below
Voltage start value
. BLK_EF is reset once the reset
delay time elapses. Activation of the BLOCK input deactivates the BLK_EF output
and resets Timer.
BLK_EF output is activated when the following conditions are met:
• Earth fault is detected by the GFC
• Fault direction is opposite to
Directional mode
setting
The estimated stabilized fundamental frequency residual current
exceeds
the internally fixed threshold, which is 1% of In. This current magnitude threshold
supervision is based on the “Amplitude” method.
1MRS759142 F
Protection functions
REX640
Technical Manual
577
To Next Page
Loading...
