ABB RELION REX640 Technical Manual page 555

1MRS759142 C
REX640
Technical Manual
• Detection of earth fault from residual overvoltage, ROVPTOV
• Delay of release MFADPSDE using TONGAPC connected to the BLOCK input
of MFA (inversed)
• Delay of release (TONGAPC: On delay time (ms)) based on known time delays
in resistor connection
• Protection operate delay time to be set smaller than the resistor connection
duration
ROVPTOV, START -output
TONGAPC, Q1 -output
MFADPSDE, BLOCK -input, inversed
MFADPSDE, START -output
MFADPSDE, OPERATE -output
GUID-901C4906-0E85-49CB-AB55-F3492A8590D4 V1 EN
Figure 299: 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. The reset
timer is activated at the falling edge of the GFC release, that is, when the zero-
TONGAPC: On delay time (ms)
Section 4
Protection functions
549