RFL Electronics GARD 8000, Инструкция по эксплуатации

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Description of Operation
GARD 8000 Distance Relay RFL Electronics Inc.
9.12.5 COORDINATION TIME FOR DIRECTIONAL UNITS
The transient block coordination timer provided for all directional units is intended for use with the
directional time overcurrent elements when they are applied in a pilot scheme. It provides transient
block for current reversals in parallel lines. The timer should be set longer than the reset time of any
carrier equipment used for communications.
9.13 DIRECTIONAL OVERCURRENT PILOT SCHEMES
The GARD 8000 Pilot schemes can be complemented with similar logic for the directional ground and
directional negative sequence elements. The schemes and logic available for these elements are
•
Permissive Underreach transfer trip
•
Direct Transfer Trip
•
Permissive overreach Transfer Trip
•
Directional Comparison Unblocking
•
Directional Comparison Blocking
•
Weak Infeed Logic
•
Transient Block Logic
These pilot schemes are intended as complement to the distance pilot logic and provide higher
sensitivity for high resistance ground faults.
The carrier send signals can be combined in the logic to be the same signal as used for the distance
relay pilot operation. In that case, careful consideration needs to be made that the schemes are
compatible with each other, and that there are no system conditions that cause different directions of
positive sequence current as compared to negative and zero sequence current.
The ground and negative sequence pilot schemes can also use their own communication channel and
then there are generally no coordination issues.
The scheme logic is very similar to the distance element scheme logic. 67G-1/67Q-1 (step 1
instantaneous ground and/or negative sequence elements) is used as a ‘Zone 1’ element. Note that the
pick-up setting for these elements should be high enough not to operate for fault outside the line. 67G-
2/67Q-2 (step 2 instantaneous ground and/or negative sequence elements) is used as a ‘Zone 2’
element, overreaching. 67G-3/67Q-3 (step 3 instantaneous ground and/or negative sequence elements)
is used as a ‘Zone 4’ element, overreaching in the reverse direction.
August 1, 2009 9-61 973.334.3100