Distance Relay Setting Examples
GARD 8000 Distance Relay
RFL Electronics Inc.
Description Range
Units
Step
Actual
67 Pilot Scheme
Selects the type of pilot scheme to use for the directional
overcurrent elements.
None
PUTT
DTT
POTT
DCUB
DCB - 1
DCB
67 Carrier Time
Sets the time delay for carrier send. Used with Permissive schemes
(PUTT, POTT, DCUB, DTT).
0 - 200
ms
10
50
67 Coord Time
Sets the coordination drop-out time delay for the carrier start signal.
Used with Blocking schemes (DCB).
0 - 50
ms
1
20
DCB 67 delay time
Sets the time delay for Directional Comparison Blocking (DCB)
trip signal. This is the amount of time the forward overcurrent
element zone will wait to receive a blocking carrier signal before
trip is released.
0 - 200
ms
10
50
67 Weak Infeed Logic Output
Set whether to use weak infeed echo (echo), week infeed trip
and echo (ECHO+TRIP) or no weak infeed logic (None) for the
overcurrent directional comparison pilot schemes.
None
Echo
ECHO+T
RIP - 1 None
Enable O/C curr. Rev. trans. blocking
Enable Transient Block Logic for the overcurrent directional
comparison pilot schemes.
No - Yes
-
1
No
8.2.12
21 DCB AND 67 DCB COORDINATION
While the 50G-1 element is intended to detect “close-in” faults in the 67 DCB scheme, sensitivity
required for 21 DCB has to take preference when using Fast carrier start. A more sensitive setting of
this element will not defeat the 67 DCB scheme as this scheme is using the forward directional action
(67G-1) of this element.
If the application can produce zero sequence and negative sequence currents in opposite directions for
an external fault, the settings need to be carefully reviewed when Fast carrier start is enabled:
1)
Disable 50G-1. The remote forward directional ground will receive a block signal from the
local reverse 50G-3 so use of the 50-G1 for the 21 DCB scheme is not necessary. (This is to
prevent that 67-G1 will have an opposite direction of 67-Q1 and cause a legitimate block signal
to drop out for an external fault.)
2)
Use zero sequence only. Then the 50G-1 element should be set for the 21 DCB scheme.
If Fast carrier start is NOT used, no coordination is required and all 50 elements are set based on 67
DCB only.
August 1, 2009
8-31
973.334.3100
Содержание GARD 8000
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