Four Channel Phase Identified Channel Logic - GE ALPS Instruction Manual

1.9 PHASE IDENITIFIED CHANNEL SCHEMES
1
a) PILOT TRIPPING
The local faulted phase determination uses the same algorithms as other ALPS relays. The permissive keying is super-
vised by the fault detecting functions (phase and ground distance, GDOC) and the local fault type determination algorithm.
Table 1–10: CHANNEL KEYING FOR PILOT TRIPPING (FOUR CHANNELS)
LOCAL FAULT TYPE
AG
BG
CG
Any interphase faults
In addition to providing the permissive signal, the receiver inputs will be compared with the selected local fault type per the
following table to determine which phase(s) to trip.
Table 1–11: PILOT KEYING (4 CHANNEL) LOGIC
LOCAL FAULT TYPE
AG, AB, ABG, CA,CAG,3PH
BG, AB, ABG, BC,BCG,3PH
CG, BC, BCG, CA,CAG,3PH
Any interphase fault
AG
BG
CG
For the fault conditions shown in Figure 1–22: INTER-CIRCUIT FAULT EXAMPLE, the ALPS on the protected line at the S
substation detects an AG fault and sends channel 1 to the remote terminal. The ALPS at Substation R detects an ABG fault
and sends channel 4 to the relay at S. The ALPS at Substation S issues a single pole phase A trip via the operation of the
Zone 1 ground distance function. The ALPS at Substation R issues a single pole phase A trip per the logic above (Local
fault type is ABG, and only channel 1 is received).
b) ZONE 1 TRIPPING
Faulted phase determination for Zone 1 tripping is the same as in the existing ALPS. This is to allow the Zone 1 elements
to maintain their high speed operation and their independence from the channel.
c) WEAK INFEED TRIPPING
The standard ALPS faulted phase determination algorithm has been supplemented by undervoltage units for Weak Infeed
trips. The phase identified channel logic scheme will use the information in the received signal as well as the undervoltage
units. If there is a local determination of the fault type, the previous table will be used to determine which phases to trip. If
there is no local fault type determination, then the undervoltage functions will be used as in the existing ALPS Hybrid
scheme. If there is no local fault type determination and no undervoltage functions have operated, then the received fault
type will be used to select the trip type.
d) REPEAT (ECHO) KEYING
If no local tripping functions have operated, the repeat keying will be determined by the local fault type determination logic
and the received channels as noted below. If any local trip functions have operated, the channel repeat logic will be blocked
and the local fault type determination will control the keying outputs. If the fault type can not be determined locally, the
received channel(s) will be repeated as received.
LOCAL FAULT TYPE
AG
BG
CG
Any LL or LLG or 3PH
1-40

1.9.4 FOUR CHANNEL PHASE IDENTIFIED CHANNEL LOGIC

XMTR #1 XMTR #2 XMTR #3
X
X
X
RECEIVER
1 2 3
X
X
X
RECEIVER
Any receivers
Any receivers
Any receivers
Any receivers
ALPS Advanced Line Protection System
1 PRODUCT DESCRIPTION
XMTR #4
X
PHASES TO
TRIP
4
A
B
C
X A, B, & C
X A
X B
X C
REPEAT KEYING
XMTR #1
XMTR #2
XMTR #3
Repeat as received
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