SERVICE MANUAL R5888C
QUADRAMHO Chapter 2
Page 53 of 74
single phase to ground faults, with 3 phase tripping for other faults, or 3 phase
tripping for all faults is also provided.
To set up the relay for a particular scheme option requires the correct code
selection number (CSN) to be set on the code switches, which are positioned on
the frontplate of the scheme logic module. Details are given in Table 8.
CSN Scheme Comments
(XY)
00 BASIC with single phase/3 phase tripping Provides basic
Zone 1
Z2t, Z3t and
SOTF action
01 BASIC with 3 phase tripping only Basic action as per 00
02 PUR with single phase/3 phase tripping Includes basic
action
03 PUR with 3 phase tripping only
04 POR with single phase/3 phase tripping
05 POR with 3 phase tripping only
06 BLOCK with single phase/3 phase tripping Includes basic action
07 BLOCK with 3 phase tripping only
08 Z1EXT with single phase/3 phase tripping
09 Z1EXT with 3 phase tripping only
Table 8: The standard scheme options
The first digit of the CSN is the left switch labelled “X” on the relay nameplate,
while the second digit is the switch labelled “Y”. The range of code selection
numbers available for scheme options is in the range 00 to 39. Positions 40 to 99
are for test options (see Sections 6.42 and 4.54). If a CSN is selected in the range
00 to 39 which does not have a scheme allocated to it, the “Relay Available” LED
is extinguished and the output contact “Relay Inoperative” (97Y–1) closes.
5.16.23 Basic scheme
This scheme controls the normal Zone 1 action, the Zone 2 and Zone 3 time
delayed trip action and the SOTF trip action. The time delays associated with Zone
2 faults (Z2t) and those for Zone 3 faults (Z3t) are set by switches on the frontplate
of the scheme logic module.
5.16.24 Permissive underreaching scheme (PUR)
The underreaching directional Zone 1 elements are used to initiate tripping and to
send a signal (85X–1 and 85X–2) to the remote end of the transmission feeder.
Operation of the overreaching Zone 2 elements plus receipt of the channel signal
(via opto isolator input CRX), gives an accelerated trip for faults occurring in the
end zones of the protected feeder. Once issued, the aided trip is only removed
when the Zone 2 elements reset. This is to allow time for breaker failure protection
operation in the event of a local breaker failure for a fault near the remote end of
the line. A delay on reset of the signal received (CRX), is needed to ensure that the
relays at both ends of a single end, fed faulted line of a parallel feeder circuit have
time to trip when the fault is close up at one end. A preset 100ms is used for this
delay. Figure 68 gives the equivalent logic diagram.
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