SERVICE MANUAL R5888C
QUADRAMHO Chapter 2
Page 57 of 74
iii) prevent the power swing blocking logic (via the pole dead logic) from
operating during the first 240ms immediately following line energisation,
when it is undesirable to prevent tripping.
b) Signal receive opto isolator.
This is energised from the signalling channel and is only effective if a signalling
scheme has been selected. In the permissive underreach and permissive
overreach schemes, receipt of a signal via the opto isolator permits Zone 2
elements to trip instantaneously, without waiting for the Zone 2 time delay
(See Figure 68 and 69, Appendix A). If the scheme selected is the blocking
scheme, then receipt of the signal via the opto isolator prevents the Zone 2 units
from issuing an instantaneous trip (See Figure 71).
This opto doubles up as “Reset Zone 1 extension” on some versions of the relay
suitable for use with miniature circuit breakers (mcb).
c) Channel in service opto-isolator
This input is energised when the signalling channel is in service. The absence of
the signal will force the blocking scheme to revert to the basic 3 step distance
scheme. If switch SW6 on the front of the scheme logic module is set to the right
hand position, then loss of the channel-in-service signal will cause the block auto
reclose output contact (96–1) to close (provided that scheme selected is a signal
aided scheme) (See Figure 73). A further feature is that absence of the channel
in service signal will force all trips in signal aided schemes to be 3 phase trips
only (See Figure 72).
d) Reset Zone 1 extension opto-isolator
This is energised from the auto reclose relay during the dead time and reclaim
time. The effect of energising this input is apparent only for the Zone 1
extension scheme, whereupon the reach of the Zone 1 measuring elements
reverts back to normal Zone 1 reach, otherwise they have extended Zone 1
reach.
When a version of the relay is supplied for use with miniature circuit breakers
(mcb) instead of VT fuses, this opto is used for this purpose. The signal receive
opto doubles up as “Reset Z1 extension” on some versions of the relay.
When used with mcb’s this opto is energised via a normally open contact on the
mcb (mcb closed) to ensure correct blocking of the protection when the mcb
operates If there is not a normally open contact available on the mcb (mcb
closed) an interposing relay is required. This must operate in less than 10ms to
ensure correct operation of the relay.
e) Inhibit power swing blocking opto-isolator.
This is energised by the auto reclose relay during single pole auto reclosure
conditions and its action is to prevent operation of the power swing blocking
feature during such conditions (see Figure 60).
5.16.30 Scheme logic control of auxiliary relay outputs
All output contacts from the relay have fleeting closure which lasts for
approximately the duration of the line fault, with the exception of the voltage
transformer supervision contact (97X–1) and the relay inoperative alarm contact
(97Y–1) both of which are sealed in.
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