SERVICE MANUAL R5888C
QUADRAMHO Chapter 2
Page 62 of 74
The A, B and C LEDs indicate which phases were involved in the fault that
caused the circuit breaker to be tripped. This can be accompanied by the Z2 or
Z3 LED to show that the fault was cleared in time delayed Zone 2 (Z2t) or time
delayed Zone 3 (Z3t). If neither Z2 nor Z3 are lit, the fault was in Zone 1.
As an example, consider the case of an A, C display given after a fault
condition has occurred. This shows that a C–A fault has taken place, was
detected and cleared successfully in Zone 1 time. It may be interpreted that the
fault did not remain “On” for a time long enough to run out the Z2t or Z3t
timers, since neither the Z2 nor Z3 LEDs were energised.
b) Switch on to fault (SOTF) action recorded by LED display.
A SOTF trip condition is recorded by the LED labelled SOTF on the module
nameplate. The previous indication on the display is not extinguished for SOTF
trips, permitting identification of the faulted phases and zones for SOTF trips
occurring in auto reclose conditions. If the LED display is extinguished prior to
the SOTF trip, then only the SOTF LED will be illuminated.
c) Aided trip action recorded by the LED display.
An underreaching scheme (PUR), overreaching scheme (POR) or blocking
scheme (BLOCK) trip action aided by a signalling channel for end zone faults,
is recorded by the energisation of the “aided trip” LED. Such an action is also
accompanied by the energisation of one or more of the A, B and C LEDs to
show which phases are involved in the fault (except for weak infeed aided trips,
when only the “aided trip” LED is illuminated). Note that under normal aided
trip conditions and when the fault has been successfully cleared, neither of the
Z2 or Z3 LED are energised. In the case of the blocking scheme, aided trip
action signifies the absence of a blocking signal from the signalling channel.
5.16.42 Test facilities
A comprehansive monitoring system is provided to enable the features of the relay
to be thoroughly tested during commissioning, routine maintenance and fault
finding operations. The monitoring system includes a 25 way test socket from
which power supply voltages, clock pulse frequency, synchronous polarising,
switch-on-to-fault and many more internal features can be checked while the relay
is on the relay panel and the line is energised. All these outputs are protected
against accidental short circuits. See Table 9 for details.
In addition, a large number of test options may be selected by the code selection
switches X and Y. The test options allow all inputs to be the scheme logic, such as
individual comparators, level detectors, timers, settings, opto isolators, etc., to be
read during secondary injection and other off-line tests on the relay. The logic
states of these inputs are displayed on the eight indication LED and are also output
via the 25 way socket on the auxiliary relay module.
Further test options enable relay outputs to be tested. Switches SW1 and SW8 are
set on or off and when the pushbutton is pressed, corresponding outputs are sent
via the relevant relay output contacts and test socket terminals. A trip test of the
circuit breaker, or test of the signalling channel, can be performed conveniently by
this method.
An additional 9 way test socket is fitted to the scheme logic module to allow the
code selection switches and the pushbutton to be overridden electrically.
This permits the use of a programmable secondary injection test set so that most
commissioning, routine maintenance, testing and fault finding operations can be
performed automatically to save line outage time.
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