SERVICE MANUAL R5888C
QUADRAMHO Chapter 2
Page 61 of 74
5.16.40 Relay inoperative alarm 97Y–1
Under healthy operating conditions this contact is held open. The following
conditions will cause the relay to close the contact to give a “Relay Inoperative”
alarm and will also extinguish the “Relay Available” LED.
a) Loss of any internal voltage rails (+24V, +12V, +5V and –12V).
b) Loss of main dc input voltage to relay.
c) Removal of heavy duty connector 1Z (See Note 4, Figure 67, Appendix A).
d) Connection of socket 2, pin 2 to pin 1 (See Section 3.8).
e) Loss of internal clock signals
f) Loss of reference voltages for level detectors.
g) Code selection number (XY) of scheme logic module not that of a valid scheme.
h) Microcomputer failing to run through program loop.
I) Failure of comparator during self test routine (See Section 4.8.5).
j) Operation of unit with SW3 set to right hand position.
k) Operation of the miniature circuit breaker (mcb).
5.16.41 Scheme logic control of indication
A main group of eight red light emitting diodes (LED) is provided on the left hand
side of the scheme logic module. A further single red LED is provided on the right
hand side of the scheme logic module for power swing blocking indication.
The operation of the green “Relay Available” LED, fitted to the auxiliary relay
module is described in Section 4.8.25.
Operation of the LED’s is controlled by scheme logic software. Each LED is
separately latched by software so that the appropriate ones remain energised after
the fault has been removed. The indications may be reset manually by pressing the
reset pushbutton on the front of the module. The top seven LED’s of the main group
of eight and the PSB LED are also automatically extinguished and updated with
new information when the relay issues a trip signal. (Except when the trip is due to
SOTF action). Consequently the indication always gives the information relating to
the last fault condition. When the relay is initially energised, the LED’s are all
illuminated for approximately half a second, before being extinguished.
This feature demonstrates that the relay has established correct operation and that
the LED’s function correctly. If switch SW5 is set in the right hand position and the
reset pushbutton depressed and released, a self check is carried out on the relay
comparators. During the running of the self test, the main group of eight LED’s is
illuminated. This lasts for approximately 85ms which is sufficient to verify that the
LED function correctly.
The equivalent logic diagram of the software implementation of the indications is
shown in Figure 76.
After the occurrence of a fault, one of three distinct conditions will have been
recorded by the top seven of the main group of LEDs, a normal 3 zone distance
scheme action, a SOTF operation, or an aided trip action. How each of these
conditions may be interpreted by the LED is described in the following sections.
a) 3 zoned distance scheme action recorded on LED display.
This condition may be identified by the absence of the SOTF and the aided trip
LED being energised. The interpretation given to the remaining LEDs is then as
follows:
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