SERVICE MANUAL R5888C
QUADRAMHO Chapter 2
Page 31 of 74
Note: No contact will close until the appropriate SW switch is to the right and
the reset button is pressed.
4.9.47 The auxiliary relay module RVC 53
The two main functions of this module are to produce all the relay output contacts
and to produce a number of test signals at the test socket SK2 on the relay facia.
These functions are illustrated on the right and left, respectively, of the block
diagram, Figure 27.
The eighteen auxiliary relay units contained in this module are controlled directly
by the scheme logic module. The majority of the contacts are single, normally open
type, however, CTX, TRIP A, TRIP B, TRIP C, TRIP 3 PH and ANY TRIP each provide
two normally open contacts. The Relay Inoperative alarm contact is a single
normally closed type.
All contacts have the following rating:
Make and carry for 0.2s 7500 VA with maxima of 30A and 300V ac or dc.
Carry continuously 5A ac or dc.
Break: ac 1250VA
dc 50W resistive with maxima 5A, 300V
25W L/R =0.04s
Each contact is electrically isolated from all other contacts and ground to a proof
voltage of 2kV rms for 1 minute and can withstand 1kV for 1 minute across its
normally open terminals.
During commissioning of Quadramho it is possible to inhibit the operation of the
contacts in two ways. The first is to replace the heavy duty test plug 1Z with a plug
with an open circuit on 1Z10. This breaks the “output relays common” connection
to the relay coils. The second way is to connect pin 1 to pin 2 of the test socket
SK2 via a wire link. This opens the solid state switches in the module which
operate the relay coils. On the diagram these elements are represented by a set of
normally closed contacts linked to pin 1 of SK2.
Whenever the relays are inhibited the LED labelled “Relay Available” on the relay
facia and D on the diagram, is extinguished and the Relay Inoperative alarm
contact closed. This also happens when the relay is set to a test option or when an
internal fault in the relay is detected by the continuous monitoring circuits.
Further details of this feature are given Section 5.16.40.
Eighteen of the pins on the test socket, SK2, take outputs via a buffer circuit,
labelled “B” on the diagram, from the scheme logic module. Each output consists
of a pull down transistor and a pull up resistor of 22kΩ. The logic levels of these
outputs is either 0V or +24 V. These outputs are not inhibited with the auxiliary
relay. Five other outputs are taken to the test socket via 10KΩ resistors. These are
used to monitor the dc rails of the relay and the highest division of the master clock
frequency, MCK/28.
Since all the pins on the socket, except 0V on pin 2, have resistors connected in
series with them it is impossible to damage Quadramho by inadvertently shorting
together any number of pins via a wire link.
4.9.48 Power supply unit ZRE 01
The single pcb power supply unit is contained within a ventilated enclosure which
is mounted on the back of Quadramho. It can be detached from the main relay
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