P.O. ENGINEERING DEPT.
ENGINEERING INSTRUCTIONS
MISCELLANEOUS
TIME
B 1303
Issue 5, 3.6.59
ELECTRICAL CLOCKS - PULSE TYPE
Clock-unit, GMT 35
1. General
Clock-unit, GMT 35 is used in conjunction with a master clock (Clock No. 36) to facilitate the distribution of pulses at offices where
30 second pulses only are required or where the 30 second pulse clock capacity of an existing Clock-unit,
GMT 34 must be exceeded. The unit is designed for 24V working and is wired to
Diagram GMT35. The layout of the apparatus is shown on Drawing
P/T 79 and installation details are given in B 3301.
2. Description
The unit, which is wired for its ultimate capacity, is fitted initially with sufficient apparatus to operate twenty
30 second pulse clocks, i.e. two circuits of ten. The unit has a maximum capacity for sixty
30 second pulse clocks.
3. Additional apparatus
Resistor R1 and R3 (and resistor R2 when required) and additional apparatus for increasing the capacity of the unit should be
requisitioned separately and fitted locally as indicated on Diagram GMT35. Resistor R2 is required to limit the current through relay AR to 10mA when the unit is used with voltages higher than 24V.
4. Large installations
When the number of pulse clocks to be installed exceeds the capacity of one unit, an additional Clock-unit, GMT 35 should be provided and connected to the first unit by wiring in parallel the pulse relays connected to tags 13. Tags 2, 3 and
11 of the additional unit should be left disconnected.
5. When used in conjunction with Clock-unit, GMT 34 (see B 1302) the pulse relays should be connected in parallel, i.e. tag 13 on Clock-unit, GMT 35 should be connected to tag 5 on Clock-unit,
GMT 34. In the additional Clock-unit, GMT 35 tags 2, 3 and 11 should be left disconnected.
Diagrams
Pictures
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