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TYPE 21—Cincinnati D1
Every minute, from HH:MM:58 to HH:MM:00, relay K6 is activated, causing an output
on line A for two seconds. During minutes 07 through 58 only relay K6 activates, causing
the output on line A to be 24Vdc.
During minutes 59 through 06, relay K5 is also activated, together with relay K6, causing
the output on line A to be 60Vdc to advance all clocks. Clocks that reach the 59th minute
ahead of the master clock stop, since at this time they respond only to the 60Vdc pulses.
Hourly corrections occur during minute 59 from HH:59:l0 through HH:59:49. During
hourly corrections, 20 rapid pulses of 24Vdc are output on line A at 0.5Hz, causing all
slow clocks to rapidly advance. All secondary clocks at minutes 59, 00, or 0l do not re
-
spond to the 24Vdc, but hold until the 60Vdc signal advances them. Manual clock
advances cause a total of 62 pulses on the A line; the first five are 60Vdc and the remain
-
der are 24Vdc.
24A715/24A715M Master Clock Installation Manual
B-27
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CLK1 OR CLK2
x
x
x
x
RELAY
K6 (K8)
RELAY
K5 (K7)
II
MASTER CLOCK
FIELD CONNECTIONS
X = Normally open contact
I = Normally closed contact
10 ASB MAX.
A
COMMON
2
= 1N4004 diode or equal
2
24Vdc
COMMON
60Vdc
TO CLOCKS
Figure B-24
Cincinnati D1