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 respond 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 remainder are 24Vdc.
X = Normally open contact
I = Normally closed contact
2 = 1N4004 diode or equal |
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| RELAY |
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RELAY |
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| K5 (K7) |
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K6 (K8) |
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| I |
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CLK1 OR CLK2 |
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| MASTER CLOCK |
1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | FIELD CONNECTIONS |
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10 ASB MAX.
60Vdc
24Vdc
A
2
TO CLOCKS
COMMON | COMMON |
Figure
Cincinnati D1
24A715/24A715M Master Clock Installation Manual |