TYPE 18—National Synchronous Wired

For a list of Type 18 clocks, see the chart on the first page of this appendix.

Relay K5 is normally operated to power the clock run motors. Each hour from HH:00:00 to HH:00:28, relay K6 is operated to power the clock correction coils for 28 seconds and cause hourly corrections. Every 12 hours, from 6:00:00 to 6:27:27, relay K6 is again operated to power the clock correction coils for 27 minutes, causing 12-hour correction.

Manual clock corrections can be issued from the master during any even-numbered minute except 00.

X = Normally open contact

I = Normally closed contact

1 = V250LA4 MOV or equal

RELAY

K6 (K8)

x

CLK1 OR CLK2

1 2

10 ASB MAX.

SOURCE

POWER

 

 

RELAY

 

 

 

 

 

K5 (K7)

 

 

 

 

I

 

 

I

 

 

 

x

 

 

x

 

 

 

 

 

 

 

 

MASTER CLOCK

3

4

5

6

7

8

FIELD CONNECTIONS

 

 

 

 

 

 

 

 

 

 

 

 

CORRECTION COIL

 

 

 

 

 

 

1

 

 

 

 

 

 

RUN MOTOR

1

 

 

 

1

 

 

 

 

 

 

 

 

RETURN

Figure B-21

National Synchronous Wired

B-24

24A715/24A715M Master Clock Installation Manual