Lathem Dukane 24A715 - Manual (Page 70)

TYPE 22—Dukane Synchronous Wired (24A Series, Obsolete)
During normal operation, either 24Vac or 120Vac is furnished to the clock run motor
through relay K6. Power is removed from the run motor during power failures, while K6
de-energizes during fall daylight saving changes.
Each hour from HH:57:00 to HH:57:55, relay K5 energizes to furnish a 24Vdc signal
to the correction coil. This 55-second signal causes all secondary clocks to advance to
the 58th minute, thus synchronizing the seconds and minutes with the master clock.
The 12-hour correction occurs twice daily, beginning at 5:59:00. Every other minute
from 5:59:00 through 6:19:55, relay K5 energizes to furnish eleven 24Vdc signals of
55 seconds duration to the clock correction coils (5:59:00 to 5:59:55, 6:03:00 to 6:03:55,
6:19:00 to 6:19:55).
These eleven signals cause all secondary clocks up to 11 hours behind to advance to
5:58:00. Hours, minutes, and seconds are synchronized to the master clock after the next
hourly correction at 6:58:00. Clocks more than 11 hours behind prior to a 12-hour correc-
tion require two 12-hour corrections to advance to 5:58:00.
B-28 24A715/24A715M Master Clock Installation Manual
1 2 3 4 5 6 7 8
CLK1 OR CLK2
x
x
x
x
RELAY
K6 (K8)
RELAY
K5 (K7)
I I
MASTER CLOCK
FIELD CONNECTIONS
X = Normally open contact
I = Normally closed contact
10 ASB MAX.
TO CLOCK
RUN MOTOR
TO CLOCK
CORRECTION COIL
24Vac/120Vac
2
–
2 = 1N4004 diode or equal
1 = V250LA4 MOV or equal
1
10 ASB MAX.
24Vdc
+
Figure B-25
Dukane Synchronous Wired (24A Series, Obsolete)