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TYPE 16—Two-Wire Reverse Polarity Minute Impulse (59th Minute) with
12-Hour Correction
There are two types of type 16 secondary clocks: the two-wire reverse polarity minute
impulse covered on this page, and the three-wire minute impulse on the previous page.
Each hour, from the 59th minute through the 49th minute, a two-second pulse is transmit
-
ted between lines AB and PC (with AB positive with respect to PC), starting at the 58th
second and ending at 00 second. This causes all clocks to advance each minute. From the
50th minute to the 59th minute, transmission is such that PC is positive with respect to
AB. Clocks that are less than 10 minutes fast stop at the 59th minute, since their SR con
-
tacts transfer and require a pulse with AB positive with respect to PC to advance at this
time.
Each hour, starting at the 59th minute and 10 seconds, 20 rapid pulses at 0.5Hz are trans
-
mitted with line PC positive with respect to AB. Slow clocks are advanced at this pace.
Every 12 hours, from 6:02 through 6:44, 23 rapid pulses are transmitted each minute, line
PC positive with respect to line AB, with transmission starting at 10 seconds after and
ending at 55 seconds after. Clocks that are more than one hour slow are rapidly advanced
to the correct time.
Manual clock advances and daylight saving advances cause the master clock to transmit
62 pulses (one second ON and one second OFF at 0.5Hz). The first five pulses are trans-
mitted with line AB negative with respect to line PC. Normal minute pulses are inhibited
during these pulses. Types of secondary clocks covered by this configuration are the
same as under three-wire on the previous page.
B-22
24A715/24A715M Master Clock Installation Manual
12345678
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.
+
AB
PC
1
= V250LA4 MOV or equal
1
2
= 1N4004 diode or equal
2
24Vdc INPUT
Figure B-19
Two-Wire Minute Impulse (59th Minute) with 12-Hour Correction