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 transmitted 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 contacts 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 transmitted 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 transmitted 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.

X = Normally open contact

I = Normally closed contact

1 = V250LA4 MOV or equal

2 = 1N4004 diode or equal

 

 

 

RELAY

 

 

 

RELAY

 

 

K5 (K7)

 

 

 

K6 (K8)

 

 

 

 

 

 

 

 

x

 

I

 

 

I

 

 

 

 

 

x

 

 

x

 

 

CLK1 OR CLK2

 

 

 

 

 

 

 

MASTER CLOCK

1

2

3

4

5

6

7

8

FIELD CONNECTIONS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

AB

10 ASB MAX.

 

 

 

 

 

 

 

1

+

 

 

 

 

 

 

 

PC

24Vdc INPUT

 

2

 

 

 

 

 

 

–

 

 

 

 

 

 

 

 

Figure B-19

Two-Wire Minute Impulse (59th Minute) with 12-Hour Correction

B-22

24A715/24A715M Master Clock Installation Manual