TYPE 15—Straight Frequency

Clock correction and bell circuit operations are generated by sequentially applying various frequencies onto the 120Vac. Each bell and clock correction circuit has its own frequency and a receiver circuit that applies the associated bell or clock frequency (3,510Hz normally used for clock signals). The daylight saving feature advances clocks correctly but has no means, other than normal 12-hour correction, to correct secondary clocks at 2:00 AM. The time sequence of applying the frequencies to the 120Vac is shown below and is controlled by the bell and system relays in the master clock.

Relay

From

To

Bell Circuit 1

HH:MM:00

HH:MM:05

Bell Circuit 2

HH:MM:05

HH:MM:10

Bell Circuit 3

HH:MM:10

HH:MM:15

Bell Circuit 4

HH:MM:15

HH:MM:20

Bell Circuit 5

HH:MM:20

HH:MM:25

Bell Circuit 6

HH:MM:25

HH:MM:30

K5

(hourly correction

HH:57:54

HH:58:02

K5

(12-hour correction)

5:57:54

5:58:08

K6

(hourly and 12-hour corr.)

HH:57:00

HH:59:00

K6

(bells)

35th second of minute

30th second of

 

 

previous to bell

bell time

Note:

Bells must be programmed one minute ahead of desired time. Bells are inhibited during the 58th minute and will not work during manual clock corrections either.

X = Normally open contact

I = Normally closed contact

1 = V250LA4 MOV or equal

RELAY

 

 

RELAY

 

 

 

 

 

 

K5 (K7)

 

 

 

 

K6 (K8)

 

 

 

 

 

 

 

 

 

x

 

x

I

 

I

 

 

 

 

 

 

 

 

x

 

 

 

CLK 1 OR CLK2

 

 

 

 

 

 

 

MASTER CLOCK

1

2

3

4

5

6

7

8

FIELD CONNECTIONS

10 ASB MAX.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

120Vac

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

3,510 HZ SIGNAL

 

 

 

 

 

 

 

 

GENERATOR

AC RTN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GENERATOR

 

 

 

 

 

 

 

 

 

PRESTART

Figure B-17

Straight Frequency

B-20

24A715/24A715M Master Clock Installation Manual