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Figure 8-36.—Schematic wiring diagram of a typical telephone dialer. | Up
Construction Electrician Intermediate - Electricity handbook for electricians | Next
Figure 8-39.—Wiring diagram for a switched-voltage trigger. |
2. When FIRE-channel priority seizure has
occurred, the dialer overrides its normal end-of-cycle
stop and runs for another full cycle. This ensures
transmission of the entire priority program, even if the
FIRE-channel take-over occurred near the end of a
BURGLAR-channel cycle.
3. Even if the dialer has stopped after transmitting
the full BURGLAR-channel program and the burglar-
alarm input is still present, an input on the FIRE channel
causes immediate transmission of the FIRE-channel
program.
Each of the channels of the dialer can be triggered
by a switched dc voltage, a dry-contact closure, or a
dry-contact opening. The trigger inputs may be either
momentary or sustained. In either case, the dialer
transmits its full program, then stops and resets itself.
An input that is still present when the dialer stops must
be removed briefly and then applied again to restart
transmission on that channel. A sustained input does
not make the dialer transmit or interfere with normal
use of the telephones, nor does it interfere with
triggering and operation of the dialer on its other
channel.
When available, an appropriate dry-contact
closure should be used instead of a switched voltage
for the dialer-trigger input. Figure 8-37 shows the
preferred connections for a typical telephone
dialer.
Figure 8-37.—Preferred connections for a typical telephone dialer.
8-21
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