Railway Equipment 934, Operating Manual

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P/N R9340-0104 29 © 2010 RAILWAY EQUIPMENT CO.
REV B
5/11
D. OPERATION
With switch SS1 in the “auto” position, the unit can be activated by applying a circuit
closure between terminals TS1-1 and 2. If the outside temperature is above set point, the
unit will not start a snow melt sequence but will turn on the “indication” LED and
provide a relay contact closure between TS1-3 and 4 to indicate to the remote station that
the unit is operational.
If a circuit closure exists between TS1-1 and 2, and the air temperature is below set point,
the unit will begin a snow melt sequence. The unit executes a 0 to 300 sec. time delay
depending on the setting of the DELAY START TIMER. Then, a 10-sec. audible tone
sounds as a warning that the blower motor is about to turn on.
The airflow switch is checked to see if it is closed. If it is, the blower will display: SAIL
ON FAULT.
If the airflow switch is open the motor will turn on. After the blower motor is turned on,
the airflow switch is monitored. It closes if airflow is normal. If it does not close within
10 sec. after blower turn-on the blower displays SAIL OFF FAULT. When the airflow
switch closes a 30 second prepurge time will start. After the prepurge time is completed,
The heater contactor is activated.
When the contactor is activated the “indication” switch closure is established between
TS1-3 and 4. Heater current is checked at this time, and if an open heater is detected, a
fault will be displayed and indication will drop out, but the unit will continue to run. The
unit will run for a period of time determined by the setting of the RUN TIMER. If the
run timer is set at “0” the unit will continue to run until the circuit closure between TS1-1
and 2 is removed.
SNOW DETECTOR OPERATION. If the unit is operating with one or two optional
snow detector assemblies and moisture is detected by either (or both), a snow melt
sequence will begin, provided that the air temperature is below the set point. The unit
will start as described in Section IV Part B under (Select Snow Timer).
.
V. SEASONAL MAINTENANCE
A. SPRING:
1. Turn off electric power at source.
2. Disconnect and remove the control module. Store in a clean, dry place.