CHAMPION USN72 - Manual (Page 71)

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Part 5: BASIC SERVICE
5.3 Component Repair and Replacement (Cont.)
5.3.20 Control Circuit Explanation (Cont.)
D.) TSK - The TSK is the thermal kill switch that prevents the machine from operating when the
final rinse water in the booster is below 180 ° F. The N.O. contacts of this thermostat open on
temperature rise. When a fault occurs the indicator light TKL illuminates and the hold-in circuit
drops out. At the beginning of the day the water in the booster is cold and the steam valve is off.
If the rinse tank is filled with water and the doors are closed the valve BC1 will energize and
allow steam to flow through the heat exchanger in the booster. After a short period of time the
water in the booster will heat enough to satisfy the thermostat. If the machine has sat idle for a
while the water in the piping may cool enough to cause the thermostats N.C. contacts to open.
This condition can be corrected by holding in the START button. This causes the relay 4CR to
de-energize and power to pass through the N.C. contacts of 4CR to the final rinse valve FRV.
When the thermostat is satisfied the indicator light TKL will extinguish and the START button
can be released. If all other conditions in the pump and conveyor hold-in circuit are satisfied the
machine will automatically restart.
E.) 2CR and 3CR N.O. - The 2CR and 3CR N.O. contacts prevent the pumps from running if
there is not water in either of the two tanks. The circuit controlling these contacts have a 5 second
delay in them to allow for the ships rolling and pitching without false stopping.
F.) START BUTTON - The start button has two functions in this machine. The first, and most
obvious, is to begin the machine operating. If all other devices in the hold-in circuit are satisfied
the N.O. contact of contactor 1M will seal in the START button once it is released. The second is
to allow water to flow by the thermal kill switch after the switch has shut down the pump and
conveyor hold-in circuit. The start button acts as priming device to get hot water flowing past the
TSK so the switch will close again.
G.) STOP BUTTON - The STOP button will cause the N.O. contact of the contactor 1M to open
after the machine has begun operating. This in turn causes the hold-in circuit to drop out and the
machine to cease functioning.
H.) 1CR N.O. - The N.O. contact of 1 CR opens whenever either access door is opened. The
pump and conveyor hold-in circuit will not function until the doors are closed. This contact also
prevents the final rinse valve, FRV, from energizing and spraying hot water until the doors are
closed. This contact also will not allow any steam valve to energize when the doors are open.
This will lessen the chance that someone will get burned by a tank heater coil while cleaning the
machine.