Timer Circuits; Circuit Operation; Manual Mode Circuit Operation - Cleveland steamcraft 21-CET-8 Service Manual

Page 64 Model 21 -CET-8 Service Manual

Timer Circuits

CIRCUIT OPERATION

MANUAL Mode Circuit Operation

Printed 12/90
SteamCraft 3.1's come with cither of two types of timer control circuits, electronic
key pad or mechanical dial.
• In units with the electronic key pad timer, a 24 VAC transformer supplies control
power to the timer. The compartment thermal switch prevents countdown of the
timer until the temperature in the compartment rises above 190°F. A buzzer in the
timer panel signals the end of the cooking cycle.
• Units with the mechanical dial timer use a separate 3-second timer and buzzer to
signal the end of the cooking cycle.
This section describes circuit operation during a typical steaming cycle in manual
mode. The circuit operations specific to timed mode are also explained- For clarity
while reading the description, refer to the block diagrams. Figure 5-1 or 5-2, and the
schematic and wiring diagrams in Chapter 6.
Before starting the manual mode steaming cycle, the SteamCraft 3.1 controls are set
as follows.
• The main power switch is in the ON position.
• The water supply valves to the unit are open.
• The ON/OFF switch is in the OFF position.
• The TIMED/MANUAL switch is in the MANUAL position.
• The timer is set to 0.
With these control settings, the SteamCraft 3.1 component conditions are as follows.
• The steam generator is empty.
• The water fill, condenser, and rinse solenoid valves are dosed.
• The drain solenoid valve is open.
• The high level float switch is dosed.
• The low level float switch is open.
• The high temperature limit switch is dosed.
• The compartment thermal switch is open (key pad units only).
With the TIMED/MANUAL switch in the MANUAL position, the ON/OFF switch
controls power to the operating circuits. Switching the ON/OFF switch to the ON
position:
1. Energizes the red indicator on the ON/OFF switch.
2. Provides power to one side of the condenser and drain solenoids, heater contactor,
and the TIMED/MANUAL switch. With this switch in the MANUAL position,
component operation is controlled by the action of the float switches, which
open and dose as the generator water level fluctuates.