Cleveland steamcraft 21-CET-8, Service Manual, Page: 71 / 139

Page 64 Model 21 -CET-8 Service Manual
Timer Circuits
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.
CIRCUIT OPERATION
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 .
MANUAL Mode Circuit Operation
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 contro lled by the action of the float switches, which
open and dose as the generator water level fluctuates.
Printed 12/90