Middleby Marshall PS528 (Triple), PS528E Door Safety Switch, Blower Switch, Heat Switch

SECTION 3

OPERATION

II.COMPONENT INFORMATION AND LOCATION (Figures 3-1 and 3-2)

A. Door Safety Switch

The Door Safety Switch is located at the lower right side of control panel opening. Opening the control panel door permits this switch to open, disconnecting power to all electrical controls.

CAUTION

Do NOT touch the wires going to this safety switch. Current is always present.

B. Blower Switch

The blower switch has two positions. The switch must be “ON” or “I” for the main blowers to come on and permit the oven to run. The fan circulates the air throughout the oven and must stay on during baking and during the cool down cycle above 200°F (93°C) to prevent blower bearing damage. To protect the blower motor and bear- ings a thermostatic override is built into the oven. If the temperature inside the oven is over 180°F (82°C) the

main blower will continue to run after the blower switch is turned to the “OFF” or “O” position.

C. Heat Switch

Turning the HEAT switch to “ON” or “I” will energize the electric heating system. This switch is in series with the blower fan motor and high temperature override switch. Both switches must be closed before the heating elements an be energized.

D. Temperature Controller

The temperature controller is a solid-state, PID type to maintain the operator-set temperature. The temperature controller continuously monitors the oven temperature and turns on the modulating solid state relay controller. The heat is on for the time required to maintain a constant oven temperature.

The temperature controller contains a low-limit switch which allows the oven to cool down to 200°F (93°C) before shutting off the blower. A high-limit indication (ALM 1) will appear on the display if the oven reaches 650°F (343°C).

Figure 3-2. Interior View of Control Console

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