Middleby Marshall PS570, PS360, PS200, PS555, PS220, PS224 PS310 SEQUENCE OF OPERATION F. High Limit

e.For ovens with an On-Off gas regulation sys- tem (with solenoid valve): Temperature Controller terminals 4 & 5 (power for the primary relay contacts for the high flame solenoid valve).

For PS360EWB ovens with a modulating gas system and Temperature Controller P/N 32571: Temperature Controller terminals 4 & 5 (input signal to amplifier board).

For all other ovens with a modulating gas sys- tem: Temperature Controller terminals 15 & 16 (input signal to amplifier board).

In all ovens, the temperature-sensing thermocouple(s) send a millivolt signal to the temperature controller. As long as the temperature inside the oven is below the set point of the Temperature Controller, the Controller will do the following:

1.For ovens with an On-Off gas regulation system: If the temperature sensed by the thermocouple(s) is below the set point on the Temperature Controller, the Controller energizes the high flame solenoid. When the solenoid is energized, the solenoid valve permits 100% gas flow. Power to the solenoid is cut when the temperature reaches the set point, which closes the valve. This permits on-off gas flow to the burner.

When power is cut to the high flame solenoid, the burner will remain ON in the low flame mode. When the temperature drops a few degrees, the Tempera- ture Controller will again energize the high flame solenoid, which opens the valve and restores gas flow to 100%.

An indicator on the Temperature Controller will show whether the high flame solenoid is energized (or whether the burner is activated, which is effec- tively the same). This indicator varies by Tempera- ture Controller model. Refer to the instructions for the appropriate Temperature Controller for an illus- tration and description of this indicator.

2.For ovens with a modulating gas system: In re- sponse to the signal from the thermocouple(s), the Temperature Controller sends a 4-20mA signal to the amplifier board. The amplifier board converts this to a 0-20VDC signal which is sent to the modu- lating gas valve. The valve opens or closes in pro- portion to the signal from the amplifier board, al- lowing the gas flow to be regulated as required from 0-100%.

An indicator on the Temperature Controller will show whether the burner is activated. This indica- tor varies by Temperature Controller model. Refer to the instructions for the appropriate Temperature Controller for an illustration and description of this indicator.

SECTION 1 - SEQUENCE OF OPERATION

F.High Limit

NOTE: Most PS200-Series and PS360-series gas ov- ens use the high limit feature of the Temperature Con- troller. All other oven models use a separate High Limit Control Module. Refer to the wiring diagram for the appropriate oven model to check whether a separate High Limit Control Module is used.

The high limit relay will shut the oven burner OFF:

1.If the high limit thermocouple senses an oven tem- perature above 650°F.

2.If the signal from the high limit thermocouple is lost.

An indicator on the Temperature Controller will show a high limit condition. This indicator varies by Tempera- ture Controller model. Refer to the instructions for the appropriate Temperature Controller for an illustration and description of this indicator.

G.Cooldown

NOTE: PS200VL-series ovens do not include a cooldown feature.

When the heat and blower Switches are turned OFF the cooldown relay will allow the blowers to remain ON until the oven temperature falls to 200°F (93°C).

During cooldown, the Temperature Controller will con- tinue to show the oven temperature.

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