Electric oven theory of operation – XLT XD-9007A (ELEC Oven Version – B1, AVI Hood Version – B) User Manual

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The first part of the Theory of Operation explains how electrical power is delivered to the

oven and initial sequences when the main operator switch is turned on. The remainder of the The-
ory of Operation section explains the function of components in alphabetical order. These compo-
nents are also listed on the schematic.

Line voltage for Standard Ovens is assumed to be 208/240/480 VAC, 3Φ, 60 Hz.

Line voltage for World Ovens is assumed to be 380 VAC, 3Φ, 50 Hz.

Power originates at the electrical connection on the wall. Line voltage is then carried into

the oven through the power cord to the Power Block (PB). A wire connects Line 2 to the Terminal
Strip (TS), which serves as a “neutral” for the single phase components. Several jumpers are used
to bridge along the TS to make connection points for multiple “neutral” lines from all single phase
components inside the Control Box and the Main Fan Motor (M1). A wire connects line 1 to Ter-
minal T11 on Relay 1 (R1) and acts as the “hot” leg for all of the single phase components. From
there, a wire connects single phase power through the normally closed High Limit Switch (S3),
then through Circuit Breaker 1 (CB1), then to the Main Switch (S1). Three phase power is applied
to Contactors 1 & 2 (C1 & C2) through Circuit Breakers 5 & 6 (CB5 & CB6) and the PB. Unless
the power supply on the wall has no power, the single phase and three phase circuits just described
have power at all times.

When S1 is turned on, line voltage will be carried thru the switch simultaneously to three

locations via two parallel circuits:

Terminal T6 of R1

Centrifugal Switch (S2) located in M1


Power Supply (PS)

When the Main Switch (S1) is turned on;

1. The Oven Fan Motor (M1) located in the Back Wall will run.
2. The Fans (M3) located on the Control Panel will run.
3. The Temperature Control (TC) should display both the actual and set-point temperatures.
4. The Conveyor Control (CC) should display the belt time.
5. The conveyor belt should move.