XLT XD-9006A (GAS Oven Version – C, AVI Hood Version – B) - Manual (Page 11)

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GAS OVEN THEORY OF OPERATION
M4 - (Australia ovens only) - The Burner Blower Motor is a dual-voltage, shaded pole motor that
supplies air for combustion. A Centrifugal Switch (S4) is physically mounted internally to prove
rotation.
PS - The Power Supply rectifies line voltage to 24 VDC, and supplies power to the Conveyor Con-
trol (CC). A 4 amp fuse is used to provide over current protection, which is mounted on the PS
itself. There are no other fuses used anywhere else.
PU - The Pick-Up is physically mounted within the Conveyor Motor (M2) and utilizes hall effect
technology integral to the M2 to monitor the rotation speed. The hall effect signal is transmitted to
the CC, which converts it into linear travel speed of the conveyor.
R1 - R1 is a 30-minute off delay relay which functions as a cool down timer. Applying power to
T6 activates the relay, which sends a voltage signal out from T9. When power is removed from
T6, voltage continues from T9 for 30 minutes. T9 supplies voltage to the Main Fan Motor (M1)
through a Circuit Breaker (CB2), and also supplies voltage to the FPPG (M3) Fan. M1 and M3 are
the only components that will continue to operate for 30 minutes after S1 is turned off. The off
delay relay is a safety feature to allow the oven to cool down to room temperature, and to eliminate
heat stress on the components of the oven.
R2 - Proving Relay (Australia ovens only) - The proving relay is a safety device to ensure that the
Temperature Control (TC), Signal Conditioner (SC), and the Burner Control (BC) do NOT have
24 VAC until the Burner Blower Motor (M4) is spinning at full speed. The proving relay proves
that there is no M4 rotation. Once M4 achieves full RPM, R2 works in conjunction with the Cen-
trifugal Switch (S4) to prove that there is fan rotation.
24 VAC is supplied by the XFMR to terminal 6 on R2. At this point in time, this serves no
function. An additional wire connects terminal 6 with the common switch contact of S4. When
the motor is at rest, 24 VAC is carried through NC switch contacts in S4 to terminal 9 on R2. At
this point in time, this also serves no function. Another wire connects terminal 9 to terminal A to
activate the relay coil. When the coil in R2 is activated, the relays switch state. When that hap-
pens, then 24 VAC is carried from terminal 6 to terminal 9, which supplies power to terminal A in
order to keep the coil energized. These events occur in a very short amount of time.
When M4 achieves full RPM, S4 will change state. Voltage will then be applied to termi-
nal 4 of R2. Since R2 is energized, terminal 4 is connected to terminal 7, which supplies 24 VAC
to TC, SC, & BC.
If the main switch is cycled, the XFMR will disable and not supply the proving relay volt-
age and the proving relay will go back to NC. Before reactivating R2, M4 must come to a com-
plete stop or S4 will not go back to NC to reactivate proving relay.
RP – The Rectifier Plug has an integrated full-wave bridge rectifier circuit. It converts 24 VAC
from the Burner Control (BC) into 22 VDC that is sent to the Multi-Valve (V1-V2).