Vulcan-Hart VC4G Service Manual page 49

VC4G & VC6G SERIES FULL SIZE CONVECTION OVENS - ELECTRICAL OPERATION
3. Power switch (S1) turned ON.
A. Component cooling fan energized.
B. Power ON light (Amber) comes ON.
C. Power to one side of the following
components: Normal ROAST timer terminal
1, ROAST & HOLD timer terminal 1,
transformer primary (T1).
NOTE: Power is available to the oven light switch
(wire #20) to turn the oven cavity lights ON when the
light switch is turned ON; and power is available to the
normally open N.O. side (wire #28) of the door switch
contacts and connects power to additional
components when the door switch contacts are
CLOSED (door closed).
1) Transformer (T1) energized.
a. Power (24VAC) to one side of the
following components: heat relay
(R3) normally open (N.O.)
contacts, high limit --- connected
through the normally closed
(N.C.) contacts to the 1st valve
(safety) on the dual solenoid gas
valve.
a)
NOTE: Gas does not flow to the burner until the 2nd
valve (main) is energized.
2) With door switch closed, power is
applied to motor speed (Hi/Low) relay
(R1) normally open (N.O.) contacts
and hold relay (R2) common (C).
a. Motor speed relay (R1) is
energized through hold relay (R2)
normally closed contacts (N.C.).
Relay contacts (R1) change state
and the normally open (N.O.) set
of contacts close.
a)
b)
c)
1st valve (safety) on the gas
valve energized.
Power is connected through
the function switch (S3)
contacts and convection fan
motor is energized (fan
speed hi).
When the convection fan
motor reaches operating
speed, the centrifugal switch
(N.O.) on the motor closes.
Power to normally open
(N.O.) side of internal relay
contacts (terminal 7) on the
temperature control board.
3)
4. Oven reaches set temperature.
A. Temperature control de-energizes internal
relay and the normally open (N.O.) contacts
OPEN.
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Power is also connected back through
a second set of contacts on the power
switch (S1) to terminal 8 on the
temperature control board.
a. Solid state temperature control
energized. If the oven
temperature is below set point,
the temperature control will
energize its internal relay. The
normally open (N.O.) contacts
close and apply power to the
following components:
a) Heat light (clear) comes ON.
b) Power is connected through
the centrifugal switch
contacts on the convection
fan motor, heat relay (R3) is
energized, (R3) contacts
(N.O.) close and the heating
circuit is powered.
c) Ignition control module is
energized.
d) No ignition light (red) comes
ON, module performs a self
diagnostic test for 4 seconds,
2nd valve (main) on the gas
valve is energized. Gas
starts to flow to the burner,
sparking begins, the "no
ignition" light goes out and
burner lights. Sparking
continues for up to 7 seconds
or until a flame is
established. If a flame is
"sensed", the "no ignition"
light stays out and burner
remains lit. If a flame is not
"sensed" after 7 seconds of
sparking, the "no ignition"
light comes back on, 2nd
valve (main) on the gas valve
is de-energize and gas flow
to the burner stops. Ignition
trial cycle repeats after a 15
second purge between
cycles for two additional tries
before locking out. To reset
after a lockout, turn power
switch (S1) OFF then ON.
F24682 Rev. D (1016)