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Revision 7/F3512
© Moffat Ltd, January 2005
E35 Turbofan Ovens
Oven Lamps
The two oven lamps (12 volt halogen) are on
whenever the Power switch is on. The oven
lamps are supplied with 12 volts from an
electronic lamp transformer fitted on the
oven’s control switchgear assembly. The oven
lamps are on with the oven door open and
closed.
Bake Timer
The 60 minute bake timer is a mechanical timer
and can therefore be operated with the oven’s
power ON or OFF. However only with the oven’s
power switch On and the oven door closed will
the timer turn on the time-up buzzer and time-up
indicator neon on the control panel. The buzzer
and time-up indicator provide indication that the
time setting has run down to zero and at this point
will remain on continuously until the 60 minute
timer has been manually set back to the Off
(vertical) position. The 60 minute timer does not
control any other part of the oven’s operating
system as the timer is independent of the
temperature control, heating, fan, or steam
system.
Oven Vent
The oven vent is a manual operation by way of
the Vent knob on the control panel.
The vent knob directly rotates the vent shaft
through 90 degrees to open and close the vent.
The vent shaft passes through a rotary switch
mounted behind the control panel and this switch
is used to switch on or off the Vent indicating
neon. In the vent open position the indicator is
illuminated. The oven vent restricts venting of the
oven when in the closed position, however the
vent flap is fitted with a spring loaded
over-pressure flap which relieves excess
pressure created during oven steaming. This
avoids steam pressure escaping out of door seals
etc, if the oven is steamed with the vent closed.
The spring pressure on the over-pressure vent
flap ensures that only excess steam is lost out of
the vent.
Door Switch
The oven has a door switch, mechanical
micro-switch below oven opening, which breaks
the power supply to the oven fan, temperature,
and steam control circuits when the door is
opened. Additionally, opening the oven door will
remove power from the Bake Timer buzzer and
indicator, and the vent position indicator neon.
3.2 EXPLANATION OF CONTROL
SYSTEM
The E35 Turbofan convection oven features
multi-function operator controls, and a combined
fan motor and steam control system.
A correct understanding of their operation is
required before carrying out any service or fault
repair work. The control device functions are
explained as follows:
Circuit Protection
All models are fitted with a 3 pole circuit breaker,
from which a control circuit is taken from L1
circuit breaker, and this control circuit is fitted with
a 6A circuit breaker. The 3 pole main circuit
breakers are rated 25A/pole for 3P+N+E/GND
and 1P+N+E/GND supply models, and 40A/pole
for 3P+E/GND (no neutral) models. These pro-
vide control circuit protection via the 6A circuit
breaker, and load circuit protection via the 3 pole
circuit breakers.
Additionally, the 3 pole circuit breaker is
mechanically connected to a Shunt Trip breaker,
which in the event of the oven fan motor
overheating will trip the 3 pole circuit breakers to
isolate power from the unit. The Shunt Trip is
directly connected to thermal limit switches in the
motor windings, and the supply Neutral (or L3 on
3 phase, no neutral models). A supply from the
6A control circuit breaker is connected to the
motor thermal switches. Should any of the motor
windings overheat, the thermal switches close
and supply power to the Shunt Trip, which in turn
trips (triggers) and mechanically trips the 3 pole
circuit breaker.
Accordingly, causes of circuit breakers tripping
can be ascertained with the above knowledge,
and this is covered in more detail in the Fault
Diagnosis section.
Power On/Off
A Power switch on the control panel isolates
power to the operator controls of the oven. With
the power switch OFF all functions of the oven
are inoperable.
An integral cooling fan, behind the control panel
used to keep the electrical controls of the oven
cool, is on continuously whenever the power
supply to the oven is on. Switching the oven
control panel Power switch off will leave the
cooling fan running.
With the Power switch ON (illuminated neon
indicator), power is supplied to all operator
controls.
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