Section 2 Operation; Operating Sequence Description; Off Condition; Cooking Condition - Electrolux EI30SM55JB Technical & Service Manual

Operating Sequence Description

The following is a description of component functions
during oven operation.

OFF CONDITION

Closing the door activates the door sensing switch and
secondary interlock switch. (In this condition, the monitor
switch contacts are opened.)
When oven is plugged in, 120 volts A.C. is supplied to the
control unit. (See Figure 2-1).
1. The display will show "ENJOY YOUR OVEN, PRESS
CLEAR AND TOUCH CLOCK".
To set any program or set the clock, you must first
touch the STOP/CLEAR pad. The display will clear,
and " : " appears.

COOKING CONDITION

Program desired cooking time by touching the NUMBER
pads. Program the power level by touching the POWER
LEVEL pad and then a Number pad.
When the START pad is touched, the following operations
occur:
1. The contacts of relays are closed and components
connected to the relays are turned on as follows.
(For details, refer to Figure 2-2)
RELAY CONNECTED COMPONENTS
RY-1 Oven Lamp / Fan Motor / Fan Motor
RY-2 Power Transformer
RY-7 Turntable Motor
2. 120 volts AC is supplied to the primary winding of
the power transformer and is converted to about
3.3 volts AC output on the filament winding, and
approximately 2000 volts AC on the high voltage
winding.
3. The filament winding voltage heats the magnetron
filament and the H.V. winding voltage is sent to a
voltage doubler circuit.
4. The microwave energy produced by the magnetron
is channeled through the waveguide into the cavity
feedbox, and then into the cavity where the food
is placed to be cooked.
5. Upon completion of the cooking time, the power
transformer, oven lamp, etc. are turned off, and the
generation of microwave energy is stopped. The
oven will revert to the OFF condition.
6. When the door is opened during a cook cycle, moni-
tor switch, door sensing switch, secondary interlock
switch, and primary interlock relay are activated with
the following results. The circuits to the antenna
motor, the cooling fan motor, the turntable motor, and
the high voltage components are de-energized, and
the digital read-out displays the time still remaining in
the cook cycle when the door was opened.
7. The monitor switch is electrically monitoring the
operation of the secondary interlock switch and door
sensing switch is mechanically associated with the
door so that it will function in the following sequence.
(1) When the door opens from a closed position, the
primary interlock relay, door sensing switch and
secondary interlock switch open their contacts,
and then the monitor switch contacts close.
(2) When the door is closed from the open position,
the monitor switch contacts open first. Then the
contacts of the secondary interlock switch and
door sensing switch close, and contacts of the
relay (RY1) open.
If the secondary interlock switch and primary interlock
relay (RY2) fail with the contacts closed when the door is
opened, the closing of the monitor switch contacts will
form a short circuit through the monitor fuse, secondary
interlock switch, relay (RY1) and primary interlock relay
(RY2), causing the monitor fuse to blow.
2-1
Operation