TurboChef NGC (Tornado) User Manual

21
THE MICROWAVE SYSTEM
The Microwave System is the most complex system in
the oven. Proper care must be taken during servicing
to protect both the operator and technician.
OVERVIEW OF A MICROWAVE CIRCUIT
The Microwave Circuit consists of a Magnetron
and Voltage Doubler Circuit. The Voltage Doubler
consists of a special step-up transformer, a capacitor
and a diode.
MONITOR CIRCUIT DESCRIPTION
In addition to understanding the High Voltage
Circuit, it is imperative to understand how the
Monitor Circuit operates. The Monitor Circuit is
a failsafe circuit designed to protect the operator if
both the Primary and Secondary Interlock Switches
fail to operate normally.
The Monitor Circuit consists of the Primary and
Secondary Interlock Switch, Monitor Safety Switch,
Monitor Relay and the F3 Fuse. When the Cook
Door closes during normal operation, the Monitor,
the Secondary and the Primary Switches close in the
order listed above. When all switches are closed,
the Microwave System is allowed to operate.
If during normal operation, either Interlock Switch
opens - such as when the Cook Door opens - the
Control System will turn Off the Microwave. If the
Monitor Switch opens before both the Primary and
Secondary Interlock Switches - abnormal operation
- the Monitor Switch de-energizes the Monitor Relay.
When this occurs, a dead short is placed across L1
and L2. The short then blows the F3 Fuse, which
permanently interrupts power to the Microwave
System until both the Primary and Secondary
Interlock Switches are repaired.
Figure 13 shows a schematic of the Monitor Circuit.
M
ake sure to note the following:
o
Primary and Secondary Switches interlock the
High Voltage Control Signal.
o
Normal Operation: When the K2 and K3 Relays
energize, power is supplied to the High Voltage
Transformers.
o
Abnormal Operation: When K2 is energized
and K3 is un-energized (via an opening of the
Monitor Switch) L1 and L2 short to blow the
F3 Fuse and failsafe.
Figure 14 on the following page details the theory of
operation of the Microwave High Voltage Circuit.
7
9
A
B
1
4
3
6
1
2
1
2
CDP
NC
NO
7
9
A
B
1
4
3
6
+24 VDC
F3 FUSE
20 AMP
(BLOWN)
+24 VDC
LINE VOLTAGE
(L1)
LINE VOLTAGE
(L2)
K2 HV
RELAY
T1
HV TRANSFORMER
3
3
T2
HV TRANSFORMER
MONITOR SWITCH
(OPEN)
K3 MONITOR
RELAY
CONTROL
CDM
CONTROL
CDS
CONTROL
C
NC
NO
C
NC
NO
C
PRIMARY AND SECONDARY
INTERLOCKS (CLOSED)
 : Monitor Circuit - shown in failsafe state.

TurboChef NGC (Tornado) Specifications

General

Brand	TurboChef
Model	NGC (Tornado)
Category	Oven
Language	English