Market Forge 3100-D Service Manual
SERVICE & PARTS
MANUAL
DUAL MATIC
STEAM COOKER
Model 3100
MARKET FORGE CANADA LTD.
Mississauga. Ontario, Canada
Form Number S2124 3/78 Printed in U.S.A.
TABLE OF CONTENTS
1.2 Basic Functioning
1-1
2.2 Setting In Place
2-1
2.3 Mechanical Connections
2-1
2.4 Installation Check
-
Out
2-1 2.4.1 Initial Control Setting
2-1
2.4.2 Cooker
Check
-
Out 2-1
3.2.1 Generator Start
-Up 3-1 3.2.2 Preheating
3-1
3.2.3 Pressureless Steam Cooking
3-1
3.2.4 Pressure Cooking
3-1
3.2.5 Shut-Down Procedure
3-2
4.2 Steam Circuits
4-1 4.2.1 Steam Inlet Line
4-1
4.2.2 Steam Exhaust and Drain
Lines
4-1
4.2.3 Pressure Safety Line
4-1
4.2.4 Evacuation Line
4-2
4.2.5 Pressure Indicator Line
4-2 4.3 Electrical Circuits
4-2 4.3.1 Control Circuit Components
4-3 4.3.2 Pressure Cooking Operation
4-4 4.3.3 Pressureless Cooking Operation
4-4
5.2 Trouble
-
Shooting Guides
5-1
5.3 Electrical Fault Isolation
5-1
5.4 Electrical Trouble
-
Shooting Procedures
5-5
5.4.2 Electrical Inspection
5-5 5.4.3 Selector Switch
5-5
5.4.4 60-Minute Timer
5-5 5.4.5 10-Minute Timer
5-7 5.4.6 Push
-
Button Timer
5-7 5.4.7 Door Interlock Switch
5-8 5.4.8 Solenoid Valves
5-8
5.4.9 Buzzer
5-8
5.4.1.0
Indicator Light
5-8
6.2 Preventive Maintenance
6-1 6.2.1 Door Disassembly and Cleaning
6-1
6.2.2 Safety Valve Check
6-2
6.2.3 Door Fulcrum Cleaning
&
Lubrication
6-3
6.3.1 Door Assembly
6-3 6.3.2 Exterior Panel Removal
6-4
6.3.3 Control Panel Removal
6-4 6.3.4 Pressure Relief and Check Valve
6.3.5 Steam Trap Replacement
6-5
6.3.6 Jet Pipe Replacement
6-6
6.3.7 Inlet Solenoid Valve Replacement
6-6
7.2 Ordering Information
7-1
Paragraph Paragraph
SECTION 1 INTRODUCTION
1.1 Description 1-1
SECTION 5 TROUBLE-SHOOTING
5.1 General 5-1
1.3 Service 1-1
SECTION 2 INSTALLATION
2.1 Assembly 2-1
5.4.1 Incoming Power 5-5
2.4.3 Shut-Down Procedure 2-2
SECTION 3 OPERATION
3.1 Operating Controls and Indicators 3-1
3.2 Operating Procedures 3-1
5.4.1.1 Wiring 5-9
SECTIONS MAINTENANCE
6.1 General 6-1
3.3 Cleaning 3-2
SECTION 4 PRINCIPLES OF OPERATION
4.1 General 4-1
6.3 Repair and Replacement 6-3
Replacement 6-4
6.3.8 Exhaust Solenoid Valve Replacement 6-6
SECTION 7 ILLUSTRATED PARTS LIST
7.1 General 7-1
S2124
LIST OF ILLUSTRATIONS
3-2
Pan Support Removal
3-2
Cooking Mode
5-1
Wiring Diagram, Dual Matic
5-6
Figure
SECTION 1 INTRODUCTION
1-1 Model 3100 Dual Matic Steam Cooker 1-2
SECTION 3 OPERATION
3-1 Dual Matic Controls and Indicator 3-2
SECTION 4 PRINCIPLES OF OPERATION
Page
4-1 Pictorial Diagram — Steam Circuits 4-2
4-2 Pictorial Diagram, Electric Circuits, Pressure
4-3 Pictorial Diagram, Electric Circuits, Pressureless
Cooking Mode
SECTION 5 TROUBLE-SHOOTING
4-4
4-5
5-2 Schemat ic Diagram, Dual Matic 5-9
SECTION 6 MAINTENANCE
6-1 Door Spring Disengagement 6-2
List of Tables
SECTIONS 3 OPERATION
3-1 Controls and Indicators 3-3
SECTION 5 TROUBLESHO OTING
5-1 Operator’s Trouble-Shooting Guide 5-1
Figure
6-2 Door Removal 6-2
6-3 Gasket Removal 6-2
6-4 Door Seal Tension Adjustment 6-3
6-5 Control Panel Removal
6-6 Pressure Relief and Check Valve
Replacement 6-5
6-7 Steam Trap Replacement 6-5
6-8 Jet Pipe Alignment 6-6
6-9 Inlet Solenoid Valve Replacement
6-10
Exhaust Solenoid Valve Replacement 6-7
SECTION 7 ILLUSTRATED PARTS LIST
7-1 Cabinet & Frame Assembly 7-2
7-2 Cooking Compartment & Plumbing 7-4
7-3 Door Assembly 7-6
7-4 Door Latch
7-5 Door Fulcrum & Switch 7-8
7-6 Control Panel 7-9
7-7 Electrical Component Panel 7-10
Page
6-4
6-7
7-7
5-2 General Trouble-Shooting Guide 5-2
5-3 Electrical Fault Isolation Guide 5-4
SECTION 6 MAINTENANCE
6-1 Preventive Maintenance 6-1
SECTION 1 INTRODUCTION
1 -1
S2124
This service and parts manual contains general information, installation, operation, principles of
operation, trouble-shooting, and maintenance information for the Market Forge Dual Matic Steam
Cooker. Also included is a parts list in which each replaceable part is identified and shown in an
accompanying exploded view.
1.1 DESCRIPTION
The Market Forge model 3100 Dual Matic is a
dual-mode compartment cooker which may be used
as either a pressure steam cooker or a free-vented
pressureless steam cooker. It consists of a cooking
compartment fitted with electrically controlled steam
circuits for application of steam by the cooking method
and for the duration selected by the operator. The
cooking compartment and all control components are
enclosed within stainless steel cover panels with
operator controls displayed on a single front mounted
panel.
A separate steam source required for operation of
the Dual Matic is normally purchased with it, in which
case the cooker is factory mounted with all steam,
drain and electrical interconnections completed.
Figure 1-1 shows one Dual Matic/Generator
configuration with the cooker on a 24" 610 mm wide
cabinet base containing an electrically powered steam
generator, (model suffix E). Other applications include
the Dual Matic on a gas -fired generator, (model suffix
G), a steam coil generator (model suffix SO, or a
cabinet containing steam pressure controls for direct
connection to a remotely located generator (model
suffix D). The model 3100 may also be combined with
other cooking equipment or installed banked with a
second Dual Matic on a single larger cabinet base.
1.2 BASIC FUNCTIONING
The Dual Matic may be converted from a pres sure
steam cooker to a pressureless, free-vented steam
cooker simply by placing a mode selector switch in the
required position followed by use of simple electric
controls:
1. For pressure cooking the compartment is
automatically sealed by the closing of an
exhaust valve and evacuation of air through a
steam trap as steam is injected. The compart ment
remains at approximately 14 Ibs. steam pressure
until the operator-selected cooking duration ends.
Fresh foods, defrosted frozen foods and frozen
entrees are cooked in this mode.
2. For pressureless cooking the compartment remains
vented to the drain system while steam is injected.
In this manner a continuous flow of steam
circulates throughout the compartment and out the
exhaust for the cooking duration. This mode allows
frozen foods to be defrosted, or defrosted and
cooked in a single operation.
1.3 SERVICE
Required service, both preventive and corrective, is
explained in Section 6. Should repairs be required, a
network of authorized agencies is available to assist with
prompt service. A current Directory of Authorized Serv ice
Agencies may be obtained by contacting:
Product Service Department
Market Forge
35 Garvey Street
Everett, Massachusetts 02149
Telephone: (617)387-4100
Product Service Department
Market Forge Canada, Ltd.
1375 Aimco Blvd., Unit 5
Mississauga, Ontario Canada L4W 1B5
Telephone: (416)621-9252
The model and serial numbers must be referenced
when corresponding with Market Forge. The data plate
containing the serial number pertaining to the equipment is
located on the left end of the bottom front trim ledge.
DUAL MATIC STEAM COOKER
Figure 1-1. Model 3100 Dual Mafic Steam Cooker
SECTION 2 INSTALLATION
S2124
2.1 ASSEMBLY
The Dual Matic is factory mounted on a cabinet
base containing either a steam generator or direct
steam connections for the cooker. The assembled unit
is shipped bolted to a skid with cabinet feet in a
separate container. Steps required for assembly are as
follows:
1. Remove the four bolts which fasten the equipment
frame to the skid.
2. Install feet in threaded mounting locations of cabinet
frame.
3. Mount the two pan support racks on studs located
inside the cooking compartment.
4. Attach doors and panels. Detailed instruc tions are
enclosed with the panels.
2.2 SETTING IN PLACE
If possible a location should be selected under an
exhaust hood which will remove small amounts of
water vapor emitted when the cooker door is opened.
Level the unit in final location by turning the adjustable
feet. Using the cabinet top as a reference, obtain level
adjustment left -to-right and front-to-back.
NOTE: If unit is to be placed directly in front of
a wall which will eliminate rear access, remove
the four Phillips head screws which secure the
top to the back. With screws removed the top
can be lifted off for future servicing of internal
components.
2.3 MECHANICAL CONNECTIONS
Since the Dual Matic is interconnected at the
factory to the steam generator or direct steam
plumbing, no field connections are required to the
cooker. All electrical and plumbing connections are
routed to the steam generator cabinet through the 6"
752 mm high space between the floor and the bottom
edge of the cabinet frame. Connection locations for the
Dual Matic mounted on steam generators of electric,
gas, and steam coil utility and direct connected steam
are shown in separate Installation Instructions for each.
2.4 INSTALLATION CHECK-OUT
After the Dual Matic is completely assembled and
all mechanical connections made to its steam source
(steam generator or direct steam connection plumbing),
both steam source and cooker must be
given a thorough check-out before being put into
operation. Check-out procedure for the Dual Matic
mounted on steam generators of electric, gas and
steam coil utility or direct connected steam are
given in separate Installation Instructions for each.
Procedures for the Dual Matic Cooker only are included in subsection 2.4.2. If the Dual Matic fails to
perform as described, consult Table 5-1 and 5-2 of
the trouble-shooting guide for corrective action. If
difficulty arises with the generator, reference the
separate service and parts manual for that equipment.
Before making this check-out the operator must
be thoroughly familiar with the operating procedures
in Section 3, and with the function of each control
described in Table 3-1. Reference Figure 3-1 for
identification of controls required in the following
procedures.
2.4.1 Initial Control Settings
Before beginning the start -up procedures for the
Dual Matic the instruction plate and service manual
for the steam generator must be consulted and all
start-up procedures completed to supply 15 psi
steam to the steam inlet circuit for the cooker.
1. All steam generator controls are in the operating
mode and 15 psi steam is applied to the Dual
Matic inlet plumbing.
2. Both cooker timers (Figure 3-1; 4, 6) are in the
OFF position.
3. Cooker compartment is empty of all information
materials and the door is open.
2.4.2 Cooker Check-Out
2.4.2.1 Pressure Cooking Mode (Figure 3-1)
1. Close cooker compartment door, being certain
latch handle (1) is securely engaged.
2. Place selector switch (2) in PRESSURE COOKING (down) position.
3. Set 60-MINUTE Ti mer dial (4) at "4-minute"
position. Indicator light (3) will turn on. Operation
is correct if operating pressure (13-15 psi
indicated on gauge) is attained before 4-minute
time elapses. Indicator light will turn off and
buzzer will sound at end of 4-minute period.
2-1
2-2 DUAL MATIC STEAM COOKER
4. Turn timer dial (4) to OFF. Buzzer will shut off.
5. Open cooking compartment door.
4. Repeat #3 to check 2-Pan operation at 4 1/2
minute duration and 3-Pan operation at 5 1/2
minute duration. (Timer accuracy ± 5%)
2.4.2.2 Safety Valve (Figure 3-1)
5. Open cooking compartment door.
1. Close cooker compartment door, being certain
latch handle (1) is securely engaged.
2. Place selector switch (2) in PRESSURE (down)
position.
3. Set 60-MINUTE Timer dial (4) to "4-minute"
setting. Pressure gauge (5) will indicate a pres sure rise.
4. Pull out on SAFETY VALVE knob (8). If safety
valve is operating correctly, the pressure will drop
sharply in response to release of steam from
compartment.
5. Release SAFETY VALVE knob (8). Safety valve
should close allowing pressure to rise again.
6. Turn 60-MINUTE Timer dial (4) to OFF position.
7. Open cooking compartment door.
2.4.2.3 Pressureless Cooking Mode (Figure 3-1)
1. Close cooking compartment door, being certain
latch handle (1) is securely engaged.
2. Place selector switch (2) in PRESSURELESS
COOKING (up) position.
3. Set 10-MINUTE Timer dial (6) to "1-minute" and
press 1-PAN push button (7). Operation is correct
if indicator light (3) lights and steam is passed
into cooker and continuously exhausted for a
period of 3^ minutes. At end of cycle buzzer will
sound and indicator light will turn off. (Timer
accuracy ± 5%)
2.4.2.4 Door Shut-Off Switch (Figure 3-1)
1. Close cooking compartment door, being certain
latch handle (1) is securely engaged.
2. Place selector switch (2) in PRESSURELESS
COOKING (up) position.
3. Set 10-MINUTE Timer dial (6) to "1-minute" and
press 1-PAN push button (7). Inlet valve will
open allowing steam to pass through cooking
compartment.
4. With cooker in operation lift door handle (1) and
open door slightly. If operation is correct, inlet
valve will close stopping steam flow into cooker.
Timer will continue to run with indicator light on.
5. Close door and secure latch. Inlet valve will open
for remainder of timed cycle.
6. Return 10-MINUTE Timer dial (6) to OFF
position and open cooker door.
2.4.3 Shut-Down Procedure
No shut-down procedure is required for the Dual
Matic except to check that both timer dials (4, 6) are
in the OFF position and the compartment door is
open. Consult the steam generator instruction plate
and complete the generator shut down procedure.
NOTE
Before final check-off of the Dual Matic/
Generator system for use in cooking, generator
start-up and shut -down must be completed two
more times to insure cleanliness and proper
operation.
S2124
SECTION 3 OPERATION
3.1 OPERATING CONTROLS AND INDICATORS
All of the controls required to operate the Dual
Matic are listed in Table 3-1, together with a short
functional description of each. Figure 3-1 shows the
physical location of each control and indicator.
3.2 OPERATING PROCEDURES
The Dual Matic may be used as either a pres sureless steam cooker which defrosts and cooks
frozen food, or as a steam pressure cooker to cook
fresh and defrosted foods. Instructions for operation
in either cooking mode are included in this section.
Consult Test Kitchen Bulletin #54 for detailed
cooking information.
3.2.1 Steam Source Operation
The Dual Matic is supplied mounted on a cabinet
containing either a steam generator or controls for
direct connected steam. Manual controls are ac cessed by opening the cabinet door. Start up procedure for the steam source is completed once
before each daily operating period of the cooker. (For
steam generators see instruction plate.)
3.2.2 Preheating
Before each initial operation of the cooker, and at
any other time when the cooking compartment is
cold, a 3-minute preheating period is required. To
preheat the cooker put steam source into operation
and proceed as follows:
1. Close cooking compartment door and lock
securely in place by pressing down on latch
handled).
2. Place cooking mode selector switch (2) in the
PRESSURE COOKING position.
3. Set 60-MINUTE timer (4) to "3-minute" setting.
4. Turn off buzzer which sounds to indicate
cooking is complete by setting 60-MINUTE
timer dial (4) to OFF position.
5. Allow pressure to return to "0-PSI" (5). Open
door by pulling up on latch handle (1). Allow
remaining vapor to escape before raising door
to full open position.
3.2.3 Pressureless Steam Cooking
Before loading the cooker, be sure compartment
is hot. See 3.2.2 for preheating instructions.
1. Slide pans of food into cooking compartment pan
supports.
2. Close cooking compartment door and push down
on latch handle (1) to engage lock.
3. Place cooking mode selector switch (2) in
PRESSURELESS COOKING (up) position.
4. Set 10-MINUTE timer (6) to required cooking
time.
5. Press pan selector button 1, 2 or 3 (7) coinciding
with the number of pans loaded in cooker.
NOTE To activate control circuit, the timer must be
set first, then the pan selector button pushed.
6. Turn off buzzer which sounds to indicate cooking
is complete by setting timer dial (6) to the OFF
position.
7. Open door by pulling up on latch handle (1).
8. Unload by sliding pans of food from pan supports,
taking care to avoid hitting compartment opening.
3.2.4 Pressure Cooking
Before loading the cooker be sure compartment
is hot. See 3.2.2 for preheating instructions.
1. Slide pans of food into cooking compartment pan
supports.
2. Close cooking compartment door and push down
on latch handle (1) to engage lock.
3. Place cooking mode selector switch (2) in
PRESSURE COOKING (down) position.
4. Set 60-MINUTE Timer (4) to required cooking
time.
5. Turn off buzzer which sounds to indicate cooking
is complete by setting 60-Minute timer dial to the
OFF position.
6. Allow pressure to return to "0-PSI" (5). Open door
by pulling up on latch handle (1). Allow remaining
vapor to escape before raising door to full open
position.
3-1 S2124
3-2 DUAL MATIC STEAM COOKER
7.
Unload by sliding pans of food from pan sup
ports,
Figure
3-2.
Pan Support Removal
Figure 3-1. Dual Mafic Controls and Indicators
taking care to avoid hitting compartment opening.
3.2.5 Shut-Down Procedure
No shut -down procedure is required for the Dual
Matic except to check that both timer dials (4, 6) are in
the OFF position, and the compart ment door is open.
When all cooking has been completed for the day the
steam source must be shut off. (For steam generators
see instruction plate.)
3.3 CLEANING
After each period of daily operation (more
frequently as required to maintain cleanliness), the Dual
Matic should be thoroughly cleaned by completing the
following steps.
1. Remove left and right side pan supports (Figure 3-2)
by lifting front up and forward to disengage from
mounting studs. Wash with detergent, rinse, and set
aside for reassembly.
S2124
OPERATION 3-3
pressed.
set.
TABLE 3-1 CONTROLS AND
INDICATORS (See figure 3-1)
Figure 3-1 Ref. Description Function
1 Latch Handle Secures cooker door in closed position. Lift to open.
2
Selector Switch
PRESSURELESS
COOKING/PRESSURE
The cooking mode selector switch. Placed in up
position for pressureless cooking; down position for
pressure cooking.
3 Indicator Light (Red) Indicates when lit that cooker is in operation.
4
60-Minute Timer
(Pressure cooking)
5 Pressure Gauge
Controls pressure cooking mode cycle duration. Time
manually preset from 0-60 minutes.
Indicates steam pressure (psi/Kg/cm2) inside cooker
chamber during pressure cooking mode of operation.
Controls pressureless cooking mode cycle duration in
6
10-MinuteTimer
(Pressureless Cooking)
conjunction with pan selector buttons. Time manually
preset from 0-10 minutes before selector button
Compensates for cooking time differential between 1, 2
7
Pan Selector
Buttons
1/2/3
or 3 pans of food loaded into the compartment for
pressureless mode. Button coinciding with number of
pans loaded is pressed after the 10-MINUTE timer is
Steam release safety valve opens automatically in the
8
Pressure Release Knob
(Safety valve)
unlikely event that a malfunction causes ex cessive
steam pressure in compartment. Pull out on knob to
operate manually.
2. Wash cooking compartment interior using mild nonabrasive water. Rinse and dry thoroughly.
CAUTION
Failure to wash compartment may result in pitting
of the aluminum surfaces. Use only mild detergent
suitable for use with aluminum.
3. Replace pan supports in compartment and leave door
open.
S2124
SECTION 4 PRINCIPLES OF OPERATION
4.1 GENERAL
The Dual Matic Steam Cooker consists of a
cooking compartment into which pans of food are
loaded through an inward opening door. The
compartment is fitted with electrically controlled
steam circuits to apply steam in either the pressure or
pressureless methods and for the duration selec ted
by the operator. The principles of operation in this
section include an explanation of steam and electrical
circuits as well as pressure cooking and pressureless
cooking operation.
4.2 STEAM CIRCUITS
The steam circuits consist of the piping, solenoid
valves, steam trap, and safety valve required to
provide controlled steam application to the cooking
compartment. A simplified diagram of these circuits is
shown in figure 4-1.
NOTE Figure 4-1 is strictly a pictorial schematic
diagram and is not intended to show the actual
configuration of the circuits. All components are
shown in correct relationship with each other.
However, the diagram does not show their actual
locations or position within the cooker.
As shown in the diagram, steam inlet and ex haust connections are normally connected at the
factory directly into a steam generator on which the
cooker is mounted. The generator is equipped to
supply constant, regulated steam at 14-15 psi. Steam
exhaust is directed into the generator drain system
where it is condensed to water prior to entry into the
building drain system.
Both steam inlet and exhaust lines are equipped
with solenoid valves which are operated by the
electrical control circuit. Both are two-position valves
— the inlet valve normally closed, the ex haust valve
normally open. The inlet valve is opened whenever
the control circuit is activated in either the pressure or
pressureless modes. The exhaust valve is closed
only when the control circuit is activated in the
pressure mode.
4.2.1 Steam Inlet Line
A steam supply line is plumbed from the
generator output to a 1/2" IPS elbow fitting con
nected to the input side of the steam inlet solenoid
valve. At all times when the cooker is not in operation the valve remains closed to prevent steam from
entering the inlet line. During operation the inlet
solenoid valve is opened by activation of the control
circuit. Steam at 15 psi enters the 1/2" line
connected to a coupling in the bottom rear of the
cooking compartment. A jet pipe mounted in the
coupling inside the compartment directs steam
uniformly throughout the interior. Steam continues to
enter the compartment in this manner until the
control circuit closes the solenoid valve.
4.2.2 Steam Exhaust and Drain Lines
Steam exhaust and compartment drainage are
drained from the cooking compartment by a single
line connecting with the steam generator drain
system. A perforated cylindrical strainer mounted inside the cooking compartment at the bottom allows
steam, condensation and cooking drainage to enter
the exhaust line. The line connects to the inlet side
of the exhaust solenoid valve. Except when the valve
is closed by the control circuit, activated in the pres sure mode, exhaust and drainage pass through the
valve into the 3/4" drain line to a waste outlet 'T.
Drainage passes from the cooker into the drain
system of the steam generator.
4.2.3 Pressure Safety Line
A branch of the drain and exhaust line provides
pressure overload protection for the cooking compartment in the unlikely event of equipment malfuntion. The inlet side of a pressure relief valve is
connected with the compartment through a coupling
in the right side. Pre-set to open automatically at
pressures in ex cess of 15 1/2 psi, the valve may
also be operated manually for test purposes by
pulling out on a knob mounted on the control panel.
The knob is connected by a steel cable and suitable
sheaves to the manual release lever at the top of the
valve. The lever is spring-loaded to return to the
closed position when the knob is released.
When the safety valve is opened, steam is allowed to pass into a 3/4" line connected to a sideoutlet T' fitting in the drain line. A check valve
mounted between the safety valve and the T' fitting
prevents back-flow from the drain line.
rev. 3/78 4-1 S2124
4-2 DUAL MATIC STEAM COOKER
STEAM
TRAP
STEAM IN
Figure 4-1. Pictorial Diagram — Steam Circuits
4.2.4 Evacuation Line
A separate line between the cooking compart -
ment and the drain provides for evacuation of air
during cooking in the pressure mode. An elbow
fitting mounted into the top of the compartment is
connected through a 1/4" ID tubing line and suitable
fittings to the inlet side of a steam trap. The trap
functions as a chamber evacuator to eliminate air
which passes into it from the cooking compartment.
It is a thermostatically operated valve device preset
to open automatically when air, vapor, or
condensate at temperatures lower than 240° F
enters. The trap closes automatically when steam
above 240° F enters. Discharge from the trap
passes into a %" ID line connected to the waste
outlet "T" of the drain line.
S2124
4.2.5 Pressure Indicator Line
A pressure gauge mounted in the control panel
constantly monitors the steam pressure inside the
cooking compartment. Connection is made through a
1/8" IPS tubing connected to a compression fitting at
the top of the compartment.
4.3 ELECTRICAL CIRCUITS
The electrical circuits of the cooker control the
power to activate timer motors and energize solenoid
operated valves and circuits which in turn control
application of steam to the cooking compartment. The
cooker operates on 120V, 2 amp 60 Hz (50 Hz on
special order) electrical service connected to all
circuits from a 2-pole terminal block mounted to the
cooker frame inside the
PRINCIPLES OF OPERATION
4-3
front cover panel. Power input to the terminal block is
connected at the factory from the elec trical circuits of
the steam generator on which the cooker is mounted.
Power is supplied to the control circuit at all times
when the shut -off device for the generator/cooker
system (supplied by the user) is in the ON position.
dial through a gear reduction and clutch mechanism.
The timer dial is manually set for any interval of
operation from 0 to 60-minutes as read on the calibrated dial face. The manual rotation of the dial
moves the common element of the timer switch from
the neutral position to the contact which connects with
pressure mode controls and energizes the timer
motor. When power is applied to the motor, the dial
4.3.1 Control Circuit Components
The control circuit is shown in pictorial diagrams in
figures 4-2 and 4-3. A brief description of the electrical
circuit elements follows.
rotates until the indicator dart coincides with "0minutes." At this point the common element of the
timer switch is transferred to a second contact,
interrupting the circuit to the timer motor, solenoid
valves and indicator light, and applying 120-volts to
the buzzer. Contact to the buzzer circuit remains
4.3.1.1 Selector Switch. The selector switch is a
double-pole, double-throw, two-position switch
(PRESSURELESS COOKING/PRESSURE COOKING). When the switch is in the PRESSURELESS
position those control circuits required for cooker
operation as a free vented system are connected.
Operation begins only after the 10-MINUTE timer dial
is set followed by pressing a pan selector push button.
When the switch is in the PRESSURE position those
circuits required for cooker operation as a pressure
system are connected. Operation begins when the 60MINUTE timer is set.
closed until the dial is manually turned to the OFFposition, returning the common element of the timer
switch to the neutral position.
4.3.1.5 10-Minute Timer. The timer operates in the
same manner as the 60-MINUTE timer but with a
maximum time setting of 10 minut es. The manual
motion of setting the timer dial moves the common
element of the timer switch from the neutral position
to the contact which connects with pressure-less
mode controls, the timer motor and the pan-selector
push-button switch. The timer motor is activated only
after the push button timer has "timed out." The
remainder of operation is the same as for the 60-
4.3.1.2. Indicator Light. The indicator light is
minute timer.
connected into both the pressure and pressureless
cooking mode circuits. It remains lighted (red) at all
times when either the 60-MINUTE timer, or the 10MINUTE timer and the push-button timer are set. It
turns off at the end of the timed cooking duration.
4.3.1.6 Push -Button Timer (pan selector). The
Timer is a three-button solid state capacitor discharge
timing device powered by a separately mounted
120V/36V step-down transformer. The switch
functions to compensate for the alteration in cooking
time associated with cooking 1-pan (2 1/2 minutes), 2-
4.3.1.3 Door Interlock Switch. The interlock switch is
a single pole, two-position, microswitch with normally
open contacts. The switch lever is operated by an
actuating pin mounted in the door latch assembly.
When the door is open the pin remains retracted with
the switch contacts in the normally open position.
When the door latch is engaged to secure the door,
the actuating pin is moved against the switch lever to
pans (3 1/2 minutes), or 3-pans (4 1/2 minutes) of
food in the pressureless mode. When a button is
pressed a light inside is lit and the button is held in the
depressed position by a latching device. Contacts to
externally controlled circuits are closed and internal
timer circuits energized. At the end of the timed
duration (plus the 10-MINUTE timer setting) a
solenoid operates to release the latching device.
close the contacts. Connected into the circuit with the
steam inlet valve, the door switch acts as a protective
device to interrupt valve operation unless the door is
closed.
4.3.1.7 Buzzer. The buzzer is an alarm device which
operates by oscillation of a striker against the core of
an electromagnet. When either the 60-MINUTE or 10-
MINUTE timer dials reach "0-minutes" the buzzer coil
is energized to sound the buzzer. Movement of either
4.3.1.4 60-Minute Timer. The timer contains a 120volt synchronous motor which drives a timing
timer dial to the OFF position opens the contact to the
buzzer coil to shut it off.
S2124
Loading...