Lincoln Impringer Conveyor Oven 1200 - Manual (Page 5)

Impinger I -–1000 Series Service Manual - International 5
increase or decrease as the DC voltage from the board increases or decreases
respectively. As the motor turns, it drives both the reducer gearbox and the Tach.
Generator. The Tach. Generator is a DC voltage generator, which supplies a voltage
to the DC motor control board and is used as a reference for maintaining a constant
conveyor speed.
TlME/TEMP DISPLAY The Time/Temp. Display is energized when the Fan Switch is closed, supplying 120
VAC to the primary of the 12.6 volt Transformer. The secondary output of the
transformer, normally 13 to 14 VAC (depending on input), with a center tap is
supplied to terminals 1,2, and 3 of the Time/Temp Display. The center tap is terminal
2. The display works on a balanced input and center tap voltage to each leg must be
1,2 the total reading.
The speed side of the Time/Temp. Display uses a slotted disc (cemented to tach.
coupling) to break the infra-red light beam of the optical switch (mounted on gear
motor) producing electrical pulses that are transmitted to the display. The display
converts these pulses into a read-out of minutes and seconds.
The temperature portion of the display uses a Thermistor Probe to sense oven
temperature. The thermistor outputs a resistance proportional to the oven
temperature. This resistance is then converted by the display into a temperature
reading.
SEQUENCE OF OPERATIONS 1028 / 1029 / 1228 / 1229
MODEL 1028 - 380Y/220 VAC - 50 HZ - 3 PHASE
MODEL 1029 - 415Y/240 VAC - 50 HZ - 3 PHASE
MODEL 1228 - 380Y/220 VAC - 50 HZ - 3 PHASE - DUAL BELT
MODEL 1229 - 415Y/240 VAC - 50 HZ - 3 PHASE - DUAL BELT
POWER SUPPLY
Electrical Power to be supplied to the Oven by a five conductor service.
Black conductor is Hot
Red conductor is Hot
Orange conductor is Hot
White conductor is Dedicated Neutral
Green conductor is Ground
MAIN FAN CIRCUIT Electrical power is permanently supplied through 3, 50A fuses to the normally open
contacts of the Mercury Contactor. Power is also supplied through 1, 10A fuse to the
normally open contact of the Main Fan Relay, through a 1A Fuse to the normally
open Double Pole Main Fan Switch, and to the normally open Cool-Down
Thermostat (thermostat closes at 160°F and opens at 140°F.) Closing the Main Fan
Switch supplies 220 or 240 VAC to the primary of the control circuit Step Down
Transformer. (The transformer steps the voltage down to 120 VAC for the control
circuit.) 120 VAC is supplied to the coil of the Main Fan Relay. The coil of the relay is
energized, the normally open contacts close, energizing the Main Fan Motor. Closing
the Main Fan Switch also supplies power to the 12.6 VAC Transformer, the Control
Box Cooling Fan, and the Heat and Conveyor Switches.
TRANSFORMER (12.6
VAC) Upon closure of the Fan Switch, 120 VAC is supplied to the primary of the 12.6 VAC
Transformer. The Transformer steps the voltage down to 12.6 VAC (normally 13 to
14 VAC) with a center tap, and supplies power to the Time/Temp. Display. The
voltage from each leg of the Transformer's secondary to the center tap should be
one half of the secondary voltage.
HEAT CIRCUIT Closing the Fan Switch and the normally open Heat Switch supplies 120 VAC
through the normally open Air Pressure Switch, and the normally closed Hi-Limit
Thermostat (manually re-settable, opens at 190°F) and, the 3A Fuse, to the L1
terminal of the Temperature Control Board, the coil of the Mercury Contactor, and to
the Heat Indicator Light.
TEMPERATURE
CONTROL When the Heat Switch is closed, 120 VAC is supplied to the Temperature Control.
The Temperature Control Potentiometer (2.5K ohm) is adjusted to desired
temperature. The Thermocouple will provide varying millivolts to the Temperature
Controller. The Temperature Controller switches the L 2 line of the Contactor coils at
intermittent intervals to maintain desired temperatures.