Scotsman EC 106 - Electrical Sequence

Page 28
Page 28
OPERATION - CONTROL SEQUENCE
At the start of freezing cycle the evaporator
temperature sensor controls the length of the first
part of the freezing cycle. As it reaches a predeter-
mined temperature it supplies a low voltage current
to the P.C. BOARD in order to activate the
electronic timer which takes over the control of
the freezing cycle for a pre-fixed time according
to the DIP SWITCH keys setting (see Tab. B).
NOTE. The evaporator temperature sensor,
factory pre-set, is the same for all the models
and is not adjustable in the field.
Once completed the timed portion of the freezing
cycle the system goes automatically into the
defrost cycle which has also a pre-fixed length. At
completion of the defrost cycle the P.C. BOARD
command the unit to start again a new freezing
cycle.
OPERATION - ELECTRICAL SEQUENCE
The following charts illustrate which switches and
which components are ON or OFF during a
particular phase of the icemaking cycle.
Refer to the wiring diagram for a reference.
BEGINNING FREEZE
Electrical components (Loads) ON OFF
Compressor ...........................................
•
Fan Motor (Air cooled only) and TRIAC ........ •
Hot Gas Valve ........................................ •
Water Inlet Valve.................................... •
Water Drain Valve (Not on EC 106) ....... •
P.C.Board Relay 1 Coil .......................... •
P.C.Board Relay 2 & 3 Coil.................... •
Water Pump ...........................................•
P.C.B. Timer........................................... •
Elctronic Controls & Sensors ON OFF
Evaporator Sensor .................................
•
Condenser Sensor ................................. •
Ice Level Control ....................................•
TIMED FREEZE
Electrical components (Loads) ON OFF
Compressor............................................
•
Fan Motor (Air cooled only) and TRIAC ........ ••
Hot Gas Valve ........................................ •
Water Inlet Valve.................................... •
Water Drain Valve (Not on EC 106) ....... •
P.C.Board Relay 1 Coil .......................... •
P.C.Board Relay 2 & 3 Coil.................... •
Water Pump ...........................................•
P.C.B. Timer........................................... •
Electronic Controls & Sensors ON OFF
Evaporator Sensor .................................
•
Condenser Sensor ................................. ••
Ice Level Control ....................................•
HARVEST (Drain portion - first 15/30 sec.)
Electrical components (Loads) ON OFF
Compressor............................................ •
Fan Motor (Air cooled only)and TRIAC ......... •
Hot Gas Valve ........................................ •
Water Inlet Valve....................................•
Water Drain valve (Not on EC 106) ....... •
P.C.Board Relay 1 & 2 Coil.................... •
P.C.Board Relay 3 Coil ............................... •
Water Pump ...........................................•
P.C.B. Timer........................................... •
Electronic Controls & Sensors ON OFF
Evaporator Sensor ................................. •
Condenser Sensor ................................. •
Ice Level Control ....................................•
HARVEST (Water filling portion)
Electrical components (Loads) ON OFF
Compressor............................................
•
Fan Motor (Air cooled only)and TRIAC ......... •
Hot Gas Valve ........................................ •
Water Inlet Valve....................................•
Water Drain valve (Not on EC 106) ....... •
P.C.Board Relay 1 & 2 Coil.................... •
P.C.Board Relay 3 Coil ............................... •
Water Pump ........................................... •
P.C. Board Timer ................................... •
Electronic Controls & Sensors ON OFF
Evaporator Sensor .................................
•
Condenser Sensor ................................. •
Ice Level Control ....................................•
OPERATING CHARACTERISTICS
EC 106-126-176
Freeze Cycle
Average Discharge
Pressure A/C: 9.5÷8.5 bar (130÷110 psig)
Average Discharge
Pressure W/C: 10.5÷9.5 bar (150÷135 psig)
Suction Pressure
End Freeze Cycle: 0 ÷ 0.1 bar (0 ÷ 1 psig)
EC 126-176 (R404a) - 206-226
Freeze Cycle
Average Discharge
Pressure A/C: 15÷17 bars (220÷245 psig)
Average Discharge
Pressure W/C: 17 bars (245 psig)
Suction Pressure
End Freeze Cycle: 1.7 bar (24 psig)