Ice Making Sequence Of Operation - Manitowoc 820C Serie Manual De Instalación, Operación Y Mantenimiento

Section 3

Ice Making Sequence of Operation

Ice machines and storage bins produce and store ice for
human consumption and product cooling.
NOTE: The power button must be depressed and the water
curtain/ice dampers must be in place on the evaporator
before the ice machine will start.
Water Purge Cycle
The ice machine purges any remaining water from the water
trough down the drain.
Freeze Cycle
Water flows across the evaporator and the refrigeration
system chills the evaporator. Ice builds on the evaporator
and the freeze cycle continues until the ice thickness probe
senses a sheet of ice has formed. The ice thickness probe
signals the control board to start a harvest.
Harvest Cycle
Any remaining water is purged down the drain as refrigerant
gas warms the evaporator. When the evaporator warms, the
sheet of cubes slides off the evaporator and into the storage
bin. If all cubes fall clear of the water curtain (or ice damper)
the ice machine starts another freeze cycle.
Off Cycle
If the water curtain or ice damper are held open by ice cubes
the ice machine shuts off. When the water curtain or ice
damper closes, the ice machine starts a new cycle at the
water purge.
Control Board Timers
The control board has the following non-adjustable timers:
• The ice machine control board will set its own install date
after 100 freeze and harvest cycles.
• The ice machine is locked into the freeze cycle for 6
minutes before a harvest cycle can be initiated.
• The maximum freeze time is 60 minutes, at which time
the control board automatically initiates a harvest
sequence.
• The maximum harvest time is 3.5 minutes. The control
board automatically initiates a freeze sequence when
these times are exceeded.
Part Number: 000013325 Rev 02 6/17
Safety Limits
Safety limits are stored and indicated by the control board
after three cycles. The number of cycles required to stop the
ice machine varies for each safety limit.
• Safety Limit 1 - If the freeze time reaches 60 minutes,
the control board automatically initiates a harvest cycle.
If 6 consecutive 60-minute freeze cycles occur, the ice
machine stops.
• Safety Limit 2 - If the harvest time reaches 3.5 minutes,
the control board automatically returns the ice machine
to the freeze cycle. If 500 consecutive 3.5 minute harvest
cycles occur, the ice machine stops.
A safety limit is indicated by a flashing control board light
labeled SL1 or SL2. Refer to Section 5 if you receive a safety
limit indication.
Safe Operation Mode
Allows the ice machine to operate up to 72 hours if the ice
thickness probe and/or water level probe sensors fail.
• When the control board starts the safe mode, an alert
is flashed on the LCD display to notify the end-user they
have a production problem.
• The control board automatically initiates and monitors
the safe mode. The control will automatically exit the safe
mode if a normal signal is received from the input.
• After 72 hours, the control board will enter a standby
mode and turn off.
Operation
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