4. Turn the motor current calibration adjustment
fully clockwise. This will force the guide vanes
to close part way.
5. Turn the thermostat adjustment (item 4, Fig. 3)
to “Cooler” (fully counterclockwise).
6. Set the capacity control switch (item 2, Fig. 3)
to “Inc” position.
7. Slowly turn the motor current calibration
adjustment counterclockwise, allowing the
guide vanes to open until the motor current
reaches 5 percentage points above the electrical
demand setting.
NOTE: There is a time lag of several seconds
due to feedback capacitance in the motor
current circuit. When motor current calibration
setting is adjusted, this time lag should be
allowed for.
8. Check the foregoing motor current calibrations
with machine under “Auto” control as follows:
a. Close vanes manually (capacity control to
“Dec”).
b. Turn capacity control to “Auto.” Vanes
should stop opening at electrical demand
setting.
9. If control was calibrated at less than 100
percent load, turn electrical demand adjustment
setting to 100 percent. Control is now auto
matically calibrated for 100 percent full load
motor current.
This is a two-step motor current limiting
circuit. At 100 percent full load motor current,
the vanes will stop opening any further. If the
motor current should increase to 105 percent
due to some change in load cpnditions, the
vanes will close until the motor current is
reduced to about 102 percent. If the motor
current is reduced to 98 percent or below, the
control will respond to leaving chilled water
temperature. The electrical demand adjustment
allows the operator to reduce the maximum
current drawn by the motor, minimizing the
electrical demand rate during the off season
operation.
NOTE: If control cannot be calibrated with
above procedure, check voltage signal from
signal resistor in starter. At 100 percent full
load current, voltage between terminals 23 and
24 inside control panel must be 0.5 ± 0.1 volts.
If not in this range, check sizing of resistor in
starter.
CHILLED WATER CALIBRATION PROCEDURE
1. Turn throttle range calibration adjustment
(item 5, Fig. 3) fully clockwise.
2. Turn chilled water thermostat (item 4, Fig. 3)
until design chilled water temperature is main
tained. Mark thermostat at this position. If
capacity control vanes hunt, turn throttle range
calibration adjustment counterclockwise in
small increments until hunting ceases. Chilled
water thermostat may require resetting.
Trimming Refrigerant Charge — After the machine
has been placed in operation, it may be necessary
to adjust the refrigerant charge to obtain optimum
machine performance.
When machine full load is available, add o,
remove refrigerant slowly until the difference
between leaving chilled water temperature and the
cooler temperature reaches design conditions or
becomes a minimum. Shut the machine down and
allow refrigerant level to equalize between vessels.
Mark the level indicator (items 23, 24 or 25, Fig.
1) and maintain that shutdown refrigerant level.
IIMSTRUCTIIMG THE CUSTOMER OPERATOR
Be sure the operator carefully reads the 19EA
Operating and Maintenance Instructions.
Point out the following components; explain
their function and the system in which they are
used.
Compressor
Guide vanes, vane motor and linkage
Refrigerant-cooled motor
Transmission
Unishell
Cooler, condenser
Relief valve, isolation valves
Utility Vessel
Float chambers, sight glasses
Relief valves, charging valve
Dehydrator
Importance of proper operation
Valves and system operation
Sight glasses, gage
Lubrication System
Oil pump, cooler, filter
Solenoid, plug-cock
Heater, thermostat, temperature gage
Oil level and temperature
Pumpout System
Compressor, condenser, oil separator
Valve designation and cycle
Control System
Manual switches, gages and lights
Operating controls, safety controls
AuxiUary and special controls
Auxiliaries
Starter(s), pumps, cooling tower
Describe Refrigeration Cycle
Review Maintenance
Scheduled, extended shutdown
Importance of Log Sheet Record
Importance of water treatment
Check Operator Knowledge
Start-stop procedure
Safety and Operating Controls
Carrier Service
Advise operator of availability, and method of
ordering parts.
Review Operating and Maintenance Instructions.
Manufacturer reserves the right to change any product specifications without notice.
CARRIER AIR CONDITIONING COMPANY • SYRACUSE,
lEW YORK
Tatalnn Nn FS31-929
