Carrier 19DA - Manual (Page 5)

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Check Operation of Safety Controls - Disconnect
main motor leads at starter to prevent compressor
motor operation while performing safety control
check. Push the START button. Manually open
the following safety controls to be sure they de­
energize the ICR coil, causing the main starter
contacts to open and stop the compressor. Anti­
recycle timer, item 6, Table 2, can be set for
minimum time per this safety check.
1. Chilled water low-temperature cutout and re­
cycle switch (item 1, Table 2).
2. Chilled water flow switch (in chilled waterline).
3. Refrigerant low-temperature cutout switch
(item 2, Table 2).
4. Low oil pressure cutout switch (item 5, Table 2).
5. Condenser high-pressure cutout switch (item 4,
Table 2).
6. Bearing and motor winding high-temperature
cutout switch (in motor terminal box - remove
one wire to OPEN switches).
7. Oil pump starter auxiliary contact (in oil pump
starter).
8. Chilled water and condenser water pump safety
interlocks (in pump starters).
9. Any other interlock shown on job blueprint.
Purge - Open all purge operating valves (Fig. 2).
Place valves in NORMAL AUTOMATIC position.
Operate purge pump momentarily by placing purge
switch in MANUAL position. Then place purge
switch in AUTO position.
START-UP
Preliminary Checks
WATER SUPPLY - Before checking compressor
rotation, ensure that water supplies to the cooler,
condenser, and oil cooler are available, and that
the water pumps are running.
COMPRESSOR ROTATION - Set capacity control
to MANUAL (Honeywell), or HOLD (Barber-
Colman). Press machine START button and let
compressor motor come up to speed, then press
machine STOP button. Check motor rotation thru
sight glass in the motor end bell (Fig. 1). Motor
rotation must be clockwise to result in coun­
terclockwise rotation of the compressor (when
viewed from motor end).
COMPRESSOR OPERATION
1. Press machine START button and let com­
pressor come up to speed. Press machine
STOP button and listen for any unusual sounds
coming from the compressor and transmission
housing as compressor coasts to a stop.
NOTE: The antirecycietimerprevents rapid
recycling of the compressor and is factory
set to allow one start every twenty minutes, ;
2. Press machine START button and let compres­
sor continue running. Check oil pressure and
oil temperature (Fig. 1).
3. Ensure that condenser water and chilled water
are circulating, and that chilled water tem­
perature does not drop below the design tem­
perature shown in Job Data.
4. Ensure that the refrigerant agitator solenoid
valve(s) are operating. The agitator valve(s)
are open when the inlet guide vanes are closed.
When the vanes open, and the vane motor crank
angle reaches approximately 42° from the ver­
tical centerline, the valve closes. The two
valves on the 19DA31 size compressor operate
in step sequence at approximately 42° and 28°
vane motor crank angle.
While the inlet guide vanes are being opened
manually (see "Motor Overload Module"),
listen for the sound of the refrigerant agitator
solenoid valve(s) closing.
Setting Safety Controls - Before setting safety
controls, set the capacity control to MANUAL
(Honeywell) position or HOLD (Barber-Colman).
Place a clamp-on ammeter on one of the three
starter leads and slowly open prewhirl vanes.
(Do not exceed 100 percent full load amperage.)
Perform the safety checks in the following table;
Table 2 - Setting Safety Controls
SAFETY OR CONTROL DEVICE RECOMMENDED SETTING
1. Chilled Water Low-Temperature
Cutout and Recycle Switch (Fig. 2)
-TEMPERATURE ADJUSTMENT
1. Set this switch to break at approximately 5 F below de­
sign chilled water temperature, or at 36 F, whichever
is higher.
2. Set the differential at 10 F plus or minus 1 F so that
when the machine shuts down automatically at approx­
imately 5 F below the design chilled water temperature
it will restart at approximately 5 F above the design
water temperature.
3. This control must break ahead of the refrigerant low-
temperature cutout switch or the machine will not re­
cycle automatically.