Carrier 19DG - Manual (Page 3)

Perform dehydration as follows:
1. Connect dehydration pump to the cooler
charging valve (Fig. 1).
2. Ensure that all valves on the purge assembly are
closed. Valve identification numbers are listed
on the purge valve operation plate (Fig. 1).
3. Remove the A-B swing connection (see valve
operation plate) and connect a mercury
manometer (absolute pressure type) to the
bottom common connection.
4. Operate dehydration pump until manometer
reads 29.80 in. Hg ref 30-in. bar. (0.1 psia);
continue to operate pump for 2 more hours.
5. Close cooler charging valve; stop dehydration
pump; record manometer reading.
6. After a 2-hour wait, read manometer again. If
reading has not increased, dehydration is com­
plete. If reading has increased, repeat steps 4
and 5.
7. If reading continues to rise after several dehy­
dration attempts, check for a machine leak by
repeating the Refrigerant Pressure Test.
Inspect Piping — Refer to piping diagrams provided
in Job Data and inspect piping to cooler, condenser
and oil cooler. Ensure that flow direction is correct
in all cases and that all piping specifications are
met.
CHECK WATER ELOW — Water flow thru con­
denser and cooler must meet job requirements.
Measure the water pressure drop across cooler or
condenser or across the pumps. Check to see that
water flow agrees with design flow.
Oil cooler water should meet the following
requirements:
Clean water
Max water temperature
85 F
Max inlet working pressure 200 psi
Water vel in tube, ft/sec 10 max — 6 min
Water flow, gal./min 7 max — 4 min
Water press, drop, psi diff 5 max — 2 min
Valves and/or controls Field supplied
Field Wiring — Prior to starting equipment,
refer to wiring diagrams in Job Data and check
power supply as follows:
1. Connect a voltmeter across power wires to
compressor motor starter and measure voltage.
Compare this reading with voltage rating on
compressor and starter nameplates.
WARNING; Do not attempt to check high
voltage supply without proper equipment.
Serious personal injury can result.
2. Check that ampere rating on starter nameplate
matches ampere rating on compressor motor
nameplate.
3. Ensure that voltage to oil pump starter agrees
with oil pump nameplate value.
4. Check that electrical supply to oil heater and
purge pump is 120 volts.
5. Test compressor motor and its power lead
insulation resistance with a 500-volt insulation
tester such as a megohmmeter. Proceed as
follows:
a. Open starter main disconnect switch.
b. Test the three phases of compressor motor,
phase-to-phase and phase-to-ground, with
tester connected on the motor side of the
starter contactor in the starter. Take a
resistance reading at a 10-second interval
and at a 60-second interval for each phase.
c. Divide the 60-second resistance reading by
the 10-second reading. This gives the polari­
zation ratio. The polarization ratio must be
1.15:1 or higher. Both the 10-second and
60-second resistance reading must be 5.0
megohms or higher.
If readings are unsatisfactory, repeat tests at
motor terminals with motor power leads dis­
connected. This will indicate whether fault is
in motor or in motor power leads.
Check Starter — Before starting the 19DG
Machine, open the main disconnect and then check
starter.
1. Remove contactor arc chutes. Be sure con­
tactors move freely, and that shipping string is
removed. Replace arc chutes.
2. Check contactors for dirt and rust. Clean
contact magnet surfaces lightly with sandpaper.
Do not sandpaper or file silverplated contacts.
Apply a very thin coat of petroleum jelly to
magnet surfaces and then wipe it off. If starter
has been in a dusty atmosphere, vacuum clean
the cabinet and wipe with Unt-free cloth.
3. Remove fluid cups from magnetic overload
relays. Add dashpot oil to cups per instructions
on relay nameplate. Dashpot oil is shipped in
small vials usually attached to starter frame
near relays. Use only the dashpot oil shipped
with starter. Do not substitute. Overload relays
are factory set for 108% of motor full load
amperage
and resetting is not normally
required.
4. Check transfer timer for proper time setting.
On Star-Delta starters, timers have adjustable
ranges of 10 seconds to 3 minutes and are
factory
set at one minute. On Auto-
Transformer starters, timers have adjustable
ranges of zero to 60 seconds and are factory set
for 30 seconds.
5. With main disconnect switch open, manually
open and close main control relay (ICR) to be
sure it operates freely.
Oil Charge — The oil charge is shipped in the oil
reservoir. Check sight glass (Fig. 1) to be certain oil
is in the reservoir. If oil must be added, it must
meet Carrier’s oil specification as listed in the
19DG Operating and Maintenance Instructions.
Charge oil thru the oil reservoir charging valve
(Fig. 1). With machine at vacuum, oil is drawn
from the oil container. Continue charging until oil
reaches middle of sight glass (Fig. 1).