Table 4 — setting safety controls, Jz, —’ ''bi – Carrier 19CB User Manual
Page 8
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knob on demand limit control at 100% and turn
calibration screw fully clockwise.
Place a clamp-on ammeter on one of the 3
starter leads. Be sure ammeter scale is set so that
compressor full load amperage will register be
tween midway and just under the top of the scale.
Install jumpers between ^ and [^, and
between
and
11
Close disconnects, start
compressor and check oil pressure and temperature
(Fig. 2). With compressor running, operate the
guide vanes with capacity control switch or pneu
matic thermostat. Do not exceed 100% full load
amps.
1. Check controls 1 and 2 as indicated in Table 4.
2.
Stop machine, open disconnects, remove
jumpers and check controls 3, 4 and 5 as
indicated.
Table 4 — Setting Safety Controls
SAFETY OR CONTROL DEVICE
1. Chilled Water Low-Temperature Cutout and Recycle Switch
(Fig. 1)
'TEMPERATURE AD.IUSTMENl
^ O,
DIFFERENTIAL ADJUSTMENT
JZ, —’ ''Bi*
Set this switch to break at approximately 5 F below design
chilled water temperature, or at 36 F whichever is higher
Set the differential at 10 ± 1 F so that when the machine shuts
down
automatically
at
approximately
5
F
below
the
design
chilled water temperature it will restart at approximately 5 F
above the design water temperature.
This
control
must
break
ahead
of
the
refrigerant
low-
temperature
cutout
switch
or
the
machine
will
not
recycle
automatically
2.
Refrigerant Low-Temperature Cutout (Fig. 6)
CUTOUT
ADJUSTMENT
Set refrigerant low-temperature cutout at 33 F or one degree below
design
refrigerant
temperature,
whichever
is
lower,
while
checking
temperature at thermowell near control center
SAFETY OR CONTROL DEVICE
STOP
MACHINE,
REMOVE
JUMPERS
AND
PEREORM
RE
MAINING CHECKS.
3.
Condenser High-Pressure Cutout (Fig. 6)
CUTOUT ADJUSTMENT .f.'
COVER
JiEFRlG
ii
114
SETTING
15 psig
45 psig
RESET
BUTTON
CUTOUT SCALE
The
condenser
high-pressute
cutout
is
factory
set
to
shut
the
machine
down
when
condenser
pressure
reaches
setting
listed.
Isolate the switch and check setting with a metered supply of air
4. Oil Heater Thermostat (Fig. 2)
Set the oil heater thermostat to maintain a minimum oil reservoir
temperature of 140 F at shutdown.