McQuay seasoncon ALP-067A, Установка и техническое обслуживание

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It takes about 120 seconds to warm the heater element enough to open
the bimetallic contact thus allowing time for the pressure differen-
tial to develop.
If during operation, the differential drops below 10 PSI, the heater
element will be energized and the compressor will stop. The control
can be reset by pushing the reset button on the control. If the com-
pressor does not re-start,
allow a few minutes for the heater element
and bimetallic contacts to cool and reset the control again.
To check the control, pump down and shutoff all power to the unit.
Remove the compressor fuses, and install a voltmeter between termin-
als "L" and "M" of the oil pressure control. Turn on power to the
unit control circuit (separate disconnect or main unit disconnect de-
pending on the type of installation). Check to see that the control
stop switch (Sl) is in the "on" position. The control circuit
should now be energized but with the absence of the compressor fuses,
__
no oil pressure differential can develop and thus the pressure actu-
ated contacts of the control will energize the heater element and
open the bimetallic contacts of the control within 120 seconds. When
this happens, the safety relay is de-energized, the voltmeter read-
ing will rise to 115V and the compressor contactor should open. Re-
peated operations of the control will cause a slight heat buildup
in the bimetallic contacts resulting in a slightly longer time for
reset with each successive operation.
LINE (SEE NOTE
NEUTRAL
HEATER ELEMENT
CONTACT
L
LINE (SEE NOTE
NEUTRAL
BIMETALLIC CONTACTS SAFETY RELAY
NOTES:
1. Hot only when the unit thermostat calls for compressor
to run.
2. Hot only when other safety control contacts are closed.
High Pressure Control
The high pressure control is a single pole pressure activated switch
that opens on a pressure rise to de-energize the entire control cir-
cuit except for compressor crankcase heaters. It senses condenser
pressure and is factory set to open at 380 PSIG and can be manually
reset closed at 315 PSIG. To check the control, either block off
condenser surface or start the unit with fuses in only one fan fuse
block (FBll) and observe the cut-out point of the control by watch-
ing condenser pressure rise. The highest point reached before cut-
out is the cut-out setting of the control.
CAUTION: Although there is an additional pressure relief device in
the system set at 425 PSIG, it is highly recommended that
the
"control stop"
switch (Sl) be close at hand in case
the high pressure control should malfunction.
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