McQuay seasoncon ALP-067A Installation And Maintenance Data page 48

NOTE:
Compressor Lockout - Optional
Compressor lockout consists of a solid state time delay wired in
series with
rapid compressor cycling when cooling demands are erratic.
cuit illustrated above is for the lead compressor in each refriger-
and circuit.
same function but is wired differently (see unit wiring diagram).
When the unit thermostat no longer calls for cooling and the com-
pressor contactor
the circuit preventing compressore re-start.
The circuit remains open for a period of 5 minutes so that if the
unit thermostat should call for cooling before the delay period has
expired, the compressor will not re-start.
time delay will close its contacts to complete the circuit and be
ready for start up.
er to terminal 4 is interrupted and resets closed automatically af-
ter the time delay period.
To check the control, the compressor(s) must be running initially.
Move the pumpdown switch (PSl or PS2) to the "man. pumpdown" posi-
tion.
Immediately after the compressor(s) have stopped running,
move the pumpdown switch back to the "auto. pumpdown" position.
lead compressor should not re-start for 5 minutes.
pressor in the refrigerant circuit should start approximately 20
seconds after the lead compressor,
high enough to require it.
the same way.
page 48
Line is only hot when the unit thermostat calls for compressor to run.
the compressor
The circuit for the second compressor(s) performs the
have opened, the lockout time delay breaks open
The time delay opens its contacts whenever pow-
LINE
(SEE NOTE)
NOTE:
Hot whenever freeze control and high
pressure control permit safe operation.
contactor(
Its purpose is to prevent
provided that the cooling load is
Each refrigerant circuit can be checked
TIME DELAY
TO UNIT THERMOSTAT
After 5 minutes, the
The second com-
The cir-
The