Time Delay - McQuay seasoncon ALP-067A Installation And Maintenance Data

Part Winding Start - Optional
Part winding start is available on all voltage units and consists of
a solid state time delay wired in series with the contactor that ener-
gizes the 2nd winding of each compressor motor.
limit current in-rush to the compressors upon start up.
pressor starts, the contactor for the first motor winding is energized
instantly while that for the second motor winding is delayed for 1
second.
Control checkout is best accomplished by observation as each contac-
tor is pulled in to see that the 1 second delay occurs before the
second contactor pulls in.
LINE
PART WINDING

TIME DELAY 1

LINE .-%..,
Low Ambient Start - Optional
Low ambient start is available on all units as an option with Fantrol
and included automatically with optional Dampertrol.
a solid state normally closed time delay wired in series with a relay.
These are both wired in parallel to the liquid line solenoid valve so
that when the solenoid valve is energized by the unit thermostat, the
low ambient start relay is also energized through the time delay.
The relay has contacts that essentially short circuit the low pres-
sure control and allow the compressor to start with the low pressure
control open.
After about 2 3/4 minutes, the time delay will open and de-energize
the relay. If the system has not built up enough evaporator pressure
to close the low pressure control, the compressor will stop.
time delay can be reset to its original normally closed position by
moving the pumpdown switch(es) (PSl or PS2) to the "man. pumpdown"
position.
Moving the pumpdown switch back to the "auto. pumpdown"
position will again energize the relay for another attempt at start
up
. If the system has built up enough evaporator pressure, the com-
pressor will continue to run.
To check the control, turn off all power to the unit and remove the
wire(s) (No. 113 & 213) leading to the low pressure control(s) (LPl
& LP2) from terminal 4 in the unit control center.
pressor fuses and jumper across terminals L & M of the freeze con-
trols(s) and oil pressure safety control(s).
circuit by turning on the control circuit disconnect or main power
disconnect (depending on the installation) and the control stop
switch Sl.
The compressor contactors should pull in instantly.
Its purpose is to
As each com-
NEUTRAL
COMPRESSOR CONTACTOR
NEUTRAL
COMPRESSOR CONTACTOR
(2nd MOTOR WINDING)
It consists of
Remove the com-
Energize the control
The
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