Manual 2100-573A
Page
16 of 21
MOTOR START DEVICE
Single Phase (-A) model compressor circuits are
equipped with a 25 ohm PTCR (Positive Temperature
Coefficient Resistor) motor starting device as standard
equipment.
The PTCR is wired in parallel with the run capacitor.
When voltage is applied, and device is cool, its low
resistance permits a large current to flow in the auxiliary
windings - increasing the motors available starting
torque. The device then rapidly heats up, and the current
levels drop to a few milliamperes. The PTCR then
becomes self-regulating, passing just enough current to
maintain its temperature to remain in the high resistance
state. Once the voltage source is removed, the device
then cools down and the resistance drops, and is then
ready for the next compressor start cycle.
PRESSURE SERVICE PORTS
High and low pressure service ports are installed on all
units so that the system operating pressures can be
observed. Pressure tables can be found later in the
manual covering all models. It is imperative to match
the correct pressure table to the unit by model number.
Be careful to observe whether unit is operating in high
cool or low cool when utilizing the charts.
Alarm Relay Output
Alarm terminal is output connection for applications
where alarm relay is employed. This terminal is
powered whenever compressor is locked out due to HPC
or LPC sequences as described.
NOTE: Both high and low pressure switch controls
are inherently automatic reset devices. The
high pressure switch and low pressure
switch cut out and cut in settings are fixed by
specific air conditioner or heat pump unit
model. The lockout features, both soft and
manual, are a function of the Compressor
Control Module.
ADJUSTMENTS
Adjustable Delay on Make and Delay on Break
Timer
The potentiometer is used to select Delay on Break time
from 30 seconds to 5 minutes. Delay on Make (DOM)
timing on power-up and after power interruptions is
equal to 2 minutes plus 10% of Delay on Break (DOB)
setting:
0.5 minute (30 seconds) DOB =123 second DOM
1.0 minute (60 seconds) DOB =126 second DOM
2.0 minute (120 seconds) DOB =132 second DOM
3.0 minute (180 seconds) DOB =138 second DOM
4.0 minute (240 seconds) DOB =144 second DOM
5.0 minute (300 seconds) DOB =150 second DOM
During routine operation of the unit with no power
interruptions the compressor will operate on demand
with no delay.
Typical Settings for Dual Unit Installation:
Unit 1: DOB set at 2 minutes, and DOM is 132 seconds
Unit 2: DOB set at 4 minutes, and DOM is 144 seconds
