33
There are three different options to control tons per circuit
when using an unloading compressor. The first is to use
drop solenoid valve control as illustrated above and let the
suction cutoff unloaders “ride” with the load. The second is to
use drop solenoid valve control as illustrated above with
electric unloaders and let the control algorithm determine the
combination of solenoid valves and unloaders to limit tons per
circuit to acceptable limits. The third is to limit the minimum
amount of unloading so that tons per circuit is within accept-
able limits.
Electric Heaters —
Electric heaters may be factory-
installed or factory-supplied for field installation.
Motor Start/Stop Stations
All field-installed wiring, including the electrical ground,
MUST comply with the National Electrical Code (NEC) as
well as applicable local codes. In addition, all field wiring must
conform to the Class II temperature limitations described in the
NEC.
Refer to Fig. 59 and 60 for optional factory-installed motor
start/stop station wiring diagrams.
WARNING
To avoid possible injury or death due to electrical shock,
open the power supply disconnect switch and secure it in
an open position during installation.
CAUTION
Use only copper conductors for field-installed electrical
wiring. Unit terminals are not designed to accept other
types of conductors.
Fig. 59 — Sinlge-Phase Motor Start/Stop Station Wiring Diagram
LEGEND
GND —
Ground
TB
—
Terminal Block
a39-4124
Fig. 60 — 3-Phase Motor Start/Stop Station Wiring Diagram
a39-4123
LEGEND
GND —
Ground
TB
—
Terminal Block
