Carlyle Compressor Div. P O Box 4808 Syracuse, NY 13221
Phone: 800-462-2759 Fax: 315-432-3274
12
Appendix A - Functional Overview
LonCEM FUNCTIONAL LOGIC
START-UP SEQUENCE
n A 20 second time delay between
compressor starts is built into the
module. The time delay is active at
initial module power-up, or whenever
the compressor is called for before
20 seconds of off-time has elapsed.
n CEM supplies power to the contactor
and Oil Solenoid
n 1.25 seconds after startup, the CEM
checks for reverse rotation
n 30 seconds after startup,
compressor is loaded
n 30 seconds after startup, safeties
and VI control begins
n 180 seconds after startup, CEM
begins to monitor oil system
pressure drop
MOTOR COOLING CONTROL
n The motor cooling valve will be
energized when the motor
temperature reaches 180F and will
de-energize when the temperature
drops below 165F
n When the motor temperature
reaches 220F the CEM will unload
the compressor until the temperature
drops below 205F
n If the motor temperature reaches
240F the CEM will shut off the
compressor until the temperature
drops below 200F
INPUT DEVICE FAILURES
n The module will shut off the
compressor if it detects any failure of
an input device (thermistors,
pressure transducers)
DISCHARGE TEMPERATURE
CONTROL
n The motor cooling valve will be
energized when the discharge
temperature reaches 205F and will
de-energize when the temperature
drops below 190F
n If the discharge temperature reaches
230F the CEM will shut off the
compressor until the temperature
drops below 200F
OIL PRESSURE DIFFERENTIAL
PROTECTION
n If the pressure differential between
oil and suction drops below 45 psi
for 90 continuous seconds, the
compressor will be shut off
OIL SYSTEM PRESSURE DROP
SAFETY
n If the pressure differential between
discharge and oil increases to 35 psi
for 15 continuous seconds an alarm
code will flash
n If the pressure differential between
the discharge and oil increases to 50
psi for 15 continuous seconds the
compressor will be shut off
VI CONTROL
n The VI coil is energized when the
pressure ratio is greater than 4.9:1
and will de-energize when the
pressure ratio drops below 5.1:1
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