32
Fig. 27 — Paragon Slide Valve Control Illustration
5.3.5 Compressor Protection
Motor and discharge temperature control for a screw
compressor is critical. Excessive motor and discharge
gas temperatures can cause premature compressor fail-
ure; therefore, control of these temperatures is very
important. The CCM monitors these temperatures
through the use of the factory-installed 5K thermistor in
the motor w
indings and a field-installed 5K thermistor in
the compressor discharge temperature thermo-well.
When the thermistors indicate an overheated condition,
the CCM will perform the following:
• Energize a liquid injection valve, sending cool liquid
into the motor compartment.
• Override the Slide Valve and restrict the compressor
from unloading and or force the compressor to fully
load to reduce motor and or discharge temperature.
• Trip the compressor off.
Motor Temperature (Tm) will have the following functions:
• Control a motor cooling valve to provide liquid injec-
tion to the motor compartment.
• Override the compressor slide valve to reduce motor
temperature.
• Turn the compressor off on an overheated motor
temperature condition.
• See Table 13: Motor and Discharge Temperature
Control Points and Table 14: Slide Valve Override
Control Points for Tm control points.
Motor Temperature (Td) will have the following functions:
• Override the compressor slide valve to reduce dis-
charge temperature.
• Turn the compressor off on a high discharge tem-
perature condition.
• See Table 13: Motor and Discharge Temperature
Control Points and Table 14: Slide Valve Override
Control Points for Td control points.
5.3.6 LED Fault Indication
The CCM will provide an LED ala
rm output signal to the
System Controller when a compressor fault condition
arises. See Tables 15 and 16.
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