Section 5
OPERATION
26
5.9 PURPOSE OF CONTROLS -- SUPERVISOR II (CONTINUED)
CONTROL OR INDICATOR PURPOSE
FLUID PRESSURE---P3 Continually monitors injection fluid pressure and shuts
down the compressor in the event of low fluid pressure.
FLUID FILTER DIFFERENTIAL SWITCH Continually monitors fluid filter differential and gener-
ates an alarm when the fluid filter needs replacement.
INLET FILTER MAINTENANCE SWITCH Monitors condition of compressor inlet air filter and indi-
cates when replacement is required.
FLUID LEVEL SIGHT GLASS Indicates fluid level in the sump. Proper level is not to
fall below the center of the sight glass. Check level
when compressor is shut down. DO NOT OVERFILL.
COOLER BYPASS VA LVE Regulates flow of fluid to and around the cooler. De-
signed to maintain a minimum operating temperature of
180_F(82_C); used for fast w a rm---up on start---up.
MINIMUM PRESSURE/CHECK V ALVE Maintains minimum of 50 psig (3.4 bar) in the com-
pressor sump. Valve piston restricts receiver air dis-
charge from receiver/sump when pressure falls to 50
psig (3.4 bar). Also incorporated in this valve is a ter-
minal check valve which prevents line pressure back-
flow into the sump during unload conditions and after
shutdown.
PRESSURE RELIEF VALVE Protects compressor by venting compressed air in
excess of 200 psig (13.8 b ar) to atmosphere.
MODULATING INLET VALVE Regulates the amount of air allowed to enter the air
compressor. This regulation is determined by the
amount of air being used at the service line. Also acts
as a check valve to prevent reverse compressor rota-
tion at shut down.
SOLENOID VALVE Bypasses the pressure regulator valve causing the in-
let valve to close when the compressor reaches maxi-
mum operating pressure. Also activates blowdown
valve.
WATER REGULATING VALVE Regulates the amount of cooling water used in the
(water---cooled only) cooler to keep the compressor running at a normal op-
erating temperature of 170_F(77_ C).
5.10 SUPERVISOR II OUTPUT RELAYS
RELAY OPERATION
RUN RELAY (K1) Contact closure energizes the compressor starter.
*---DELTA (K2) A timed contact used to provide wye---delta transition
time.
UNL OAD/LOAD (K3) Controls ON LOAD/OFF LOAD operation of the load
control solenoid valve.
COMMON FAULT (K4) May be used to provide remote indication of any pre---
alarm, maintenance or fault shutdown condition.
DRAIN VALVE (K5) Controls optional solenoid valve to provide automatic
condensate removal.
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