protection is provided by the safety relief valve on the
condensate sump reaches the high-level setting of LS5,
receiver.
the switch opens to de-energize the control relay (3CR).
This opens the 3CR contacts, which, in turn,
The selector switch (1SEL) is set for
de-energizes the SV7 solenoid. The normally open
AUTOMATIC-120 psig operation. Shutdown control
solenoid valve opens to drain the condensate sump.
is the same except that the shutdown sequence is
When the liquid level drops to the low-level setting of
initiated by the opening of the pressure switch (PS2) at
LS5, the switch closes to energize 3CR and SV7. This
a rising air pressure of 120 psig.
shuts the drain valve.
HIGH AIR DISCHARGE TEMPERATURE.--
Abnormally high air temperature at the compressor
Shutdown System
discharge closes the temperature switch (TS),
energizing the control relay (14CR). The 14CR contacts
Automatic shutdown of the compressor occurs
close to light the HIGH AIR DISCHARGE
when one or more of the following conditions exist:
TEMPERATURE light on the annunciator panel and to
High air receiver pressure
energize the latching relay (2CR). Normally closed
2CR contacts in the high-voltage circuit open to
High air discharge temperature
de-energize UV, which de-energizes M. This stops the
High dew point temperature at the dehydrator
motor. Other 2CR contacts close to sound the remote
safety shutdown alarm and to maintain power to 14CR.
High or low injection (fresh) water levels
This keeps the HIGH AIR DISCHARGE
Low lube oil pressure
TEMPERATURE light illuminated even if TS opens
after the compressor has shut down, allowing operators
Low injection water pressure
to determine the cause of the shutdown.
High condensate sump level
HIGH DEW POINT TEMPERATURE.--
Abnormally high dew point temperature in the
HIGH AIR RECEIVER PRESSURE.-- When
dehydrator will close the temperature switch (HDP),
the compressed air pressure at the receiver exceeds the
rising pressure setting of the pressure switch (PS1 or
and if the relay (4TR) has closed, energize the relay
PS2), one of the following shutdown sequences is
(15CR). The 15CR contacts close to light the HIGH
initiated:
DEW POINT lamp on the annunciator panel and to
energize 2CR. This functions to stop the compressor,
The selector switch (1SEL) is in the MANUAL
sound the alarm, and maintain the indication (through
mode of operation. T h e c o m p r e s s o r w i l l b e
15CR).
automatically y stopped by the pressure switch (PS1)
tripping at 125 psig rising pressure. This will
HIGH WATER LEVEL.-- An excessively high
de-energize the main motor contactor (M), which opens
water level in the separator-holding tank will close the
the M contacts in the motor leads.
level switch (LS1), energizing the relay (11CR). The
11CR contacts close to light the HIGH SEP/HLDG
The selector switch (1SEL) is in the
TANK LEVEL lamp on the annunciator panel and
AUTOMATIC-125 psig operating position. The
energize the on-delay (timed-to-close) timing relay
compressor is under control of the normally closed
(STR). The 5TR contacts close in 3 to 5 seconds to
contact of the pressure switch (PS1). When a rising
energize 2CR (if LS1 has remained closed). The 2CR
pressure of 125 psig causes PS1 to open, compressor
shutdown is delayed for 10 minutes by the timing relay
contacts actuate to shut down the motor, sound the
(1TR). The control relay (1CR) is de-energized by the
shutdown alarm, and maintain the indication (through
opening of PS1. This initiates closing of the air intake
11CR).
butterfly valve (solenoid SV4 energized) and opening
LOW WATER LEVEL.-- An excessively low
of the air bypass line. The compressor runs unloaded
water level in the separator will close the level switch
with discharge air recycling back to the compressor
(LS2) and energize the relay (12CR). The 12CR
inlet. After 10 minutes (provided PS1 remains open),
contacts affect 5TR and 2CR. They also light the LOW
the 1TR contacts time open to stop the compressor drive
SEP/HLDG TANK LEVEL lamp on the annunciator
motor by de-energizing the motor contactor (M).
panel.
During the 10-minute time out, excessive air pressure
5-19
