1. The control relay (SCR) in the low-voltage
LAMP TEST PUSH BUTTON-- Checks for
circuit is energized. The SCR contacts in the
burned-out fault indicator lamps. It is located on the
high-voltage circuit close, energizing the undervoltage
annunciator panel.
relay (UV). The UV contacts close, lighting the remote
LOADED RUNNING TIME METER-- Records
ENABLE RUNNING lamp, making power available to
the time in hours that the compressor is operated in a
the safety shutdown circuits and to the contractors, the
loaded condition.
relays, the switches, and the solenoids in the
high-voltage circuit.
TOTAL RUNNING TIME METER-- Records
the total compressor operating time in hours for both
2. When the UV contacts close, the motor
loaded and unloaded operating conditions.
contactor (M) is energized. This closes the M contacts
in the high-voltage circuit to start the motor. the M
ENABLE RUNNING LAMP (WHITE)--
contacts in the low-voltage circuit close at the same
Indicates that the compressor is in an operative
time, energizing the LOADED RUNNING TIME
condition, whether or not the machine is actually
meter (LHM), the TOTAL RUNNING TIME
running. It is located on the controller door.
meter (ETM), both local and remote MOTOR
MOTOR RUNNING LAMP (GREEN)--
RUNNING lamps, and the dehydrator refrigeration
Indicates that the compressor is running in either a
pump motor.
loaded or unloaded condition. It is located on the
3. The injection water solenoid valve (SV1) and
controller door.
the two timing relays (4TR and 6TR) are energized at
OVERLOAD RESET PUSH BUTTON-- Resets
the same time as the motor contactor.
the controller overload relay after an automatic
4. Actuation of SV1 opens the valve to permit the
shutdown is caused by a motor overload. If not pressed
flow of injection water. Relay 4TR is a timed-to-close
to reset, the compressor cannot be restarted.
(on-delay) relay that closes 2 minutes after it is
energized to make the high dew point temperature
FRESHWATER LEVEL SIGHT HOLE--
switch (HDP) operative in the safety shutdown circuit.
Allows checks to be made to ensure sufficient water is
Relay 6TR is a timed-to close (on-delay) relay that
in the holding tank to permit starting the compressor.
closes 12 to 15 seconds after it is energized to make the
The compressor must be shut down and repressurized
oil pressure and injection water pressure switches (PS4
before the sight hole plug can be removed. It is located
and PS3) operative in the safety shutdown circuit. (This
in front of the separator-holding tank.
permits start-up by preventing safety shutdown while
COMPRESSOR DISCHARGE THERMOM-
the lubricating oil and injection water system pressures
E T E R -- Indicates the temperature of the air
build up to normal values.)
discharging from the compressor. It is mounted on the
5. The compressor is now running fully loaded
separator-holding tank and indicates the air temperature
under control of the receiver air-pressure switch
in the separator.
(PS1) and with all control and shutdown circuits
As you read this section, look at the air compressor
operative.
schematic diagram (fig. 5-9), as the sequence of the
NOTE: The motor will not start when the selector
manual and automatic modes of operation of the LP air
switch (3SEL) is turned ON unless the pressure
compressor, the injection water level control, the
switch (PS1) is closed and the air discharge
condensate drain control, and the shutdown system are
temperature switch level control, the condensate
discussed. The numbers/letters in parentheses
drain control, and the shutdown system are
correspond to the electrical components on the
de-energized. The numbers/letters in parentheses
schematic.
correspond to the electrical components on the wiring
diagram.
Manual Operation
The compressor is stopped in the MANUAL mode
The operator places the controller in the manual
of operation by one of the following actions:
mode of operation by positioning the selector switch
The high receiver air-pressure switch (PSI)
(1SEL) to the MANUAL position and turning the
opening at 125 psig rising pressure
selector switch (3SEL) to the ON position. This initiates
the following sequence:
5-14
