Dunham-Bush ACXi 165-5SP-LN, Installation, Operation And Maintenance Manual

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4.0 ELECTRICAL
reaches the high pressure set-point, and
turn on the alarm indicator lamp on the
control box. The high discharge
pressure alarm will be recorded by the
micro-computer. Reset by pressing the
RESET button on the micro-computer.
Setpoint is 360 psig.
4.6.5 Oil Level Switch (LS)
An oil level switch is located in each
compressor. If low oil indication
(digital input is OFF) persists for 60
seconds during compressor operation,
the microcomputer will then shut down
the compressor. The status of the float
switch can be seen on the computer
display or the associated LED of the
Digital I/O Board. Failure is indicated
on the alarm pilot light. The low oil
alarm code will be recorded by the
computer. Press the RESET key to reset
the system. See Section 5.8 concerning
oil level.
4.6.6 Overload Protector (OL)
A solid state overload protects each
compressor by three phase current
monitoring to prevent high current
draw. The trip setting is factory set and
is reset by pressing button on overload
after correcting problem. The RESET
button on micro-computer must also be
pressed to clear the alarm. A no-run
error is stored in the microcomputer.
4.6.7 Phase Control Relay (PCR)
The PCR protects the unit from the
following electric supply malfunctions:
Under-voltage, phase reversal, under-
voltage and single phasing. If the PCR
trips, a control relay (lCR) will de-
energize and open the control circuit. A
LED light, located on the PCR,
indicates a good voltage supply. The
power loss A setpoint is factory set to
0.0 to allow automatic start after PCR
failure. Compressor will not start for 15
minutes after failure. To select manual
reset, set power loss A setpoint to 1.0.
In this case, a power loss alarm will be
stored by the microcomputer and
RESET must be pressed to start.
4.6.8 Sensor Alarm (Microcomputer)
If the computer measures an analog
value (temperature, pressure, volts.) that
is far beyond normal operating values,
the associated compressors are
shutdown. The computer then stores the
alarm code corresponding to the sensor
alarm. A sensor alarm indicates a
problem in the analog measurement
system.
4.6.9 No-Stop Alarm
(Microcomputer)
If the microcomputer turns off a
compressor, but the compressor digital
input does not turn off, a No-Stop alarm
is generated. The computer will turn off
the control power relay which disables
all compressor control circuits and will
turn on the alarm light. This alarm
indicates a wiring or hardware error.
4.6.10 Low Differential Pressure
Alarm (Microcomputer)
For proper lubrication, a compressor
requires a 30 psi differential pressure
between condenser and evaporator
pressures. If the differential pressure is
less than 30 psi for 3 minutes while a
compressor is operating, all
compressors will be shut down. The
microcomputer will store the low
differential pressure alarm code and
turn on the alarm light. The RESET key
must be pressed to clear the alarm.
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