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090.040-M (MAR 12)
Page 36
ANALOG OUTPUTS
An Analog Output is the portion of the hardware that
the Quantum™ HD uses to provide control. With the
Quantum™ HD, this output is typically a 4-20 mA sig-
nal that is outputted to an external device. This de-
vice is usually a customer specifi c application, such as
to simply receive a signal back from the Quantum™
providing the Slide Valve Position to an external ap-
plication (perhaps a PLC), as an example. The output
can be set as a 0-20mA signal in the calibration of
the output by accessing Menu > Calibration > Output.
The 4-20mA signal can be altered if necessary to a
Vdc signal by using a resistor at the input of the de-
vice being controlled. Refer to the following chart for
values:
Original
Desired
signal
signal
4-20mA
1-5Vdc
4-20mA
2-20Vdc 500 ohm, 1%, 1/2 watt
0-20mA
0-5Vdc
0-20mA
0-10Vdc 500 ohm, 1%, 1/2 watt
TROUBLESHOOTING THE ANALOG INPUTS AND OUT-
PUTS
Some problems that are encountered involve trou-
bleshooting the Analog inputs and outputs. The Ana-
log Board has twelve Analog I/O board connectors
labeled P4 through P10. The external Analog devices
are wired to a connector plug. Position 1 connects
to the plus (+) of the external device for channel 1,
position 2 connects to the signal (SIG) of the exter-
nal device for channel 1 and position 3 connects to
ground (GND) of the external device for channel 1.
Position 4 connects to the plus (+) of the external
device for channel 2, position 5 connects to the signal
(SIG) of the external device for channel 2 and position
6 connects to ground (GND) of the external device for
channel 2, as shown below:
Channel 2
+ Power
Channel 1
Channel 1
Signal
+ Power
Each channel is setup through software calibration
for the proper transducer type and range, and each
transducer must be calibrated through the appropri-
ate sensor calibration screen. Improper setup of ei-
ther the hardware or software will result in improper
operation or range.
The most common fault associated with the improper
reading of the analog channels other than hardware
or software setup problems fall into one of the fol-
QUANTUM™ HD COMPRESSOR CONTROL PANEL
MAINTENANCE
Resistor to use
250 ohm, 1%, 1/4 watt
250 ohm, 1%, 1/4 watt
Channel 2
GND
Signal
GND
lowing categories:
•
Sensor fault
•
Wiring problem
•
Improper grounding of system.
An open wire, shorted or shunted wire, or faulty sen-
sor will usually give a reading at either the minimum
or maximum end of the range scale. An erratic read-
ing or a reading that seems to fl oat up and down
is usually indicative of a grounding problem. When
a single transducer or cable is shorted to earth (or
system) ground, this can show up as a whole assort-
ment of problem channels. The easiest way to fi nd a
short to earth problem is to disconnect all the sensor
plugs and ohm out each plug screw terminal to earth
for open (infi nite) impedance. All sensors should read
open to earth with the exception of the CT motor
current channel. One side of the CT is grounded in
the Motor Control Center (MCC). (The third pin on
pressure sensors is ground.)
REPLACING A DEFECTIVE ANALOG BOARD
The procedure to replace an Analog board is outlined
below:
1.
Shut off control power.
2.
Unplug all connectors from the board.
3.
Remove the old board from the machine and
remove the new board from its packing and
place both on an anti-static surface.
4.
Check that all jumpers and dipswitches are
properly setup on the new board as it was
on the old board.
5.
Install the modifi ed replacement board in
the panel.
6.
Plug all connectors back in.
7.
Turn on control power.
8.
After replacing or installing an Analog Board
and powering on the control panel, select
[Redetect I/O Comms] from the Menu >
Service > Communications screen. This se-
lection provides a method to detect all con-
nected Analog and Digital boards. If a board
has been removed, a communication error
shutdown will be issued until this key is se-
lected.
The [Redetect I/O Comms] key resets the memory of
the processor as to which boards it requires commu-
nications from. Therefore, it is important to check the
[About] screen to see which boards have been de-
tected relative to the I/O boards actually in the panel.
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Table of Contents
Troubleshooting
