20
Field Wiring
4.3
Analog Outputs
The 4 analog outputs are labeled AO1 to AO4 in Figure 16. They have short-circuit and
thermal protection. They provide 10 mA with a maximum voltage of 10 VDC to control the
speed of a motor, the position of a valve or damper, or light intensity using electronic ballasts
with 0-10 V inputs.
To ensure that analog outputs operate correctly, follow these guidelines:
•
Use 18 AWG stranded wire.
•
Limit the distance between the field device and the controller to 10 m (30 ft). Mircom
recommends shielded wire for noisy environments.
•
If this distance is not possible, longer wire runs with shielded wire are allowed up to 30 m
(100 ft). Connect the shield to the
0V
terminal on the controller, making sure to isolate
the shield on the other end. Failing to do so creates ground loops.
•
When possible, route the wiring inside metal piping and ground the piping for better
results.
•
Avoid running any analog signals near sources of electric noise such as: motors,
ballasts, fluorescent lamps, variable frequency drives, high energy contacts, RF (radio
frequency) transmitters, microwave ovens, and any other equipment that generates
electromagnetic interference.
•
Keep a minimum distance of 30 cm (1 ft) between analog output wiring and any
conductor carrying more than 24 VAC.
•
Follow good wiring and installation practices, and follow all local regulations and
electrical codes.
•
Use the terminal labeled
0V
to connect the return signal or common.
Attention: Do not connect 24 V to the controller when the voltage input selection
jumper is set to 12 VDC.
To prevent damage to the controller, do not connect 24 V to the
controller when the voltage input selection jumper is set to 12 VDC.
Caution:
An appropriate UL listed class 2 power supply or transformer with
necessary protection devices such as fuses or breakers should be used
to limit the risk of fire. All local codes and regulations for installation
must be observed.
Caution:
Applying any external voltage less than 0 V or greater than 10 V will
damage the analog outputs.
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