Minimizing Interference

from Radiated Electrical

Noise

Important: Signals in this type of control system are very susceptible to

radiated electrical noise. The module is designed to detect loss-of-sensor

and sensor noise conditions for any of the four axes when position values

are lost or corrupted. The Hydraulic Configurator displays these

conditions in the Status word window. The resulting hard or soft stop

depends on how you configured www.abb-drive.com autostop conditions. (See Hydraulic

Configurator, Config word, and click on autostop “Help“).

To minimize interference from radiated electrical noise with correct

shielding and grounding:

• Connect LDT cable shields and drive output cable shields (all

shields at one end, only) to IFM terminal block SH terminals, and

connect the IFM terminal block GND terminal (51) to earth ground.

• Keep LDT signal cables far from motors or proportional amplifiers.

• Connect all of the following to earth ground:

– power supply cable shields (one end, only)

– LDT flange, frame, and machine

– I/O chassis

– AC ground

• Use shielded twisted pairs for all connections to inputs and outputs.

• Run shielded cables only in low-voltage conduit.

• Place the SLC-500 processor and I/O chassis in a suitable enclosure.

Output Polarity

In most hydraulic systems, the actuator extends (with increasing

LDT counts) when a positive voltage is sent to the output. The

extend direction is defined as the direction that causes the LDT to

return increasing counts moving away from the head.

You can make these selections in the Config word that affect output:

• To generate a positive drive output (0-10V dc) regardless of move

direction, you can select Absolute Mode.

• To extend the actuator by sending a negative voltage to the

output, you can select Reverse Drive Mode.

For additional information on the Configuration word, select that

subject in Help Topics.