Important Wiring Considerations

Use the following guidelines when planning the system wiring for the module:

• Install the SLC 500 system in a NEMA-rated enclosure.

• Disconnect power to the SLC processor and the module before wiring.

• Make sure the system is properly grounded.

• Group this module and low-voltage DC modules away from AC I/O or

high-voltage DC modules.

• Shielded cable is required for high-speed input signals A, B, and Z. Use

individually shielded, twisted pair cable lengths up to 300 m (1000 ft.).

• Shields should be grounded only at one end. Ground the shield wire outside

the module at the chassis mounting screw. Connect the shield at the encoder

end only if the housing is isolated from the motor and ground.

• If you have a junction in the cable, treat the shields as a conductor at all

junctions. Do not ground them to the junction box.

Considerations for Reducing Noise

In high noise environments, the 1746-HSCE2 inputs may accept “false” pulses,

particularly when using low frequency input signals with slowly sloping pulse

edges. To minimize the effects of high frequency noise on low frequency signals,

the user can do the following:

• Identify and remove noise sources.

• Route 1746-HSCE2 input cabling away from noise sources.

• Install low pass filters on input signals. Filter values are dependent on the

application and can be determined empirically.

• Use devices which output differential signals, like differential encoders, to

minimize the possibility that a noise source will cause a false input.

Electronic Protection

The electronic protection of the 1746-HSCE2 has been designed to provide

protection for the module from short-circuit and overload current conditions. The

protection is based on a thermal cut-out principle. In the event of a short circuit or

overload current condition on an output channel, all channels turn off within

milliseconds after the thermal cut-out temperature has been reached.

IMPORTANT

The module does not provide protection against reverse

polarity wiring or wiring to AC power sources. Electronic

protection is not intended to replace fuses, circuit breakers, or

other code-required wiring protection devices.

Auto Reset Operation

IMPORTANT

1746-HSCE2 outputs perform auto-reset under overload

conditions. When an output channel overload occurs as

described above, all channels turn off within milliseconds

after the thermal cut-out temperature has been reached. While

the overcurrent condition is present, the module tries resetting

the outputs at intervals of 500 ms. If the fuse cools below the

thermal cut-out temperature, all outputs will auto-reset and

resume control of their external loads as directed by the

module until the thermal cut-out temperature is again reached.

Removing power from an overloaded output channel would

also allow the fuse to cool below www.abb-drive.com the thermal cut-out

temperature, allowing auto-reset to occur when power is

restored. The output channel then operates as directed by the

module until the thermal cut-out temperature is again reached.

To avoid auto-reset of output channels under overload

conditions, monitor the fuse blown status bit (FB1) in the

module’s status file and latch the output off when an

overcurrent condition occurs. An external mechanical fuse

can also be used to open an output circuit when it is overloaded.