Rockwell Automation 1746-HSCE2 Multi-Channel High-Speed Counter Installation Instructions - Manual (Page 14)

14 Multi-Channel High-Speed Counter
Publication 1746-IN002A-US-P
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.
Auto Reset Operation
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.
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 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.