User manual

Publication 1763-UM001E-EN-P - March 2015
Installing Your Controller 23
Disconnecting Main Power
The main power disconnect switch should be located where operators and
maintenance personnel have quick and easy access to it. In addition to
disconnecting electrical power, all other sources of power (pneumatic and
hydraulic) should be de-energized before working on a machine or process
controlled by a controller.
Safety Circuits
Circuits installed on the machine for safety reasons, like overtravel limit
switches, stop push buttons, and interlocks, should always be hard-wired
directly to the master control relay. These devices must be wired in series so
that when any one device opens, the master control relay is de-energized,
thereby removing power to the machine. Never alter these circuits to defeat
their function. Serious injury or machine damage could result.
Power Distribution
There are some points about power distribution that you should know:
• The master control relay must be able to inhibit all machine motion by
removing power to the machine I/O devices when the relay is
de-energized. It is recommended that the controller remain powered
even when the master control relay is de-energized.
• If you are using a DC power supply, interrupt the load side rather than
the AC line power. This avoids the additional delay of power supply
turn-off. The DC power supply should be powered directly from the
fused secondary of the transformer. Power to the DC input and output
circuits should be connected through a set of master control relay
contacts.
WARNING
Explosion Hazard
Do not replace components, connect equipment, or
disconnect equipment unless power has been switched off.
WARNING
Explosion Hazard
Do not connect or disconnect connectors while circuit is
live.