Allen-Bradley micrologix 1500, Руководство пользователя

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Publication 1764-UM001A-US-P
2-4 Installing Your Controller
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 or disconnect
equipment unless power has been switched off.
WARNING
!
Explosion Hazard - Do not connect or disconnect connectors
while circuit is live.