Sensor and Pre-actuator Power Supply Control by Alarm Relay
Original instructions
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How to Set Up Sensor and Pre-actuator Power Supply
It is recommended that control of the different power supplies is set up in the following sequence.
Step
Action
1
Switch on the power supply to the PLC and the inputs (sensors), using the contactor KM (see diagram).
2
When the PLC is in RUN mode and running on MANU/AUTO, switch on the output power supply (pre-actuators), using the contactor KA. Only in AUTO, this is controlled by the alarm relay contact in each power supply.
Note:
In alternating current, the contactor KA controls the supply sensors.
In direct current, the contactor KA controls the supply pre-actuators and the supply sensors.
NOTE: Before restarting the installation following a stop (caused by a power outage or an emergency stop), observe the recommendations given in the General Safety Instructions.
Example 1
The following diagram shows a PLC station supplied by alternating current:
Example 2
The following diagram shows a PLC station supplied by direct current: