Chapter 4 Installing Hardware
4-19
①
Direct-current power supply
②
Emergency stop using an external switch.
③
Fuse: to protect the output circuit, a fuse having a breaking capacity between 5 A to 10 A is connected
to the common terminal.
④
Alternating-current power supply
⑤
A relay or a solenoid valve is used as a DC load. A diode is connected in parallel to absorb the surge
voltage that occurs when the load is OFF.
⑥
An electromagnetic contactor is used as an AC load. A resistor and a capacitor are connected in
parallel to absorb the surge voltage that occurs when the load is OFF.
Electromagnetic contactor
Y0.7
⑦
A bulb (incandescent lamp) is used as a DC load. A thermistor is connected in series to absorb the
surge current that occurs when the load is ON.
A bulb (neon lamp) is used as an AC load. A thermistor is connected in series to absorb the surge
current that occurs when the load is ON.
○8
Mutually exclusive output: For example, Y0.3 controls the clockwise rotation of the motor, and Y0.4
controls the counterclockwise rotation of the motor. This interlock circuit and the program in the PLC
ensure that there are protective measures if an abnormal condition occurs.