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The difference between PNP and NPN sensor

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These types of sensors are only found in digital sensor category. The digital sensor is that sensor which gives 24V/0V DC output. PNP and NPN sensors   Let's consider an example of three wire sensor. It has brown (24Vdc) wire, blue (0Vdc) wire and black wire. Black wire that is wire which gives us output of sensor. If we receive 24Vdc from black wire that sensor is PNP type and if we receive 0Vdc from black wire that sensor is NPN sensor. Wiring with PLC Now   the question arises, how to connect sensor with PLC?  1. PNP Wiring  If your sensor is PNP, you must go for source input PLC and commen terminal of PLC must be connected to 0Vdc. 2.NPN wiring  If you choose NPN sensor, you must go for sink type PLC and commen terminal of PLC must be connected to 24Vdc. Why do we give supply opposite of sensor output to commen terminal of PLC? In this case an optocoupler plays its role. You will find such type of ...
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How electromechanical relay works?

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Electromechanical Relay              Relay has played a vital role in factory automation. Factory automation wouldn't have succeeded without this magical instrument.It is like a switch that connects or disconnects two circuits. But instead of manual operation a  relay  is applied with electrical signal, which in turn connects or disconnects another circuit.  Relays  can be of different types like electromechanical, solid state. Electromechanical  relays  are frequently used. Operating principle         As you can see in above picture, we have  employed 3 trips for switching purpose. One strip has been placed between two strips is called as common strip.         Since two strips are in contact due to spring force, that contact is called as NC (normally closed). As we know whenever we give electric supply to copper wounded coil, it gets energ...
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