If you need a sensor output that energizes when detection occurs, which type should you use?

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Multiple Choice

If you need a sensor output that energizes when detection occurs, which type should you use?

The idea is to have the output energize only when the sensor detects something. A normally open contact is open when the sensor is idle and closes the circuit as soon as detection happens. That means current starts flowing and the output energizes exactly when detection occurs. If you used a normally closed contact, the circuit is closed (energized) when there’s no detection, and it opens (de-energizes) when detection occurs, which is the opposite of what you want in this case. Having both normally open and normally closed contacts in parallel could energize the load even when nothing is detected because the normally closed path would be conducting in the idle state, leading to false energization. So the best choice for energizing on detection is the normally open type.

The idea is to have the output energize only when the sensor detects something. A normally open contact is open when the sensor is idle and closes the circuit as soon as detection happens. That means current starts flowing and the output energizes exactly when detection occurs.

If you used a normally closed contact, the circuit is closed (energized) when there’s no detection, and it opens (de-energizes) when detection occurs, which is the opposite of what you want in this case.

Having both normally open and normally closed contacts in parallel could energize the load even when nothing is detected because the normally closed path would be conducting in the idle state, leading to false energization.

So the best choice for energizing on detection is the normally open type.

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