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	Safety Device Safety Measue Categories
	Identification of Risk Sources
	Three Key Points for Protection Against Mechanical Hazards
	Grounding Instructions by Output Form (NPN/PNP)
	Basic Safety Circuit Concepts
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	Calculation Example of Safe Distance

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Grounding Instructions by Output Form (NPN/PNP)

Grounding wires of devices or equipment are connected to the 0 V side in many cases.
When connecting to a 0 V plane, PNP output must be selected in order to meet the safety standard. Following are the reasons.

An Example of Using NPN Output


	If this part is disconnected and ground fault occurs, the voltage drops from 24 V to 0 V and power is continuously input to the connected equipment regardless of whether the switch is turned on or off, causing danger to the user.

An Example of Using PNP Output


	Even if this part is disconnected and ground fault occurs, the voltage is maintained at 0 V and no power is input to the connected equipment regardless of whether the switch is turned on or off. Therefore, it is safe.

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