# Inductive load protection



## john d (Aug 18, 2012)

Hi

When it comes to PLC outputs that use transistors, how good are they protected against inductive loads ?. Well it's clear that a PLC output should not have a high current or high voltage at its terminals but instead a small 24VDC interposing relay if the system were running on 24VDC. The coil inside the interposing relay is counted as an inductive load even though its a small coil. The question is, do the manufacturers like AB and Siemens provide any internal protection against inductive loads like a snubbing diode ?


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## oliquir (Jan 13, 2011)

transistor output already have internal reverse diode or some sort of filter, i have never burned transistor output with small relays loads. most of the time they are made exactly for that, but for some larger loads they may need additionnal protection. 
i have found this 
http://support.automationdirect.com/docs/an-misc-032.pdf


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## jblkiller (Jun 1, 2011)

*diode*

http://forum.unitronics.com/index.php?/topic/2735-flyback-diode/


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## JoshAllen (Jan 20, 2014)

These are what I normally use for extra protection.
http://www.clrwtr.com/Weidmuller-MICROOPTO.htm


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