Fast current sensing relay

Question

Hi 
 I'm looking for a current sensing relay that will respond in less than 50 ms

mapj1 · Answer

What sort of current level are you looking to sense, and how much power are you hoping to switch on or off? There are electronic techniques that operate sub-millisecond (even sub-microsecond), but if you have a need to close a 100A contactor that response will be the limiting factor. Also be aware of the EMC susceptibility of a fast device to fast transient currents that would normally be ignored, and most electronic devices are deliberately slugged to emulate a mechanical one ;-) 
 For example the Carlo Gavazzi ones are made in two models for each rating, one slugged (few hundred msec) and the other 'fast' a few tens of msec, and they are nothing special. 
 "Type Selection Input current Reaction time Type no. 2 - 20 A AC Standard DIA53 S724 20A 5 - 50 A AC Standard DIA53 S724 50A 10 - 100 A AC Standard DIA53 S724 100A 2 - 20 A AC Fast DIA53 S724 20A F 5 - 50 A AC Fast DIA53 S724 50A F 10 - 100 A AC Fast DIA53 S724 100A F " 
 data sheet docs.rs-online.com/.../0900766b813e14c8.pdf 
 Mike.

Fast current sensing relay

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