ELA
Senior Member
- Occupation
- Electrical Test Engineer
Yes, I was not exposing the thermal element to a ramp current.
As I said the Instantaneous test was a side note and I was not looking for an exact value, just to determine that the trip has an electronic setpoint that was significantly above that required to detect the 75A min for an arc.
The actual value may be a little higher but 195A is fairly close to the instantaneous region of a standard QO120.
If an accurate time/amp value were my goal I would have pulsed the line with a limited number of cycles made available via an external phase fire unit.
It was a very interesting learning experience.
When people talk about nuisance tripping there are many more reasons that may occur other than the instantaneous trip value being reached.
What a lot of people do not recognize is that any electronic device can be made to act abnormally ( or nuisance trip) if exposed to enough Electromagnetic Interference (EMI).
It is possible to cause electronic trip units to trip at vary low 60 hz currents if exposed to a high enough level of high frequency interference. AFCI's are especially susceptible in that area since they are attempting to use higher frequency currents as part of the signature indicating the presence of an arc. Some manufactures are likely better at designing in protections against nuisance trips than others.
As I said the Instantaneous test was a side note and I was not looking for an exact value, just to determine that the trip has an electronic setpoint that was significantly above that required to detect the 75A min for an arc.
The actual value may be a little higher but 195A is fairly close to the instantaneous region of a standard QO120.
If an accurate time/amp value were my goal I would have pulsed the line with a limited number of cycles made available via an external phase fire unit.
It was a very interesting learning experience.
When people talk about nuisance tripping there are many more reasons that may occur other than the instantaneous trip value being reached.
What a lot of people do not recognize is that any electronic device can be made to act abnormally ( or nuisance trip) if exposed to enough Electromagnetic Interference (EMI).
It is possible to cause electronic trip units to trip at vary low 60 hz currents if exposed to a high enough level of high frequency interference. AFCI's are especially susceptible in that area since they are attempting to use higher frequency currents as part of the signature indicating the presence of an arc. Some manufactures are likely better at designing in protections against nuisance trips than others.
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