Contactor rapidly pulling in and dropping out.

[Fred B]

There are multimeters that have a min/max function that will show the surge load no need for a scope for that even though a scope is a neat tool to see what is happening vs just having the meter reading. Could also be a "dirty" signal causing the chatter and that would be detectable by the scope.

 

[kwired]

There are multimeters that have a min/max function that will show the surge load no need for a scope for that even though a scope is a neat tool to see what is happening vs just having the meter reading. Could also be a "dirty" signal causing the chatter and that would be detectable by the scope.

Min/max won't show you any kind of oscillation pattern though, just a minimum and a maximum, you don't know exactly when they were registered.

 

[ATSman]

Read the specs on the 43B. It can be used as a single channel oscilloscope.

 

[ptonsparky]

Read the specs on the 43B. It can be used as a single channel oscilloscope.

Not near the resolution of today's meters but usable.

 

[Flicker Index]

I have a contactor that pulls in a drops out rapidly and continuously when started. I know it's from a chattering relay that supplies the 120VAC control power. My question is would a solenoid type tester such as an Ideal Vol-Con detect this? My digital multimeter doesn't respond fast enough to detect the change. any and all suggestions on a certain Brand or model of tester would be greatly appreciated>

Small filament light bulb in parallel with the meter like the 15W one you'd use in a night light or in a microwave oven. Observe behaviors.

 

[richard.jackson]

There are multimeters that have a min/max function that will show the surge load no need for a scope for that even though a scope is a neat tool to see what is happening vs just having the meter reading. Could also be a "dirty" signal causing the chatter and that would be detectable by the scope.

Thanks, will have to check into this.

 

[richard.jackson]

Min/max won't show you any kind of oscillation pattern though, just a minimum and a maximum, you don't know exactly when they were registered.

Could be very helpful.

 

[richard.jackson]

Soft starters shouldn’t be chattering, at all. Since we have to guess, my guess would be that a gate firing circuit for one of the SCRs of the soft starter is dead or dying, likely the pulse transformer. If the gate doesn’t fire one of the SCRs, the result is a DC pulse going out to the motor in each cycle, which makes the motor fight itself due to negative sequence current, pulling high current and in all likelihood, causing a severe voltage drop that is pulsating in rhythm with the failed SCR, causing the contactor coil to chatter.

Bottom line, replace the control board of your soft starter. Check the SCRs too, one shorted SCR can have a similar effect, but most soft starters have shorted SCR detection that would throw a fault.

Thanks for the information, I am currently waiting for a soft start.