Damaged Servo Motors

Get the equipment manufacturer involved without delay.

You don't explicitly say that there is a step-down transformer to get 110 v from 415 v, but I suspect there is one (or more). Try putting MOV's on each side of the transformer.

you are probably getting transients from the power interruptions. You will need bypass capacitors and the correct joule and voltage rating MOVs.

The MOV needs to be rated above the peak AV voltage on the lines it protects. The joules are determined by the amount of current broken by the power interruption, which might require some expertise to estimate.

The bypass capacitors catch the very short pulses, and would be ceramic 5000 Volt .01 uf.

At normal voltages they pass nothing, but they pass ultra short pulses to ground. the MOVs are a little slower and miss the ultra short pulses, but get the longer ones the capacitor misses.

Hello aurizon,

Thanks for the info. Just to make myself clear, is this devices (mov) similar to surge arrestor? I had tried surge arrestor once but the result was unsuccesful. Any way I will study more detail on your suggestion.

Thanks.

yes, they are a type of surge arrestor. Metal oxide varistor.

http://en.wikipedia.org/wiki/Varistor

your systems needs to have a high speed line monitor attached to a recording scope or some such, to analyze the transients to design something to limit the surges.

http://www.testequipmentdepot.com/fluke/powermeter/435.htm

A company who analyzes transients in your area will have one of these machines, or something like it. The power company you get your electricity from should have one and since they sell you the power, they might analyze at low cost?

It is possibly you have current surges and need an inline inductive limiting coil. The size of this coil is determined by the current flow and the nature of the transient.

If you want proper answers, you need to post your location, give full accurate details of the way voltage is supplied to the machines, the exact voltage and frequency that the machines need and details of how the mains is lost (if true).....

The better your information, the better will be the help.

The help already given is about as good as possible with regard to your almost complete lack of information....sorry, but that is the truth......

My personal experience of CNC with steppers has given me to understand that mains loss is simply dangerous for any power electronics around.....

What you may need is a UPS for each running CNC machine if the mains where you live is completely unreliable. But make sure that the UPS is dimensioned far, far bigger than a machine would appear to need.......then you can let the job run to a preset breakpoint (you do set break points don't you?), which would allow it to continue again once power is restored without having to throw away the workpiece......

You said you have 50 Hz at your mains supply, so frequency is not an issue since your machine's control runs at 50 Hz.

You need to make sure that the machine transformer taps are set so, that you get the exact secondary voltage as stated at the name-plate, use a meter.

If you have frequent stops and alarms, check the codes. I understand that you have run cables to each machine, check the lenght, gauge and proper grounding; you could have voltage drops at peak currents; that causes "low bus voltage" alarms to any decently designed servo amplifier.

As per the ground, veryfy that you don't have ground loops and that your ground is tight and properly sized (gauge). Bad grounds create a lot of noise that give you a whole lot of funny faults at your drives.

Finally, follow the recommended surge protection techniques posted by others in this thread.

Yahlasit