Large load on the neutral with 220v 1-phase servos, good or not?

[jeeybee]

Here in Sweden we have 1-phase 220v and 3-phase 380v and many servos up to 3kw is 1-phase 220v (or 3-phase 220v but that we dont have here so we have to connect it to only one phase) which if I nees three servos of 3kw it will put a quite large load on the neutral wire,
So the question is: Is that good? can this cause problems?

Would it be recommended to use a 380v-220v transformer?

Thanks.

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[OlfCNC]

Here in Sweden we have 1-phase 220v and 3-phase 380v and many servos up to 3kw is 1-phase 220v (or 3-phase 220v but that we dont have here so we have to connect it to only one phase) which if I nees three servos of 3kw it will put a quite large load on the neutral wire,
So the question is: Is that good? can this cause problems?

Would it be recommended to use a 380v-220v transformer?

Thanks.

Your Phases to Neutral is still 220V only on a 3phase 380V mains system, because the line to line Voltage is 380V and for that the line to neutral is 220V.
So, what you can do is separate the servo drives, for example if you have 3 servo drives all with single phase inputs then connect drive 1. to L1 - N, drive 2 to L2 - N, drive 3 to L3 - N.
This way your drives will load your 3 phases separately so the load will be approximately in balance.
Here is some reading for you about 3 phases mains votlages: https://www.quora.com/What-is-differ...eutral-voltage

I just reread your post and see you worrying about the neutral wire.
I think that however it will sure be loaded much with 9kW of total and it will be not the optimal solution for sure, but the neutral should have been sized to handle that,
otherwise the electricity provider would not give out a permission for the mains installation if the neutral could not handle that load if the phases and the fuses can.

[jeeybee]

Yes that I know and already do

[jeeybee]

There is also the risk that if the neutral would be disconnected for some reason it would be much more severe than if a phase was disconnected, however big that risk is.
I just wonder what the praxis is in an industrial environment?

[mike_Kilroy]

Here in Sweden we have 1-phase 220v and 3-phase 380v and many servos up to 3kw is 1-phase 220v (or 3-phase 220v but that we dont have here so we have to connect it to only one phase) which if I nees three servos of 3kw it will put a quite large load on the neutral wire,
So the question is: Is that good? can this cause problems?

Would it be recommended to use a 380v-220v transformer?

Thanks.

How many of these do you have or envision? If only a few, I would not worry to much about it... why? because....

- Yes, the neutral will carry currents not there with 3 phase loads, but... where is the neutral from? Isn't it from your power company? THEY have a transformer somewhere with the wye connections. Unless I am mistaken, the neutral wire comng off that transformer will be sized the SAME as the 3 phase wires, no? THIS may be your concern? If so, ASK THEM. Verify the neutral wire gauge is the same as the 3 phase gauges.
- the neutral itself in the transformer feeding you is capable of the same loading as the 3 phase, no? If so, there is no problem there, just your worry about the gauge of wire from that source to YOU?
- I assume you are a customer using 380v 3ph in enough load that a few kw of servo load would not effect the 1ph output voltage if the neutral somehow disappeared - very different that in USA where if our neutral disappears on a single house, the voltages on either side can vary greatly.
- if you have many of these servo requirements, why not buy the proper 3ph input model drives??
- It sounds like you may want to buy a simple smallish 380v delta to 220v wye iso xfmr and stop worrying about the what ifs? Just ignore the neutral on the 220v wye secondary and your worries are over.

[jeeybee]

Ok thanks for your answer.