converting 3ph motor to single phase inverter

[123brez]

hi ive just done a job today on a high speed door i have romoved the old 3ph contol panel and converted it to a single phase inverter panel that runs 16amps.

the supply is from a 20amp 3ph mcb and all i have done is removed l2 and l3 from the isolator to run the panel.

once i had set up the door it started to trip the mcb, i dont think it is anything on the door as it would normally blow the control fuse on the board.

i was wandering if i need to remove the 3ph mcb and put in a single 20amp mcb in could this be the cause?

cheers

 

[silva.foxx]

Unless the mcb detects imbalance across the phases, it's unlikely. Is the mcb type c?

On the side of the inverter is usually the input and output current ratings. Does the input satisfy the rating?

Also, you say you replaced 3ph with 1ph... did you do anything with the motor connections?
ie reconfigure to delta for the lower voltage 3ph to UVW (if it is a dual voltage motor)?

I would say it would be good practice

 

[pmac10]

i would say very good practice mr Foxx, once almost started a fire forgetting that bit, ( friday night, end of shift, beer calling)

 

[Darkwood]

If its speed control you were after why didnt you just get a 400v in 400v out inverter as all the power cables mcb etc were already in place the motor connections would stay the same too? May i ask why you changed it to single phase when you already had everything available?, if the previous control wasnt from an inverter then all you would need to address is the strict screening and bonding issues associated with running motors through inverters.

 

[silva.foxx]

Hey up, pmac... I didn't finish the "...good practice" sentence above... I was to put about removing the 3ph mcb for a 1ph mcb, but as we know, once it becomes a 1ph supply, someone would soon find uses for the remaining two ph then the opportunity for 3ph is lost!

Anything you are asked to fit as temporary... always fit with permanance in mind, as it's more likely than birth, death & tax!

(pmac - thanks for your kind message towards end of Dec... thought I'd replied yet I can't see it in my PM sent box)

 

[pmac10]

yes silva, know what you mean, found a 13A plug and socket in one of the roof voids today labelled 'temp supply to computer hub (temp from 1997)

 

[silva.foxx]

...'temp supply to computer hub (temp from 1997)

Oh aye... one of those... pretty recent is that!

I had to "lash-in" some stuff last week. I let it be known it was lashed and promptly removed the temporary "lash" before I went off shift!

 

[pmac10]

I let it be known it was lashed and promptly removed the temporary "lash" before I went off shift!

now that, i would say is good practice

 

[pmac10]

If its speed control you were after why didnt you just get a 400v in 400v out inverter as all the power cables mcb etc were already in place the motor connections would stay the same too? May i ask why you changed it to single phase when you already had everything available?, if the previous control wasnt from an inverter then all you would need to address is the strict screening and bonding issues associated with running motors through inverters.

as op hasnt replied, i guess it would be cost, 3phase in/out cost a fair bit more than 1in/3out, obviously we,d need to know motor size.

 

[123brez]

as op hasnt replied, i guess it would be cost, 3phase in/out cost a fair bit more than 1in/3out, obviously we,d need to know motor size.

Its a 1ph in 3ph out inverter and I fitted a new motor to match 133\230v and I've set perameters in panel to match.

 

[silva.foxx]

Any info on the inverter and motor, brez?

.

 

[TF and the wire]

As above, we need to know the size of the motor in amps of kW. For example 10kW sigle phase is a higher current than 10kW 3 phase.

 

[123brez]

1.1 kw and its running at 133v we have put it on a single 20A type b which seems to have done the trick