380v Machine in the UK

[Lucien Nunes]

380V motors have often been used directly on 400V UK mains, although can run slightly hot at the high end of the tolerance band due to increased iron loss, and approaching magnetic saturation. We have a few that have been in use for decades on our workshop supply which sits around the 410V mark. However, the correct method is indeed to use a step-down autotransformer and the one James links would give you the option for true 400V input or traditional 415V which is still what a lot of substations provide, although 'rebranded' as 400V for harmonisation purposes. That transformer is a slightly undersize though, as the motor input is 12.4kVA (18.8A at 380V) for a 12.5 PS (metric horsepower) output.

 

[James]

380V motors have often been used directly on 400V UK mains, although can run slightly hot at the high end of the tolerance band due to increased iron loss, and approaching magnetic saturation. We have a few that have been in use for decades on our workshop supply which sits around the 410V mark. However, the correct method is indeed to use a step-down autotransformer and the one James links would give you the option for true 400V input or traditional 415V which is still what a lot of substations provide, although 'rebranded' as 400V for harmonisation purposes. That transformer is a slightly undersize though, as the motor input is 12.4kVA (18.8A at 380V) for a 12.5 PS (metric horsepower) output.

I agree with everything above.
P.s. in the spec sheet (1st link ) it gives the part number for the 30kva version too.

My thoughts on this were that, often especially with older machines the motors were over specified and almost never use the full load they are rated too.

Depending on the amount of load on the machine and the duty cycle you may find the 10kva ok but if you want to be certain then go for 30kva version.

 

[Eren1999]

380V motors have often been used directly on 400V UK mains, although can run slightly hot at the high end of the tolerance band due to increased iron loss, and approaching magnetic saturation. We have a few that have been in use for decades on our workshop supply which sits around the 410V mark. However, the correct method is indeed to use a step-down autotransformer and the one James links would give you the option for true 400V input or traditional 415V which is still what a lot of substations provide, although 'rebranded' as 400V for harmonisation purposes. That transformer is a slightly undersize though, as the motor input is 12.4kVA (18.8A at 380V) for a 12.5 PS (metric horsepower) output.

Thank you all for your replies.

I managed to get in touch with the manufacturer and they have advised that it is fine to run on 400v without a transformer. We've hooked it up and all works fine, no sign of overheating.

Our electrician measured our voltage at 415v though, but given how expensive it will be to buy a transformer I think it'll be cheaper to replace the motor if and when it dies on us