3 phase motor

[Duncan Bennett]

Can someone help me with this?

I almost exclusively deal in domestic work, but I've been asked - by a mate - to install a car lift in his garage.

It's a three phase, 400v 6.4amp motor which outputs 2.2kW. I'm running from the Distribution board in swa to the control switch.

My question is, what size of 3 phase Circuit Breaker should i install at the board? Can I get away with 6amp breaker? Also, what's the story with B, C & D curves?

Thanks

 

[Engineer54]

Can someone help me with this?

I almost exclusively deal in domestic work, but I've been asked - by a mate - to install a car lift in his garage.

It's a three phase, 400v 6.4amp motor which outputs 2.2kW. I'm running from the Distribution board in swa to the control switch.

My question is, what size of 3 phase Circuit Breaker should i install at the board? Can I get away with 6amp breaker? Also, what's the story with B, C & D curves?

Thanks

Oh Dear!!

 

[Duncan Bennett]

Oh dear what?

 

[Spoon]

Just a couple of points.I take it that the garage has 3 phase going to it?
Do you know that this work is notifiable?

 

[Duncan Bennett]

Yes, it has a three phase distribution board - it's a factory unit. And yes, I realise it's notifiable. And thanks very much for taking the trouble to answer, my knowledge of three phase is written on my thumbnail.

 

[Engineer54]

Yes, it has a three phase distribution board - it's a factory unit. And yes, I realise it's notifiable. And thanks very much for taking the trouble to answer, my knowledge of three phase is written on my thumbnail.

Then you clearly should not be undertaking work on a system you don't understand!!

 

[Spoon]

Do you have the manual or made and model of the car lift? If not it might be worth trying to Google it and see if there is any info in the manual. Some equipment specify MCB ratings.

 

[Duncan Bennett]

Then you clearly should not be undertaking work on a system you don't understand!!

Very nice of you to say so, Engineer 54. I sat my apprenticeship in '79, ran my own business for 20 years and did exclusively domestic work. I assume you're a genius who has only ever worked on systems you understood completely and ..... oh I could go on but what's the point ... you sound as though you're too far up your own backside to hear any of this in any case.

 

[Duncan Bennett]

Do you have the manual or made and model of the car lift? If not it might be worth trying to Google it and see if there is any info in the manual. Some equipment specify MCB ratings.

Hi Spoon. Thanks for your help. It's an OMA lift manufactured in Italy, but I can't find any more info than that. The lad I'm helping out is just starting his business. The fact is that in all the time i've worked, I just haven't had much at all to do with three phase. Any help would be appreciated.

 

[telectrix]

duncan, that's not the way to endear most respected members !. eng.54 has a valid point. you should know how to do this. firstly, it is not notifiable. part p only applies to domestics. secondly, you select your MCB according to the cable and load. as it's a motor, a c type breaker is recommended. i'm sure you can work the rest out. if not, then leave it to someone who can.

 

[Knobhead]

6.4A is wrong for a 2.2KW 400V motor. It’s for a delta connected 230V motor, for 400V you will have to connect it in star.

 

[Duncan Bennett]

duncan, that's not the way to endear most respected members !. eng.54 has a valid point. you should know how to do this. firstly, it is not notifiable. part p only applies to domestics. secondly, you select your MCB according to the cable and load. as it's a motor, a c type breaker is recommended. i'm sure you can work the rest out. if not, then leave it to someone who can.

Hi Telectrix.

Thanks for your informative answer. It's wired in 1.5 multi-strand and, at 2.2kW, my first thought was to install a 10amp, triple-pole breaker. I just thought I'd check - I find these boards are normally really helpful.

However, I don't think answering "OH DEAR" to a users question is particularly helpful or RESPECTFUL. Respect is earned; if he wants to 'dismiss' questions out of hand then he should just do that and not answer. However, if he takes time to answer only to achieve the belittling the questioner, then that gains no respect in my book.

 

[Knobhead]

How is this motor connected? See my last post.

 

[Duncan Bennett]

6.4A is wrong for a 2.2KW 400V motor. It’s for a delta connected 230V motor, for 400V you will have to connect it in star.

Hi Tony. You've just made the point of why I come onto these boards in the first place - my lack of knowledge about CERTAIN aspects of the trade.

I'm reading the details I gave off the plate that's attached to the motor: Volts 400; ph. 3N-; Hz 50; Amps 6.4; kW 2.2.

?

 

[Engineer54]

Very nice of you to say so, Engineer 54. I sat my apprenticeship in '79, ran my own business for 20 years and did exclusively domestic work. I assume you're a genius who has only ever worked on systems you understood completely and ..... oh I could go on but what's the point ... you sound as though you're too far up your own backside to hear any of this in any case.

For someone that claims to have been in the industry since 1979, and hasn't a clue about MCB curves, let alone simple motor protection beggars believe!!
I'm sure during all those years you came into contact with multi phase motors, domestic (plenty of 3 phase domestic installations) or otherwise.

As for not knowing anything about the differences between B / C / D MCB's, I'm just not going to comment.