Motors and Star Delta Question

[dlt27]

Hi and thanks for any replies.
I am predominantly an install electrician and don't have a lot of experience dealing with motors so any help would be greatly appreciated.
I have been asked to connect a CNC machine, a dust extractor and a pump.
The CNC is straight forward as it is just connected to a rotary isolator, however the pump and extractor are just free standing motors and the name plates are in Chinese. I know the pump is 5.5 KW 3 phase and the extractor is 3KW 3 phase.
1. Am I right in thinking both should be wired through DOL starters with I think when calculated results in a 8.5A and 4.8A overloads with 0.9 power factor correction. (Guy who sold machines said rotary isolators were adequate for starting the motors)
2. Up to what size motors can a DOL starter be used.
3. How do I determine if they should be connected in Star or Delta as can't tell from name plate (What would happen if I connected them up wrong, ie connect in Delta and should be Star or vice versa?)
4. Am I right in thinking a DOL starter should always be used with motors because it provides protection to windings on start up and also it prevents motor restarting on power failure.
5. How do you determine if a Star Delta starter should be used with a motor?
Thanks again if you have got time to explain.
I

 

[LeeH]

Dol starters have stop starts on them so doesn't that satisfy emergency switching?.
Aren't dol starters just contactors with overloads built in?
I also read up on CE marking. I will let customer know!
I am meeting supplier of machines Wednesday so that should be interesting.
Thanks again

Google functional safety. What is required is based on a risk assessment and SIL equations that would make my head explode.

 

[Spoon]

Contact the Chinese manufacturers, I'm sure they will be happy to send you a CE sticker you can put on the motors..

Don't touch the motors that are not CE. If something goes wrong then it's your head on the block.

 

[Darkwood]

Connecting thousands of machines in my time I can tell you now that that machine is not designed or built for sale in the UK, I suspect it has been sourced direct from China with no interim seller thus it is still plated in Chinese and you have next to no instruction for the electrics which if it were to comply should provide you with all the necessary info of how to connect it all up, fuse sizing etc.
The motors and machine will more than likely require a step down TX and I would advice against direct connection to the mains.
Given you also have expressed the supply is converted single phase you need to look into the limitations of the converter and see if it will handle the inrush and on that note the single phase supply itself needs to cope too.
As a first step into this kind of work I would strongly advice against taking on this particular job, their are too many unknown variables here that you probably couldn't answer.

I would probably at a quick guess be looking at a multi-tapped TX with 380v output for the machine.
I would be considering VSD's controls for the motors that way you can program the parameters of the motors and run it then off the 400v supply, this will also reduce inrush issues on your 1-3ph supply converter.

I personally would also be concerned initially about the quality and safety of this product, as it has no CE approval it is highly unlikely to meet our safety standards and anyone using it or asking others to use it could be in breach of H&S laws, if the machine does indeed have a high standard of safety and does meet our standards but just lacks paperwork then it should be assessed and given a CE mark by a third party before use.... given I guess it has been bought cheap then I would be surprised if it met the standards and received a CE stamp.

As you are the person connecting up the machine and designing and installing the controls for the motors then you yourself take on responsibility regarding the machines compliance as it does not have the required CE approval - Good Luck! ... I recommend you walk away from this one.

 

[RWJ]

Sometimes you have to say no. If the customer doesn't respect that, they're not worth it, so walk away.

 

[elsparko]

my mum ordered a phone from china, it worked for all of 3 days, the chinese didnt even want the phone back but refunded

i have a customer that wants to re-use some downlights on a £110k extension, the joiners were less than cautious when taking down the plasterboard, most of them are smashed, i dont know how to break the news to these millionaires that they may have to spend an extra couple of hundred.

 

[Andy-1960]

Also need to consider that the motor should be IE3 compliant, doubt the Chinese have heard of that either!
One other thing to note is the fault level from the converter may be insufficient to operate over current devices in the prescribed time in the event of an over current fault. Maybe worth looking into as this could affect your design and the sizing of your cables.

 

[rapparee]

Contact the Chinese manufacturers, I'm sure they will be happy to send you a CE sticker you can put on the motors..

Don't touch the motors that are not CE. If something goes wrong then it's your head on the block.

And even if they are CE marked, be careful, they're not Chinese Export

http://www.icomuk.co.uk/News_Article/3794/17103/