Permissible inrush current single phase

Hi

I have had the misfortune to buy a Lincat Combination Oven for my Hotel.

These normally come in 10kw three phase.  3 x  13amps That's not too bad.

I have the single phase version 1 x 39 amps. Not so good.

It is operating at 1 second on 39 amps

                          0.2 second off  0 amps

                          Cycling continually. for hours.

I have a 40kva single phase supply and can hear the current hammering away incessantly. Lights flickering etc. I asked the manufacture for details of soft starting

and duty cycle. They say this is the way they were designed to work. Bang on and Bang off --1 second cycle continually.

I don't have a current (Hee Hee)  Reg book. So I ask is there a reg in place that covers the single phase load criteria.

To add insult to injury-- I have a three phase 65kva standby set.-- I would not put that destructive abuse on one of my 20kva phases.

it would shake it apart. So I cannot run it.

Regards -- Tony

Parents
  • It's not really an inrush problem, more of a pulsed load, and it does sound like the sort of thing designed to cause trouble- especially to gesnet derived  supplies
    There is not a lot  in BS 7671 relating to pulsed loads, but there are certainly recommendations on ENA side of things that are types of load the DNO will not accept withoug consultation.
    See this doc

    The key line in there is probably.y Equipment with a rated current < 75 A can be connected to LV public electricity supply systems under this stage without reference to the network operator providing it conforms to the technical requirements in BS EN 61000 3 3 and the service current capacity is confirmed as being adequate for connection of the equipment.

    so what does  EN 61000 3 3 permit.? Well  assuming you do not have the rather pricey standard this leaflet may be of help, but basically it all depends on the number of events per minute, but if it really is 60 events per minute, then they need to be aiming for something rather less than 1% dip on load.- so in big handfuls the supply needs a PSSC at the point the oven final circuit connects in parallel to any other load of at least 3,9kA.
    Now this is a rare enough requirement that really the makers ought to mention it in the instructions.

    It might be fun to ask for the results of the testing to EN61000 that they should have done as part of their CE marking data pack. I bet they have not.

    mike

Reply
  • It's not really an inrush problem, more of a pulsed load, and it does sound like the sort of thing designed to cause trouble- especially to gesnet derived  supplies
    There is not a lot  in BS 7671 relating to pulsed loads, but there are certainly recommendations on ENA side of things that are types of load the DNO will not accept withoug consultation.
    See this doc

    The key line in there is probably.y Equipment with a rated current < 75 A can be connected to LV public electricity supply systems under this stage without reference to the network operator providing it conforms to the technical requirements in BS EN 61000 3 3 and the service current capacity is confirmed as being adequate for connection of the equipment.

    so what does  EN 61000 3 3 permit.? Well  assuming you do not have the rather pricey standard this leaflet may be of help, but basically it all depends on the number of events per minute, but if it really is 60 events per minute, then they need to be aiming for something rather less than 1% dip on load.- so in big handfuls the supply needs a PSSC at the point the oven final circuit connects in parallel to any other load of at least 3,9kA.
    Now this is a rare enough requirement that really the makers ought to mention it in the instructions.

    It might be fun to ask for the results of the testing to EN61000 that they should have done as part of their CE marking data pack. I bet they have not.

    mike

Children
  • Many thanks for that Mike.

    It was made in Denmark by Houno but Badged as a Lincat to me. There is a CE certificate in the pack. But no mention of EN 61000.

    I will look at that. It is under warrentee and I can't put a spanner on it. Also it has not functioned correctly, since installation. So I have taken out a case against Lincat Ltd.

    They insist that the one second continual abuse, on my system is correct to design. But any Engineer can see with modern control gear, this is not correct. Soft starting and on / off cycling has been achievable for many years.

    Tony