Peak startup load

[gc100]

Hi,

 

I'm in a sticky situation whereby the DNO is only wanting to give me a connection to my barn conversion by putting a transformer outside with 11Kv to that. They are quoting £55K+VAT !!

 

I'm wanting them to put a kiosk by the nearest pole mounted transformer and then run 500meters across our fields to the barn. This will be somewhat cheaper (still £35K!). However the DNO contact is basically saying that he does't think an air source unit would comply with P28, which from my reading is about equipment not drawing too much peak load to drop the voltage at the transformer.

 

Talking to the ASHP suppliers they are full of confidence that max load for the unit we need would be 28A and it has soft start etc. Talking to the electrician company who would be connecting from kiosk to the barn see no reason why an ASHP would cause any issue as the "the DNO is supplying a normal house connection"

 

However I imagine I will get caught in the middle if we end up fitting an ASHP and then get flickering lights or cause the neighbour on the same pole flickering lights. The DNO will argue that my setup does not conform to P28 etc.

 

So my question is has anyone had any issue with voltage drops at startup??  You can see even equipment with soft start still draw way more power at startup than they claim (Figure 2) : https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=6985842

 

Here is a case study about it: http://www.networkrevolution.co.uk/wp-content/uploads/2015/02/CLNR-Heat-Pump-Case-Study-V1.0-CDT.pdf

 

 

Any thoughts?

 

 

Edited May 23, 2019 by gc100

[Jeremy Harris]

Modern inverter controlled heat pumps have zero startup current surge.  In fact, our has a lower startup than a vacuum cleaner, by a long way.  The DNOs are way, way behind the curve with this, and are still working to really old, pre-inverter technology, heat pumps, that did tend to have a pretty hefty starting current.

 

Best bet is to try and educate them.  They tried it on with me and I just sent them a detailed description of the 30 second inverter start sequence, how both the starting demand and power factor was dynamically managed by the heat pump control system and then I heard nothing more from them...

[ProDave]

What KVA rating supply are they offering for the direct 230V option (the £35K option)  and what distance does this have to travel?

 

I found the DNO start having kittens when you tick the "heat pump" box on the form.  It might be best just not to mention that, tell them you are having an oil boiler, and "change your mind" later on and choose the ASHP.  There really is no problem with a modern inverter driven ASHP ours certainly has no measurable start up surge.

[scottishjohn]

I have just put in a request for this "secret  house" which is along way from a 3phase pole 

so we will see what they say to me 

i,ve asked for 60kva 3 phase