House hold heat pumps and start-up current

Question

House hold heat pumps and start-up current

hhhansen (Electrical)

(OP)

27 Feb 12 08:27

Hi out there
I am doing network studies on the LV distribution grid. According to prognosis we are facing a future with a huge amount of heat-pumps installed in the private house hold. I looked at a datasheet on a heat pump and it turned out that the starting current of the compressor is around 25 A. It is well known that induction motors inherently have starting current of 5 - 6 x nominal current.

My concern is about what happens when a large amount of heat-pumps are started-up simultaneously in terms of voltage drop, blown fuses in the 10 kV/0,4 kV distributions transformer LV switchboard. Can any of you share some experiences =? and/or are able to recommend litterature from studies, demonstration projects etc.

B.R. Hans-Henrik Hansen

waross (Electrical) · Answer 1 · 2012-02-27 10:51:26

Many modern heat pumps have a built in random start delay of up to a few minutes. Simultaneous starting is not the issue that it once was.

Bill
--------------------
"Why not the best?"
Jimmy Carter

cranky108 (Electrical) · Answer 2 · 2012-02-27 14:48:42

Besides that many thermastats also have a random restart/start feature.

A heat pump is not that much different than compressor air-conditioning used in many cities.

I would think the worst load impact would be all the backup heaters on in the really cold days.

davidbeach (Electrical) · Answer 3 · 2012-02-27 15:33:15

Yeah, but the strip heaters respond quite graciously when presented with lower voltage due to overloading. Completely unlike those greedy compressor motors that just stall on slightly lowered voltage and then pull down the voltage for everybody else.

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