On 2017-07-11, Dave, I can't do that wrote:

Hi, we recently installed a window version of a swamp cooler. As such,
it plugs into a wall outlet in the lounge-room. It has a new 1/3-hp
(252-Watt) two speed motor from HomeDepot.

When it turns on either in Low or High, the voltage dips for almost a
second from 125vac to 117vac then back up to 125vac. The dimming is
maybe 20% longer for the High speed.

Still within specs. Why worry about it? Does anything
misbehave during those dips?

Is there some way we can soft-start this or what? It makes the lights
dim in the house for that short period.

With that motor -- maybe a loose belt to let it slip as it goes
up to speed?

For real soft start, replace it with a three-phase motor and a
VFD. You can program the VFD for a fairly wide range of starting times.

Enjoy,
DoN.

--
Remove oil spill source from e-mail
Email: | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---