[RE-wrenches] Autotransformer caution

[Hilton Dier III]

In the last list someone mentioned putting the transformer behind the 
pressure switch for the well pump so it won't be sitting there idling 
24/7. It's a good idea, but watch out for the double surge. When the 
contacts close you'll get a surge load from the well pump trying to lift 
a column of pressurized water, but also a surge from the transformer as 
the coils energize. I have seen a few inverters have trouble handling 
that stacked surge. If the inverter is significantly oversized compared 
to the pump/transformer it will be ok. Otherwise you can get a time 
delay relay that waits a second (or so) after it gets actuator power 
before energizing. In that case you'd want to adjust the pressure switch 
to come on a few PSI higher than usual so the customer doesn't 
experience a momentary loss in pressure.

Best,

Hilton

-- 
Hilton Dier III
Renewable Energy Design
Partner, Solar Gain LLC
453 East Hill Rd.
Middlesex, VT 05602