On Wed, 12 Jul 2017 08:09:24 -0700 (PDT), "Dave, I can't do that"
wrote:
Using a watt-meter thingy, on Low it draws about 5.1-A and on High 6.3-A. I say "about"
as it fluctuates up/down by 0.1-A or so.
During the start, it very briefly shows 16-A or 17-A but there could be a little over-swing in that too.
It comes and goes in the blink of an eye, sometimes I don't even see it at all.
So what do I actually need to do with the caps? I have some
oil-filled start caps around the place somewhere.
This is the motor.
https://www.lowes.com/pd/Dial-Steel-...-Motor/1016109
Based on knowing what actual motor you have, I'll modify my previous
post just a little.
This is a fan-duty motor but it is a very low quality motor, as one of
the Lowe's commenters noted.
A 1/3 motor should draw 746 watts * 0.33333. = 249 watts real power.
That translates to 249 watts / 120 volts = 2 amps. This is the real
power the motor is drawing to do the useful work of turning the fan.
The rest of the (let's average) 6 amps is "wattless" or imaginary
current. The power factor is 2 real amps / 6 total amps = a power
factor of 0.35. This is extremely poor. A quality motor when fully
loaded will have a power factor of 0.90 or better. As the commenter
noted, this is from the motor having little iron and copper inside it.
Basically, a cheap chicom substitute.
Since this is a fan-duty motor, it probably draws about 6X running
current while starting. So 6 running amp * 6 = 36 starting amps.
That much current load, applied suddenly, will cause lamp flicker.
This flicker will be exacerbated if you have an inadequately sized
pole pig (transformer) or more commonly, an undersized drop from the
utility.
I fought my utility for a long time over this issue. When we built
this cabin in 1970, it received a 100 amp box. About 10 years ago we
installed a heat pump and a 200 amp box. Severe light flickering
happened each time the heat pump started.
I traced the cause to the service drop being only 4 gauge aluminum
wire, severely undersized for a 200 amp panel.
I spent about half my life as a utility engineer so I could take on
the engineer at the utility. I provided him hard measured evidence of
the voltage drop but he ultimately refused to order a larger drop.
So I cut a tree down across the line and pulled it down.
The replacement drop is #0 gauge (still too small) and I still get a
bit of flicker but not nearly so bad as before. The primary feeding
our little mountain community is 25 miles long and is only 7200 volts
so some sag is happening on the utility side.
So you need to take a look at your service drop and see if you can
tell if it's too small. If you have a digital volt meter that has a
high/low peak reading function, you can connect it between neutral and
an otherwise unused breaker in your panel and record the voltage dip
at your service entrance when you start the swamp cooler. If the dip
at the panel is much over 3 volts, your drop and perhaps pole pig is
undersized.
A study years ago determined that the average person could detect the
flicker in a tungsten lamp at a 3 volt threshold. Electronic lights
(CFLs and LEDs) are even worse because there is no thermal inertia.
So my revised advice would be: a) determine whether your utility
service is adequate, b) take that motor back and buy a quality
name-brand motor such as GE or Emerson and only after that pursue what
I described in my previous post regarding fixing the inrush and power
factor problem.
You asked in your first post if the motor could be soft-started. The
answer is yes. Soft starters are available but most use a 3 phase
motor (single phase to the soft starter). A quality (non-chicom) soft
starter will cost several hundred dollars so I recommend the other
things first.
John
John DeArmond
http://www.neon-john.com
http://www.tnduction.com
Tellico Plains, Occupied TN
See website for email address