Bob Darrah wrote:

7000 rpm, 2 HP,  well, maybe for a short time.

Bob Darrah

I don't follow you Bob. The mill does not run at 7000 RPM of course.

I have two 8 inch A belt pulleys on the mill spindle and a
3 inch water pump pulley so the  mill spindle must run
at about 2600 RPM to get 7000 at the pump. As I recall
I think my top CC mill spindle RPM is 2500 so that should give me
6,650 RPM. Not quite 7000 but up there.

Paul Lamar

My contention is you may not have enough HP to turn it that fast.

Granted,

my impeller is larger than stock, I used a 3 HP lathe and couldn't

maintain

6000 RPM.  Kept blowing the breakers.

Bob Darrah

Sounds interesting Bob. What kind of pump were you using? 20B?
Did you get any data like GPM or pressure drops you can share with us?
Of course 3 HP at 6000 RPM is a good data point. What were the pressures
or "heads" when you blew the breaker?

I assume you had a 30 amp breaker in there.
In theory 30 amps at 110 volts  is 3300 watts or 4.4 HP.
Given 80% motor efficiency that should be around 3.5 HP.

BTW your experience and Bill's experience correlate well and really show
the stupidity of of those puny 12 volt electric water pumps being
hyped now-a-days. 3 HP is 2,238 watts. 2,238 watts is 186 amps
at 12 volts. One would need a couple more alternators :)

Paul Lamar

As Bill Shertz pointed out, with AC motors there is often a big phase shift
and you can draw large current flows to pop breakers, without actually
drawing the HP (Watts) that you thought you were getting. You need to
get a dedicated wattmeter to evaluate the power electricaly
Vance

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