Patriarch wrote:
Robatoy wrote in
:

snip of a good analogy

Rob

PS. I decided not to participate in the 100+-post 220 volt discussion
for two reasons: LRod was doing just fine by himself and why would I
confuse everybody with facts?
A two-pole induction motor, with no load, in North America will run at
3600 RPM not 3450 or 3500
A four-pole induction motor, with no load, in North America will run
at 1800 RPM, not 1760 or 1745
Put a strobe on the shaft. Slippage doesn't occur till a load is put
on. When you take an amp-probe of a 2 HP Baldor(Quality) motor, with
nothing on the shaft, it can draw as little as 1 amp. When you add a
load, increasing it bit by bit (say..a clutch..or a sawblade in a
piece of wood), all that happens is that the current will increase to
the point where either the breaker blows or the motor bursts into
flames. It is the point at which the motor bursts into flames
(preventable with bigger gauge windings and better cooling) which tell
you the rated HP. (Just prior to the motor stalling there will be a
reduction of RPM under somewhat controlable conditions.
If your motor, under no load, say at 120 volts, draws 1.5 amp then,
when it puts out 2 HP it will draw 750x2/120= 12.5 amps PLUS 1.5 amp =
14 amps. Period. That will happen if the breaker is rated at 15 or 20
or 30 amps. (No semantics, please)
None of this works on universal (brushed) motors.



Does EVERY THREAD need to devolve into an electricity discussion?!!!
;-)
Relax, if it wasn't for electricity you'd have to read this by
candlelight, or put the computer by the window;-)
Joe