Re: Horse Power on a motor label
Originally posted by physis:
So then I'm not crazy? SPL.00 is meaningless...
Well SPL is likely meaningless, but what does that have to do with you being crazy
Originally posted by physis:
...If I do the math I get:
230v. x 15A. = 3450w.
3450 / 746 = 4.625 HP
As noted by TomB, single phase motors are nowhere near to 100% efficient. NEC 430 shows a 230V, 2hp motor draws 12A
Originally posted by charlieb:
Perhaps they are taking credit for the horsepower that would be generated, briefly, at the moment of starting. ...
I don't think so. I've never measured a single phase motor, but I suspect that the starting load is highly inductive. For example, at the instant of starting, the current is high, the voltage is still nominal, speed is 0rpm, it doesn't matter what the torque is, the hp output is zero.
I've never seen the speed/torque curve for a 1ph motor, but as I recall (code phrase meaning I did not look it up) 3ph, Design B motor pulls out about 225% rated torque and 90% rated rpm, This gives about 2x rated hp.
Nope, doesn't apply to vaccuum cleaners or compressors.
Originally posted by ramdiesel3500:
... They are saying the entire tool is 5.5 HP. Not the motor. I believe under maximum load conditions, a 1 HP motor can produce up to 5 or so horsepower for a short burst. ...
I don't think so. Motors run where the load/speed curve crosses the motor torque/speed curve. So vaccuums and compressors will never load the motor to the madison avenue rating.
Originally posted by templdl:
... The only think that I use the rating for is to compare products assuming the 3hp is better than 2hp even though the rating doesn't mean a darned thing. ...
I'm not even sure of that. I've got a small, light weight, industrial grade compressor I use for a framing nailer. Its 120V with a 15A cord, rated at 1hp. I don't think this particular one is lying. If I connect two nailing guns, and it runs constant, it will occassionally trip a 20A CB. I really doubt Sears best 5.5HP will keep up with it.
If I had to pick one from the "big book" (or was it "box") - (in either case, yuck, ick, wash my mouth out, Bad Dog), I'd look at the free cfm, motor amperage, and tank volume.
Originally posted by infinity:
... And advertising this as a 5.5 HP isn't illegal? ...
Well if I said it in court, the junior engineers scoutpost would take away my secret decoder ring, break my slide rule, and make me eat a raw rutabaga. The court system would just call it lying.
Madison Avenue likely calls it "Inovative, proactive, leading edge information transfer. Concept is supported by previously unknown new math techniques and computer generated fuzzy logic."
carl