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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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#1
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Motor Horsepower
If an electric motor with 80% efficiency is pulling 16A at 120V, what is the
horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? Jon |
#2
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Motor Horsepower
On 2011-02-09, Jon Danniken wrote:
If an electric motor with 80% efficiency is pulling 16A at 120V, what is the horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? Sounds right to me. i |
#3
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Motor Horsepower
On Wed, 9 Feb 2011 13:00:32 -0800, "Jon Danniken"
wrote: If an electric motor with 80% efficiency is pulling 16A at 120V, what is the horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? If you're trying to figure out how much HP is being produced at the shaft you also need to account for power factor. A typical small induction motor will draw around 60% of its nameplate current with *no* load. 80% efficiency sounds high for a 2HP single phase motor. Full load amps for a normal 2HP induction motor is closer to 25A @ 120V. -- Ned Simmons |
#4
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Motor Horsepower
Yes, I'll agree with that.
-- Christopher A. Young Learn more about Jesus www.lds.org .. "Jon Danniken" wrote in message ... If an electric motor with 80% efficiency is pulling 16A at 120V, what is the horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? Jon |
#5
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Motor Horsepower
On Wed, 09 Feb 2011 15:10:56 -0600, Ignoramus25972
wrote: On 2011-02-09, Jon Danniken wrote: If an electric motor with 80% efficiency is pulling 16A at 120V, what is the horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? Sounds right to me. i Pretty close for 16 amp running current - but how much does it draw on startup??? Most motors that will draw 16 amps on startup will draw closer to 7 under normal running conditions - which is 1 HP. Not 2 many real 2HP motors will start on a standard 15 amp breaker or fuse, and many will not start on a standard 20 amp breaker or fuse. A 20 amp slow-blow fuse will GENERALLY start a 2HP motor under a reasonable(light) load like an unloaded compressor or a 10" table saw. |
#6
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Motor Horsepower
Jon Danniken wrote:
If an electric motor with 80% efficiency is pulling 16A at 120V, what is the horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? Jon |
#7
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Motor Horsepower
"Jon Danniken" wrote in message
... If an electric motor with 80% efficiency is pulling 16A at 120V, what is the horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? I also mostly agree based on a chart I have here. 2 HP AO smith 120V motor pulls: 16.4 to 16.6 at 3600 RPM 17 to 17.8 for 1800 RPM -- Regards, Joe Agro, Jr. (800) 871-5022 01.908.542.0244 Automatic / Pneumatic Drills: http://www.AutoDrill.com Multiple Spindle Drills: http://www.Multi-Drill.com Production Tapping: http://Production-Tapping-Equipment.com/ Flagship Site: http://www.Drill-N-Tap.com VIDEOS: http://www.youtube.com/user/AutoDrill TWITTER: http://twitter.com/AutoDrill FACEBOOK: http://tinyurl.com/AutoDrill-Facebook V8013-R |
#8
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Motor Horsepower
Ignoramus25972 wrote:
On 2011-02-09, Jon Danniken wrote: If an electric motor with 80% efficiency is pulling 16A at 120V, what is the horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? Sounds right to me. Thanks Iggy, I appreciate that. Jon |
#9
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Motor Horsepower
Joe AutoDrill wrote:
"Jon Danniken" wrote in message ... If an electric motor with 80% efficiency is pulling 16A at 120V, what is the horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? I also mostly agree based on a chart I have here. 2 HP AO smith 120V motor pulls: 16.4 to 16.6 at 3600 RPM 17 to 17.8 for 1800 RPM Thanks Joe, that is in line with my measurements as well. Jon |
#10
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Motor Horsepower
On Thu, 10 Feb 2011 11:09:37 -0500, "Joe AutoDrill"
wrote: "Jon Danniken" wrote in message ... If an electric motor with 80% efficiency is pulling 16A at 120V, what is the horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? I also mostly agree based on a chart I have here. 2 HP AO smith 120V motor pulls: 16.4 to 16.6 at 3600 RPM 17 to 17.8 for 1800 RPM That must be a capacitor start/capacitor run motor, not a more typical cap start. The run capacitor improves the power factor, lowering the line current. -- Ned Simmons |
#11
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Motor Horsepower
On 02/09/2011 03:00 PM, Jon Danniken wrote:
If an electric motor with 80% efficiency is pulling 16A at 120V, what is the horsepower? Going by (16)(120)(0.8)/746, I get about 2 HP. Is this right? Unless you measure the current with a phase-sensitive ammeter, you are measuring two totally unrelated values. The problem with AC (I'm assuming from "120 V" that this is an AC motor) is that the phase angle is extremely important. Many motors will have only a small variation in measured current from no-load to full load. the difference is that the phase angle between voltage and current shifts dramatically from no load (current lags nearly 90 degrees from voltage) to full load, where current and voltage are nearly in phase. The POWER drawn changes just as dramatically, from maybe 200 Watts to 1900 W. But, you will likely see a 2 HP motor will draw 11 - 13 A at idle. Jon |
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