What is True Horsepower of Taiwanese and Chinese Electric Motors?

[Bob Deroeck]

The machines in my workshop include 3 Baldor motors, a Dewalt Motor on my old RAS, and three motors made in Taiwan or China. The larger Baldor motors include NEMA Nominal Efficiency and Power Factor on the motor nameplate. There is no such information on the Dewalt motor or the Taiwan or Chinese motors. Using the formula: HP = Voltage x Amps x Eff x PF/746 gives the following:

Baldor 3 HP motor on PM66 tablesaw: HP = 230 x 15.0 x 0.76 x 0.79 = 2.78 HP. I'm guessing the HP on the Baldor nameplate is a "nominal" horsepower that is rounded off. So, 2.78 HP is rounded off to 3 HP. Any comments on this assumption?

Baldor 4.5 HP motor on Laguna LT18 bandsaw: HP=230 x 18.2 x 0.84 x 0.97/746 = 4.57 HP. Pretty close to nameplate 4.5 HP.

Baldor 3/4 HP motor on Clausing drill press: Nameplate does not show efficiency or power factor. Amps is 5. For true 3/4 horsepower, efficiency x PF = 0.486. This could be achieved with an efficiency of 0.70 and a power factor of 0.70. Are these numbers reasonable for a small Baldor motor built in the 1960's-70's? I'm guessing that they are.

Dewalt 3 HP motor on RAS: Nameplate does not show efficiency or power factor. Amps is 18. For true 3 horsepower, efficiency x PF = 0.54. This could be achieved with an efficiency of 0.72 and a power factor of 0.75. Are these numbers reasonable for a Dewalt motor built in the late 1940's to 1950's? I'm guessing that they are.

Chinese 3 HP motor on Delta DC-380 Planer: Nameplate shows 230v and 15 amps. Efficiency and PF are not shown. For true 3 horsepower, efficiency x PF = 0.65. This could be achieved with an efficiency of 0.81 and a power factor of 0.80. I'm skeptical that efficiency and PF would be higher on this motor than the Baldor 3 HP motor shown above. If we assume that both efficiency and PF are 0.70, then the true HP would be HP=230 x 15 x 0.7 x 0.7/746 = 2.27 HP. Is this Chinese motor really a 2 1/4 HP motor, masquerading as a 3 HP motor? Or does this Chinese motor have higher efficiency or power factors than a Baldor motor of the same claimed HP?

Chinese 1 HP motor on Grizzly G0555 Bandsaw: Nameplate shows 220v and 5 amps. Efficiency and PF are not shown. For true 1 horsepower, efficiency x PF = 0.678. This could be achieved with an efficiency of 0.848 and a power factor of 0.80. I'm skeptical that efficiency and PF would be significantly higher on this motor than the Baldor 3/4 HP motor shown above, which has a combined efficiency x PF of 0.486, if it is a true 3/4 HP. If we assume that both efficiency and PF are 0.70 for the Chinese motor, then the true HP would be HP=220 x 5 x 0.7 x 0.7/746 = 0.72 HP. Is this Chinese motor really a 3/4 HP motor, masquerading as a 1 HP motor? Or does this Chinese motor have higher efficiency or power factors than a Baldor motor of similar claimed HP?

Chinese 2 HP motor on Powermatic Jointer: Nameplate shows 230v and 9 amps. Efficiency and PF are not shown. For true 2 horsepower, efficiency x PF = 0.72. This could be achieved with an efficiency of 0.90 and a power factor of 0.80. I'm skeptical that efficiency and PF would be significantly higher on this motor than the Baldor 3 HP motor shown above, which has a combined efficiency x PF of 0.60. If we assume that both efficiency and PF are 0.70 for the Chinese motor, then the true HP would be HP=230 x 9 x 0.7 x 0.7/746 = 1.36 HP. Is this Chinese motor really a 1 1/3 HP motor, masquerading as a 2 HP motor? Or does this Chinese motor have higher efficiency or power factors than a Baldor motor of similar claimed HP?

I'm trying to figure out whether the claimed HP on the asian motors is significantly overinflated or whether these newer asian motors have been designed for higher efficiency and/or power factor than that on the older Baldor motors. If you've guessed that I'm leaning towards the former, you've guessed right.

Comments?

Bob DeRoeck








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[Bill White]

HP ratings are a relative notation today. I'm convinced that the 6 HP rating on my Ridgid vac is a number applied under no load circumstances just before the motor explodes while running at 60 zillion RPMs.
I just use the tooling as designed without even thinking about HP.
Bill

[Michael W. Clark]

Nameplate HP on the Baldor (and most motors) should be shaft output power, 3HP at the shaft. If you calculate the HP based on electrical input, you will need more "HP" worth of watts to overcome the motor inefficiencies. I would assume the asian motors are rated the same way.

Been awhile, but PF is not necessarily inefficiency and it changes with the load (as does efficiency also). PF is the ratio of real to apparent power (kVA/kW). The utility must supply you more kVA to overcome a bad power factor from an inductive load.

[Mike Henderson]

Induction motors are different than universal motors and the HP calculations used are different. In general, the HP rating of an induction motor is the maximum continuous HP that the motor can produce. Not so with universal motors. Actually that's just a marketing choice - you could rate universal motors the same as induction motors but somehow, they started doing universal motors on peak HP and not continuous HP and that's just the way it is now.

The techniques for determining the HP of an induction motor are pretty standard but that doesn't mean that all manufacturers of induction motors rate their motors accurately. It's quite possible that some of the Asian motors are rated at a higher HP than another manufacturer would rate them.

Mike

[Carl Beckett]

I was going to say - that I would be surprised if 3hp induction motor manufacturer could get away with fudging the hp rating.

But then I considered duty factor. That is, maybe a motor is capable of a particular HP but not for all that long before it heats up and derates. I think this is what the smaller motors do now (things like a shop vac - 6HP ... really? I dont think so)

but then I see motors listed as 'Farm duty' Or 'Compressor duty'. For the compressor I assumed this means capability to handling start up demands. For farm duty I just assumed a more continous duty factor.

(but also I will suggest that US manufacturers are not immune to marketing ... I worked for some time at US based industrials, and if the market went a particular direction with specifications then we chased right after it. No different than an Asian manf would)

And if I really wanted to stir up controversy - I would argue that at this point in history, Asia has a superior manufacturing technical capability than does the US. Practice makes perfect, and we have systemically been practicing less and less. Sad. But imo true across a number of areas. So if manufacturing technology matters, then an Asian manufacturer may very well have the edge. My point being that dont assume that just because it is made in Asia, that it is inferior.

[Peter Kelly]

My point being that dont assume that just because it is made in Asia, that it is inferior.

I think you could say that about Japan or Korea with many products. Otherwise, I encourage you to read this book: http://www.amazon.com/Poorly-Made-Ch.../dp/0470928077

[Ken Fitzgerald]

Peter,

It's important to point that the book is a result of one man's opinion....the author..... Who gains financially from making contraversial statements that would enflame readers and encourage more people to read the book..........the author........

[Peter Kelly]

The book is an account of a western manufacturing agent's experience doing business in China, not an op-ed piece. I'm not sure how you found it controversial.

[Carl Beckett]

I think you could say that about Japan or Korea with many products. Otherwise, I encourage you to read this book: http://www.amazon.com/Poorly-Made-Ch.../dp/0470928077

An interesting book (didnt read it but I do get where the author is coming from, and its true - sometimes). And interesting (and mixed) comments along with it. I do understand it gets the blood stirring (my own as well!), but I was only speaking from my own direct experience developing and manufacturing products made in China (and other parts of the world, including Singapore, Thailand, Europe (Spain, England, Ireland), Eastern Europe (Czech Republic and Hungary)), India, and of course multiple US based factories.

In addition to traveling directly for inspections in all of these places, I spent two years directly managing a factory in Puerto Rico, and have spent considerable time and energy arguing/evaluating where a particular product should be made (where I often argued China as not the best place - an argument that I lost more than once. At the same time I have to concede that the US has lost its leadership in some areas - as much from a lack of application than the desire/ability.

Broad sweeping, one size fits all generalizations are rarely 'true' (of course, sometimes they can be 'generally' true). My experience with China - as with other places is, you get what you negotiate, demand, and monitor. But be careful - if you are expecting something for nothing you rarely get it. And if you expect a supplier to have your best interest at a priority higher than their own, you rarely get that either (at the same time, forcing a suppliers to go bankrupt is not in the companies best interest either)

To bring this back to the original question: Are motors made in Asia over inflating HP ratings?

I think its a question of what the OEM specified or demanded (independent of where it was produced). If I am a US manufacturer and source a component in Asia (or anywhere else for that matter), I have to provide a specification for that component to meet. I am also responsible (to the markets and to my customers - and legally) to ensure that specification is met. It doesnt matter where its manufactured. At least in some industries, you cant just make up an advertised specification without some legal justification. Its true that if one company starts manipulating the way a product is spec'd, then other companies can follow suit or hold tight to their legacy method. That then becomes a marketing decision based on the knowledge of the customer. Often customers do NOT take the time to understand it, and just want to buy the product with the higher number (people like one or two numerical data points to make a decision on - no more - and this is very often inadequate)

[John Lifer]

Does it really matter if a motor is rated at 3hp or 2.5? or for that matter 3.5? Maybe if you are purchasing new machine and rating one Co against another, but If it will cut or perform satisfactorily what difference is it? We don't rate in half hp once it gets over 1hp, so if it is a 1.76 hp actual, it would be a 2hp. or 1.49 should be a 1hp. My issue is more with does the motor hold up to use over long time.

[Ken Fitzgerald]

The book is an account of a western manufacturing agent's experience doing business in China, not an op-ed piece. I'm not sure how you found it controversial.

Peter, it's still a book based on one person's experience and therefore, I wouldn't place much emphasis on it. Right here at SMC one person has a complaint about a particular product and he rants about it constantly and his experience with that company's customer service. 8-12 others have the same machine, have not had a problem with the machine and felt the customer experience was stellar. So who do you believe? One person or the multitude?

Until my sudden deafness forced my retirement nearly 2 years ago, I worked for a very large global corporation. We used parts manufactured in European countries, Eastern Europen countries, Japan, Mexico, Brazil, South Korea, India, Taiwan and yes, China. We had problems with parts from all those countries. While intially we did have problems with parts manufactured in China, after careful documentation and verification, the problems were eventually resolved. I had similar problems with parts manufactured in Italy and the controlling agents for that manufacturer was in France. It took me 10 months to get changes in cost reduced manufacturing process returned to the original process. Others here in the States were experiencing the same failures I was but nobody took the time to document it. The others were just reordering.

As Carl stated.....you have to provide specifications and be responsible for your own quality control.

[Jeff Duncan]

I can't help with the technical aspect of your question, but I don't feel as though HP is real solid measure of work anyway, there's room to fudge it regardless of origin. Aside of that here's my feeling in general....there's a reason they sourced motors made in Asia....b/c they're cheaper. They sourced cheaper motors b/c they needed to make the machines cheaper. In reality the Grizzly was made entirely in Asia and possible your jointer too! So from that we can determine that cost was obviously a concern in your buying these machines, meaning quality was secondary.....which is the case for many of us here BTW. So my question would be why are you concerned with whether or not the hp is a "true" rating? I'd be more concerned with other aspects of the machine that may have been compromised for "value engineering" that could negatively affect it's performance and longevity over the motor.....but that's just me

So I agree with John, I'm not concerned necessarily with actual hp....just that it's a sufficient amount for the machine and work I'm doing With that I'll leave the math behind the motors to those smarter than me

JeffD

[Peter Quinn]

I hear what Bob is saying, how can these Asian import motors say 3 hp and draw so few amps? I've asked myself the same thing. Simple, they are over rated. The older Dc-380's nameplate said 2hp, they changed it to 3hp but barely change the amp draw. My youghurt is several ounces smaller than previously but the price has remained constant, but I am now hungry sooner after breakfast. Hmmm. Fact is a lot of people don't care what it says as long as it works. In an industrial situation where a machine gets used to its limits daily over rating a motor leads to failures, financial loss, and anger. In the home shop? Mostly we buy more than we need any way, so if its less than it says its of little importance. Still, honesty would feel better to me.

[Patrick Grady]

Motor torque and power are important variables regarding power tools. I have always been mystified by the 'amps' ratings of motor power. Amps have nothing to do with power. 'Amps' is a marketing stupidifrication of motor ratings and here is why: suppose a circular saw cutting 3/4 ply draws 7 AMPS. Well if you added twenty spotlights into the internal circuitry of the saw then the circular saw might draw 7.8 AMPS. The lightbulbs added light but added nothing to the power of the saw. In other words inefficient power-wasting motors might draw more amperage and get higher power ratings. AMPS ratings has always been a joke. I know all about power factor and capacitors but they are variables that have nothing to do with motor power ratings (they are variables that find importance in the transmission and delivery of electricity not the comsumption of it. I have never understood why smart knowledgeable craftsmen stood for this motor ratings fraud over the last twenty years.

[David Malicky]

Dual capacitor single-phase motors (capacitor start, capacitor run), with proper sizing of the run capacitor, should have a power factor close to 1.0. For example, that Baldor 4.5 HP at 0.97. Single-phase motors with only a start capacitor (and all 3 phase motors) have lower PFs. Since dual-capacitor single-phase motors are the standard for woodworking equipment, and it's not tough to spec the right run cap, the PF on those can usually be assumed to be 1.0. http://books.google.com/books?id=Irj...page&q&f=false

For shop vacs (universal motors), the peak HP is of course a useless marketing spec. The amps in small print on the back label is a pretty good measure -- that relates to the size extension cord needed for safety, so it's the actual continuous running amps.

As Mike and Carl mentioned, there are standards for how induction motor HP is calc'd, but the service factor and duty period must be known to do apples-to-apples comparisons. When a US company specs a single-phase induction motor, they usually assume a Service Factor (SF on the nameplate) of 1.15 -- i.e., the motor can make 15% more HP and amps than its rating. But SF 1.0 is also quite common and conversely, pool pump motors often have SF > 1.5. Asian motors probably assume 1.0, if nothing is stated.

"Duty" also varies, both in % on/off time and meaning. Continuous Duty motors are the most robust; they can run at rated HP*SF indefinitely without overheating. Intermittent Duty motors state HP assuming some % duty cycle. These are typical and perfectly appropriate for most woodworking machines, but that % duty offers some wiggle room to over-rate. Baldor is certainly more conservative than HF. Compressor Duty means the motor is designed for high starting torque (probably a NEMA C design), but does not need to run continuously. Farm Duty is designed for high starting torque, continuous running, and are totally enclosed.

I don't doubt a "2 HP" Asian motor can produce 1.75 - 2 HP at intermittent duty. The main weaknesses will be overheating after some period of time (possibly quite short) and a relatively high likelihood of insulation damage if overheated. A 2 HP, SF 1.0 Baldor may not make any more HP, but it should be able to happily run at its nameplate ratings for SF and duty.