High Efficiency?

Define, "high service factor".

Depending on the design, yes, it it possible.

Service factor is only required on the nameplate if it is above 1.15. A 10 HP motor operated at a service factor of 1.15 will produce 11.5 HP

Although it is done, operating the motor at the rated service factor will shorten the motor life.

Lyn, I support (technically), electric submersible pumps made in Sweden, where "service factor" is not used. Here in the states, it is routine for me to be asked what service factor, as if it were a deciding factor for comparison. I have to explain that the submersible pump market demands high efficiency, high power to wieght ratios, together with the cost in field strength for elongated rotor/stator packages. That being said, you cannot operate in an overload condition. Thanks for the reply.

This is gonna get semantically complicated.

Let's stick with the example of the 10 HP motor with a 1.15 service factor. If I'm operating the motor at 11 HP, is the motor overloaded, or operating within its design limits?

Submersible pumps, due to the difficulty of service/replacement may be considered differently, I don't know.

All of the pumps I've ever used were (mostly) vertical applications in sumps.

if you have an engine with a "redline of 5000" it will tag that number and be fine. driving it for hours will still destroy it before its time. the original question is poor. high efficiency and service factor are different specs.......I see no real world question here just wasting time on a theory without a genuine application. if you're operating a motor and its getting hot, lower the load or up the HP to meet the load

Sure it's possible. It all depends on how one defines "high" for each term. This sounds to me much more like a useless advertisement brag.

I apologise for wasting time, or for advertisement. Have a nice day!

I think it was a fine question, considering the hoopla surrounding high efficiency motors and their adaptation by industry.

I still say yes, to the original question.

Thanks, "High efficiency" is the advertising brag. "Service Factor" without the disclaimer of time, ambient temperature and correct line voltage, is fake insurance.

Time, ambient temperature and correct line voltage would not affect a HE motor any differently, I think.

A 10 HP HE motor is roughly 6% more efficient.

Running above the design service factor affects motor life due to elevated operating temperature.

Usually in submersible pump motor applications, the ambient temperature is a real non-issue as the medium being pumped is being relied upon for coolant flow. All other things being "equal", I would want a motor with a higher service factor than one rated strictly to 1.0 nameplate power. The nearer one is to the power limit of a motor, simply put, there is more heat to dissipate, I don't care how efficient that motor may be.

These considerations have been based upon purely electrical characteristics, but at some point on the load curve of a motor, certain mechanical issues come into play as well, as vibration, bearing loads, shaft torque, thrust, all change with variant conditions. Especially in any down hole situation, one does not want to have to "pull" that motor to replace it.

I believe (for me at least), this closes the proceedings.

Agreed.

Adios.

No need to apologise at all. We're all here to kill some time in one way or another in the first place. Second, many advertisements frequently blur the lines of real engineering metrics by never citing where or how they define their terms. So asking if any recognized engineering agency (NEMA) properly sets the definition of a metric and if two metrics are mutually exclusive is a reasonable request. I'm glad to hear that NEMA does set a standard for both metrics of high efficiency and service factor. I still see no reason for them to be mutually exclusive or related to each other in any way.

I don't see what the fuss is about, both terms are clearly spelled out in NEMA MG-1.

Section 12.51 has a table of applicable service factors, and Sections 12.58 has tables for Nominal, High, and Premium Efficiency motors, plus refernces to the IEEE testing standards. Generally speaking as you add more copper, iron, and lower friction bearings the efficiencies go up.

I suspect that manufacturers "grade" their motors' efficiencies the same way semiconductor manufacturers "grade" their chips, by testing them and labeling them according to which level they fall into.

Yes.

Of course, the likelihood of someone actually MAKING such a motor depends on what you call a high service factor- simply being over 1.15, or a specific requirement (say 1.3) as well as any other unusual specs.

And operating the motor above unity normally reduces the efficiency anyways, so you are better off having a motor correctly spec'd, if normal operating conditions allow.

When portability (weight) is a factor, along with limits in dimensions for portability, wire to water calls for "high efficiency". Submersible pump design calls for a performance curve that includes running to the left or right of the best efficiency point which is produced for clear water at room temperature. Taking this into consideration, when I get rubber stamped requests for motor performance, service factor is routinely included. Trying to explain why our service factor is actually 1.01 leads to further explanation. This is why I asked you guys.

Then you're on the right track, pick an operating point on the composite pump/motor curve and show them the difference in efficiencies for the various class of motors. Also show them that there is no savings in undersizing/specifying a motor a 10HP motor to be constantly loaded to 11.5HP, and it may even cost more over the life cycle of the project due to multiple motor replacements and system downtime.

My opinion is that service factor should not be considered in selecting a motor.

Agreed, it's more of a "fudge-factor" to accommodate occasional, short term overloading instead of its usage in this thread as a way to purchase a knowingly undersized motor instead of paying more for a properly sized one.

My experience with service factors closely parallels the use of the term horsepower between the U.S. and Europe, IEC verses NEMA, mm2 verses AWG, MSHA permissible mine equipment lack of concept, so on and so forth. I am not complaining, it is job security.

My 1HP pool pump motor has a tag on top that says

Kind of reminds me of the old audio amplifier power rating system, 100W RMS suddenly became 1,000W Peak Power! Same nonsense on certain brands of shop vacs, 6.5 Peak HP (measured in "air watts"??)...at the end of 20ft of 16-2 wire and a 15 amp plug.

I haven't bothered to hook an amp probe around the pump leads, but I doubt the motor is drawing even close to 1 HP.

Yes, but the associated cost is significant.

I have to frequently warn the marketing segment not to inflate horsepower ratings be cause it can push the starter equipment ratings or generator size into the next step up. This can represent a substantial increase in cost.