5 hp motor

Dan1900 · Feb 2, 2018

I ordered a 5hp motor and it just came in today. All of my experience with motors, electrical, etc has been in 120v and the biggest motor I have dealt with so far is a 1.75hp single phase motor, 120v, 1725 rpm, 15 amps.

Now this new motor that came in has me scratching my head. It is actually a bit smaller than the 1.75hp motor and that is where I am confused. I would think larger hp, larger motor, no? Unless the voltage has any effect? Not seeing any other info online.

The new motor is 5hp, 3450 rpm, 220v, 15-16 amps. An online calculator tells me that a 220v motor @ 15 amps is really a 4hp motor. But it's still not clicking why it would be smaller than my 120v motor rated at less than 1/2 the hp? Could it be the faster rpm? Higher voltage?

FYI the new motor is about 6.5" diameter x 10" length (not including shaft).

Richard King · Feb 2, 2018

Hopefully you looked in the catalog for the frame number and in catalogs you scroll down the page that shows the mount and mount plate dimensions and the other spec's The new one must have a plate with the Frame number on it,
On many of the imported motors connection info is inside the cover where you run your wires to. Everything electric now-a-days has become smaller. Where did you buy it? Those folks should have answers for you.

sfriedberg · Feb 2, 2018

We can't compare apples to apples unless you give us a more complete description of both the old and new motors. Frame types? TEFC or ODP or naked frame? Service factor/service type? Duty cycle? The new motor is also single-phase, or three-phase?

6.5" diameter does seem a bit puny for a 5HP motor. The standard NEMA frame sizes for a 3450RPM 5HP motor would be 184T (TEFC) or 182T (ODP), both of which are about 8.75" diameter, and close to 16" (184T) or 15" (182T) overall length including the 2.75" long shaft.

If I had to speculate, I'd guess that you got "a deal" on a non-standard or "definite purpose" motor, probably with limited duty cycle or some other operational constraint that keeps it from burning itself up despite having lighter windings than a standard motor. But I probably wouldn't have to guess if you shared all the info on the motor.

JST · Feb 2, 2018

Somewhere around I have a 5 HP motor that is not too far from that size. At 3450 rpm, the torque requirement is lower, so diameter can be less. That's one factor.

Dan1900 · Feb 2, 2018

Here is all the info off the ebay page. Both motors are single phase.

Brand new
5 SPL HP - quick google tells me this is "special" hp? What the hell is "special" about hp?
3450 RPM
208-230V
Open Drip-proof
56 Frame
Ball Bearings
Rotation: CW Facing End Opposite Shaft
60Hz
SF: 1 Protection
Rigid Base
Full Load amps: 15.0
Shaft: 5/8" x 1 7/8" keyed shaft

This motor is going to be put inside of a pretty large 16" wide wood jointer. I am really going to need the most power I can get if I want to face joint boards. I want to make sure this motor will fit the bill and I really don't want to a) waste time to install it and find it's underpowered, b) waste the money to ship it back

I think even if the motor mfg'er is fudging their numbers a bit I should be ok with a "true" 3.5-4 hp motor for this application no?

sfriedberg · Feb 2, 2018

Dan1900 said:
5 SPL HP - quick google tells me this is "special" hp? What the hell is "special" about hp?

It means the motor is not rated according to true, continuous power output. The "5 HP" rating is inflated, but we can't tell you how much just from "SPL" because it depends on how [strike]badly the manufacturer cheated[/strike] how creative the manufacturer was in their rating procedure.

You may remember about 10 years ago, shop vacs had motor ratings that were about 2x to 2.25x higher than the actual power output. Then there were a bunch of lawsuits and the FTC got involved so that makers can not longer claim "peak HP" as standard HP. That's what SPL HP means: the power produced by the motor as it is in the throes of burning itself up.

15A full load for a 3450RPM (3600 synchronous) single phase motor means it's basically a 3HP motor, not a 5HP motor.

rons · Feb 2, 2018

Dan1900 said:
Now this new motor that came in has me scratching my head. It is actually a bit smaller than the 1.75hp motor and that is where I am confused. I would think larger hp, larger motor, no? Unless the voltage has any effect?

Don't sweat over it. Same kind of size differences here at my place.

Danny VanVoorn · Feb 2, 2018

I've seen motors that were so old the whole thing was made out of beautiful castings like a work of art and weighted a couple of hundred pounds. Comparatively a new motor with twice or more HP was half the size and weight?
Dan

MattiJ · Feb 3, 2018

My best guess from amps and frame size is that you have 3.5hp motor.

Americans and their marketing horsepowers :angry:

DDoug · Feb 3, 2018

You've got to watch that some motors are "intermittent duty"

I have a scissor lift with a 3 hp motor, interm. duty, that looks smaller than a 1/2 h.p. motor

I see them all the time on surplus center, to be used on a car lift.

Dan1900 · Feb 3, 2018

The motor is rated compressor duty so it shouldn't have issues running for extended periods of time. I don't think it will need to anyways for the purpose of jointing unless I am milling a large batch at once.

I do have another follow up question. Is it possible to reuse the on/off switch that came with the tool? It was being used to run a 440v, 3 phase motor. Or do I need to buy a single phase 220v switch?

Now a more general purpose question regarding 220v, I am going to have to make some changes to the shop to get 220v added. In looking online it looks like you can find 220v in either 3 prong (like a standard 120v but one of them is rotated 90 degress), or 4 prong (angled, like a washer dryer plug). Does anyone know the difference? Is the 3 prong one not technically grounded? I was always under the impression you needed 4 wires for 220v.

Tony Quiring · Feb 3, 2018

You need 2 wires for 240 vac...L1 and L2.

Next you need one wire for "Safety ground"

The fourth wire would be neutral which is optional.

If you have 120 volt stuff in the machine then use 4 wire.

In our shop we used the now not used 3 prong dryer plugs as "Standard 240" outlets for welders or other "portable" stuff as they are found at yard sales for a couple bucks.

These are used for 240 vac only equipment that does not need a neutral.

We use a "range 50 amp" one for the 7.5 hp compressor to meet current needs.

For The BP we have a power cord made from truck trailer wire that has the dryer plug so it can plug into the standard 240 outlet and wires in the cord come out at the plug end with seperate plug for the 120 vac stuff on the mill.

You have many options that all can work but are limited by code and budget as well as work to get power from panel to tool.

Best option is to visit your building department and discuss with them since you are asking we assume power not in your wheelhouse.

They can give guidance regarding code as some places require full upgrade to GFI if you touch any part and may also get picky over type of outlets used.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

jim rozen · Feb 3, 2018

Dan1900 said:
I ordered a 5hp motor and it just came in today. All of my experience with motors, electrical, etc has been in 120v and the biggest motor I have dealt with so far is a 1.75hp single phase motor, 120v, 1725 rpm, 15 amps.

Now this new motor that came in has me scratching my head. It is actually a bit smaller than the 1.75hp motor and that is where I am confused. I would think larger hp, larger motor, no? Unless the voltage has any effect? Not seeing any other info online.

The new motor is 5hp, 3450 rpm, 220v, 15-16 amps. An online calculator tells me that a 220v motor @ 15 amps is really a 4hp motor. But it's still not clicking why it would be smaller than my 120v motor rated at less than 1/2 the hp? Could it be the faster rpm? Higher voltage?

FYI the new motor is about 6.5" diameter x 10" length (not including shaft).

1) did you by mistake buy a three phase motor where you wanted single phase?

2) look at the nominal temperature rating compared with your old motor. Newer motors
come with higher temp. insulation which makes them smaller overall.

Dan1900 · Feb 3, 2018

So what you're saying is I have a few different options for wiring the 220 receptacles in my shop. Is there a standard 220 plug style? If I were to buy a new tool pre-wired 220 what would I expect to find on the plug end?

Tony Quiring said:
You need 2 wires for 240 vac...L1 and L2.

Next you need one wire for "Safety ground"

The fourth wire would be neutral which is optional.

If you have 120 volt stuff in the machine then use 4 wire.

In our shop we used the now not used 3 prong dryer plugs as "Standard 240" outlets for welders or other "portable" stuff as they are found at yard sales for a couple bucks.

These are used for 240 vac only equipment that does not need a neutral.

We use a "range 50 amp" one for the 7.5 hp compressor to meet current needs.

For The BP we have a power cord made from truck trailer wire that has the dryer plug so it can plug into the standard 240 outlet and wires in the cord come out at the plug end with seperate plug for the 120 vac stuff on the mill.

You have many options that all can work but are limited by code and budget as well as work to get power from panel to tool.

Best option is to visit your building department and discuss with them since you are asking we assume power not in your wheelhouse.

They can give guidance regarding code as some places require full upgrade to GFI if you touch any part and may also get picky over type of outlets used.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk

Dan1900 · Feb 3, 2018

I bought the tool used. I am not seeing a temp rating anywhere on the new motor but it does say INS-B?

jim rozen said:
1) did you by mistake buy a three phase motor where you wanted single phase?

2) look at the nominal temperature rating compared with your old motor. Newer motors
come with higher temp. insulation which makes them smaller overall.

JST · Feb 3, 2018

Class B in NEMA ratings is not a high temp class, hot spot around 120C or so, and general temperature 10C lower. There are several hotter classes.

Monarchist · Feb 3, 2018

Dan1900 said:
So what you're saying is I have a few different options for wiring the 220 receptacles in my shop. Is there a standard 220 plug style?

Aye - whole tribe of them. Sorted by rated current, basically.

If I were to buy a new tool pre-wired 220 what would I expect to find on the plug end?

At best, I'd hope for a Hubbell twist lock.

Bare tip-stripped-only wires or NO wires for many, just a recommendation to follow local code.

Electric kitchen ranges and electric dryers that need a separate "pigtail" or HVAC that wants a Sealtite pre-wired "whip" are examples of the most common ones. Water heaters with pigtails for wire nuts another.

Machine-Tools, it may be a box with a local disconnect or a magnetic "starter". Up to the installer to meet code when wiring to that.

Perhaps the most common of 220 VAC + cordsets by global "count", given it is on coffee and teapots, skillets, rice-cookers, TV & audio and such, presents the same IEC female socket as the typical computer does in the USA. A cord with "local-compatible" distant end then depends on any given country's standards. Typically 15A or less, though

There exist higher-current versions - we just don't see them as often, stateside.

Otherwise? General-use cordsets are common in the rest of the world for 220 +, but NOT common, USA. No cord. No plug.

Most of our 220+ is bespoke, and "hard" wired, or near-as-dammit - given a dryer or kitchen range might go 5, 10, even 40 years without being unplugged.

beckerkumm · Feb 3, 2018

Compressor duty motors are often INT use and open drip so they tend to be be lower end. I'm not a single phase guy but farm duty motors are a good value as they are single phase and built pretty well. A TEFC farm duty is the more appropriate choice for a planer. Dave

Jraef · Feb 5, 2018

As others have sail, the "SPL" means the "5HP" is a marketing gimmick, not a real number. What that means is that the motor will DEVELOP a brief torque surge that, at the rated speed, can be calculated as "5HP" for that moment. "Brief" is something like 2-3 seconds every 10 minutes. AC induction motors have a "torque / speed curve" and on that curve, a motor will develop a peak torque, called "Break Down Torque" (BDT) at around 85-90% rated speed. This is the torque a motor develops to RE-accelerate a load after a change. But in developing that torque, the motor will pull 200-250% of is full load current, and it can't do that for very long without resting to cool down. In the industrial world, BDT is not used in determining HP, because the real formula for HP is based on Full Load Torque (FLT) and base slip speed, then Full Load Amps (FLA) is based on the same thing. In the industrial world, we need accuracy and consistency.

It's BS, but people get away with it in the retail consumer world for some reason. Legally, they must show the actual operating watts, but if they don't show the real FLA, then they must show what's called the MOCP (Maximum Over Current Protection) and MCA (Minumum Circuit Ampacity) so that you can properly size the conductors and breaker or fuses. But don't put a lot of credence in that HP value, it's basically meaningless.

5 hp motor

Aluminum

Diamond

Diamond

Diamond

Aluminum

Diamond

Diamond

Titanium

Titanium

Diamond

Aluminum

Titanium

Diamond

Aluminum

Aluminum

Diamond

Diamond

Hot Rolled

Titanium

Similar threads