Changing 50 cycle fan motor to 60 cycle

[Gooserider]

A lot may depend on the TYPE of capacitor and the type of motor involved... Remember there are two sorts of capacitors, and depending on the motor type and design, you may see only one, or both...

From Wikipedia

Motor capacitors include 2 common types, run capacitors and start capacitors :
Run capacitors: - Run capacitors are designed for continuous duty, and they are energized the entire time the motor is running.[1] Run capacitors are rated in a range of 3-70 microfarads (mfd), with voltage classifications of 370V or 440V.[1] Single phase electric motors need a capacitor to energize a second-phase winding. If the wrong run capacitor is installed, the motor will not have an even magnetic field, and this will cause the rotor to hesitate at those spots that are uneven. This hesitation can cause the motor to become noisy, increase energy consumption, cause performance to drop, and cause the motor to overheat. However, a motor will not be ruined just because a run capacitor is faulty.
Start capacitors: - Start capacitors briefly increase motor starting torque and allow a motor to be cycled on and off rapidly.[1] Start capacitors have ratings above 70 microfarads (mfd), with three major voltage classifications: 125V, 250V, and 330V.[1] A start capacitor stays energized long enough to rapidly bring the motor to 3/4 of full speed and is then taken out of the circuit, such as by a centrifugal switch that releases when rotating at or around that speed.

Examples of motor capacitors are: a 35 mfd, at 370V, run capacitor, or an 88-108 mfd at 250V start capacitor.[1]

Given that the period of a 50hz current is going to be different than that of a 60hz current, I can think that changing the size of a cap-start motor's capacitor (which changes the time constant of the circuit) might definitely improve a motor's starting ability, without changing it's running characteristics AT ALL since the start cap is taken out of the circuit as soon as the motor is up to speed...

Likewise changing a run capacitor might also improve the situation, as again you have slightly different time constants involved.

Gooserider

 

[Singed Eyebrows]

Yes, & how the cap is hooked up makes a difference too. Frank, when you get this cap setup could you briefly describe how they want it hooked up? Jim/Jebatty, The Stratos is the Smart drive you mention. Whether this is a proportioning controller is something I don't know yet. It appears this is designed for furnace, heating fans etc from their website. You are right , you sure dont want a fan starting & stopping or large speed changes every little while to control temps. It needs to modulate in a controlled manner. I don;t think the Tarm needs this though. This was more for my Atmos, Randy

 

[ohbie1]

Will do. I'll take a couple of pix too. BUT my salesman tells me that NO instructions come with this capacitor. How's that for a reputable company! Thanks again for your interest and help.

 

[pybyr]

Will do. I'll take a couple of pix too. BUT my salesman tells me that NO instructions come with this capacitor. How's that for a reputable company! Thanks again for your interest and help.

Open hood; identify existing capacitor.

Hold new capacitor.

Take leads off of old capacitor.

Dismount old capacitor.

Mount new capacitor.

Attach leads to new capacitor (AC motor capacitors do not have polarity).

I suspect that they don't give instructions on account of the fact that if the above is too challenging, then someone should let someone else do it.

 

[pybyr]

Let me confess up front-- I am the un-annointed king of over-thinking things.

And, with that disclaimer out of the way, really, don't sweat the difference between the 50/60 Hz motor or the cap; if Bioheat will send you a cap that they say is better, say thanks and put it in.

they're not offering a cap to "choke" the motor; it's almost assuredly a capacitor-run motor that needs a cap anyways, and they're likely just supplying a cap that will be more efficient at 60 Hz than the"stock" cap that was meant for 50 Hz.

Put your frets and sweats somewhere else, as you are almost sure to get more return on your investment anywhere else in your overall big-picture system- whether it's getting further ahead on your wood for the following year, or doing some more insulating or air sealing on your house.

Sounds good. I only brought up the question bcause I was thinking in terms of how long the fan motor would last being run overspeed, not really the efficiency of the setup.

Huge categories of AC motors are 50/60 rated, even if not so marked, and as mentioned before, virtually _all_ 50 rated motors will run OK- with no strain or heat, etc., at 60- just a little bit faster. The additional speed is not enough to strain bearings, which inherently have more than enough margin that the speed difference is irrelevant; other forces in the motor will also not be adversely affected to any real degree by the slight fractional increase in speed.

 

[pybyr]

Pbyr; The only way a cap is going to slow the motor down is to choke it. I though most everybody understood that choke meant shifting the phase etc. some. I'll be more explicite next time. This has nothing to do with efficiency, this is just an attempt to slow the motor down & not have the expense of a new motor in my opinion. I don't feel this is a good fix, an engineer friend I talked to didn't feel it was a good fix, Stratos did not feel it was a good fix even though it might slow it down. It's easy to not "fret" about someone elses boiler. I still think Frank deserves what he said he was promised & thats a 60 hz motor, Randy

None of us are saying that the different cap will slow the motor- it really can't- maybe that's what you think/assume it's doing, but, if you are using a cap to slow a motor, you've got things hooked in an pretty unconventional and inefficient (and probably unsafe) circuit arrangement.

What this "new cap" from Bioheat almost undoubtedly involves is changing out a cap that's already there, and that was selected to optimize the operation of the motor at 50 (but that is still OK at 60) for one that has been selected to make the motor ideally happy at 60. It's not about slowing it down.

And, as mentioned before, it's exceedingly common for motors to be designed for either 50 or 60, and any motor that is designed for 50 is almost certain to also do very well at 60 (but not the other way around). The difference in forces on bearings is nil, as are any other changes in forces, and if anything, the motor windings are likely to run slightly cooler at 60.

The variation in speed is not that significant, and I expect that air adjustments on the boiler have more than enough margin to deal with the variation. I would not put anything as an obstruction in the flue, nor would I vary from recommended barometric damper settings.

There are lots of things worth worrying about and working to get "just right" but this motor/cap issue is not one of them. Put new cap in; find other things to enjoy or worry about that amount to more.

 

[Singed Eyebrows]

I would have no issue with the new cap not slowing the motor down. If it is just put in place of an existiong cap it probably won't. If it is installed differently it might by causing a bit of heat. So we can probably agree that the fan is going to spin fast either way. This is not the way Tarm builds a boiler normally. This is a quality engineered boiler & this speed difference is way out of tolerence for me & sounds like Frank too. That fan is supposed to run a certain rpm as the exchanger/turbulators etc are designed for this. "thats close enough" wouldn't be good enough for me. You suspect air adjustments on the boiler will take care of the overdraft & this is what I said to Frank, choke the air down about 20 percent & this should be fine in absence of the motor Frank says he was promised. There are some things in life that need to be done right & getting the proper design draft in this boiler is one of them. Then, you can mellow out take it easy & enjoy burning wood, Randy

 

[jebatty]

...a quality engineered boiler & this speed difference is way out of tolerence for me...

This discussion has gotten way out of proportion to any materially relevant factor. The draft fan has an adjustable damper to provide the proper draft based on individual burning circumstances. The few additional motor rpms in moving from 50 to 60 cps just doesn't matter. Regardless of a 50/60 cps motor, the damper likely needs to be adjusted anyway based on individual burning characteristics. For example, I burn dry pine and aspen -- hot, fast burning. I have to damper down the fan considerably to keep flue temps within an acceptable range. If someone hasn't had to adjust the damper, great -- try it, and you may be surprised by the control you have over your burn rate. Maybe many are not even aware of the adjustment. Discover it and experiment, if you want.

My bet is that a person will experience more variation in burning characteristics in moving from one kind of wood to another, or higher to lower moisture content or vice versa, or size of splits, or wood load in the firebox, than will ever be noticed by a 50 cps motor running on 60 cps.

In sum, running a 50 cps motor at 60 cps simply is not a material engineering factor and does not introduce any material intolerance factor.

 

[kabbott]

...a quality engineered boiler & this speed difference is way out of tolerence for me...

This discussion has gotten way out of proportion to any materially relevant factor. The draft fan has an adjustable damper to provide the proper draft based on individual burning circumstances. The few additional motor rpms in moving from 50 to 60 cps just doesn't matter. Regardless of a 50/60 cps motor, the damper likely needs to be adjusted anyway based on individual burning characteristics. For example, I burn dry pine and aspen -- hot, fast burning. I have to damper down the fan considerably to keep flue temps within an acceptable range. If someone hasn't had to adjust the damper, great -- try it, and you may be surprised by the control you have over your burn rate. Maybe many are not even aware of the adjustment. Discover it and experiment, if you want.

My bet is that a person will experience more variation in burning characteristics in moving from one kind of wood to another, or higher to lower moisture content or vice versa, or size of splits, or wood load in the firebox, than will ever be noticed by a 50 cps motor running on 60 cps.

In sum, running a 50 cps motor at 60 cps simply is not a material engineering factor and does not introduce any material intolerance factor.

I would agree with this statement, however I think the more important issue seems to be he was promised a replacement/fix for something that may not
have been needed. This info really should come from the dealer/manufacturer/installer......someone official. My hunch is the people offering the solution may
not understand the issue themselves or atleast failed to explain it properly.

 

[Singed Eyebrows]

I sure would like to see draft readings off the exchanger end tank at 50 hz & 60 hz. Then you can better understand if this is a problem or not. Frank was promised a motor as stated, then he was to be given a conversion to put him in the same shape as if he was given the proper motor in the first place. I haven't heard yet how this 50 hz motor with a different cap hung off it is exactly the same as a 60 hz motor. It would be nice if Frank could get the 60 hz motor & then start fiddling with draft from there instead of starting from who knows where, Randy

 

[kabbott]

I would add that a 60hz motor is going to run the same rpm as the 50hz motor run on a 60hz supply. So unless the fan itself is changed along with the
motor then I don't see the point of changing it from an airflow perspective. I mean its gonna run 20% faster for a given number of poles no matter
what correct?

 

[pybyr]

I sure would like to see draft readings off the exchanger end tank at 50 hz & 60 hz. Then you can better understand if this is a problem or not. Frank was promised a motor as stated, then he was to be given a conversion to put him in the same shape as if he was given the proper motor in the first place. I haven't heard yet how this 50 hz motor with a different cap hung off it is exactly the same as a 60 hz motor. It would be nice if Frank could get the 60 hz motor & then start fiddling with draft from there instead of starting from who knows where, Randy

Man, I hereby quit this thread... I am one to obsess about thousandths of inches, or parts per million, when it might matter, when working on precision machinery, frequency alignment of sensitive electronic equipment, benchrest rifle barrels, matching bullet sizes to get max accuracy at 100-200 yards, and the like.

But--

If you want someone to try to prove to you that the sky won't fall, when you're dealing with variables that have immense rounding errors-- and- as JEbatty said, are small in comparison to the variables introduced by which armload of wood, of which species, or how-long seasoned it was, I don't want to play your game.

Have fun trying to prove whether the sky won't fall.

My own neuroses feel much more technically and socially useful when they try to focus on details and variables that might prove salient and/ or sapient.

People who say "prove that this is not a problem" are over-abundant in today's world compared to people who actually roll up their sleeves, get deep grease stains in their hands, busted bleeding knuckles, and sore muscles, trying to SOLVE a real problem that makes a sh*t worth of a difference. And by the way, I'm not just any rural redneck, I am a rural redneck by choice with high honors for a couple of big highfalutin degrees from a highfalutin University and a different highfalutin Law School. I read cast-off College physics textbooks for fun on sick days in 4th Grade even though I always struggled in Math.

Enjoy masturb***tin with your abstract worries about ultimate theoreticalefficiencies of dinkly lil' motors and caps

 

[ohbie1]

I would add that a 60hz motor is going to run the same rpm as the 50hz motor run on a 60hz supply. So unless the fan itself is changed along with the
motor then I don't see the point of changing it from an airflow perspective. I mean its gonna run 20% faster for a given number of poles no matter
what correct?

Not correct. I got this chart from the internet.

FREQUENCY
POLES 50 HZ SPEEDS (RPM) 60 HZ SPEEDS (RPM)
SYNCHRONOUS FULL LOAD
(Typical) SYNCHRONOUS FULL LOAD

2 3000 2850 3600 3450
4 1500 1425 1800 1725
6 1000 950 1200 1150
8 750 700 900 850
Looks like the 50 run on 60 is 20% faster.

 

[pybyr]

I would add that a 60hz motor is going to run the same rpm as the 50hz motor run on a 60hz supply. So unless the fan itself is changed along with the
motor then I don't see the point of changing it from an airflow perspective. I mean its gonna run 20% faster for a given number of poles no matter
what correct?

Not correct. I got this chart from the internet.

FREQUENCY
POLES 50 HZ SPEEDS (RPM) 60 HZ SPEEDS (RPM)
SYNCHRONOUS FULL LOAD
(Typical) SYNCHRONOUS FULL LOAD

2 3000 2850 3600 3450
4 1500 1425 1800 1725
6 1000 950 1200 1150
8 750 700 900 850
Looks like the 50 run on 60 is 20% faster.

it's still a rounding error compared to what variables are introduced in one armload of wood-- of varying species and moisture levels, compared to the next armload. and the post that you are replying to is trying to point out, and the point that is going over the anxiet-ists' heads, that even if they supply you with a nominal 60 Hz motor, it is INDEED going to run 20% faster than a 50 Hz motor- that's just applied physics.

At which point, the only theoretical option would be for someone to put a wimpier blower wheel on it to move less air at a given speed- except that all the other variables (what wood you burn- species and dryness) matter a whole lot more

 

[kabbott]

I would add that a 60hz motor is going to run the same rpm as the 50hz motor run on a 60hz supply. So unless the fan itself is changed along with the
motor then I don't see the point of changing it from an airflow perspective. I mean its gonna run 20% faster for a given number of poles no matter
what correct?

Not correct. I got this chart from the internet.

FREQUENCY
POLES 50 HZ SPEEDS (RPM) 60 HZ SPEEDS (RPM)
SYNCHRONOUS FULL LOAD
(Typical) SYNCHRONOUS FULL LOAD

2 3000 2850 3600 3450
4 1500 1425 1800 1725
6 1000 950 1200 1150
8 750 700 900 850
Looks like the 50 run on 60 is 20% faster.

Correct a 4 pole motor run on 50hz is 1425 and on 60hz is 1725. Maybe I was not clear, An example..... A 4 pole motor is going to run at 1725 on 60hz
no matter if it was designed to run on 50hz or not. A 50hz 4 pole motor will run at 1725@60hz just the same as a 60hz 4 pole motor will run at 1725@60hz .

Example.....say you have a 50hz-4 pole motor....you replace it with a motor designed for 60hz, also 4 pole. they will both run at the same speed...
your not changing the frequency so the rpm will not change.

 

[Gooserider]

Just out of curiosity, I thought I'd check some numbers on fans that are rated for both, to see how much difference it makes... I ended up at the NMB website, where I found a bunch of 50/60HZ rated fans... [/ur] Given it's a Euro spec fan, I figured it was probably a 240 volt model. So I took one that looked like a possible based on the pics I've seen of the fans in an EKO... By my eyeball, about the same (~6") size, fairly high airflow volume...

I couldn't post the PDF as the forum doesn't allow it, but attached a couple jpg's I pulled out of it showing the fan curve and the ratings for that size...

Picking one model out of the list (the 5915PC-24T-B20-A00), and trimming the specs a bit...

 Hz   A     W    RPM  CFM.  m3m "H20  Pa   Noise  
 50  0.10 22.0 2200 141.2 4.00 .393  98.0  46.0 
 60  0.11 26.0 2600 166.0 4.70 .472 117.6  50.0

Going from 50 to 60 Watts, we see that the fan pulls a little more current, and dissipates a little more heat, while spining about 18% faster, and moving somewhat more air, at a slightly higher pressure, and making a little more noise... However those are the "free air" and "sealed box" values, neither are terribly representative of the "real world" operating environment of a fan... If you look at the B20 fan curves for 50 and 60 Hz, you will note that while there is a noticeable difference, it isn't that big compared to the overall output of the fan, especially near the middle of the curve where it is hopefully working...

Obviously since this is just a random example, I would expect the actual curves from the OP's fan to be different, but spot checking several of these, I found similar overall results...

Gooserider

 

[ohbie1]

I would add that a 60hz motor is going to run the same rpm as the 50hz motor run on a 60hz supply. So unless the fan itself is changed along with the
motor then I don't see the point of changing it from an airflow perspective. I mean its gonna run 20% faster for a given number of poles no matter
what correct?

Not correct. I got this chart from the internet.

FREQUENCY
POLES 50 HZ SPEEDS (RPM) 60 HZ SPEEDS (RPM)
SYNCHRONOUS FULL LOAD
(Typical) SYNCHRONOUS FULL LOAD

2 3000 2850 3600 3450
4 1500 1425 1800 1725
6 1000 950 1200 1150
8 750 700 900 850
Looks like the 50 run on 60 is 20% faster.

it's still a rounding error compared to what variables are introduced in one armload of wood-- of varying species and moisture levels, compared to the next armload. and the post that you are replying to is trying to point out, and the point that is going over the anxiet-ists' heads, that even if they supply you with a nominal 60 Hz motor, it is INDEED going to run 20% faster than a 50 Hz motor- that's just applied physics.

At which point, the only theoretical option would be for someone to put a wimpier blower wheel on it to move less air at a given speed- except that all the other variables (what wood you burn- species and dryness) matter a whole lot more

I never meant to start an efficiency argument. My only concern was that the motor wil fail prematurely. Months ago when I researched running a 50 on 60, I came across a couple of websites that said "It will run, but have a shorter life"......That and the fact that I don't like being played for a sucker. What I never added to this post was the fact that they delayed my shipment 1 week and told me it was because they were waiting for the 60 cycle fan to come in and include it with the shipment. Had I not checked the motor tag, or had someone else do the job, they would have forgotten about me.

 

[pybyr]

I would add that a 60hz motor is going to run the same rpm as the 50hz motor run on a 60hz supply. So unless the fan itself is changed along with the
motor then I don't see the point of changing it from an airflow perspective. I mean its gonna run 20% faster for a given number of poles no matter
what correct?

Not correct. I got this chart from the internet.

FREQUENCY
POLES 50 HZ SPEEDS (RPM) 60 HZ SPEEDS (RPM)
SYNCHRONOUS FULL LOAD
(Typical) SYNCHRONOUS FULL LOAD

2 3000 2850 3600 3450
4 1500 1425 1800 1725
6 1000 950 1200 1150
8 750 700 900 850
Looks like the 50 run on 60 is 20% faster.

it's still a rounding error compared to what variables are introduced in one armload of wood-- of varying species and moisture levels, compared to the next armload. and the post that you are replying to is trying to point out, and the point that is going over the anxiet-ists' heads, that even if they supply you with a nominal 60 Hz motor, it is INDEED going to run 20% faster than a 50 Hz motor- that's just applied physics.

At which point, the only theoretical option would be for someone to put a wimpier blower wheel on it to move less air at a given speed- except that all the other variables (what wood you burn- species and dryness) matter a whole lot more

Might I add, based on some efforts that I made in the early 2000s to import a really small test batch of Janfire and Pellex pellet burner heads, that the Euros' perception of US-ers as a bunch of partly informed and highly-complaining customers were the main, most huge. impediment that nixed such explorations? I worked to convince the mfgrs and distributors that I was not of such ilk, but they seemed to have already been poisoned by such interactions--- and we wonder why new technologies are slow to arrive here?

 

[Singed Eyebrows]

I'm not ready to quit this thread yet, it's just getting interesting. Frank, What you might want to do is get a Euro inverter off Ebay. They are 12VDC to 220 50hz AC. This would give you battery backup & might not be a bad thing. It will also run your boiler with the proper CFM or as one poster says CFM range. These are very reasonable in price. I don't think you want to cut firewood for 15 years only to find you've been blowing 10 percent of the heat up the chimney. Flue gas temps are not a measure of heat going into the chimney, flue gas + CFM is. This is complicated by the adjustable air as a poster mentioned. I still think you need to start somewhere. I can loan or sell you a very accurate Magnahelic draft gauge. This mess didn't need to happen with the proper motor. / In the future you might want to compare draft settings with other members for different woods etc. I don't see how you do this with the setup you have now. I'm no more impressed with a certain idiots rantings now than when this thread was started, understand Trevor?

 

[Gooserider]

{mod hat on} Gentle reminder, lets keep it on the subject of the technology, not personalities... A whiff of smoke every once in a while can be tolerated, but open flameage will cause me to bring out the extinguisher....
{mod hat off}

Gooserider

 

[Singed Eyebrows]

Sorry Goose, Consider me backed off, Randy

 

[jdavi581]

Hello,
I am a process engineer for Marathon Electric. I do not design motors, but I have picked up a lot along the way. We build Electric Motors from 25 frame to 6805 frame.
We sell all of our motors around the world, low and high voltages, inverter duty, 50 and 60 Hz.
The fan needs x amount of power to spin it at y RPM. As long as the wire in the stator is thick enough to support the amperage needed, all is well. THe wire does not care about the Hz or RPM, but the the fan load does. THe faster the fan spins, the more load the motor has on it (moving more air) the more amps the motor needs, and the hottor the motor runs leading to failure. You can pull 5 HP out of a 1 HP motor, but it will not last too long. For your fan, the engineers probably got a motor slighty larger than needed in case of exporting or other in-efficiancies. All this for a relatively simple problem, right? All that really matters is the amperage draw of the motor VS the nameplate rating. Basically, measure the amperage the motor draws with the fan wide open. Compare this to the nameplate rating. If it is less,
you are just fine. If it is over, you may run into overheating and early death depending on the SF rating. Multiply the NP amps by the SF, and this is the max allowable amps. If you are over this, you are definatly going to need to change something or your motor is going to fail prematurely. if this is the case, I would close off the inlet to the fan temporarly with the ammeter hooked up until you are within the nameplate specs for the amperage.
I hope this helps you fix your problem.

 

[ohbie1]

. Multiply the NP amps by the SF, and this is the max allowable amps. If you are over this, you are definatly going to need to change something or your motor is going to fail prematurely. if this is the case, I would close off the inlet to the fan temporarly with the ammeter hooked up until you are within the nameplate specs for the amperage.
I hope this helps you fix your problem.

Thanks for the info. I will measure the amperage to see what the draw is. I don't understand what you mean about closing the fan inlet. Wouldn't this action cause it to be more difficult for the fan to suck air, and therefore raise the amperage needed?

As a postscript to this thread, I'd like to thank Randy(singed eyebrows) for all his encouragement. I did email Tarm with my concerns and received a call from the president. At first he disputed my claim that the "fix" capacitor was exactly the same as the existing one. He then asked someone there to give him a kit, after examining it, he agreed with me. He said that the manufacturer(Baxi) sent Tarm that kit, and that he never really questioned them. He apologized, said he would put in a call to Denmark and find out what's going on, and that he would call me back, but to be patient because it might take some time.

 

[Singed Eyebrows]

Hope this all works out for you Frank. The Tarm is a great boiler,hopefully they can sort this, Randy

 

[dirttracker]

Frank,

Power draw for a fan (or a pump) is related to [flow rate] x [pressure rise] for the fan. For fans under normal operation (i.e. not around 0 flow or around max unrestricted flow) small changes in flow through the fan do not cause much, if any, change to the pressure rise across the fan. For this reason, adding a restriction to the fan outlet (the adjustable damper on your Tarm) will lower the flow rate at an almost constant pressure rise and result in a lower power consumption.

Note: This relationship only works for fans and centrifugal pumps, positive displacement pumps do not follow this relationship.

As far as your fan is concerned, follow what Doityourself said, measure the current and check it against the nameplate rated values to be sure it's not out of spec. I doubt it will be, but it's worth a check for your peace of mind. I should check mine for the same issue.

Eric