Please help identifying this capacitor, to buy the same or an equivalent

Thread Starter

PUAR

Joined Jun 28, 2018
11
Hello community
I kindly ask for your help to identify this capacitor, as the title says. This is from an old 1/2 hp single phase motor (siemes elmo-g attached to a buchi fluid bed dryer). I have more than 1.5 years working with the motor without it, but now I'm trying to do control ithe speed and results are not as expected, so I would like to discard the lack of the capacitor as a factor.
Please find the picture attached, and thanks beforehand for your help.
 

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SamR

Joined Mar 19, 2019
2,782
It is a dual run capacitor marked 0.22uF X 500pF Y 250VAC

0.22uF is odd... is it 22uF? that would be a 22/5 dual run cap

can you test the capacitance?
 

MisterBill2

Joined Jan 23, 2018
7,279
The 0.22 MFD capacitance label is clear enough but the rest of the label is not clear enough to understand what it means. 200picofarads is not a reasonable value for a capacitor associated with a motor that size, and so we need to see the rest of the label much more clearly. Also we need to know a lot more about the motor, such as any connections shown on the nameplate, and what other data is there. Even the 0.22 MFD value is rather small for a motor capacitor, and so it seems that there is other information needed to provide a correct answer. Otherwise folks are just handing out guesses.
 

Thread Starter

PUAR

Joined Jun 28, 2018
11
Hello SamR, MisterBill2
Thanks for your replies.
I can take better pictures tomorrow for the unclear parts, but it's not clear enough because the ink has vanished a little though.
Anyways, i can provide right now a motor plate picture. Please see attachment.
 

MisterBill2

Joined Jan 23, 2018
7,279
OK, now the motor plate clearly specifies a TEN microfarad capacitor, (C=10uF), rated at 450 volts, which should be a NON-Polarized type. An added note is that if the motor does not have a starter switch or a starting relay, that needs to be a RUN capacitor instead of a starting rated capacitor. The difference is in the current handling ability. While starting draws more current it is only for a second or two, while a run capacitor the current is continuous.
And now, looking at that capacitor, it might possibly be a double capacitor with the two sections used in series to get the voltage rating, and close to the capacitance rating. BUT that is strictly a guess until the whole label can be understood.
 

MisterBill2

Joined Jan 23, 2018
7,279
OK, now the capacitor is clear. It is indeed a dual capacitor, each section being 0.22 microfarad, and the green wire is the common. the part of the label that is rubbed off is the "X 2"
"0.22uF X2 ,500, pF Y"

It is physically way to small to be a dual 22mFd @ 250 volts capacitor. AND, in addition, the green and yellow stripe wire would only be connected to a case ground. That wire color code is ONLY for the safety ground, which would not be part of a run circuit on a motor. Thus the capacitor that you need is the 10 microfarad 450 volts unit called for on the motor plate.
 

MisterBill2

Joined Jan 23, 2018
7,279
That could certainly be the case. But that still leaves the fact that this is not a motor run capacitor, although it may have been installed in that position, or possibly not. Reviewing the first post makes it unclear what sort of speed control is being attempted. A capacitor-run motor with a far to small capacitor would not have good load to speed characteristics, I don't think. So another set of questions include is another capacitor in place on the motor, and what sort of speed control is desired, or being implemented. Once again we have lots of information not provided, leading to a string of guesses.
 

Thread Starter

PUAR

Joined Jun 28, 2018
11
Hello everyone
Thank you so much for your interest in helping me, I really appreciate it.
Here, as I said, I upload new pictures of the capacitor. It's broken so I don't know if trying to measure anything would give a reading.

To me, it says
0.22uF X + 2x2500pF Y
cF 250V~
25/085 HPG
70579-F3 R5
 

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MaxHeadRoom

Joined Jul 18, 2013
21,623
How many terminals? Maybe show a picture of the motor terminal box.
If as the label shows, you need a 10μf 400v AC motor run rated capacitor.
I suggest obtaining the correct version, stay away from those of Chinese origin, N.A. type preferred, I use CDE oil filled paper for quality.
Max..
.
 

MisterBill2

Joined Jan 23, 2018
7,279
Certainly having a motor run capacitor of adequate quality would be very important, and so now the question becomes one of what has been serving as the motor run capacitor? And what sort of speed control is intended to be provided. Having a correct run capacitor will certainly help the motor hold a steady speed, and that might be all that is required. But certainly we need more information to be able to provide good advice instead of best guesses. So is there a motor run capacitor? And what sort of speed control is intended?
 

Thread Starter

PUAR

Joined Jun 28, 2018
11
OK, now the motor plate clearly specifies a TEN microfarad capacitor, (C=10uF), rated at 450 volts, which should be a NON-Polarized type. An added note is that if the motor does not have a starter switch or a starting relay, that needs to be a RUN capacitor instead of a starting rated capacitor. The difference is in the current handling ability. While starting draws more current it is only for a second or two, while a run capacitor the current is continuous.
And now, looking at that capacitor, it might possibly be a double capacitor with the two sections used in series to get the voltage rating, and close to the capacitance rating. BUT that is strictly a guess until the whole label can be understood.
Please allow me to further expand on this.
The motor is connected to a contactor controlled by a DCS from which I give the start/stop signal. Without any attempt to control the speed, that is connecting it directly to the contactor without a VFD or SCR, the motor almost instantaneously starts at what I call full speed (more on this on the next quote).

That could certainly be the case. But that still leaves the fact that this is not a motor run capacitor, although it may have been installed in that position, or possibly not. Reviewing the first post makes it unclear what sort of speed control is being attempted. A capacitor-run motor with a far to small capacitor would not have good load to speed characteristics, I don't think. So another set of questions include is another capacitor in place on the motor, and what sort of speed control is desired, or being implemented. Once again we have lots of information not provided, leading to a string of guesses.
What I am trying to accomplish is the air flow control of the buchi fluid bed dryer mentioned on the original post. For that, I first started trying for months with a VFD without success, then I came across a SCR and finally managed to vary the air flow.
More on that was posted on this thread:

https://forum.allaboutcircuits.com/...e-ac-induction-motor-possible-options.138759/

It is not a thread of my own, but is a fairly short thread, so if you or anyone had the time to quickly read though it to undestand more about what I did please be my guest.

Right now, I'm using a Smartfan Nimbus II speed controller (https://controlresources.com/ac-fan-control-ac-motor-control-smartfan-nimbusii/). I just installed it yesterday and although it does vary the airflow (sensed as deltaP- green line in the charts attached), once it goes below certain speed value (full speed) it can't go back to it even if the control signal is 100%. First chart is starting the motor with this sequence: set control signal to 100% (20mA) then start the contactor. Second chart is starting the motor with this sequence: set control signal to 0% (4mA) then start the contactor (by the nimbus II config, values below 9mA put it to "idle speed" which is 50%).
 

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MaxHeadRoom

Joined Jul 18, 2013
21,623
If intending to control the rpm electrically, there is no suitable way at present to do it reliably, for a cap run or start 1ph motor, both triac and var freq. controllers do not do it, at least in a practical way.
The Triac/SCR version can end up heating and harming the motor.
If wishing to use a 1ph VFD, you will need a 3ph motor for control.
Max.
 

mvas

Joined Jun 19, 2017
537
Hello everyone
Thank you so much for your interest in helping me, I really appreciate it.
Here, as I said, I upload new pictures of the capacitor. It's broken so I don't know if trying to measure anything would give a reading.

To me, it says
0.22uF X + 2x2500pF Y
cF 250V~
25/085 HPG
70579-F3 R5
See my message #10 and the URL Link.
That device is 3 capacitors inside one case ... an AC Line Filter.
 

Thread Starter

PUAR

Joined Jun 28, 2018
11
How many terminals? Maybe show a picture of the motor terminal box.
If as the label shows, you need a 10μf 400v AC motor run rated capacitor.
I suggest obtaining the correct version, stay away from those of Chinese origin, N.A. type preferred, I use CDE oil filled paper for quality.
Max..
.
Hello Max, I remember you from the previous thread I was asking for help. Thank you.
Right away i'm going to try get a picture of the terminal box, if I manage to open it.

Certainly having a motor run capacitor of adequate quality would be very important, and so now the question becomes one of what has been serving as the motor run capacitor? And what sort of speed control is intended to be provided. Having a correct run capacitor will certainly help the motor hold a steady speed, and that might be all that is required. But certainly we need more information to be able to provide good advice instead of best guesses. So is there a motor run capacitor? And what sort of speed control is intended?
Hello MisterBill2
1-red) Actually, the motor has been runnig for more than a year without any capacitor.
2-blue) I think I answered this question in my previous post, most likely I took too long to answer and that's why you had to ask again. My bad. If that is not the answer you were expecting, would you be so kind to explain to me what do you mean with "what sort of speed control is intended to be provided"? I know only basic stuff of electronics and nglish is not my native language so maybe there's sonmething I'm missing.
 

MaxHeadRoom

Joined Jul 18, 2013
21,623
Right now, I'm using a Smartfan Nimbus II speed controller . I just installed it yesterday and although it does vary the airflow once it goes below certain speed value (full speed) it can't go back to it even if the control signal is 100%. ).
That is a typical of Triac controlled PSC motors, they have to have 100% to start.
Your PSC motor is right on the upper limit, as anything over 0.5hp is usually the maximum
Max.
 
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Thread Starter

PUAR

Joined Jun 28, 2018
11
How many terminals? Maybe show a picture of the motor terminal box.
If as the label shows, you need a 10μf 400v AC motor run rated capacitor.
I suggest obtaining the correct version, stay away from those of Chinese origin, N.A. type preferred, I use CDE oil filled paper for quality.
Max..
.
Here are the pictures of the panel: It seems to me the connections are made as the bottom drawing of the first picture.
 

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