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Post by turbokinetic on Feb 2, 2020 2:10:50 GMT
After successfully un-seizing a CA last year on a video; and several since then privately - I've taken some measurements in a video.
https://youtu.be/btWh2gTko2Y
Thoughts? Thanks! David
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Post by coldspaces on Feb 2, 2020 3:00:07 GMT
Nice job showing us the results of the different methods.
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Post by turbokinetic on Feb 2, 2020 15:27:33 GMT
Nice job showing us the results of the different methods. Thanks! It was surprising how much more torque was possible, actually.
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chad
New Member
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Post by chad on Feb 2, 2020 17:44:59 GMT
Thanks for the video David....Really interesting stuff..Reminds me a lot of the tests that I sometimes witnessed in the refrigeration test labs at Appliance Park Louisville AP5. Years ago I had a neighbor that was a production engineer in refrigeration GE Louisville....he had a 1970 era GE 2 1/2 ton Central Air unit.. Compressor would stick sometimes at spring startup.....we would add about 50 more "mikes" to the run winding (PSC Motors in residential GE compressors) and comp would kick off and would be fine for rest of cooling season. (WE removed the extra capacitor after starting) I asked the product service engineers in our bldging 6 and they said if the compressor were to stop at exactly top dead center on one cylinder it could result in the starting problem. I believe this fact caused the addition of starting kits being added to the product....GE Central Air was located in Tyler Texas but the engineering was done mostly at Louisville Appliance Park. Business was sold to Trane in the early 80's. I always believed that GE regretted the sale …. they had an excellent product. Chad
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Post by cablehack on Feb 2, 2020 23:09:32 GMT
Great video, David! Fascinating to see the tabulated results. I was surprised that the starting cap didn't increase the torque at 120V as much as I expected. I was also previously worried about GE's recommendation of applying 240V - but you've shown the windings won't go up in smoke by the time it starts (or should start!). The two phase starting should be very easy to implement in my part of the world since the mains supply is three phase 240/415V. Hopefully, I won't ever need to try it.
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Post by elec573 on Feb 7, 2020 7:31:47 GMT
Very interesting and the video was very nice also . I’d say that this would not be for someone , that’s not familiar with these old fridges . But for us old fridge geeks we really appreciate it.
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Post by don on Mar 7, 2020 17:08:18 GMT
Thank you TURBOKINETIC ! Super job of using visual aids and putting the different electrical configurations for unseizing the CA compressor into perspective. When I opened the seized CA compressor that I had seize on me I found it to be locked up solid. Using a back and forth movement using the top mounted fan as a handle I was able to create a tiny rotational movement that I was able to gradually expand until it grudgingly completed a full rotation. At the same spot of each rotation there was a perceptible drag. When I completely disassembled the compressor I found copper plating on various steel surfaces. The drag I had felt when rotating the fan was caused by a deposit of copper plating on the bottom surface of the rotor/ compressor assembly. That deposit of copper plating had reduced the end play (up/down) movement to zero which had seized the assembly. I placed a piece of PLASTI GAGE on that deposit and reassembled the compressor to measure the end play after I had unseized the machine and it measured less than .001. PLASTIGAGW will only measure down to .001. This is shown in these links. monitortop.freeforums.net/thread/824/observations-opening-ca-compressor-stuckmonitortop.freeforums.net/thread/868/lard-oil-copper-platingMy inch/lbs hand torque meter had a provision so I could put a T handle on it so it would be like using the top mounted fan on the compressor to measure my wrist torque. I clamped the Torque meter into a vise and using my wrist on the T handle I approximated the maximum torque I would have used in a back and forth movement to free the compressor. The black dial on this torque meter shows 33 inch lbs which is just under 3ft/lbs which approximates the 2.4 ft/lbs and 2.9 ft/lbs obtained from your 240 volt trials. In comparison the .620 ft/lbs and .71 ft/lbs you obtained using 120 volts were comparatively just nudges to obtain 6 - 8 inch/lbs with my wrist. drive.google.com/drive/folders/1jXKjdQ0sh9buVRY8HYKKcoUc1ISw6ia6Cablehack had earlier suggested reversing the 120 volt motor by switching the wiring and putting a capacitor in the run winding. That way a person could create a back and forth movement to free the compressor. Thanks to your measurements I can see that the back and forth nudges might not be enuf and the 240 volts torque measurements were closer to the torque I probably used with my wrist. I never had a need to experiment with electric motors. Is there a way to reverse the 120 volt motor with the 240 volts applied so that a person could loosen the motor with a back and forth movement?
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Post by turbokinetic on Mar 7, 2020 18:59:29 GMT
Thank you TURBOKINETIC ! Super job of using visual aids and putting the different electrical configurations for unseizing the CA compressor into perspective. When I opened the seized CA compressor that I had seize on me I found it to be locked up solid. Using a back and forth movement using the top mounted fan as a handle I was able to create a tiny rotational movement that I was able to gradually expand until it grudgingly completed a full rotation. At the same spot of each rotation there was a perceptible drag. When I completely disassembled the compressor I found copper plating on various steel surfaces. The drag I had felt when rotating the fan was caused by a deposit of copper plating on the bottom surface of the rotor/ compressor assembly. That deposit of copper plating had reduced the end play (up/down) movement to zero which had seized the assembly. I placed a piece of PLASTI GAGE on that deposit and reassembled the compressor to measure the end play after I had unseized the machine and it measured less than .001. PLASTIGAGW will only measure down to .001. This is shown in these links. monitortop.freeforums.net/thread/824/observations-opening-ca-compressor-stuckmonitortop.freeforums.net/thread/868/lard-oil-copper-platingMy inch/lbs hand torque meter had a provision so I could put a T handle on it so it would be like using the top mounted fan on the compressor to measure my wrist torque. I clamped the Torque meter into a vise and using my wrist on the T handle I approximated the maximum torque I would have used in a back and forth movement to free the compressor. The black dial on this torque meter shows 33 inch lbs which is just under 3ft/lbs which approximates the 2.4 ft/lbs and 2.9 ft/lbs obtained from your 240 volt trials. In comparison the .620 ft/lbs and .71 ft/lbs you obtained using 120 volts were comparatively just nudges to obtain 6 - 8 inch/lbs with my wrist. drive.google.com/drive/folders/1jXKjdQ0sh9buVRY8HYKKcoUc1ISw6ia6Cablehack had earlier suggested reversing the 120 volt motor by switching the wiring and putting a capacitor in the run winding. That way a person could create a back and forth movement to free the compressor. Thanks to your measurements I can see that the back and forth nudges might not be enuf and the 240 volts torque measurements were closer to the torque I probably used with my wrist. I never had a need to experiment with electric motors. Is there a way to reverse the 120 volt motor with the 240 volts applied so that a person could loosen the motor with a back and forth movement? Hi Don. Thanks for the kind feedback on my video! I did play with the reversal idea, using a capacitor in the run winding. It was possible to make the motor run in reverse this way, however it was incredibly weak. I tried various capacitor configurations and could never get more than weak, gradual acceleration in reverse. With the converter motor and pre-phase shifted power, it is possible to create the full torque shown in the test in either direction. Simply reverse the rotation of the converter motor and the motor receiving power from it will be reversed. As for the one you opened, do you know what ever became of it? Sincerely, David
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Post by don on Mar 8, 2020 10:06:40 GMT
Thanks for the quick reply. Thanks to your measurements If I were to obtain another seized CA I would not hesitate to apply 240 volts in an effort to unseize it. I would though add and remove the capacitor into the run winding alternating back and forth even if the reversal was weak. It would allow the forward rotation to obtain a momentum against the seizure.
I had cut the top open so I could remove the compressor so that the top would be lighter. I had the thought that in case I modified a machine with a condensing unit mounted elsewhere I would be able to have a lightweight top to make the machine look original. The motor did not weigh much and the top was still almost as heavy. The metal was stored outside and rusted and all of it went to a scrap collection.
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Post by turbokinetic on Mar 8, 2020 14:37:43 GMT
Thanks for the quick reply. Thanks to your measurements If I were to obtain another seized CA I would not hesitate to apply 240 volts in an effort to unseize it. I would though add and remove the capacitor into the run winding alternating back and forth even if the reversal was weak. It would allow the forward rotation to obtain a momentum against the seizure. I had cut the top open so I could remove the compressor so that the top would be lighter. I had the thought that in case I modified a machine with a condensing unit mounted elsewhere I would be able to have a lightweight top to make the machine look original. The motor did not weigh much and the top was still almost as heavy. The metal was stored outside and rusted and all of it went to a scrap collection. Cool, I think I read that copper plating is most likely in high temperature and marginal lubrication areas; so if the unit were under undue stress because of NCG's, it could very well exacerbate the problem. It seems to me that the key to getting one to live again is to get the excess pressure out of the system ASAP so that it will have a chance to circulate oil without immediately overloading. The reason I asked about your old compressor was because of where the operational stator used in the video came from. Another collector (who is not online) had it in his stash that he downsized. He mentioned that someone gave it to him; so I was curious it could be the same one. I have a feeling there aren't that many "bare" CA compressors kicking around out there LOL!.
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Post by don on Mar 8, 2020 16:29:04 GMT
Much or most of my refrigeration HVAC experience was with semi-hermetic compressors with oil level site glasses and oil drain plugs. With most compressor replacements we would typically test the oil with a Sporlan acid test kit to check for acidity. If the test showed the oil was acidic we would use filter driers rated for acid removal changing them often. Semi hermetic compressors have oil drain plugs so we would often change the oil maybe several times. We would declare the job done after a sufficient run time and an acid test kit showed it was no longer acidic. According to this link SECTION 10 - methyl formate decomposes into carbon monoxide and carbon dioxide and formic acid and methanol fscimage.fishersci.com/msds/97142.htm Hence the Formic Acid in the compressor would make the mineral oil acidic resulting in copper plating: "Copper pennies are useful in demonstrating the concept of copper plating. A simple lemon bath is used to demonstrate this process. Lemon juice is a natural acid that attacks the oxidized copper-oxygen bond, releasing it from the surface of the pennies. Placement of a metal such as an iron nail in the lemon bath containing suspended copper ions results in a simple copper plating of the iron nail." en.wikipedia.org/wiki/Copper_platingI would suggest that maybe copper plating could not take place if a CA compressor were in constant use and could only happen if it sat idle for an extended time? When I opened up the CA compressor that had seized I was astonished at how shiny the copper was which in hindsight was probably caused by being in contact with acidic oil. It would be interesting to test the oil for acidity from a CA compressor that had seized.
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Post by cablehack on Mar 8, 2020 23:01:31 GMT
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Post by turbokinetic on Mar 9, 2020 15:00:02 GMT
I remember seeing those pictures. That is vile! So glad it didn't also attack the compressor motor in some way. But after 7 years if that had happened it would have made its self known by now. And again it's worth repeating how nice your restored unit and cabinet looks.
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Post by allan on Mar 16, 2020 1:29:51 GMT
Awesome work! Could you direct me to your earlier post where you showed the connections for the running motor to the stalled one?
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Post by don on Mar 31, 2020 12:19:19 GMT
Again your tests and measurements are informative and enlightening! What the measurements definitely show is the eye opening positive relationship between voltage and torque.
Since the source converter motor used would have had a run winding with a lower winding resistance/turns and a start winding with a higher resistance/turns the transformer effect would have been a +300 voltage induced into the converter motor start winding. The +300 out of phase voltage is thus the voltage applied to the start winding of the CA test motor.
Is it possible that the increased out of phase voltage obtained from that wiring arrangement further proves the positive relationship between voltage and torque?
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