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05-24-2009, 10:24 AM   #31

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Your right. I used the wrong formula. I did my calc based on a single feed.Peak would be roughly 345 volts(varies with motor RPM, uF of the cap).If the capacitor is reading 370volts while under load. Part of the voltage is from the motor, and part from the line feed. But not in equal proportions.While the capacitor always sees 60hertz. Its used to alter the sinewave(hence the hertz also). And its voltage is determined by the RPM of the motor also(the voltage increase is from the start windings).Checking uF while under load.amps*2650/volts=uF.volts measured across capacitor while motor is running.4.5 amps times 2650=11,925divided by 364volts=32.76uFs.4.28 amps times 2650=11,342 divided by 346volts=32.78uFs.

05-24-2009, 11:52 AM   #32
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Quote:
 Originally Posted by beenthere Your right. I used the wrong formula. I did my calc based on a single feed.Peak would be roughly 345 volts(varies with motor RPM, uF of the cap).If the capacitor is reading 370volts while under load. Part of the voltage is from the motor, and part from the line feed. But not in equal proportions.While the capacitor always sees 60hertz. Its used to alter the sinewave(hence the hertz also). And its voltage is determined by the RPM of the motor also(the voltage increase is from the start windings).Checking uF while under load.amps*2650/volts=uF.volts measured across capacitor while motor is running.4.5 amps times 2650=11,925divided by 364volts=32.76uFs.4.28 amps times 2650=11,342 divided by 346volts=32.78uFs.
Don't they derate the cap voltage?
If I had a cap rated at 370vrms I wouldn't put more than 1/2 to 2/3rd of that rms voltage into it.

 05-24-2009, 12:00 PM #33 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,406 Rewards Points: 7,802 Common to actually read a bite higher then 370 volts. Depends on the load the motor is working under. Compressors can read different from one week to the next. Varing with the load the compressor is under from the indoor and outdoor conditions. The 370, is only the insulation, not the allowable load voltage. The insulation will break down quicker at 385 volts, then at 365 volts. On systems that the cap goes out a lot. Its usually best to go up to the 440 volt cap. The manufacturer, selects the cap to save them money, while still meeting load requirements at 95°F DB OD temp, and 80°F DB 67°F WB indoor temps.

 05-24-2009, 06:16 PM #34 Member   Join Date: May 2009 Location: Brooklyn, New York (NYC) Posts: 1,124 Rewards Points: 500 been there 6;30AM; I'm certain you're aware (just to enhance your statement that the Voltage rating of the capacitor has no bearing on the actual voltage at the terminal/s) that the voltage rating of the Capacitor is the DIELECTRIC voltage. Meaning that above the rated voltage the Capacitor will break down and cease functioning as one!
 05-24-2009, 06:33 PM #35 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,406 Rewards Points: 7,802 Yes, its the dielectric insulation. However. I never seen a 370 volt rated run cap that failed because it was runing at 380 volts when the compressor was under a heavier then normal load. Unless it was constantly running at that higher voltage. Even those. Ran for long periods of time before the cap failed. I like to think of it as a guarranntee. A 370 volt rated cap is guarrantied to not spark internally up to 370volts. A 440 volt up to 440 volts. How much higher after that, before internal sparking occurs, is anyones guess.
05-24-2009, 07:02 PM   #36
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Quote:
 Originally Posted by yuri Can get the old ticker up to 165 BPM and maintain it.
". . .the formula "220-your age" for estimating maximum heart rate. Unfortunately, this formula is not very useful because it can be easily off by more than 20 beats on the high or low side. For me at age 54 this formula says my maximum heart rate should be 166, but I happen to know from more accurate tests that it's at least 25 beats higher than that."

Yu R how old?

 05-24-2009, 07:09 PM #37 Hvac Pro     Join Date: Nov 2008 Location: Winnipeg, Canada Posts: 15,989 Rewards Points: 116 It is a recommended number based on age IMO not actual physical condition. I have a cardio monitor feature on my treadmill and can watch my heart rate when running. When I ran outside without one I had no idea what I was doing and ran until I ran sort of ran out of air/saw stars, not very scientific. I can hit close to 170 but the trick is not to stay there for more than a minute for safety reasons. I am getting a Polar monitor watch for running outside. The key to fitness is to maintain your heart rate at 85% for 20 minutes or more to gain cardio fitness. Started work when I was 18, been at it for 30 yrs.
05-24-2009, 07:45 PM   #38
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Quote:
 Originally Posted by yuri It is a recommended number based on age IMO not actual physical condition. I have a cardio monitor feature on my treadmill and can watch my heart rate when running. When I ran outside without one I had no idea what I was doing and ran until I ran sort of ran out of air/saw stars, not very scientific. I can hit close to 170 but the trick is not to stay there for more than a minute for safety reasons. I am getting a Polar monitor watch for running outside. The key to fitness is to maintain your heart rate at 85% for 20 minutes or more to gain cardio fitness. Started work when I was 18, been at it for 30 yrs.
If you can run up 6 flights of stairs in 20 seconds and you weigh 150# you've put out 1 hp. I tried to do 2 hp on a cardio machine but the max it would read was 900w (1.2 hp).
My resting rate is down to 46 BPM so the formula is not too good for me.

 05-24-2009, 08:41 PM #39 Hvac Pro     Join Date: Nov 2008 Location: Winnipeg, Canada Posts: 15,989 Rewards Points: 116 Everybody is different so one formula cannot fit all. As I get in better shape I can sustain a faster average speed at the same heart rate. That is how I judge success. Hit 5 mph today.
 05-24-2009, 08:52 PM #40 Newbie   Join Date: May 2009 Location: Cincy, OH Posts: 13 Rewards Points: 10 Ok, start winding . . . I have a feeling my tech has not a clue, probably need to call another company soon because there is no telling if replacing the fan will do the trick if the compressor could have a short. Can anyone PM Referral in Cincy? Also, tomorrow, I will get a short video on YouTube so you know what I am talking about. No, the fan ran in the CORRECT direction with the compressor OFF. That was that way when the wire clip on "C" fell off the capacitor (I verified that at least the second time, the wire was NOT burnt). Now that a new cap is in, the fan will run in the CORRECT directly until the compressor kicks in. I am as confused as you guys are as to why the fan runs a few seconds before the compressor kicks in. All I know is I can duplicate the problem, so it's not a one off thing. Will post link tomorrow, stay tuned.
 05-25-2009, 06:26 AM #41 Member   Join Date: May 2009 Location: Germany Posts: 42 Rewards Points: 25 I've only seen that once, many years ago on a Panasonic window shaker. It turned out to be the wiring ( a service tech. screwed it up), I sure don't remember exactly which wires were crossed, but I do know it's possible (on a Panasonic anyway). I'd probably start by reversing the power at the outlet and then checking the chassis for power (just in case). Not a fix, but may give you a hint and be an indicator of a shorted winding or a stuck relay. Then I'd pull off the starting relay, give it a good shake so I could hear the ball (contact) rattle. Ohm it right side up, then upside down. Ohm the three poles on your compressor to each other and then to the compressor hosing. Just for the heck of it do a voltage check with the compressor running. I've got a foggy thought in mind, that if the start relay is stuck closed, it may unbalance the phase. Or a short in the compressor winding or the fan being wired into the wrong side of the capacitor, may be causing a phase differential (more current (watts) one direction than the other). Just a thought, "reality is the crossroads where theory and function coincide" . Last edited by Bigfoot; 05-25-2009 at 06:36 AM.
 05-25-2009, 06:36 AM #42 An old Tradesmen   Join Date: Oct 2008 Location: Somewhere Posts: 34,406 Rewards Points: 7,802 Reversing the leads/wires of a single phase feed, weather a 120 or 240 volt circuit, won't change motor rotation.
05-25-2009, 10:48 AM   #43
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Quote:
 Originally Posted by beenthere Reversing the leads/wires of a single phase feed, weather a 120 or 240 volt circuit, won't change motor rotation.
If some sort of phase problem is there (capacitor or inductance) on one side (phase direction) and not the other, a flatter wave form, it can do odd things to a (inductance/rotating field) motor. I'm guessing the voltage might be different on one leg than the other (the average voltage would be higher on one leg using a simple volt meter after reversing the plug/power supply) or a simple horseshoe amp meter might show different amp draw on one leg more than the other. Just a theory.
Like I've said, I've only seen it once and now that I think about it it was a Westinghouse and not a Panasonic. I've seen it bunch of times on multi phase motors. I'm going to venture a guess and say the fan power is hooked up to the wrong side of the capacitor, the out side instead of the in side. And/or the starter relay is stuck closed. Another simple test with a horseshoe amp meter, it should peak, then the amp draw should fall off after the compressor motor has started and the starting relay has opened.
You may have to read into my language a bit, most of my experience is hands on and not theory.

Last edited by Bigfoot; 05-25-2009 at 11:44 AM.

 05-25-2009, 11:35 AM #44 Member   Join Date: Jul 2008 Location: NW of D.C. Posts: 5,990 Rewards Points: 2,000 I maybe can see a motor starting in the wrong direction, but I can't imagine it reversing direction once running. This is a good question for the motor manuf.
05-25-2009, 12:29 PM   #45
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## puzzled as to why A/C fan motor reverse/s direction, etc.

Again, I'm wandering outside my field of expertise! But a good guess on my part for the reason that the fan motor kicks in a few seconds before the compressor is that there should be air circulation when the comp. is activated. No defect there.
As for the possibility that the A/C tech who replaced the capacitor on your unit may have hooked up something wrong. It happens to the best of us. Since you have an IDEA of what's cooking inside your unit, may I suggest you call him (or her. To be Politically Correct) back and run through your ideas with him! Personally, I've seen an AC serviceperson tell a customer (when I happened to be on scene for a different matter) that the reason for the Central unit n.w. was that the Compressor was shorted out! When I was asked to look at the unit, I found that All Three phases were OK (no shorted windings) and the defect was @ the contacts, Where Two out of Three phases were burned out. After replacing the Main Contact terminal and the 100Amp. Safety Switch the unit worked fine!!!

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