Author Topic: Any one able to tell me what capacitor this is? for replacement  (Read 321 times)

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Offline Cannibal_pyro

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Any one able to tell me what capacitor this is? for replacement
« on: October 25, 2019, 04:35:11 pm »
came out of this motor, which came out of a band saw (not original to saw)
 

Offline Benta

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Re: Any one able to tell me what capacitor this is? for replacement
« Reply #1 on: October 25, 2019, 04:48:49 pm »
It's a paper cap, most likely 400 V. Your picture of the spec label is practically unreadable, you'll have to copy the info by hand or take a better picture.
 

Offline Cannibal_pyro

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Re: Any one able to tell me what capacitor this is? for replacement
« Reply #2 on: October 25, 2019, 06:15:28 pm »
srry i was able to read it in pic.
MODEL: 5KC73AB206A
TYPE: KC
FRAME: 73A
HP: 3/4
PH: 1
CY:60
RPM: 1725
115/230
10/5
40C CONT
 

Offline floobydust

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Re: Any one able to tell me what capacitor this is? for replacement
« Reply #3 on: October 25, 2019, 06:21:39 pm »
Tough, it's a vintage motor and nothing for datasheets or parts. GE motor 5KC73AB206A, start capacitor 9CG107812.

What is the nameplate "539" about?
1944 1/2HP version of the 5KC uses 247-270uF, so it could be as high as 539uF??

Otherwise, you'll have to guess and try one, it will just growl and not move or take a long time to start if it's too small. A bandsaw does not have a heavy start-up load.
 

Offline Benta

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Re: Any one able to tell me what capacitor this is? for replacement
« Reply #4 on: October 25, 2019, 08:17:30 pm »
A capacitance that high is totally unrealistic. My guess would be around 5 uF for this size of motor.
The name plate part saying 10/5 might give a hint: 10 uF for 115 V, 5 uF for 230 V.

« Last Edit: October 25, 2019, 08:19:28 pm by Benta »
 

Offline tooki

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Re: Any one able to tell me what capacitor this is? for replacement
« Reply #5 on: October 25, 2019, 08:55:29 pm »
A capacitance that high is totally unrealistic. My guess would be around 5 uF for this size of motor.
The name plate part saying 10/5 might give a hint: 10 uF for 115 V, 5 uF for 230 V.
No, the field containing "10/5" is labeled "A", so I'm preettty sure it's the current. ;)
 
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Online MagicSmoker

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Re: Any one able to tell me what capacitor this is? for replacement
« Reply #6 on: October 25, 2019, 08:57:30 pm »
A capacitance that high is totally unrealistic. My guess would be around 5 uF for this size of motor.
The name plate part saying 10/5 might give a hint: 10 uF for 115 V, 5 uF for 230 V.

That would be true for the run capacitor, if it had one, but not for the starting capacitor. Old split-phase capacitor-start motors like this usually have a centrifugal switch that opens up the start winding after coming up to speed. Since the start capacitor isn't in circuit very long it is usually a bipolar electrolytic these days, though you might be able to get an oil and or film dielectric type, too.

OP: capacitor value in Farads can be roughly estimated by the equation: FLA / (6.28 * Hz * Vrms)

Where FLA = Full Load Amperage; Hz equals mains frequency (60Hz in the US; 50Hz most other places); Vrms is the mains voltage (either 115 or 230 as listed on the nameplate).

Assuming 10A FLA and 115Vrms at 60Hz that gives a starting capacitor value of 0.000231F or 231uF (sometimes referred to on this kind of capacitors as MFD). The value is not super critical, however, and the standard size of 220uF should work fine but deliver a little less starting torque (not a problem for a bandsaw).

 

Offline Benta

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Re: Any one able to tell me what capacitor this is? for replacement
« Reply #7 on: October 26, 2019, 06:40:14 pm »
A capacitance that high is totally unrealistic. My guess would be around 5 uF for this size of motor.
The name plate part saying 10/5 might give a hint: 10 uF for 115 V, 5 uF for 230 V.
No, the field containing "10/5" is labeled "A", so I'm preettty sure it's the current. ;)

I wasn't able to read that, sorry. Perhaps I need better imaging SW (or the OP a better camera).
 

Offline SiliconWizard

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Re: Any one able to tell me what capacitor this is? for replacement
« Reply #8 on: October 26, 2019, 06:44:21 pm »
It's a paper cap, most likely 400 V. Your picture of the spec label is practically unreadable, you'll have to copy the info by hand or take a better picture.

Yeah. It almost looks like a firecracker. ;D
 

Offline Benta

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Re: Any one able to tell me what capacitor this is? for replacement
« Reply #9 on: October 26, 2019, 06:55:26 pm »
It's a paper cap, most likely 400 V. Your picture of the spec label is practically unreadable, you'll have to copy the info by hand or take a better picture.

Yeah. It almost looks like a firecracker. ;D

Good joke. The outside is actually phenolic, the dielectric is paper.
 


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