Any one able to tell me what capacitor this is? for replacement - Page 1
Forum section: electronics / general

author: Cannibal_pyro
author_rank: Newbie
timestamp: October 25, 2019, 04:35:11 pm
content: came out of this motor, which came out of a band saw (not original to saw)

author: Benta
author_rank: Super Contributor
timestamp: October 25, 2019, 04:48:49 pm
content: 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.

author: Cannibal_pyro
author_rank: Newbie
timestamp: October 25, 2019, 06:15:28 pm
content: srry i was able to read it in pic.MODEL: 5KC73AB206ATYPE: KCFRAME: 73AHP: 3/4PH: 1CY:60RPM: 1725115/23010/540C CONT

author: floobydust
author_rank: Super Contributor
timestamp: October 25, 2019, 06:21:39 pm
content: 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.

author: Benta
author_rank: Super Contributor
timestamp: October 25, 2019, 08:17:30 pm
content: 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.

author: tooki
author_rank: Super Contributor
timestamp: October 25, 2019, 08:55:29 pm
content: Quote from: Benta on October 25, 2019, 08:17:30 pmNo, the field containing "10/5" is labeled "A", so I'm preettty sure it's the current.

author: MagicSmoker
author_rank: Super Contributor
timestamp: October 25, 2019, 08:57:30 pm
content: Quote from: Benta on October 25, 2019, 08:17:30 pmThat would be true for theruncapacitor, 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).

author: Benta
author_rank: Super Contributor
timestamp: October 26, 2019, 06:40:14 pm
content: Quote from: tooki on October 25, 2019, 08:55:29 pmI wasn't able to read that, sorry. Perhaps I need better imaging SW (or the OP a better camera).

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 26, 2019, 06:44:21 pm
content: Quote from: Benta on October 25, 2019, 04:48:49 pmYeah. It almost looks like a firecracker.

author: Benta
author_rank: Super Contributor
timestamp: October 26, 2019, 06:55:26 pm
content: Quote from: SiliconWizard on October 26, 2019, 06:44:21 pmGood joke. The outside is actually phenolic, the dielectric is paper.