Craftsman 1/2HP motor, 5 wire field windings?

[Blackjackjacques]

I added numbers to the diagram to show which ones lead to the stator windings.View attachment 253082

Normally, the hot is fed to the protective devices like your overload switch, while the neutral is connected to the common node. But it appears from your drawing that this is reversed. This may possibly explain why your GFCI is now tripping when before it did not - that is, if the white / black conductors have since been reversed.

 

[CluelessNewB]

Normally, the hot is fed to the protective devices like your overload switch, while the neutral is connected to the common node. But it appears from your drawing that this is reversed. This may possibly explain why your GFCI is now tripping when before it did not - that is, if the white / black conductors have since been reversed.

I agree with you that the hot side should feed the protection device. I would argue that both the hot and neutral should be completely isolated from ground. If reversing the wires stops the GFCI from tripping I believe there is still an underlying problem that needed fixing. (The problem may have been the starting cap.)

 

[markba633csi]

Keep in mind that testing a capacitor for it's microfarad value doesn't tell you if the cap is electrically leaky to the case. For that you do a resistance measurement from the cap terminals to the case. Should be 0.5 to 1.5 megohm or more
Mark S.
ps didn't you say the motor would start and run without the GFI? If so then your capacitor is OK, although it might be leaky enough to trip the GFI. You could prove that by letting the cap dangle free from the motor and see if the GFI still trips.
BTW, what is the printed microfarad value of the flat cap?

 

[Blackjackjacques]

I agree with you that the hot side should feed the protection device. I would argue that both the hot and neutral should be completely isolated from ground. If reversing the wires stops the GFCI from tripping I believe there is still an underlying problem that needed fixing. (The problem may have been the starting cap.)

We are on the same page, and I concur, the neutral and ground should be isolated at the appliance. However, older appliances do not always adhere to such a protocol, where the grounding conductor is also the neutral such as in the older 2-prong plug days. I have a number of such appliances, including some older vacuum tube test equipment that I have to energize through an isolation transformer because the branch circuit device is a GFCI. The problem may very well still be the cap - but I thought that the neutral conductor feeding the thermal trip element to be a flag - especially given the report that all worked well before re-wiring, etc.

 

[jakes_66]

That sounds strange. A reliable test I use for electrolytic capacitors is with an analog ohm meter set to Rx1K. I first connect the leads across the cap terminals to see the meter kick up towards infinite ohms and then reduce slowly, and then reverse the leads to do the same. If it performs as such in both directions - the cap is good. I do not trust some of the digital handheld cap measuring devices - although my Fluke seems to be reliable.

The old capacitor is a flat 'sardine can' type shown in the photos. A gentle shake yields a rattling sound... not good. I suspect that it's internally shorted. I wish I had an old analog meter to watch the trends as you described, but I only have this cheap DMM. At least it has a Capacitor setting... I should have checked for a short to the cap housing, but after getting the low capacitance measurement I went ahead and ordered a new one.

I

The old capacitor is made by Aerovox, part number 5205028 and 124-165 MFD rating at 125VAC. I suspect it is quite old. I searched for a good 20 minutes online before I concluded that this style is no longer available. The new one is the round 'can' style.

We are on the same page, and I concur, the neutral and ground should be isolated at the appliance. However, older appliances do not always adhere to such a protocol, where the grounding conductor is also the neutral such as in the older 2-prong plug days. I have a number of such appliances, including some older vacuum tube test equipment that I have to energize through an isolation transformer because the branch circuit device is a GFCI. The problem may very well still be the cap - but I thought that the neutral conductor feeding the thermal trip element to be a flag - especially given the report that all worked well before re-wiring, etc.

Thank you for the direction here. I will reverse the black and white leads when the new capacitor arrives. This kind of info is invaluable to me.

 

[Blackjackjacques]

The old capacitor is a flat 'sardine can' type shown in the photos. A gentle shake yields a rattling sound... not good. I suspect that it's internally shorted. I wish I had an old analog meter to watch the trends as you described, but I only have this cheap DMM. At least it has a Capacitor setting... I should have checked for a short to the cap housing, but after getting the low capacitance measurement I went ahead and ordered a new one.

View attachment 254059View attachment 254060View attachment 254061View attachment 254062I

The old capacitor is made by Aerovox, part number 5205028 and 124-165 MFD rating at 125VAC. I suspect it is quite old. I searched for a good 20 minutes online before I concluded that this style is no longer available. The new one is the round 'can' style.



Thank you for the direction here. I will reverse the black and white leads when the new capacitor arrives. This kind of info is invaluable to me.

Gotcha - and I agree, it can't be too good if you hear something rattling. I have seen many capacitors in my life, maybe not as many as some of the more wiser folks herein, but I have never seen a cap as you show here - and your sardine can analogy is on target. It should not make any difference if your replacement is round vice any other shape - Good luck and let us know what you learn.

 

[jakes_66]

Success!!!

After some delay I was able to get the new capacitor wired up to the motor and presto. The motor hums nicely and no more tripping the GFI. I never did resolve why there are (5) wires going to the field windings... However it did occur to me that these windings may have been designed for dual voltage, just wired this way for my application.

Now on to drum switch. It's an older Dayton model 440X I think... I bought it used and just pulled the cover to find that only (4) of the (6) contact fingers are in place. I'll have to dig up some more.

Thanks for all your input. Looking forward to finishing this restoration!

-Jake