Capacitor question

I have an old H-A-S static phase converter that I am currently running my Bridgeport with. I know it's not the best, but it works kinda.

When I power the phase converter on I can hear the relay "buzz" when I start up the BP the relay snaps and the contacts open. Seems to be working correctly. The relay would open dropping out the start capacitors.

But I wanted to check the voltage and be sure they were in the correct range, according to the HAS manual. I found that the voltage on the 3rd leg was much lower than the manual said it should be. So I pulled the caps to test them.

Here's what I found,



These are attached to the relay, so I believe that they are the start capacitors. They are Mallory 108-130MFD 330VAC. They measure 117 uF. (Can't make the symbol for some reason.) So does this reading indicate that the caps are all good? Or do I need to disconnect them and test each individually? Are they in series as I think?

There is also a separate capacitor that I think is the run cap. It is connected to terminals 2&3. 1&2 are line voltage. Seems odd to me that it is a 20MFD 500VAC cap. It shows 22.8uF. Seems to me that this one should be a larger capacitance size. But I didn't build the unit. I'm just guessing.



Not much to the unit. The relay is working, the only other item is the variable resistor and it seems to be working as well.

RonRock said:

They are Mallory 108-130MFD 330VAC. They measure 117 uF.

Click to expand...

The four capacitors are connected series-parallel. There are two pairs that are series-connected and those pairs are connected in parallel. This make the effective capacitance equal to that of one (i.e. 108-130 uF) but the combination has a voltage rating of twice that of the individual capacitors. To review, capacitors in parallel are additive but in series the effective value for a pair is (C1 * C2) / (C1 + C2). For like-valued capacitors in series this simplifies to C/2.

The four caps are probably OK - to test them individually you'd have to disconnect some of the white wires.

Don Kinzer said:

The four capacitors are connected series-parallel. There are two pairs that are series-connected and those pairs are connected in parallel. This make the effective capacitance equal to that of one (i.e. 108-130 uF) but the combination has a voltage rating of twice that of the individual capacitors. To review, capacitors in parallel are additive but in series the effective value for a pair is (C1 * C2) / (C1 + C2). For like-valued capacitors in series this simplifies to C/2.

The four caps are probably OK - to test them individually you'd have to disconnect some of the white wires.

Click to expand...

Series-parallel those tricky devils. New to me. But now that you tell me I can see it. I hope.



Left and right sides=Series
Top and bottom =Parallel

I think that I'll leave it alone and concentrate on my RPC build.

Always good to learn something new. Thanks Don

RonRock said:

But I wanted to check the voltage and be sure they were in the correct range, according to the HAS manual. I found that the voltage on the 3rd leg was much lower than the manual said it should be. So I pulled the caps to test them.

Here's what I found,

View attachment 220940

These are attached to the relay, so I believe that they are the start capacitors. They are Mallory 108-130MFD 330VAC. They measure 117 uF. (Can't make the symbol for some reason.) So does this reading indicate that the caps are all good? Or do I need to disconnect them and test each individually? Are they in series as I think?

There is also a separate capacitor that I think is the run cap. It is connected to terminals 2&3. 1&2 are line voltage. Seems odd to me that it is a 20MFD 500VAC cap. It shows 22.8uF. Seems to me that this one should be a larger capacitance size. But I didn't build the unit. I'm just guessing.

View attachment 220939

Not much to the unit. The relay is working, the only other item is the variable resistor and it seems to be working as well.

Click to expand...

The start caps would have nothing to do with your low 3rd leg. Indicate which terminals are "+" and "-" on the black case caps before an assumptions.

The large 20uf cap is alone and feeling pretty useless. Might need a few companions.

Thanks Rons, that's what I thought about that 20uF.

I don't see any +/- marking on the caps. I did put a black marker dot on each of them in the same terminal position as a way for me to try to indicate the same terminal on each. Helped me decide that they were in series. But I was still unsure as the wire connection just didn't seem right to me. Now I know why, Series-Parallel. Head Slap!

Maybe I will look for some additional 500VAC caps and see if I can bump that leg up.

Better to have a second cap from the third leg to the other hot lead (the one not connected to the 20uf can).

(removed the "+" "-" sentence. They black caps looked like polarized ones. duh)

RonRock said:

Left and right sides=Series
Top and bottom =Parallel

Click to expand...

Your observation is correct.

rons said:

Should either be "+" "-" or "pos" "neg" [markings].

Click to expand...

AC circuits like these use non-polarized electrolytic capacitors. There aren't any positive/negative markings on them due to their being non-polarized. Although there are some exceptions, you'll not often find polarized electrolytic capacitors in an AC circuit.

Don Kinzer said:

AC circuits like these use non-polarized electrolytic capacitors. There aren't any positive/negative markings on them due to their being non-polarized. Although there are some exceptions, you'll not often find polarized electrolytic capacitors in an AC circuit.

Click to expand...

Thanks for that info. I did not see any markings on the caps we are discussing here. I had already reassembled the unit so did not look further. But I just picked up several run caps for my RPC build. They are new stock from Surplus Center (cheapies, not USA) They don't have a clear mark + or - although they do have a mark that looks to be a small spray paint dot on top. Some are near one terminal some are so close to center it would be hard to say which terminal.

Got me wondering if I need to keep positive terminal on one side of a set of parallel capacitors. I wasn't sure how it would matter with AC voltage circuit.

A.C. capacitors do not have terminal markings so do not waste time imagining where they should go.
As to the run cap, it may be right as it is. This is a H-A-S converter which has no similarities to the rotary phase converters we discuss here. Few of the participants here have studied the H-A-S design. It is a very good converter but requires a 12 wire motor which is not commonly found used. The VOLTAGE measurements will be different than those found in a balanced rotary.
For those Ineretested, look up H-A-S phase converter by Steelman Electric.
I posted links and patent numbers for these about ten years ago.
Bruce

I figured that the 12 wire motor conversion may have been the issue with the way that the H-A-S . I don't want to cut into the motor wiring of my BP motor. Another reason for the RPC build.

I'll do a search and see if I can find your H-A-S info.

Was there a label on the converter saying what size motor it was for? The run cap being 20 UF suggests maybe 1 HP. Bob

Toolnut is correct, you need a 12 lead motor for that HAS converter to work properly.

Here are the links.

How to Install Static Converters | Static Converter Manufacturer

US2922942A - Phase conversion motor system
- Google Patents

SAF Ω