Wiring headaches on my new grinder

[hustlebird]

wow, hot mess is right. He really fubared that .

I'll grab some pictures of his switch setup tonight when I get out there. FUBAR is one way to describe it.

 

[Bi11Hudson]

these grinders can't accomodate 25 cycle current (?!?)

One thing about the motor, I believe there's 9 wires coming out of the motor here, 3 tied off on blue, and 2 in each set on the white (x2) and black taped pairs.

25 cycles / Hertz is was very common in heavy industrial applications. When I was at U S Steel, it had been eliminated but a lot of the old machinery was still sitting around. It was also common for "underground" applications. (coal mines, et al) Underground coal mines have extremely serious explosion danger. The 25 Hertz was somehow related to that. It also was a factor with generators, they can run slower. Many were attached to steam engines that powered other equipment, pumps, overhead line shafts and the like.

As an aside, most "modern" generators are 2 pole or 4 pole, running at 3600 or 1800 RPM respectively. With a 6 pole or 8 pole generator running at a slower speed, 25 and 40 hertz are easy enough. (PS/120) I have never encountered a 40 Hz machine, but they were said to be common, especially in the "South Pacific" prior to WW2.

The 9 wires is also very common, still is, for 3 phase motors. The way your's is wired is for 220 volts. They are easily converted to 440. The wire numbers may not be readable now. But T1, T2, and T3 are paired with T7, T8, and T9 respectively and terminated to the lines., T4, T5, and T6 are tied together and not terminated. Essentially two "sets" of windings made up in shunt. (parallel)

It is possible to identify the wires with a lantern battery, a compass, and a buzzer. Although difficult if you are not familiar with motors. I highly recommend marking each lead distinctively before disassembling the "FUBAR" mess of connections. T1, T2, and T3 are not "carved in stone" absolute, but are determined relative to the others. T7, T8, and T9 will be connected in shunt with T1, T2, and T3 respectively. That leaves the three tied together with no connection. T4, T5, and T6 can be determined by reading resistance continuity to T1, T2, and T3. The easiest method is to mark the power lines L1 and L2. the third "ghost" leg as L3. The other side of the capacitors will be connected to L1 or L2, depending on which direction rotation is desired.

.

 

[benmychree]

This is interesting, if I measure the draw with this SPC config running should I make that 2/3's adjustment? Could the capacitors that are in use tell me anything? Maybe just what he thought it was sized like? I have a note of 70uF per kW that I pulled from a youtube video or two I've watched trying to understand how its currently configured. Am I on the right track with that way of thinking?


This sounds like the way I will be going. I have/use VFD's for my Lathe and Mill already. The parts doc on Vintage Machinery (This one) actually lists an 8" x 1/2" disc wheel for this thing. See page 13. It looks like the 1-1/2 was a 1/2" disc thickness as well. As an aside - its crazy how old some of these machines are! I was just read about how these grinders can't accomodate 25 cycle current (?!?). And several references to 2-phase current. Back in the beginning days of electricity! Thanks for the info, I think 2hp is probably going to be around the mark for this.


I'm pretty excited to take care of this thing and get it going. The No 3B, which is the newer model of this grinder, came with a 3HP motor, so I was starting from that point. It also came with a 10" x 3/4" wheel though (50% bigger), so maybe 2 HP is on the money. I'm going to try and size the capacitors on it, and with the SPC only running at 2/3rds now. I think 2HP may be alright for it. Fortunately I have a 2HP VFD on the way from Wolf Automation sometime eventually, maybe... So If that ever arrives I'll have a home for it.



One thing about the motor, I believe there's 9 wires coming out of the motor here, 3 tied off on blue, and 2 in each set on the white (x2) and black taped pairs. This is vaguely similar / familiar to what I did for my bridgeport, though I don't remember the exact details there. Does that lend credence to the SPC wiring? Again I plan to hopefully chart out everything tonight, as well as finish getting it put back together.

Thanks for all the replys already!

The 9 wires means that it is a dual voltage motor, likely 220 - 440 V

 

[hustlebird]

25 cycles / Hertz is was very common in heavy industrial applications. When I was at U S Steel, it had been eliminated but a lot of the old machinery was still sitting around. It was also common for "underground" applications. (coal mines, et al) Underground coal mines have extremely serious explosion danger. The 25 Hertz was somehow related to that. It also was a factor with generators, they can run slower. Many were attached to steam engines that powered other equipment, pumps, overhead line shafts and the like.

As an aside, most "modern" generators are 2 pole or 4 pole, running at 3600 or 1800 RPM respectively. With a 6 pole or 8 pole generator running at a slower speed, 25 and 40 hertz are easy enough. (PS/120) I have never encountered a 40 Hz machine, but they were said to be common, especially in the "South Pacific" prior to WW2.

The 9 wires is also very common, still is, for 3 phase motors. The way your's is wired is for 220 volts. They are easily converted to 440. The wire numbers may not be readable now. But T1, T2, and T3 are paired with T7, T8, and T9 respectively and terminated to the lines., T4, T5, and T6 are tied together and not terminated. Essentially two "sets" of windings made up in shunt. (parallel)

It is possible to identify the wires with a lantern battery, a compass, and a buzzer. Although difficult if you are not familiar with motors. I highly recommend marking each lead distinctively before disassembling the "FUBAR" mess of connections. T1, T2, and T3 are not "carved in stone" absolute, but are determined relative to the others. T7, T8, and T9 will be connected in shunt with T1, T2, and T3 respectively. That leaves the three tied together with no connection. T4, T5, and T6 can be determined by reading resistance continuity to T1, T2, and T3. The easiest method is to mark the power lines L1 and L2. the third "ghost" leg as L3. The other side of the capacitors will be connected to L1 or L2, depending on which direction rotation is desired.

.

Thank you for this wealth of information. I will make sure to label everything before any of it comes apart, good advice!!

 

[Dabbler]

I think you might consider finding a trusted professional to help you with this. I am thinking that this might be a 3 phase motor, each winding having a centre tap. This is consistent with dual voltage 3 phase motors, and may well explain the capacitor setup that you see.

+1 on @Bi11Hudson remarks on documentation. it should be so well photographed and documented that you ccan completely reassemble the thing and get it working the same way as it is now.

If you were to be able to find the correct current rating for your motor A VFD is an inespensive way to go.. Finding the current rating for the motor, vital for efficient VFD operation is going to be a little bit of a challenge without the motor tag or a true RMS current meter. You can guess, and be out by 20%, but closer is better. Over 20% off and some VFDs start to misbehave.

Since this is a single speed application, a rotary phase converter would be the most reliable solution with the least risk, but caries a higher cost initially. I didn't realize how valuable my RPC was to my shop until I got one. Get one overspec'd for this application and you'll find other uses for it, at least I did.

 

[hustlebird]

I ran out to grab a few measurements when I got home. For the base, it was 7” apart front to back (parallel with the shaft), and 9” side to side (perpendicular to the shaft). The shaft measured once at 1.13” and a second time at 1.25”, hoping to get a better measurement there later tonight. When measuring floor to shaft, should I be measuring to centerline? Or to the bottom of the shaft? It’s in the 5-5.25” range at the bottom.

Reading the specs it looks like it aligns pretty closely to the 3HP motors I suspected, which would make sense considering they stuck with that motor on their 3B iteration of this grinder later. Will hopefully dig into the wiring later tonight.

Thanks again everyone for the input and feedback.

 

[Dabbler]

See if the documents on the 3B tell you what the motor current at 240V is. this could simplify your pprocess a lot.

 

[hustlebird]

Unfortunately the 3B docs just say 'One motor only required, 3HP at 1750 RPM'. I did find one parts list which references a General Electric Generator, and a Westinghouse Generator

 

[Bi11Hudson]

Without having the NEMA outlines handy, whatever I speculate would be just that, speculation. I will speculate the motor to be 5HP or less. A lot of good that does alone, to be sure.

The 9 wire motor is in all likelyhood a duplex "wye" wound motor. There are still a few electricians around that can ring it out the old way. Most of them, the ones still alive, are likely retired and have become "gentleman farmers". There are several videos on the subject, I don't have any links handy. . . It is done regularly but today's method involves a couple of sensitive instruments. Very few of the "old timers" left.

To make sure it is not "delta" wound, once the leads are taken apart look for three sets of three for delta. Or one set of three and three pairs for wye. It is wired for wye, but the previous owner may have been mistaken. Rare, but does happen. . .

I neglected to point out earlier: The line side is L1-L3. The motor side is T1-T3. There are "phase sequence" meters but most old timers just hook it up and, without the belt or coupling, bump it over to find rotation. The lines on the motor should ring out as T1 paired with T4, T2 with T5, and T3 with T6. T7 through T9 are connected at the center. They should ring out as a set, For 220(240), T4, 5, and 6 are connected together. Then T1 is paired with T7, T2 with T8, and T3 with T9. In the old way, T1, 2, and 3 are hooked up and bumped over on 110 or 220 three phase. Then T7, 8, and nine are hooked to the line. If the motor runs the same direction, all is good. Hook up as described and make parts. If it runs reverse, repeat the process a couple of times to be sure. Then swap wire numbers for T7 and T9, and reconnect.

110 (120) volt three phase did, and still does, exist. It is rare today for motors to run on 120 volts, but way back when I have worked on several. I bring this up because of the apparent age of the motor. The reference to 25 cycles being the give away. The 120 volt motors I worked on were fractional horsepower. A larger motor can be run on 120 volts but power drops off dramatically. Most hospitals use a delta transformation to acheive 120 and 240 volts. There may be 3 phase 120 volt instruments but not likely. They would most likely use 240 volt so the instrument could be used with field generators. A hospital ground is different from a residential system. Neutral as such does not exist and either side of the line is above ground. This paragraph is not really relevant to the topic, I just got wound up. My apologies. . .

.

 

[hustlebird]

Well, I tried my best to make this clean looking, and it is easier to read then my hand scribbles would have been. The left icon is supposed to be the source, and the M is the motor.

The switched capacitor is the AEROVOX one, the unswitched is listed as 40uf and has a model number of 40-4D.

I did manage to look at the wiring off the motor a bit closer, and there's tags pairing 2 and 8 together, and 1 with 7. there's a group of 3 wires tied together and they're missing tags, and then 3 is tied to one I couldn't make out (I'm guessing 9). Looks like its wired for 220 3-phase.

The DPST switch on this thing is a literal blade switch: