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Wiring up a Static Phase Converter

Shiseiji

Aluminum
Joined
Sep 15, 2014
The accompanying document specifies 10 gauge wire for connecting to the main. So I diligently ordered some and a panel that can handle 10hp. Panel arrived so I started mounting it and placing the converter so it can be wired up. Surprise! When I opened the static phase converter everything is wired up with 14 gauge! Still shaking my head. Not convinced the wiring block will even take 10 gauge lugs. The wiring left on the back appears to be 14 gauge (eyeball calibration, accuracy not confirmed), the wiring in the panel where I checked the motor voltage also appears to be 14 gauge. Wiring diagram I have doesn't appear to have gauge specified. Comments?
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The accompanying document specifies 10 gauge wire for connecting to the main. So I diligently ordered some and a panel that can handle 10hp. Panel arrived so I started mounting it and placing the converter so it can be wired up. Surprise! When I opened the static phase converter everything is wired up with 14 gauge! Still shaking my head. Not convinced the wiring block will even take 10 gauge lugs. The wiring left on the back appears to be 14 gauge (eyeball calibration, accuracy not confirmed), the wiring in the panel where I checked the motor voltage also appears to be 14 gauge. Wiring diagram I have doesn't appear to have gauge specified. Comments?

There is a phase converter forum, so you would probably get better answers there: https://www.practicalmachinist.com/vb/transformers-phase-converters-and-vfd/
 
It never hurts to use a larger than necessary wire. How much amperage you pull depends on if you max out the converter or run conservative. Keep in mind that the two conductors for the mains handle all current and the secondary three phase splits that current between three wires. Also the individual wires in the photo are short and have a lot of air space around them.
 
The accompanying document specifies 10 gauge wire for connecting to the main. So I diligently ordered some and a panel that can handle 10hp. Panel arrived so I started mounting it and placing the converter so it can be wired up. Surprise! When I opened the static phase converter everything is wired up with 14 gauge! Still shaking my head. Not convinced the wiring block will even take 10 gauge lugs. The wiring left on the back appears to be 14 gauge (eyeball calibration, accuracy not confirmed), the wiring in the panel where I checked the motor voltage also appears to be 14 gauge. Wiring diagram I have doesn't appear to have gauge specified. Comments? ...
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Unless the motor/generator wiring has been replaced, it's #10. How are you determining the gauge of the wire?

You definitely want #10 wire for a motor/generator 10EE. The AC section of the MG draws about 100A for the first second or so as it's spinning up, that will pop a 20A fuse. You need a 30A circuit and should use 30A fuses at the disconnect on the back of the machine. Remember, the fuses and circuit breaker are there to protect the wiring in case of a short circuit. The overload device on the main AC contactor is what protects the MG from drawing too much current.

Cal
 
First thanks.
  • Rimcanyon - Appreciate the pointer
  • Superbowl - Wire gauge & safe not sorry - yep, Air gap - got it.
  • Cal - Need to listen to myself repeat - "I do not have calibrated eyeballs" & eyeball calibration = dead (me or machine)
  • Thermite - Static vs. Rotary - |Good|Quick|Cheap|

Thermite, do I respect your opinion? Very much. I have no desire to have to replace the MG.
Do I also respect what others have said about static converters? Yes.
Do I as someone who stumbled into the 10EE plan on turning anything that will challenge the ~ 65% de-rated HP? No and that was part of the |Good|Quick|Cheap| analysis.
Do I need to re-think this? Possibly. I don't have to be in a hurry, the people who are pushing me to get it running won't be bill payers if anything goes bad. Going to see what's been discussed on the other forum and price motors for a RPC.

Ron
 
I would add oversize on the incoming side is not all bad as it prevents voltage drops during transients. Recall all electrical events are not static-steady-state and are dynamic (not directly applicable but think of striking an arc).

If the wire won't fit I suggest using ring terminals with a #10 screw and #10/12 lug. Typically with yellow insulation.
 
Shiseiji,

There are a number of members here, including Bob49 (link), running motor/generator 10EEs from "static converters" and they are working out just fine for them. Since you have it in hand, go ahead and give it a try.

As Bill mentioned, the typical "static converter" is just the motor starting part of a rotary phase converter and consists of a potential relay and one or more starting capacitors. Once the motor starts, the potential relay disconnects the starting capacitor(s) and the motor limps along on two of the three phases, thus 2/3 power.

However, there are electronic static converters on the market (NOT including the top of the line Phase Perfect units) and those can be a problem. A member here had one fail and do some damage to the machine, so I would steer well clear of those.

If you have the potential relay type converter, you can improve things by adding run capacitors between the real phases and artificial phase. To do that, you need a clamp-on ammeter so that you can measure the current flowing in each phase and adjust the capacitors to balance it. Let me know if you want more information on that.

Cal
 
A five minute 20 second mile in jump boots .. or 12 miles in full battle-gear at a dead run ...carrying an M-60 ... is getting awfully close to 60 years in the rear-view mirror!

Cold War Soldier. '82 in the 2nd week of OCS Army decided to stop running in boots. Mostly. What I think about more now is running in boots and a M-17 and hoping I never had to do it for real. Now I'm biting my tongue really, really hard.
 
:) I was a SP4 with an "attitude" (not really, but makes a better story) who really just wanted to go to flight school and someone thought they were helping me by telling me to earn a commission first. So off to Benning I went . . . and that journey turned out nothing like I could ever have imagined. Some of my most enjoyable times were BSing with Sr. NCO and have one look at me and almost not as a question "You were a trooper, weren't you?" Followed by troops quietly telling me "thank you." Or, LOL, asking me, in the field, for a tool they just knew if anyone had one squirreled away, it would be me :-) Respect and willingness to follow orders is generally earned, not appointed from on high. Will never happen, but I'm a believer that every, ESPECIALLY US Officers, must spend two years "in the ranks" and get a recommendation from both their commander "and" Sr. NCO to even apply. Living in "real" open bay barracks takes the edges off most. As well as an appreciation for really stupid orders that just maybe were "poorly communicated." Anyway, thanks for sharing some of your history.
 
My 7 years in the reserves gave me a nice time in service run, 20 on Active = 27 total for pay.

"Run what you GOT!"
One of the few things Rumsfeld hit right. "You go to war with the Army you have, not the one you wish you have" I think many people would be shocked that in 2007 we were managing aircraft by individual tail number getting them out of refurb for deployment with just days to spare. Not like the days when Huey's were more easily replaced. Don't miss that !#$% at all.

Ron
 
Just trying to be simple here. when going from 3 phase amperage to single phase amperage one must multiply by 3^(1/2) or square root of 3 so 15 amps time that is 26 amps hence ten gauge wire.
 
Just trying to be simple here. when going from 3 phase amperage to single phase amperage one must multiply by 3^(1/2) or square root of 3 so 15 amps time that is 26 amps hence ten gauge wire.
Thanks. Little formal training, I have to question and be pointed to how to learn the correct answers.
 
Shiseiji,

There are a number of members here, including Bob49 (link), running motor/generator 10EEs from "static converters" and they are working out just fine for them. Since you have it in hand, go ahead and give it a try.

As Bill mentioned, the typical "static converter" is just the motor starting part of a rotary phase converter and consists of a potential relay and one or more starting capacitors. Once the motor starts, the potential relay disconnects the starting capacitor(s) and the motor limps along on two of the three phases, thus 2/3 power.

However, there are electronic static converters on the market (NOT including the top of the line Phase Perfect units) and those can be a problem. A member here had one fail and do some damage to the machine, so I would steer well clear of those.

If you have the potential relay type converter, you can improve things by adding run capacitors between the real phases and artificial phase. To do that, you need a clamp-on ammeter so that you can measure the current flowing in each phase and adjust the capacitors to balance it. Let me know if you want more information on that.

Cal

Cal, a belated thanks. I purchased the SPC based on a comment you made, but hadn't found the orginial posting. Probably because it is in a VFD thread. I wired the SPC up today, nothing. Not a even a flash on the panel. Have confirmed the 240 to the SPC, the first troubleshooting step is to swap two of the legs. Going out to try that.

I've also purchased a RPC, was supposed to be here today, maybe tomorrow. One way or another, hopefully I will get it to spin soon.

Ron
 
Cal, a belated thanks. I purchased the SPC based on a comment you made, but hadn't found the orginial posting. Probably because it is in a VFD thread. I wired the SPC up today, nothing. Not a even a flash on the panel. Have confirmed the 240 to the SPC, the first troubleshooting step is to swap two of the legs. Going out to try that.
...
Assuming that you have the factory installed Cutler-Hammer AC contactor (aka motor starter) in it's original configuration, you need to change the contactor coil wiring to operate from either a so called "static converter" or an RPC. See this link:10EE MG Starter Circuit with Cutler-Hammer Contactor - Revised

Have you verified that your contactor coil is 220/240 volts and that the motor is connected for 220 operation?

Your converter's "real phases" should be connected to AC inputs L1 and L2.

Cal
 
Thanks!
Assuming that you have the factory installed Cutler-Hammer AC contactor (aka motor starter) in it's original configuration, you need to change the contactor coil wiring to operate from either a so called "static converter" or an RPC. See this link:10EE MG Starter Circuit with Cutler-Hammer Contactor - Revised
To the best of my knowledge, all is as it left the factory. Going to read that now!

Have you verified that your contactor coil is 220/240 volts and that the motor is connected for 220 operation?
Yes.

Your converter's "real phases" should be connected to AC inputs L1 and L2.
Cal

Is it documented with the back panel open which wire is L1, L2, L3 so I can check continuity? I have the schematic and can run them down, but figured I may as well ask.
 
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Thanks! Is it documented with the back panel open which wire is L1, L2, L3 so I can check continuity? I have the schematic and can run them down, but figured I may as well ask.
Duh, just found it in the link. Which I had read months ago, and forgotten, but makes a whole lot more sense now!
 
L1 & L2 verified as the "Real phases", wire 3 moved from L3 to L2, and voila, she spins! Now to get smart on energizing the exciter. Dates indicate she was declared surplus in 2019, so she sat at least a year +.

Thanks again!

Ron
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And I can't see where to activate one on my profile. You can use shiseiji at gmail as that's mostly a spam trap. I'm in Fairfax County, ~ 2 mi. south of I95/I495 down Rt. 1. The CAMS group let's me hang out on their email list.
 








 
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