# Problems with step up delta wye transformer



## eddy current (Feb 28, 2009)

Is the secondary grounded to a ground source?


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## joebanana (Dec 21, 2010)

Is the saw new? Have you checked it? Is the load balanced? (that's a question for you to answer) Throw a "clamp on" on it and get back to us. AND check for solid/proper grounding as above ^


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## wildleg (Apr 12, 2009)

you failed to mention the draw of the motor (nameplate as well as actual under load)

also you failed to mention the size of the transformer.


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## micromind (Aug 11, 2007)

Since the transformer secondary is 230/400 and this is a common voltage for 50HZ systems, what is the HZ of the motor. 

If it's a 50HZ motor and it's being supplied by 60HZ, it's going to run faster than designed. If there's an overspeed device, it will very likely trip. 

Is there a VFD involved?

The motor doesn't care about voltage to ground, only phase to phrase. 

As noted above, what is the KVA rating of the transformer and the saw motor? 

Also, the post stated 120/208∆. This system does not exist. You can have 120/240∆ but not 120/208. 

If the building service is 120/208 then you need only the 3 phase wires at the transformer. The neutral cannot be run because there is no place to land it. 

If the neutral is run and landed on H0, there will be problems. Like odd phase to neutral voltages.


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## John Valdes (May 17, 2007)

Welcome to Electrician Talk. 
Thanks for taking the time to fill out your profile.


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## 460 Delta (May 9, 2018)

I would recommend getting a good analog meter and watch the voltage that way, digital meters cannot follow fast enough, I would also use a tong meter to watch the current also.
400 VAC is an odd three phase setup in N America, is this a Euro sourced saw? If so it will be over speeding and could cause the saw blade to rupture from centrifugal force, so be careful.


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## lilsilva99 (Jun 26, 2018)

Thanks for all the quick replys. I will update a post later today. Thanks all


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## paulengr (Oct 8, 2017)

micromind said:


> Since the transformer secondary is 230/400 and this is a common voltage for 50HZ systems, what is the HZ of the motor.
> 
> If it's a 50HZ motor and it's being supplied by 60HZ, it's going to run faster than designed. If there's an overspeed device, it will very likely trip.
> 
> ...


208/120 is a very common commercial building voltage. It not only exists but it's in the ANSI standard.

240 delta 120 is impossible since 240 / 1.732 is 138 V. You're thinking of 240/120 single phase the old Edison/GE split phase residential voltage.

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## paulengr (Oct 8, 2017)

lilsilva99 said:


> Hello all.
> New to the forum but have a question probably easily explained by the great members here.
> 
> 
> ...


90% sure that's a 50 Hz motor. Running at 20% overspeed. Sounds like some goofy controller and not just a contactor too? Arbor saw motors can be very strange even with correct voltages. Does it have a motor that looks ridiculously long and thin kind of like a submersible pump motor? 3 or 9 lead or something else entirely? What "extras" does the motor have on IT like an encoder or commutated or is it EC (electronically commutated)? As others stated sounds like an attempt to convert European 400 V to North American. Use a motor shop. This is always tricky even if you know what you are doing. If you're in the Carolinas or Virginia PM me. We get calls like this all the time with Asian and European equipment. 

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## pudge565 (Dec 8, 2007)

paulengr said:


> 208/120 is a very common commercial building voltage. It not only exists but it's in the ANSI standard.
> 
> 240 delta 120 is impossible since 240 / 1.732 is 138 V. You're thinking of 240/120 single phase the old Edison/GE split phase residential voltage.
> 
> Sent from my SM-T350 using Tapatalk


208/120 is a common voltage system but it is not derived from a delta, it is derived from a wye connection. That being said all transformer primaries will be a delta even if fed from a wye system.

240/120v Delta is a common system. You ground the mid-point of one winding which ends up giving you 120V between 2 phases and ground and 208V high or bastard leg from the other phase to ground. That is caused because of the phase angles and having an additional half winding between one phase and ground and only half a winding between the other 2 phases and ground.

See below link for the different flavors of 3 phase systems.
http://electrical-engineering-porta...ations-with-three-three-phase-hot-power-lines


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## paulengr (Oct 8, 2017)

Never heard of that bastardized 240/120wye but all I can say is transformer guys will drive you crazy if you let them.

There are wye-wye transformers. Very common utility distribution transformer because the insulation on the primary side is only phase to ground so they are much cheaper, and you can “make” one with three single phase transformers. The primary is definitely wye, not delta. You don’t have to connect the neutral but it’s not delta. It just might have a floating neutral. Let’s not forget the autotransformer version either which is in a lot of motor test stands.

Delta-wye is the best transformer for a lot of reasons including cancelling even harmonics and blocking zero sequence currents and is the most common industrially but that doesn’t mean wye primaries don’t exist.



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## micromind (Aug 11, 2007)

paulengr said:


> 208/120 is a very common commercial building voltage. It not only exists but it's in the ANSI standard.
> 
> 240 delta 120 is impossible since 240 / 1.732 is 138 V. You're thinking of 240/120 single phase the old Edison/GE split phase residential voltage.
> 
> Sent from my SM-T350 using Tapatalk


My post stated that 120/208 ∆ (Delta) is not possible. 

120/208 Y is indeed very common. 

120/240 3Ø 4 wire ∆ does indeed exist, it can be derived from 2 (Open Delta) or 3 (Closed Delta) transformers. With this system, you'll have 240 from any phase to any other phase, 120 from 2 of the phases to neutral/ground and 208 from the remaining phase to neutral/ground. 

Bet you missed the ∆ I put after the 120/208.......lol.


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## lilsilva99 (Jun 26, 2018)

*Update*

Let me start this post with a compliment to all members....as you are all very knowledgeable, and i have little knowledge of 3 phase transformers. And after this experience I cant think of anything more id like to learn about...





eddy current said:


> Is the secondary grounded to a ground source?


 *I have the secondary grounded to H0 and a bonding jumper to the transformer case which is grounded to the building steel.*


Is the saw new? Have you checked it? Is the load balanced? (that's a question for you to answer) Throw a "clamp on" on it and get back to us. AND check for solid/proper grounding as above ^*saw is new i went today to have them run the saw and amp probe it, today something wrong with the computer and they could not start it. 
*
*did amp probe the primary side and Phase A Phase B Phase C*
*this is unbalanced to me?*


you failed to mention the draw of the motor (nameplate as well as actual under load)*Nameplate 18KW-- unable to test under load today*

also you failed to mention the size of the transformer.*27KVA*


Since the transformer secondary is 230/400 and this is a common voltage for 50HZ systems, what is the HZ of the motor. 

If it's a 50HZ motor and it's being supplied by 60HZ, it's going to run faster than designed. If there's an overspeed device, it will very likely trip. 

Is there a VFD involved?* No If im wrong please correct me, but if I grounded out H0 to building steel VFD are not needed?*

Also, the post stated 120/208∆. This system does not exist. You can have 120/240∆ but not 120/208*. Correct, sorry primary is wye but only 3 phases feeding the transformer as there is no place for a neutral.*

If the neutral is run and landed on H0, there will be problems. Like odd phase to neutral voltages.*Ground from 208 wye, ground to 400V load,bonding jumper to case all tie to H0(secondary side),and case is grounded to building steel.*


90% sure that's a 50 Hz motor. Running at 20% overspeed. Sounds like some goofy controller and not just a contactor too?*Maybe?hahaThis saw has a 4 foot by 3 foot box with controls up the wazoo*.
Does it have a motor that looks ridiculously long and thin kind of like a submersible pump motor?*No its quite compact buy large I will upload some pics 
*

3 or 9 lead or something else entirely? What "extras" does the motor have on IT like an encoder or commutated or is it EC (electronically commutated)? As others stated sounds like an attempt to convert European 400 V to North American. Use a motor shop. This is always tricky even if you know what you are doing. If you're in the Carolinas or Virginia PM me. We get calls like this all the time with Asian and European equipment. 

*Totally european and now were getting TOTALLY out of my understanding of motors, EC? Encoder? Im sure i cant get the answer lol but dont know what your asking.:vs_mad:
*
*Thanks for everyones help*
*Greatly appreciated.*


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## lilsilva99 (Jun 26, 2018)

Phase A 3.2 phase B 5.2 phase C 3.8 primary of transformer


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## lilsilva99 (Jun 26, 2018)

Sorry to confirm...this is a 400V 50Hz SAW load


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## micromind (Aug 11, 2007)

lilsilva99 said:


> Phase A 3.2 phase B 5.2 phase C 3.8 primary of transformer


This would be pretty normal for an unloaded transformer. The imbalance is not out of reason.


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## paulengr (Oct 8, 2017)

lilsilva99 said:


> Sorry to confirm...this is a 400V 50Hz SAW load


EC = electronically commutated motor. Basically a DC motor with a rectifier on the rotor. Starting to show up especially HVAC.

The saw is overspeeding. Need a VFD or you have to open the black box and figure out what it all does and bypass overspeed protection. Or replace with your own black box. So VFD in this case just converts 60 Hz input to constant 400 V 50 Hz. Might also use a phase converter the same way but they tend to be a little unstable output, just cheaper at medium sizes compared to VFD or MG sets.

A nearby lumber mill (biggest in the US) moved the entire mill from Sweden. Mostly they converted or ignored the speed change. But with one saw they changed the blade size since getting a new armor motor was out of the question. Some stuff runs 480, some 400. All 60 Hz. All kinds of gyrations had to be used to make it all work. So not to say what you're doing can't work but might need to get creative.


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## micromind (Aug 11, 2007)

lilsilva99 said:


> Sorry to confirm...this is a 400V 50Hz SAW load


The speed of an AC induction motor depends on its frequency. The motor is designed for 50HZ and is being run on 60 so it'll turn faster than designed. 

For example, if the motor is 4 pole, at 50HZ it'll run very close to 1500 RPM, no load. The same motor will run very close to 1800 RPM at 60HZ. 

If there's any sort of speed detection in the controls, it'll very likely see the higher speed as a problem. 

Near as I can tell, you've got it connected correctly. 

The next step is to look at the motor current, no-load and while cutting. 

Also, get a current reading with all 3 legs (but not the ground wire) in the jaws at the same time. Anything more than zero indicates a ground fault. 

Another issue is if the motor is designed to run on 400 volts and 50HZ and it is being operating on 400 volts and 60HZ, the voltage is too low. 

Every motor has a volts/HZ ratio. In your case, 400/50 = 8/1. In order to get the 8/1 at 60HZ, you'd need 480 volts, not 400. 

Current will tell......low voltage = high current. There's a good chance it's tripping its overloads because of low voltage and therefore, high current.


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## oliquir (Jan 13, 2011)

send picture of motor and control panel


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## paulengr (Oct 8, 2017)

micromind said:


> The speed of an AC induction motor depends on its frequency. The motor is designed for 50HZ and is being run on 60 so it'll turn faster than designed.
> 
> 
> 
> ...




Careful here. I agree about ground fault but an iron core amp clamp isn’t terribly accurate especially with multiple conductors and there are legitimate reasons ground current always exists. Google system capacitance. Under 5% is fine.

Second flux current which at full load is 5-15% of total does not change with frequency. And the controller has a set voltage too. And if you do V:Hz in what is beyond the base speed you are doing constant torque but going up on both speed and keeping torque constant means exceeding rated HP (HP=torque r rpm / 5252). Alternatively operate at constant HP so you hold Volts constant. But a saw torque will be proportional to the square of speed so all kinds of reasons higher speed is bad. In practice decrease blade diameter to optimize cut speed/capacity. Constant voltage is the right move.


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## lilsilva99 (Jun 26, 2018)

*The service company who supplied the saw and transformer will be on site tomorrow to try and get it started, as the computer is failing to start up, screen blinking out of no where. 
*

*I have some pics to share, although need to post more before I can... please remove the < > *
<https://ibb.co/album/bTLFdv>

Another issue is if the motor is designed to run on 400 volts and 50HZ and it is being operating on 400 volts and 60HZ, the voltage is too low.

Every motor has a volts/HZ ratio. In your case, 400/50 = 8/1. In order to get the 8/1 at 60HZ, you'd need 480 volts, not 400. *Correct, I think weve got the saw shutdown figured out here, overloads tripping from the LV and High current.*
*I should change the transformer to 208to480 not the 400v, this will not affect the controls? or is the controllers nameplate only say 400v because it comes from europe and 50Hz systems. Should always check with someone who knows what there talking about instead of trusting the supplier--who provided the transformer--probably on the advice of the manufacturer.
*



The saw is overspeeding. Need a VFD or you have to open the black box and figure out what it all does and bypass overspeed protection. Or replace with your own black box.*Understood does anyone see a VFD in the control panel already?*

*...willl go over these things with the supplier thanks everyone.
*


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## pudge565 (Dec 8, 2007)

micromind said:


> The speed of an AC induction motor depends on its frequency. The motor is designed for 50HZ and is being run on 60 so it'll turn faster than designed.
> 
> For example, if the motor is 4 pole, at 50HZ it'll run very close to 1500 RPM, no load. The same motor will run very close to 1800 RPM at 60HZ.
> 
> ...


The volts to HZ ratio means absolutely nothing. All VFDs once you exceed the normal 60Hz will top out at the nameplate voltage rating but you can go all the way up to 400Hz on some drives. I worked in a plant that had plenty of motors running at 480V 90-120Hz. PCG hated doing that but engineering didn't want to buy the proper motors or gear boxes...


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## gnuuser (Jan 13, 2013)

judging by your pictures that is a synchronous drive motor and controllers
photo 41 confirms it.
this is a different animal than a vfd.
synchronus drives are more expensive and more sensitive to voltage and frequency ratios
as others have stated your motor is running in an over speed condition and is faulting out the system.
your controller computer may be damaged and it may not be dealing with the frequency difference very well
synchronous motors rely on error signals generated by the motor (think stepper motor drives)
incorrect error signal returning to the drive will result in the motor not operating at its optimum configuration or operating erratically.

sad to say this is a job for a syncro specialist
while i do have some knowledge about them i am by far not an expert.
synchronous motors are also DC converted from the ac supply by the drives.
their voltage and frequency requirements are far more exacting than vfd's and ac induction motors


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## oliquir (Jan 13, 2011)

the motor is asynchronous is it connected to the right side controller (is it a vfd or softstart?) or directly to a contactor


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## gnuuser (Jan 13, 2013)

in picture 61 in the lower right hand side is an inverter controller (vfd)
the entire controller cabinet appears to be set up to closely monitor the speed and torque of the saw motor.
and appears to have an asi safety monitor module as well.

a manually operated saw would not be equipped with so much control gear 
is this is an automated device?

its hard to tell the functions of the system without a wiring diagram


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## Flyingsod (Jul 11, 2013)

pudge565 said:


> The volts to HZ ratio means absolutely nothing. All VFDs once you exceed the normal 60Hz will top out at the nameplate voltage rating but you can go all the way up to 400Hz on some drives. I worked in a plant that had plenty of motors running at 480V 90-120Hz. PCG hated doing that but engineering didn't want to buy the proper motors or gear boxes...




I’m interested to know if you were there long enough to notice a decrease in motor longevity?


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## pudge565 (Dec 8, 2007)

Flyingsod said:


> I’m interested to know if you were there long enough to notice a decrease in motor longevity?
> 
> 
> Sent from my iPhone using Tapatalk


I was not there long enough to have any insight on the life of the "overclocked" motors.


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## micromind (Aug 11, 2007)

In my experience, a motor that runs at a higher HZ than it's designed for will do much better than one operated at a lower HZ. 

For example, a 460 volt 60HZ motor operating at 460 colts and 90 HZ won't last as long as it will on 60HZ but one operating at 460 volts and 10HZ will burn up pretty fast.


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## paulengr (Oct 8, 2017)

micromind said:


> In my experience, a motor that runs at a higher HZ than it's designed for will do much better than one operated at a lower HZ.
> 
> For example, a 460 volt 60HZ motor operating at 460 colts and 90 HZ won't last as long as it will on 60HZ but one operating at 460 volts and 10HZ will burn up pretty fast.



That’s mostly correct but it’s not a motor thing...it’s basic mechanics. The big thing is the fan. The fan performance is proportional to the square of speed. On a constant torque load don’t go below 50% of rated speed and with bigger loads not even that. With a variable torque load you can go down to 25% by the book and in practice usually to 10 Hz. With an inverter duty motor they have extra cooling so higher turn down and with an external fan no limits at all. Above base speed you are constant horsepower so torque falls off and cooling is going up so as long as it’s not variable torque and you don’t exceed bearing ratings (generally 90 Hz is OK on 4 or more poles) no issues. With variable torque loads like fans and pumps you will hit a “brick wall” because of the exponential increase in torque at some point



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## paulengr (Oct 8, 2017)

gnuuser said:


> judging by your pictures that is a synchronous drive motor and controllers
> photo 41 confirms it.
> this is a different animal than a vfd.
> synchronus drives are more expensive and more sensitive to voltage and frequency ratios
> ...



Not really. Synchronous motors are just that. If you understand the V curve and a couple different goofy starting methods they are straightforward. The biggest problem normally is getting
aC in your DC (blown diodes) and DC contactor issues (wear), and the fact that people don’t routinely clean out the carbon dust and inspect the rings until the slip rings arc and make a big and expensive mess.

Then again I’ve worked on large (over 5000 HP) multimotor DC drives with Ward Leonard loops on analog op amp controllers where synchronous motors are used in conjunction with DC generators...

This used to be how we did things when the biggest power semiconductor was a 16 A SCR and AC was unheard of (ever heard of forced commutation?) In a couple weeks we’re going to have a couple in the shop from a parking garage elevator. The competitors ran for the hills..,




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## gnuuser (Jan 13, 2013)

yeah the first syncro servo systems i was introduced to were the ones used in the weapons systems in the navy
these monsters relied on tube amplifier panels for the syncro error signal system and amplidyne generators for the to power the drive motors.
(these motors were moving multi ton gun and missile system)
regular calibration was required due to the torque generated to move that much weight.

later after i started working in the factory the carton erectors, sprayer systems, and palletizers our company used relied on synchronous drives.
generally they were dependable pieces of equipment.
the worst problems we had with the case erectors and palletizers was photo switches getting knocked out of alignment because some turd decided to speed the machine up past safety parameters.
the sprayers on the other hand were susceptible to heat damage (magnets for the reed switches losing strength due to excessive heat)

either system requires error signals and if anything binds the drive motor the error signal will be incorrect!
on newer drive systems an incorrect error signal (outside the programmed parameters) will send the system into a shutdown/fault mode in order to prevent equipment damage.
on the older systems it would cause very erratic operation and you had to be trained to recognize what piece of equipment was faulty without extensive troubleshooting.


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## paulengr (Oct 8, 2017)

Amplidynes use a transformer with multiple inputs generating current on a common core to work so everything is an “error” or “bias” signal. Haven’t seen one in a couple decades. Next cane analog computers / op Amps that do everything using low voltage analog signals. Much simpler and calibration hardly drifts at all. The latest versions are all digital but the control algorithms are essentially just digital simulations of the op amp control loops. Amplidyne stuff sort of died...it was way too complicated.


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## gnuuser (Jan 13, 2013)

paulengr said:


> Amplidynes use a transformer with multiple inputs generating current on a common core to work so everything is an “error” or “bias” signal. Haven’t seen one in a couple decades. Next cane analog computers / op Amps that do everything using low voltage analog signals. Much simpler and calibration hardly drifts at all. The latest versions are all digital but the control algorithms are essentially just digital simulations of the op amp control loops. Amplidyne stuff sort of died...it was way too complicated.
> 
> 
> Sent from my iPhone using Tapatalk


you got that right! now a lot less cabling and headache and a whole lot less power as well:vs_laugh:


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