[Brendan]

Hi
While running my machine it started to kick an alarm and the servos stopped and the control flickered then shut down.
Thanks to the power company I measured the voltage coming in and the outer legs had 115 volts and the center leg had 380 volts that should normally be 216 volts.
The 2 out of the 3 overvoltage fuses were blown and today the voltage is down to its normal voltage, I replaced the blown fuses and tried to power the machine back up and it blew the 2 fuses again, I checked all the other fuses and they were fine.
The Machine will not power up or even turn the light on, the 2 over voltage light by the fuses are light up as the fuses have blow.
The volatge coming into the machine now is fine.

Any ideas on what to check next?

(Thanks Progress energy)
It also took out my new Kaeser compressor.
Thanks for the help!

[tecko]

is it blowing fuses after you turn on the mains switch, or after you press the power up button

[HuFlungDung]

Wow, that is a bummer!

First off, try a reset of the main panel circuit breaker and a reset of the breaker supplying this particular machine. A partially tripped breaker could possibly be causing loss of one phase.

With power disconnected, I would remove the power leads coming in to the main transformer in the control cabinet. Check between each terminal of the transformer with an ohmmeter, to ground, to see if the transformer has a short circuit.

Could possibly be damage to the spindle inverter although I would hope it would come on with an alarm first.

There are other, smaller power supplies in the cabinet, too. In my 1996 VF3, there is a basic PC power supply for the computer circuit boards, and another small power supply for control circuits of the servo cards. Those may have been affected, but I doubt that they would cause a main short that would blow your fuses.

[gar]

070617-1430 EST USA

Brendan:

Your voltage measurements do not make sense for a delta source. Also what is an overvoltage fuse?

Assuming you have a 3 phase source, then if it is perfectly balanced the amplitude of the voltage between any pair of legs will be equal. The voltage from any leg to common (nuetral) will depend. If it is a "Y" source, then leg to common is V leg-to-leg/sq-root of 3 = Vll/1.732 = 240/1.732 = 138.6 and for 208 leg-to-leg 208/1.732 = 120.1 .

In a "Y" source you could have a transformer primary develop shorted turns and cause one secondary leg to go high relative to the other two legs.

Call your three legs A, B, C, and nuetral N. What voltage did you measure between each pair of these points?

Assume A to C was your 115 V measurement. For A to B to be 380 then, C to B has to be at least 265 V, but probably more. It could be as high as 495 V, but unlikely. It all depends upon phase angles.

Are you saying the voltage is normally 216 V between any pair of A, B, and C? If so what is the voltage from each leg to nuetral.

High probability that diodes and maybe capacitors failed and all sorts of possibilities beyond the capacitors. As Hu mention the PC power supply may have failed. But it is not too likely this would blow the main fuses.

.

[Brendan]

is it blowing fuses after you turn on the mains switch, or after you press the power up button

After I turn on the main disconnect on the back of the machine the fuses blow.

[Brendan]

Wow, that is a bummer!

First off, try a reset of the main panel circuit breaker and a reset of the breaker supplying this particular machine. A partially tripped breaker could possibly be causing loss of one phase.

With power disconnected, I would remove the power leads coming in to the main transformer in the control cabinet. Check between each terminal of the transformer with an ohmmeter, to ground, to see if the transformer has a short circuit.

Could possibly be damage to the spindle inverter although I would hope it would come on with an alarm first.

There are other, smaller power supplies in the cabinet, too. In my 1996 VF3, there is a basic PC power supply for the computer circuit boards, and another small power supply for control circuits of the servo cards. Those may have been affected, but I doubt that they would cause a main short that would blow your fuses.

I will try ohming the transformer.
There are 3 overvoltage fuses if I remove the one on the left and replace the other 2 and turn the disconnect on the fuses are OK, but when I repalce the left one and turn the main disconnect on the left and the middle fuse will blow.

[Brendan]

070617-1430 EST USA

Brendan:



Your voltage measurements do not make sense for a delta source. Also what is an overvoltage fuse?

Assuming you have a 3 phase source, then if it is perfectly balanced the amplitude of the voltage between any pair of legs will be equal. The voltage from any leg to common (nuetral) will depend. If it is a "Y" source, then leg to common is V leg-to-leg/sq-root of 3 = Vll/1.732 = 240/1.732 = 138.6 and for 208 leg-to-leg 208/1.732 = 120.1 .

In a "Y" source you could have a transformer primary develop shorted turns and cause one secondary leg to go high relative to the other two legs.

Call your three legs A, B, C, and nuetral N. What voltage did you measure between each pair of these points?

Assume A to C was your 115 V measurement. For A to B to be 380 then, C to B has to be at least 265 V, but probably more. It could be as high as 495 V, but unlikely. It all depends upon phase angles.

Are you saying the voltage is normally 216 V between any pair of A, B, and C? If so what is the voltage from each leg to nuetral.

High probability that diodes and maybe capacitors failed and all sorts of possibilities beyond the capacitors. As Hu mention the PC power supply may have failed. But it is not too likely this would blow the main fuses.

.

The overvoltage fuses are on the power supply board in the back pannel on the machine they have an LED that light up when they blow.

The voltage between the leg is equal when measuring between any of the 3 legs but when you measure 1 leg of the volt meter to ground the center leg will be 220 volts where the outer 2 legs measure 110 volts.

Every 3rd leg in the building power pannel is not usable for 110 volts, I had never seen this system until I moved to Florida but it is common down here.

When we had the power surge the center power leg was over 100 volts higher than its allready 200+ volts measuring the center leg with one lead on the meter and the other lead to ground.
I called the power comany and they said they would send somone out and this morning the voltage was back to normal.

My Kaeser compressor now turn on after replacing the fues and resetting but does not shut of once it has reached pressure.
I took digital pictures of the volatge comming in the pannel of the building do you feel the power company is liable for this?
Thanks for all the help guys!

[gar]

070617-1654 EST USA

Brendan:

You have a very common type of delta secondary with what is called a "wild leg". Also you probably only have two transformers on the pole.

One is typically larger and is the 120-0-120 single phase supply. This is a 240 V secondary with a center tap connected to your neutral and ground at the main service entrance.

The wild leg is supplied by the second transformer and has a voltage relative to nuetral = V leg-to-leg * 1/2 sq-root 3 = Vll * 0.866 = 240 * 0.866 = 207 V. If this was a two transformer system then under certain fault conditions it might not be hard to get 380 V but only for a short time before the power company transformer would burn out. The way you calculate these voltages is with a vector diagram.

Apparently in your first post you measured 115 V from one leg to neutral (ground) and from one other the same thing. Note: you must always clearly define the points you are measuring voltage between.

I do not known between which points this normal 216 V is measured.

"The voltage between the leg is equal when measuring between any of the 3 legs but when you measure 1 leg of the volt meter to ground the center leg will be 220 volts where the outer 2 legs measure 110 volts."

This statement is sort of confusing until one deduces what you might be talking about. But I really do not know. But following is a try.

I am goin to start over naming wires. You are really talking about 4 wires, A, B, C, and N (nuetral which is also grounded at the main service entrance). Let A and B be the outer two terminals on the single phase transformer and N is the center tap of that transformer. Of course if A to B voltage is 220 V, then A to N is 110 and B to N is 110. But this does not quite fit your words. If you were really talking about neutral to leg C, then for a 220 V leg-to-leg system N to C is 190.5 and not 220.

For a balanced 3 phase source the voltage amplitudes between any two pair of A, B, and C would be 220 V. But from N to C it is 220 * 0.866 = 190.5 V . If you read 216 instead of 190 someting is wrong. However, if you read 216 between A and C, or B and C this may be a reasonable normal unbalance.

The nuetral wire (center tap) is not normally brought to the HAAS machine. However, a ground wire must come from the service entrance to the chassis of the HAAS machine. This is normally about the same voltage as a nuetral wire.

The fuses you refer to are not "over voltage fuses", but are really over current fuses. There are no normal devices called fuses designed to open on an over voltage. However, an over voltage may cause a high current that is enough to cause a current blowing of the fuse. I could build an over voltage fuse, but to accomplish this function I would normally use a voltage detector to trigger an SCR or Triac or other switch to put a short on a circuit fed from a fuse causing the current fuse to blow resulting from the short circuit caused by tripping the voltage detector.

Your description of the fuses being blown are apparently small fuses and not the big fuses adjacent to the main disconnect. I am not where I can look at a machine. Thus, I can not judge what these fuses relate to. See if there is a fuse ID, then look in you HAAS manual to find out what these feed.

One possible way to get in the range of 380 from nuetral to C is if the wild transformer primary got connected to the same phase source as the single phase transformer. Some possibilities are 110-0-110-330, 115-0-115-345, or 120-0-120-360. This would not blow a pole transformer.

.

[bborb]

I had a problem once and there were these three MOV's or thyristors that needed checked. They usually are about the size of a nickel or a quarter, with two legs, (almost look like flat/round caps) and they span across the main legs of power. They are to protect against Voltage surges and become a short across two legs when damaged. Good chance this is your problem and you can ohm across them and see the short.

[Brendan]

I had a problem once and there were these three MOV's or thyristors that needed checked. They usually are about the size of a nickel or a quarter, with two legs, (almost look like flat/round caps) and they span across the main legs of power. They are to protect against Voltage surges and become a short across two legs when damaged. Good chance this is your problem and you can ohm across them and see the short.

I ohmed one of the thyristors and 1 was a dead short across he 2 legs,
This is the one where I think the fuse blows first,
Were do I get a replacement at?
Is there some kind of value thyristor to look for?
I figure this is worth a try before I call Haas and get them out as they will just replace the board for a $1 part.
Thanks for all the help!

[gar]

070619-1245 EST USA

Brendan:

The word is thyrector. MOV refers to metal oxide varactor.

Thyristor is an SCR type device. Quite different.

Littlefuse defines MOV as "a voltage dependent, nonlinear device that provides excellent transient voltage suppression. ..."
www.littelfuse.com/metal_oxide_varistor.html

There are many manufacturers. Look for a part number, and measure the diameter.

Try DigiKey or Mouser.

.

[HuFlungDung]

Gar,
I don't see the word 'thyrector' used in the Digikey or Newark catalogue. Is this another case of confusion in the techno-jargon, as this is going to make it difficult to find the device.

[Al_The_Man]

Is this another case of confusion in the techno-jargon, as this is going to make it difficult to find the device.

We can always throw a few more at you

e.g. Teccor sell many of these 'thyrector' devices but they also have Sidactor's and Diac's & Quadracs's, mainly bi directional solid-state suppression devices.
or characteristics that they only conduct at predetermined voltage levels.
A little more sophisticated than MOV's.
As Gar said, not to be confused with Thyristors.
Al.

[gar]

070619-1343 EST USA

Hu:

Do a Google search with just
thyrector
GE thyrector

Go to the Littlefuse site.

Thyrector has had long useage in terminology for a non-linear resistor for transient limiting.

Do a Google search on just
thyristor

Thyristor has a long history of useage ralating to an SCR. This useage may even predate the Triac. The SCR was invented about 1960 or slightly before. I believe the thyristor name was derived from thyratron and transistor. Because the SCR is a solid state thyratron in function.

Also check dictionary.com for thyristor. Thyrector does not show in either dictionary.com or reference.com. Do a search on Google for
thyrector definition

Another descriptor is varistor and that you will find at Mouser.

The current useage of thyrector seems to imply the equivalent of back-to-back zener diodes. But I beleive in the early 60s GE used the term for a device that was more soft in its characteristic curve than a zener diode.

.

[tecko]

Hi can you take a picture of the componant and post it. If it is what I am thinking it is. It is brown, green or red it would have 300v on it here so you would prob. have 200v on it and soldered between mains and earth or neutral

Its purpose in life is when it gets more than 200v it goes dead short and blowes the fuse. You will find them in almost any powersupply and always accross the mains.

You could "if you were mad enough " cut it out and put it in the bin, the machine will work perfect without it ...UNTIL THE NEXT POWER SURGE.....

If you know anybody that fixes welders they will have loads of them..

[Brendan]

Hi can you take a picture of the componant and post it. If it is what I am thinking it is. It is brown, green or red it would have 300v on it here so you would prob. have 200v on it and soldered between mains and earth or neutral

Its purpose in life is when it gets more than 200v it goes dead short and blowes the fuse. You will find them in almost any powersupply and always accross the mains.

You could "if you were mad enough " cut it out and put it in the bin, the machine will work perfect without it ...UNTIL THE NEXT POWER SURGE.....

If you know anybody that fixes welders they will have loads of them..

I ohmed the the little part what ever we want to call them(yellow dime sized discs there is 5 or 6 of them with 2 legs on each right below the .5 amp fuses) and one had zero resistance (connected terminal to terminal) are you saying I can cut it out of there for a test then replace it if it works? I could not see a number on them but I have not removed yet, I will get a picture tomorow.
Thanks Again!

[tecko]

Hi again

if there are 5 of them they should be wired as follows. one from each phase to ground and the other 2 or 3 across the phases. Just check this with a meter to make sure. http://rsk.imageg.net/graphics/produ...2160484t98.jpg

Yes you can remove it if we are talking about the same thing. But if you have a power surge you may be in trouble

[Brendan]

Ended up replacing the main power board and all is good, I have the old board to see if we can repair it as a spare.
Thanks for all the help!