Power supply meltdown

[dirtdiggler]

Hi All,

I ran into a big issue tonight and I can't seem to figure out why or if it's related to the Vipers.

Two of my Antek power supply's sparked up and blew out. I wired my Antek torroidal power supplies per the instructions for 220V and when I triggered my relay contacter to start them the solder near the bridge of one melted off and smoked up. Sparks flew. Not fun.

So, I re-checked all my wiring, turned a different power supply on without the Viper and re-checked the voltage output with my meter, it was at 140VDC which is correct. All seemed good so I plugged a different Viper (different axis) in and turned the power back on and everything seemd to test out great at first. I then turned the power supply off and turned it back on again and the power supply smoked up and the solder near the bridge melted off AGAIN!

So that's 2 out of 3 power supply's that are damaged now.

I attached some photos. On the Antek PS's I was told the the two middle wires get tied together and the outside wires go to the two hots from the power source. The larkens are wired per the instructions and the polarity was double checked on the power input.

I set the larken in 'test' mode without the jumpers and turned the current limit to halfway.

I even checked the all the servo armature wires with a 24V power supply and they all worked fine, no cross wiring.

Could it possibly be a weak board design on the Antek's? Take in mind these smoked up before I even had the axis running.

I also had the PS's wired at 110V at one point and they worked without any issues. So all the problems I've had are since wiring them for 220V.

Any help would be appreciated. I'm stuck on this one.

-Kirk

[dirtdiggler]

Antek got back to me and said they had this problem with a few other customers and they are sending me out new modules for the power supplies. So kudos to Antek customer support for that.

They said the high inrush current might be too much for the bridge rectifier on the unit. I noticed also the PS doesn't have any inrush current limiter, so I will probably just add one for saftey. I guess I wasn't going crazy after all.

It's back to waiting again....

[Al_The_Man]

I suspect it is not the bridge but the printed circuit capacity/connection from AC to the Bridge?
I usually put my own supplies together and prefer a hard wired connection from Toroid to Bridge & bridge to Capacitor.
Al.

[dirtdiggler]

Hi Al,

Yeah, the printed circuit board is what burnt up so you're probably right about the capacity. They said the new boards can handle more inrush without an inrush limiter but I'm still going to put one on for safety.

I recall they both burnt up on the second or third time they were turned on and off. The capacitors take a long time to bleed off....maybe 10-15 minutes? So I'm guessing when I turn the power on and off and on and off again within a few minutes there was just to much inrush getting overloaded in the printed circuits.....

[dirtdiggler]

Hey Al,

If you don't mind I have a Q regarding using a VFD (sorry for all the q's!) I bought a Teco 7300CV VFD 3HP to run my 1.5HP spindle. The VFD is a sensorless Vector type and has a built in 'dynamic braking'. It can stop the spindle in about 3 seconds as is. Apparantly I can buy a beefed up 'braking resistor' module that decreases the braking time. My series II BP currently uses an air brake with a selnoid for braking the spindle. Being that the VFD can brake on it's own do I need the air brake if i'm using the VFD for the BP?

Furthermore, if I do use the air brake, should I set the VFD to 'coast' instead of dynamically brake while applying the cnc air brake?

Thanks for your help,

Kirk

[Al_The_Man]

I don't know how it works on a BP, but the Excello I have I set up the VFD for braking and the Pneumatic brake is just used to lock the spindle when changing tools, the brake comes on when the At-Zero-Speed is activated by the VFD.
It is not wise to put on a mechanical brake on a VFD for stopping.
Al.

[Larken]

Where do you find the big powersupplys on the Antek website ?

That pcb board looks to use 1/2 oz copper. it should be 2 oz on a high powered board.
What voltage and wattage is that PS ?

I also had the PS's wired at 110V at one point and they worked without any issues. So all the problems I've had are since wiring them for 220V.

Did you have fuse in the primary ? Its possible you have something wired wrong since it worked ok on 120V.

[dirtdiggler]

Hi Larken,

They are the PS-15N140 model. Here is the link: http://www.antekinc.com/price2.html

They are sending me the new module that has an updated bridge and diode but the printed circuit board is the same one. They say that it has been tested so we will see. All I know is if the thing burns up again I'm going to just bypass the circuit board with wire.

It's a bit worrisome they didn't test this product prior to making it production.

[dirtdiggler]

Any idea what inrush limiter I should use?

Thanks,

Kirk

[scrambled]

So far, I have not had any problems with my power supplies from Antek, or with John. He is easy to work with. I ordered the wrong power supplies once, and he changed them out without any problems


Steve

[jalessi]

Dirtdiggler,

Ametherm has good information on there site, plus free samples.

http://www.ametherm.com/inrush-curre...ush-Calculator

Jeff...

[H.O]

Hi,
Just a personal reflection and thought here.... Are thermistors really a good way to go on a highly dynamic powersupply such as that for a servo motor system?

The thermistor needs to be choosen so it can withstand the maximum current but in a CNC servo motor system the load on the supply is quite dynamic so when the load on the supply is low the thermistor will cool down and it will then limit the current on when a load transient (acceleration) comes along. I guess that the smaller the thermistor is the lower the "time-lag" will be. I tried to view a datasheet on Ametherm webiste but apperently you need a login to access them.

Again, just a thought, it may not be valid IRL.

/Henrik.