Vacuum Metallization

[whippee2]

Hello, I have a question about the Vacuum Metallization using a vacuum chamber. I was a a place today where they make spot lights for vehicles and they use this process for coating the inside of the lights to give it the shiny difuser.
They were speaking about the firing sequence. Apparently there is about 2500 amps flowing through the electrodes. My question is, is this AC or DC current?
This is the first time I have seen this process and it was quite interesting.

Thanks again
Andy

 

[MacGyverS2000]

DC...

Dan - Owner

http://www.Hi-TecDesigns.com

 

[whippee2]

oh ok, that is what I thought. They have mentioned to me that they want an ammeter installed on the operators console so they can monitor the current during the firing sequence. There is currently a CT on the busbar, it is an IME TAS125. 2500 amps, VA 60. There are two leading on the side of the CT, I assume these are for the connection of a meter.
So I need to look at sourcing a DC meter then.


Thanks for the help
Andy

 

[zappedagain]

"I assume..." - BE CAREFUL WITH THAT!!! You can easily kill yourself with 60 VA.

What is a CT?

John D

 

[OperaHouse]

Maybe you shouldn't be doing this. That CT samples AC and it's output is AC. If this was your field you would know that a DC meter can't be connected to it. Your fingers are going to be in a box with a lot of lethal stuff.

 

[whippee2]

zappedagain, a CT is a current transformer. I am learning about these now and am still a rookie, therefore trying to gain some valuable information on them from more experienced people.

Operahouse, thanks for reply. I understand the the level of danger involved with this current level. I am trying to get some more information on this CT. So its output is AC, is this correct?

thanks again
Whippee

 

[IRstuff]

A trasnformet output has to be AC, but if this is an electron beam evaporator, but the electron beam itself must be DC, obviously.

TTFN

FAQ731-376

 

[OperaHouse]

To continue your education......

A CT normally has a very low voltage output when connected to a current meter. However, if it is not loaded by a current meter the voltage can be fairly high. Never try connecting the meter when the apparatus is operating.

 

[VEBill]

"Never try connecting the meter when the apparatus..."

Clarification:

...isn't powered off, discharged and safety Locked-Out.

"...operating" leaves too may openings.

 

[andybdjuk]

Hi Wippee2, many years ago I built a few vacuum evaporation systems for evaporating aluminium, silver, gold, molybdenum onto silicon sub-straits and silver onto glass for mirrors for laser holography, from small tungsten baskets and crucibles as per

http://www.tedpella.com/vacuum_html/vac2.htm

It was simply heated from a variac feeding the primary of a large step-down transformer and then the basket across the secondary I think it was about 100A at 20v AC giving of course 2kW

Andy