0
\$\begingroup\$

The company I work for started a new contract building SCR controlled power supplies. They have a 480v input that's transformed down to 12.5/15/17.5 V. In testing we can push as much as 2800 A on the load side. To deal with the current we go so far as to build custom water cooled hoses with braided copper run through them. All I know about their application is that they heat ovens.

My question is why go through the trouble of building such complex power supplies with expensive water cooled conductors to heat an oven? Wouldn't high voltage with a resistive load achieve the same effect? My only guess so far is the safety on not working around high voltage.

Thoughts?

\$\endgroup\$
7
  • \$\begingroup\$ The real application may use 480 VAC phase (or zero-cross burst) controlled to a resistive load. It may be more convenient to test at lower voltage. \$\endgroup\$
    – Mattman944
    May 7, 2021 at 21:34
  • 3
    \$\begingroup\$ Why not ask one of the engineers? \$\endgroup\$
    – qrk
    May 7, 2021 at 21:36
  • \$\begingroup\$ Maybe it's a galvanic plant. What's you role, here? You do work without knowing what you are doing? \$\endgroup\$ May 7, 2021 at 21:44
  • \$\begingroup\$ As you say, it could be a safety issue, although an oven consuming something in the region of 40-50Kw is never going to be completely safe. \$\endgroup\$ May 7, 2021 at 21:47
  • \$\begingroup\$ What do the ovens heat? At what temperatures? \$\endgroup\$
    – Transistor
    May 7, 2021 at 21:52

2 Answers 2

2
\$\begingroup\$

My guess is that it is an induction furnace. It doesn't heat the metal in the furnace (oven) by the heat dissipated in the water cooled copper coil, but instead the magnetic field created by the coil creates eddy currents in the metal in the furnace that needs to be heated. These currents in the metal cause heat dissipation in the metal, so they heat the metal from within. The bigger the amplitude of the current in the coil, the bigger the amplitude of the magnetic field strength created, the bigger the current induced in the metal to be heated, the more heat getting dissipated in the metal.

\$\endgroup\$
1
\$\begingroup\$

In a cable tray, the electrons don't care if you parallel ten 1000 kcmil aluminum wires or seven 1000 kcmil copper wires. However the person paying for the wire cares, so you use aluminum because it's 1/3 the price.

Different deal in a winding where you're all about making a lot of magnetic flux in a small space. There, density is so critical that you need copper.

Now why are they using water cooling on the windings? Transformers don't need that. You just make the copper thicker and it runs cooler, problem solved. You use the water cooling because it's in a furnace, and it's being punished by radiant heat from the items being heated up.

That all points to an induction furnace, as Cerike describes.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.