Resistor brazing

[Abhi]

I think resistor material is made up of tungsten used in vfds, may be I am be wrong.
so how to weld or braze if it is broken somewhere in the middle part.
I mean what welding rod, gas for heating, etc for a proper joint bcoz it is mounted on a shaky platform or if i say on a crane itself.

 

[gadfly56]

I think resistor material is made up of tungsten used in vfds, may be I am be wrong.
so how to weld or braze if it is broken somewhere in the middle part.
I mean what welding rod, gas for heating, etc for a proper joint bcoz it is mounted on a shaky platform or if i say on a crane itself.

I'm not sure that "repairing" a resistor is the sort of thing that should be attempted in the field. How big is this resistor, what is it for, and why not just replace it?

 

[Abhi]

I'm not sure that "repairing" a resistor is the sort of thing that should be attempted in the field. How big is this resistor, what is it for, and why not just replace it?

its 8 ohms, 5 KW rating resistor
20 strips of resistor is combined in series to form 8 ohms

 

[gar]

180614-1024 EDT

Tungsten would not normally be used as a resistor resistance material.

See http://www.resistorguide.com/materials/ nichrome.

Power resistors do not run red hot like cooking elements, but the wire does get quite hot.

https://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

I could not find one table with nichrome, brass, steel, and copper with their thermal conductivities. You have to go to different tables and different units. But brass is a better conductor of both heat and electric current than nichrome. I don't think brass used to solder nichrome wou;d be at too high a temperature when the nichrome is used as resistor material.

The following two links do not work from this post.

https://en.wikipedia.org/wiki/Nichrome
https://en.wikipedia.org/wiki/List_of_thermal_conductivities

.

 

[gadfly56]

180614-1024 EDT

Tungsten would not normally be used as a resistor resistance material.

See http://www.resistorguide.com/materials/ nichrome.

Power resistors do not run red hot like cooking elements, but the wire does get quite hot.

https://www.engineeringtoolbox.com/thermal-conductivity-d_429.html

I could not find one table with nichrome, brass, steel, and copper with their thermal conductivities. You have to go to different tables and different units. But brass is a better conductor of both heat and electric current than nichrome. I don't think brass used to solder nichrome wou;d be at too high a temperature when the nichrome is used as resistor material.

The following two links do not work from this post.

https://en.wikipedia.org/wiki/Nichrome
https://en.wikipedia.org/wiki/List_of_thermal_conductivities

.

The links worked perfectly fine for me from inside your post.

 

[petersonra]

I think resistor material is made up of tungsten used in vfds, may be I am be wrong.
so how to weld or braze if it is broken somewhere in the middle part.
I mean what welding rod, gas for heating, etc for a proper joint bcoz it is mounted on a shaky platform or if i say on a crane itself.

I am not sure you can weld it back together. Might be easier to just splice it.

 

[GoldDigger]

I am not sure you can weld it back together. Might be easier to just splice it.

:thumbsup:
A suitable crimp connector might be the best way to go. Or a split-bolt?

 

[Andy Delle]

Replace the damaged part!

Replace the damaged part!

This is not something you want to kludge in a high power VFD.

 

[Jraef]

It will be NiCh (Nickel - Chromium alloy) resistance wire, and it is not repairable. If you try to repair it, you add resistance to that element and when used in a grid like that, that element in the gris simply conducts less, so the other elements carry more of the workload and fail sooner. Just replace that element.

 

[petersonra]

It will be NiCh (Nickel - Chromium alloy) resistance wire, and it is not repairable. If you try to repair it, you add resistance to that element and when used in a grid like that, that element in the gris simply conducts less, so the other elements carry more of the workload and fail sooner. Just replace that element.

he said they were in series so if he spliced it back together the whole resistor might have a slightly higher resistance. probably not enough to make any real difference.

the ends of the resistors made this way just have terminals that are clamped on to the wire. They work fine. No reason a proper splice would not work.

 

[gadfly56]

This is not something you want to kludge in a high power VFD.

Agreed. Or have the manufacturer field repair it, if it can be done. I'm guessing you can have a really spectacular failure in a device moving 5 kW through it if it doesn't go back together right.

 

[gadfly56]

he said they were in series so if he spliced it back together the whole resistor might have a slightly higher resistance. probably not enough to make any real difference.

the ends of the resistors made this way just have terminals that are clamped on to the wire. They work fine. No reason a proper splice would not work.

Does anyone have a schematic or picture of this thing?