Transformer and Choke Grounding?

[kstylianos]

I just received my power transformers. While taking them apart to paint the housings I found a wire that goes from the windings to the screw hole (which held the unpainted housings and mounting feet). I'm guessing this is a ground that needs to be addressed as both the chassis and PTX housing will be painted (no conductivity). Is it appropriate to extend this wire (with the rest of the leads) and include it the ground-bus architecture or attach it with the IEC port chassis ground?

I'm guessing the OTX (James) should be grounded similarly?

Also received 4 open bracket filter chokes, which will be mounted under the chassis. Should I solder a lead to the mounting feet and ground these as well?

Thanks for any help.

-Charlie

[Miles Prower]

Originally posted by kstylianos
I just received my power transformers. While taking them apart to paint the housings I found a wire that goes from the windings to the screw hole (which held the unpainted housings and mounting feet). I'm guessing this is a ground that needs to be addressed as both the chassis and PTX housing will be painted (no conductivity). Is it appropriate to extend this wire (with the rest of the leads) and include it the ground-bus architecture or attach it with the IEC port chassis ground?

Looks like an electrostatic shield between the primary and secondary(ies). That needs to be grounded.

I'm guessing the OTX (James) should be grounded similarly?

Also received 4 open bracket filter chokes, which will be mounted under the chassis. Should I solder a lead to the mounting feet and ground these as well?

Thanks for any help.

The xfmrs need to be grounded, both for noise and safety considerations.

[wa2ise]

Also received 4 open bracket filter chokes, which will be mounted under the chassis. Should I solder a lead to the mounting feet and ground these as well?

If it's a metal chassis, and the chokes directly mounted to it, that would take care of the grounding of their metal frames. Of course the chassis would be grounded.

[kstylianos]

Looks like an electrostatic shield between the primary and secondary(ies). That needs to be grounded.

If it's a metal chassis, and the chokes directly mounted to it, that would take care of the grounding of their metal frames. Of course the chassis would be grounded.

The chassis is metal, but will be painted.

Would it be acceptable to to extend the wire found in the PTX and solder a grounding wire to the feet of the chokes, and gound them to the chassis, possibly at the IEC ground? Or would it be better to incorporate these grounds in the ground bus. I'm thinking IEC port ground.

Thoughts?

[astouffer]

I never thought about grounding the secondary of a transformer until I was doing some tests with a 25 watt SE transformer. Had a dummy resistor connected to the secondary and touched one end while it was running at full output. Talk about leakage, it felt like a good 100 volts or so coming through. No wonder the scope traces looked funny until it was grounded.