Hammond 290BBEX 240VAC

[p2pAmps]

Guys,

Can you experts enlighten me on the 100% correct way to wire this PT for 240VAC mains.  I understand tying the windings together just not 100% clear.  Thanks in advance

[pdf64]

Guys,

Can you experts enlighten me on the 100% correct way to wire this PT for 240VAC mains.  I understand tying the windings together just not 100% clear.  Thanks in advance

Connect black to brown, white to live, blue to neutral.

[p2pAmps]

[/quote]
Connect black to brown, white to live, blue to neutral.
[/quote]

Thanks PR.  I knew about the brn/blk but seconded guessed myself on which leg went to neutral and which to hot. 

Appreciate you straightening me out!

Cheers

[scstill]

What is the purpose of org and where to connect? seems redundant with the ground symbol.
Also, does it matter if live goes to white (recommended) or blue?

[pdf64]

What is the purpose of org and where to connect? seems redundant with the ground symbol.

I don't understand what the ground symbol means.
Nonetheless, the orange should be connected to the chassis metalwork (which must also be connected to planet earth).

Also, does it matter if live goes to white (recommended) or blue?

No, live or neutral can be connected to white or blue.

[HotBluePlates]

I knew about the brn/blk but seconded guessed myself on which leg went to neutral and which to hot. 

It is customary (expected? required?) in European gear to use a Double-Pole switch for On-Off, such that both legs are switched.

That likely reduces the impact of choosing which wire is Live/Neutral.

[p2pAmps]

I knew about the brn/blk but seconded guessed myself on which leg went to neutral and which to hot. 

It is customary (expected? required?) in European gear to use a Double-Pole switch for On-Off, such that both legs are switched.

That likely reduces the impact of choosing which wire is Live/Neutral.

Yes sir, switching both lines would be a good idea for sure.  Would you use a thermistor as well?

Cheers

[HotBluePlates]

...  Would you use a thermistor as well?

I don't have an opinion on them.  I think it's reasonable to add one if you want to ramp up voltage more slowly.

I suspect there aren't any significant issues when using modern parts from a reputable manufacturer.

[scstill]

I don't understand what the ground symbol means.
Nonetheless, the orange should be connected to the chassis metalwork (which must also be connected to planet earth).

If you notice in the picture above the 50/60hz there is a ground symbol (several lines in a triangle shape)
To me this implies the transformer chassis is grounded when mounted to the chassis.
Hence the reason for the comment that it seems redundant in connecting org to chassis ground.

[passaloutre]

Grasping at straws here but I suppose there are times when you may want the transformer isolated from the chassis, in which case the orange wire provides a ground connection to the transformer…or maybe there is an internal shield which is otherwise ungrounded and the orange wire provides a means to ground it?

In any case If it were my amp, I would bolt the transformer to the chassis and connect the orange wire to whatever power supply ground is afforded by my layout.

[tubeswell]

What is the purpose of org and where to connect? seems redundant with the ground symbol.

Faraday shield

[HotBluePlates]

I don't understand what the ground symbol means.

If you notice in the picture above the 50/60hz there is a ground symbol (several lines in a triangle shape)
To me this implies the transformer chassis is grounded when mounted to the chassis.

But if you've ever bought a power transformer from Hammond, you know they have a thick coating of varnish from when the transformer is potted.  You can't assume Hammond's transformer has continuity to the chassis just because you didn't take extra steps to isolate it.

And as Tubeswell keeps trying to remind us, this is immaterial because Orange is tied to the transformer's Faraday Shield.

Last, if the transformer would make the necessary grounding via its core/case when mounted, why would they bother adding an external wire?

[pdf64]

... the transformer chassis is grounded when mounted to the chassis. ...

I don't think a typical transformer has a 'chassis' per se.
Each lamination in the stack is made from high resistance silicon steel and oxide coated to be electrically insulated from everything else. Any screws etc that passes through the stack are usually insulated such that they don't electrically connect both side brackets.
I think that the ground system connected to the orange wire (which I agree probably indicates an electrical screen) is a drawing error, as when fastened to a typical bright metal chassis, nothing in that drawing would be inherently electrically connected to the chassis?

The physical drawing of the transformer doesn't even show or list the orange wire, and shows the red HT winding wires exiting the underside bell cover from different holes, which seems unusual 
https://www.hammfg.com/files/parts/pdf/290BBEX.pdf?v=1697661948

[DummyLoad]

... the transformer chassis is grounded when mounted to the chassis. ...

I don't think a typical transformer has a 'chassis' per se.
Each lamination in the stack is made from high resistance silicon steel and oxide coated to be electrically insulated from everything else. Any screws etc that passes through the stack are usually insulated such that they don't electrically connect both side brackets.
I think that the ground system connected to the orange wire (which I agree probably indicates an electrical screen) is a drawing error, as when fastened to a typical bright metal chassis, nothing in that drawing would be inherently electrically connected to the chassis?

The physical drawing of the transformer doesn't even show or list the orange wire, and shows the red HT winding wires exiting the underside bell cover from different holes, which seems unusual 
https://www.hammfg.com/files/parts/pdf/290BBEX.pdf?v=1697661948

Some time ago Hammond stopped bringing the primary shield lead out, if you inspect under the lower end bell, there will be a wire connected underneath the endbell to a lug placed in one of the mounting bolts, then covered by the endbell. Guess they saved themselves some wire and eliminated a lot of questions on what to do with the orange wire?

--Pete 

[scstill]

This is Hammond's response relative to the orange wire (Faraday shield as previously mentioned)

"It’s not a normal ground which as you say you get from the chassis. It is a copper shield for noise reduction between the primary and secondary (orange). Regards, Mark Mercer, Hammond Mfg. Co. Inc."