c378 & 379 pantograph "spang"

[joeykins82]

I've noticed a loud noise, somewhere between a "spang" and a "thung" from somewhere around the pantograph on both the LO 378s when running on AC and then again more recently on a GA 379. Has anyone else heard this? Any clues as to what it is? Is it normal/expected behaviour?

Request to Mod: please move this to Traction & Rolling stock, I clicked new thread in the wrong browser tab!

 

[westcoaster]

I've noticed a loud noise, somewhere between a "spang" and a "thung" from somewhere around the pantograph on both the LO 378s when running on AC and then again more recently on a GA 379. Has anyone else heard this? Any clues as to what it is? Is it normal/expected behaviour?

Request to Mod: please move this to Traction & Rolling stock, I clicked new thread in the wrong browser tab!

It's just the VCB opening and closing while going through neutral sections completely normal.

 

[swt_passenger]

Vacuum Circuit Breaker, if the OP was wondering...

Similar noises occur on everything with a pantograph...

 

[jeromeroberts]

OLE neutral section.

 

[Bald Rick]

Same on 377s. If you travel on FCC north of St Pancras and you're lucky you may even get the driver who announces on the approach to every neutral section that the train is approaching said feature, and that those in the "pan car" may hear a loud bang and not to worry.

 

[Kentish Paul]

Same on a Class 395. Its quite loud if you are under the pantograph, but nowhere near as loud as a 378.

 

[joeykins82]

I'd never noticed it on any other train, I guess it's just coincidence and I've never sat or stood beneath the pantograph on other AC stock (at least not without having headphones in and music playing)

 

[Crossover]

350's are particularly noticeable. 390's I have tended to find are less so