Electrical Arcing OLE

[MrTrainMan2001]

Hi all,

I need help from a professional please!

I need to know if these images are examples of electrical arcing or sparking? Are they something to be concerned about? Will repeated events cause damage to the OLE equipment?

Thanks for your help in advance.

 

[800301]

That is perfectly normal and nothing to be concerned about, you should see what it’s like when it’s -10 outside

 

[N1]

These would typically be examples of electrical arcing between the pantograph and the catenary. An electrical arc is a continuous spark, a spark is only momentary, so from a photograph it could be either. As above it is not uncommon and not something that is an immediate cause for concern from a safety perspective. Repeated events will cause damage to the OLE equipment, and will increase wear in the contact surfaces of both catenary wire and pantograph. Excessive arcing can also damage electrical equipment as it creates large voltage spikes and transients beyond the supply voltage range. Modern OLE and pantograph designs try and reduce arcs by increasing physical pressure between pantograph and catenary wire, increasing pantograph surface area. Stagger is also adopted (Zig-Zag of catenary wire on straight sections) to create even wear on the pantograph.

 

[MrTrainMan2001]

These would typically be examples of electrical arcing between the pantograph and the catenary. An electrical arc is a continuous spark, a spark is only momentary, so from a photograph it could be either. As above it is not uncommon and not something that is an immediate cause for concern from a safety perspective. Repeated events will cause damage to the OLE equipment, and will increase wear in the contact surfaces of both catenary wire and pantograph. Excessive arcing can also damage electrical equipment as it creates large voltage spikes and transients beyond the supply voltage range. Modern OLE and pantograph designs try and reduce arcs by increasing physical pressure between pantograph and catenary wire, increasing pantograph surface area. Stagger is also adopted (Zig-Zag of catenary wire on straight sections) to create even wear on the pantograph.

That is perfectly normal and nothing to be concerned about, you should see what it’s like when it’s -10 outside

Okay guys, thank you very much for your help. However...

Would there be any area for concern if this particular stretch of track consistently experiences sparking? For example every day the same locations create sparking, maybe due to lack of tension in contact wire or some other problem. Despite sparking causing less damage and releasing less heat than arcing, would repeated events cause some cumulative damage?

Thanks again.

 

[Ashley Hill]

you should see what it’s like when it’s -10 outside

Or going through the Severn Tunnel.

 

[TreacleMiller]

Okay guys, thank you very much for your help. However...

Would there be any area for concern if this particular stretch of track consistently experiences sparking? For example every day the same locations create sparking, maybe due to lack of tension in contact wire or some other problem. Despite sparking causing less damage and releasing less heat than arcing, would repeated events cause some cumulative damage?

Thanks again.

Not really, no.

You see it every few seconds on a cold night. In a tunnel it can look like a proper light show.

The thing to look for is any chipping to the carbon or an orange glow like sparks - that's usually the sign of damage taking place.

 

[AM9]

Okay guys, thank you very much for your help. However...

Would there be any area for concern if this particular stretch of track consistently experiences sparking? For example every day the same locations create sparking, maybe due to lack of tension in contact wire or some other problem. Despite sparking causing less damage and releasing less heat than arcing, would repeated events cause some cumulative damage?

Thanks again.

Depending on where these locations are the reason might just be where the trains are accelerating, therefore drawing higher currents. Where trains are coasting there is much less current demand, e.g. from auxiliary and hotel facilities.

 

[800301]

Or going through the Severn Tunnel.

Indeed that always makes for a nice show when taking full power in a 10 car that’s heavily loaded

 

[AlfaPendular]

Okay guys, thank you very much for your help. However...

Would there be any area for concern if this particular stretch of track consistently experiences sparking? For example every day the same locations create sparking, maybe due to lack of tension in contact wire or some other problem. Despite sparking causing less damage and releasing less heat than arcing, would repeated events cause some cumulative damage?

Thanks again.

Hi, welcome to the forum. We have some experience on the subject and always trying to learn more. I will try to send you a PM so we can share experiences.

 

[GRALISTAIR]

Okay guys, thank you very much for your help. However...

Would there be any area for concern if this particular stretch of track consistently experiences sparking? For example every day the same locations create sparking, maybe due to lack of tension in contact wire or some other problem. Despite sparking causing less damage and releasing less heat than arcing, would repeated events cause some cumulative damage?

Thanks again.

Welcome to the forum. This is an interesting thread.

 

[contrex]

That is perfectly normal and nothing to be concerned about, you should see what it’s like when it’s -10 outside

In the 1970s I read in a railway magazine an account of a ride in the cab of a WCML electric loco (class 8x) during heavy snow. The people in the cab noticed a lot of flashing and one stuck his head out to see the panto weighed down with snow and drawing quite a long arc.

 

[Sun Chariot]

Hi all,

I need help from a professional please!

I need to know if these images are examples of electrical arcing or sparking? Are they something to be concerned about? Will repeated events cause damage to the OLE equipment?

Thanks for your help in advance.

Hello

I concur with what TreacleMiller and AM9 have explained. The normal usage that I witnessed along the WCML wires during the 1980s, was exactly as per your photos.

I've sat inside a class 315 EMU when its pantograph tangled with loosened OHLE wire - the resulting arcing, was like New Year's Eve fireworks...

 

[AM9]

Hello

I concur with what TreacleMiller and AM9 have explained. The normal usage that I witnessed along the WCML wires during the 1980s, was exactly as per your photos.

The degree of arcing is proportional to the current being drawn from ther supply. A modern EMU or ac loco might have a hotel/auxiliary power draw of (say) 100kW, which from a 25kV supply is 4A, - unlikely to provoke arcing in any conditions exscept very heavy icing. When that unit accelerates hard, it's traction equipment might need as much as 5MW, which means that the pantograph/contact wire interface is then passing 200A, which could cause arcing in favourable weather conditions just through the dynamics of a lively OLE. A similar situation exists with low voltage DC 3rd rail except that the contact shoes and rail interface has a much greater surface area under multiple shoes to accommodate the muhc higher currents. For the same power draw as the 25kV example above, the hotel only current would be 133A and full traction power would be a massive 6666A! This shows the major weakness of low voltage 3rd rail power delivery, especially in icy conditions, (but that is an aspect for another thread).

 

[Western 52]

Indeed that always makes for a nice show when taking full power in a 10 car that’s heavily loaded

Indeed, I always sit in coach A on the 800s in the tunnel, right under the pantograph. Free fireworks show! I was watching it from an 802 this morning.