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Is it normal to hear AC hum inside trains?

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JustinStacey.x

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okay here's a bit of an odd question.

On all Glasgow class 314s if you sit at the front near the drivers cab a rather loud AC hum can be heard from underneath the floor, particularly when they crank it into notch 4. Personally I love this sound; but I don't know of any other trains that do it - is it normal or is it signs that the 314s are knackered?

This video on Youtube doesn't do the loudness of the sound justice, http://www.youtube.com/watch?v=3QYQVpC3_KM&feature=channel_page but it is the clearest I could find.

So, is it normal? I have never heard any other EMU make such a sound.
 
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MCR247

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Well older ones like 319s,320s & 321s do. I think 313s & 315s do also
 
MCR247

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You can hear it on the classes I listed above, but not as loud. 315s are AC. 313s are dual
 
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JustinStacey.x

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Ahh, cool, i mustn't have been listening hard enough :(
--- old post above --- --- new post below ---
Do most video cameras pick it up well or are some better than others? I really want to record the sound of it inside a 314 but I'm in two minds about whether the camera I plan to buy will pick it up or not.
 
O L Leigh

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There are a lot of things that "hum" on electric units, and not all of it is caused by AC electricity. In fact, most of the hum you get from the transformer is actually the sound of the oil pump.

There is a similar sound to the one you describe on our Cl315's and I've never been able to pinpoint precisely what is causing it. I've just put it down to the heating equipment as it seems to make the noise all the time though, as you say, it is especially harsh when pulling notch 4. It certainly doesn't appear to be the traction equipment.

Incidentally, I think that what JustinStacey says about Cl314's and similar using DC power is correct. Once the power has been drawn from the OLE at 25kV AC it is rectified and stepped-down by the transformer into DC power for all the on-train equipment, including the traction motors. Even so-called AC units like Networkers do this, but where the power is used for traction it is passed through an inverter first to turn it back into AC.

Mind you, the "hum" you can hear in that clip is just the main air compressor running and nothing to do with the electrics. Compare with this video starting at 1:16. You can hear the compressor run up until about 1:31.

O L Leigh
 
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O L Leigh

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Nope. If I'm understanding him correctly he is referring to a non-motor related hum. Besides, as I explained above, there is no AC anywhere near the motors on a Cl314.

O L Leigh
 
Daimler

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O L Leigh said:
Nope. If I'm understanding him correctly he is referring to a non-motor related hum. Besides, as I explained above, there is no AC anywhere near the motors on a Cl314.

O L Leigh
Click to expand...

Ah, OK. I appear to have got the wrong end of the stick slightly! The sound shown by JustinStacey on his video is similar to the one in the video I posted, though - even if they do come from different areas of the train.
 
O L Leigh

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Yes a lot of it is, which is because the train featured is pulling away. However, the video he linked to doesn't actually illustrate the hum very well because the sound caught by the camera is actually the main compressor (compare and contrast his linked video to mine for the proof).

I honestly don't think any microphone will adequately pick up the background hum made by a Cl314 (or similar) because it is quite quiet. I think you just have to be there.

O L Leigh
 
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JustinStacey.x

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O L Leigh said:
Mind you, the "hum" you can hear in that clip is just the main air compressor running and nothing to do with the electrics. Compare with http://www.youtube.com/watch?v=loR07DmxTmQ starting at 1:16. You can hear the compressor run up until about 1:31.

O L Leigh
Click to expand...

Cheers for your info. If you go back to the clip I posted, http://www.youtube.com/watch?v=loR07...e=channel_page after the air compressor is done and the driver applies throttle at 1:18, you can hear what I presume to be AC hum - surely thats not the air compressor? It sounds just like an electricity substation :o
--- old post above --- --- new post below ---
O L Leigh said:
Yes a lot of it is, which is because the train featured is pulling away. However, the video he linked to doesn't actually illustrate the hum very well because the sound caught by the camera is actually the main compressor (compare and contrast his linked video to mine for the proof).

I honestly don't think any microphone will adequately pick up the background hum made by a Cl314 (or similar) because it is quite quiet. I think you just have to be there.

O L Leigh
Click to expand...

Some of the 314s Ive been on are far from quiet my friend. Sit right at the front behind the driver's cab (particularly 314 202 and 314 213) and it can drown out quiet speech. And I'm not kidding!
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Daimler said:
Ah, OK. I appear to have got the wrong end of the stick slightly! The sound shown by JustinStacey on his video is similar to the one in the video I posted, though - even if they do come from different areas of the train.
Click to expand...

hey matey

they aren't my videos actually. My video camera has been out of commission for a long time but hopefully, at last, I am getting one this weekend (Dear god I hope it's good lol). I was just asking out of curiousity and cited the video I did as it was the best example. When I get my camera, I will do some on train vids of the 314s and see if I can get the AC hum which as I have mentioned in response to O L Leigh, is really quite incredible in some 314 units.
--- old post above --- --- new post below ---
Daimler said:
Presenting this, just found on YouTube: :D

http://www.youtube.com/watch?v=_owHcwQ89oY

From about 24 secs on is the sound I am familiar with!

EDIT: You also get it on BVE, with the 321 cab (or at least, you did when I played it - but that was BVE2 - I'm rather out of touch!).
Click to expand...

Holy hell... wow that is one helluva AC hum damn lol... that rivals that power station I visited last week :shock:

I HAVE to ask that guy what his camera is lol
 
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O L Leigh

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JustinStacey.x said:
If you go back to the clip I posted, http://www.youtube.com/watch?v=loR07...e=channel_page after the air compressor is done and the driver applies throttle at 1:18, you can hear what I presume to be AC hum - surely thats not the air compressor? It sounds just like an electricity substation :o
Click to expand...

Ah, that hum. Sorry but I thought you were referring to the constant background noise you get at almost all times.

No, that harsh electric snarl you get when you take power just before the motor sound takes over is that traction electronics. I don't know precisely what component(s) make the noise or why, but as I said before it's not AC.

JustinStacey.x said:
Some of the 314s Ive been on are far from quiet my friend. Sit right at the front behind the driver's cab (particularly 314 202 and 314 213) and it can drown out quiet speech. And I'm not kidding!
Click to expand...

My comment was in reference to the Cl321 featured in the video. These may be loud in the motor coach but there almost no motor or other electronics noise in the cabs.

O L Leigh
 
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Hmm, if it isn't AC then I don't know what it could be. It sounds just like the 50/60Hz AC hum that many electronics make due to the reverberations caused by alternating current. Interesting... will have to find out about that.

I was under the impression that DC electrics didn't make any sound but after watching some videos of DC trains and still hearing the hum I am beginning to wonder now. Curious!
 
O L Leigh

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Anything that vibrates will set up a hum, and it doesn't have to be the electricity that's running it. As I hinted above, electric units are full of fans and pumps that hum. However, the traction electronics do also make a certain amount of noise, but with most EMU's with DC motors this sound does not come from the AC power to the transformer. Precisely what it is that causes all the noise though, I couldn't say.

O L Leigh
 
323235

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323s make an immense humming noise in the intermediate trailors

Metrolink Trams (1000/2000 series) only do it a bit sometimes when braking in a higher notch, although Stagecoach mentioned a year or so ago that they were in the process of rewiring them to get rid of it completely as they seemed to think it was a major issue
 
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Don't 323s also make an immense 'electrical tones' noise when accelerating and decelerating? I can't decide whats better, the buzzing of some EMUs or the OO-EE OO-EE OO-EEEEE of 323s lol.

I wanna get vids before more trains get 'fixed' like they did with HSTs and Valentas :P

I found out what camera the guy who made this video http://www.youtube.com/watch?v=_owHcwQ89oY (the very loud 321) was using, or at least, I am pretty sure it was since it was his flickr I looked at and it listed this camera as the type used: http://www.flickr.com/cameras/panasonic/dmc-fz20/

Makes sence given that one takes 320x240 video with sound.

It's a pretty old one but the price is pretty damn good for a bridge camera and it will be my first proper camera. I also read really great reviews, so I bought it. Only 120 quid! Video quality isn't the best admittedly but the mic does seem great and either way its a colossal step up from what I was last using. Also a decent camera is really what I need now I am getting into photography more. All around a good buy I think.
 
O L Leigh

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The motor hum rises in pitch as the revs rise while the hum from the control equipment stays at the same pitch irrespective of speed. The only variation in control equipment hum is volume depending on how hard the unit is getting caned ranging from total silence when coasting to, in some cases, quite a harsh snarl when being given the beans. It is also more noticeable if you happen to sit on top of the control equipment which, on a Cl314, is towards the cab ends.

O L Leigh
 
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JustinStacey.x

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O L Leigh is dead right, I did an experiment today with a 314 and a 318 and I realised why I have never noticed AC hum on anything but a 314 - on the 318 I sat right in the middle under the pantograph and the buzzing snarling sound was really loud. I have never noticed it before because I only ever sit at the front of trains. I'm surprised passengers don't complain, the 318 was so loud, it wasn't even a uniform sound but rather a BBZZZZZzzzzZZZZZzzzZZZ. Yet I tried sitting the same place on a 314 and it was quieter than it would be at the front. I have also noticed a pillar on both 314s and 318s that goes from right underneath the pantograph down through the seats into the underside of the train - guess this is where the juice goes.

it's also quite nice sitting at the very front on a 314, not only do you get the 'BZZZZZZZ' but also the AWS bell - I can't wait for my camera so I can get some onboard videos!
 
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There is a constant buzz on some units such as 314s, and also there is a whine from the motors which exists on all DC motors that I know of, although the exact sound does obviously vary quite a lot between different types.

JustinStacey.x said:
I can't decide whats better, the buzzing of some EMUs or the OO-EE OO-EE OO-EEEEE of 323s lol..
Click to expand...
The former for me! I certainly do enjoy the sound of 'classic' DC motors, they make me think I am on a 'proper' EMU unlike the silly sounding 3 phase AC motors that you get these days. :P

I think the 321 (and derivatives of the 321; the 320 and 322) was the last design to use DC motors, with Class 465 Networkers being the first to use 3-phase AC motors. Which does have a slight irony to it I guess! The changeover being made around 1990.

So if I am on LM, I always want to get a 321, and on FCC I'd always want to get a 317, and so on.

This has to be one of the most interesting videos on Youtube for sound; not only can you hear the incredible thrash of a Valenta and the noise from the Marston cooler, but you can even hear the DC motor whine of the adjacent 319 (most noticeable from 00:40)...

[youtube]woaqJxkLfAA[/youtube]

Now that's what proper trains should sound like :D
 
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