Class 334 Whining Traction Motors

Status
Not open for further replies.

SPT334man

Member
Joined
5 Jul 2012
Messages
7
Hi All

Now, for all people that have been on Class 334's, you may have heard that they make a strange whining noise departing stations and arriving at stations. Now, I want to know what units from 334001-334040 that you've all heard scream.

I'd also like to know what causes them to scream, because on one occasion, they don't make much sound and the next, they howl like wolves.

These are a list of howling 334's that I've been on:
334002, 334003, 334005, 334008, 334012, 334014, 334019, 334022, 334024, 334026, 334027, 334031, 334032.
 
Sponsor Post - registered members do not see these adverts; click here to register, or click here to log in
R

RailUK Forums

350desiro

Member
Joined
31 Oct 2009
Messages
32
Location
Crewe
I would assume this noise is the Traction motors, the noise would vary depending on load, speed, temperature? and maybe the length of time since the unit last had an exam of the motors? Hope this is correct info, anyone who can devolop/correct me feel free!
 

rail-britain

Established Member
Joined
12 Aug 2007
Messages
4,102
I would suggest choosing two locations in the same direction, one where you hear it and another where you don't
Then compare units over these same locations
If there is a difference then it is clearly the units and/or the way they are being driven
 

SPT334man

Member
Joined
5 Jul 2012
Messages
7
I would suggest choosing two locations in the same direction, one where you hear it and another where you don't
Then compare units over these same locations
If there is a difference then it is clearly the units and/or the way they are being driven

Well, I was on 334's quite a lot between Hillington East and Glasgow Central before the 380's took over.

I heard 334027 whine between those two stations, but 334029 was quiet, apart from a silent hum. They weren't being driven any differently. Both accelerated quite quickly out of Hillington East and arrived at Cardonald quickly as well.

Another example was 334019, which howled between Glasgow Central and Hillington East on one occasion, but the next time, same station, same unit, it wasn't noisy at all.

P.S. I heard from someone that 334023 was a noisy unit. Is this true?
 

John55

Member
Joined
24 Jun 2011
Messages
800
Location
South East
Hi All

Now, for all people that have been on Class 334's, you may have heard that they make a strange whining noise departing stations and arriving at stations. Now, I want to know what units from 334001-334040 that you've all heard scream.

I'd also like to know what causes them to scream, because on one occasion, they don't make much sound and the next, they howl like wolves.

These are a list of howling 334's that I've been on:
334002, 334003, 334005, 334008, 334012, 334014, 334019, 334022, 334024, 334026, 334027, 334031, 334032.

All modern emus with AC motors use a form of inverter (often called a Variable Voltage Variable Frequency or VVVF drive) to convert the DC (either from 3rd rail or rectified from 25kV o/h) to drive the motors.

The earlier models including the 465s, 323s, etc had switching frequencies in the audible range and I always thought the 465s when delivered sounded a bit like a motor bike with a very small engine accelerating hard through the gears as they picked up speed.

More modern drives don't make this noise or at least much less of it as the requirements on the train builders have been tightened in recent years to include noise pollution. So when the ABB built 465s were fitted with Hitachi drives a few years ago it was very noticeable they didn't make as much noise.

I am pretty confident the noise you hear are the inverters either powering the train or regenerating.

I don't know why some are noisier than others but it is possible that the inverters are being updated on the 334s and the noise reduced as a result. Thinking about the 465s all of them seem less noisy now compared to when they were new not just the Hitachi modified ones so perhaps there is a general move to update the electronics and suppress the noise (or of course I may be going deaf).
 

rail-britain

Established Member
Joined
12 Aug 2007
Messages
4,102
The only howling noise I am aware of is the traction motor coolers
Normally it can be heard when standing opposite a train as it departs, or when sat in the motor coaches (front and rear)
When you sit in the centre coach you don't hear any such noises

Equally, sometimes there is no such noise, but it can be heard later in the journey
This suggests the coolers are not electrically responsive and more dependent on the core temperature

I suspect this was also the same reason why the Class 334 units were suspended from operation during wet snow as the traction motors heated up, then the blowers applied
 

SPT334man

Member
Joined
5 Jul 2012
Messages
7
Oh, they may be possible solutions to the noise. The inverters or the traction motor coolers.
Thanks for your comments, but there's something else that needs answering.

"Now, I want to know what units from 334001-334040 that you've all heard scream."

Also, no-one has ever taken a Class 334 sound sample. That's one thing I may attempt or someone else might try it.
 
Last edited:

rail-britain

Established Member
Joined
12 Aug 2007
Messages
4,102
"Now, I want to know what units from 334001-334040 that you've all heard scream"
I no longer record train numbers, only on specific journeys
The best thing to do is to make a list as suggested above, from observations where the conditions are fixed
Equally observe the same train, at the same location, with different drivers and compare
This should be easy enough at locations such as Dalmuir, Partick, and Airdrie
 

SPT334man

Member
Joined
5 Jul 2012
Messages
7
I no longer record train numbers, only on specific journeys
The best thing to do is to make a list as suggested above, from observations where the conditions are fixed
Equally observe the same train, at the same location, with different drivers and compare
This should be easy enough at locations such as Dalmuir, Partick, and Airdrie

That's gonna be hard in the spare time that I've got, which is....well, not a lot.

Oh, also how can I tell that a 334 is going to whine before the train even departs the station?
 

rail-britain

Established Member
Joined
12 Aug 2007
Messages
4,102
also how can I tell that a 334 is going to whine before the train even departs the station?
You will only know by continuous observation, comparing like with like
Example :
Monday 02 July Partick westbound 334001 no
Tuesday 03 July Partick westbound 334001 no
Wednesday 04 July Partick westbound 334001 yes
Thursday 05 July Partick westbound 334001 no

Once you have compiled various sightings a pattern will start to emerge
 

Eng274

Member
Joined
19 Aug 2010
Messages
796
Call me simplistic, but is the deafening whine (which if I'm thinking of the same sound, rises in pitch as the train accelerates) above the inner DMS bogies not just the traction motors?

There is a faint, very high constant-frequency noise which only appears when the motors are engaged in traction/braking, so I'm guessing it is the thyristors.

There is also a general whine that comes from under the coaches, which could be the cooling fans for the PMCFs, inverters etc. I can't recall the traction motor design offhand but they may have integral cooling fans that work off the motion of the rotor (Desiro traction motors have this feature not sure about Alstom).

I've never noticed a huge difference in sound between different units, maybe I'm not listening hard enough. Hope this gives a bit of insight!
 

John55

Member
Joined
24 Jun 2011
Messages
800
Location
South East
For interest I came across these videos on Youtube which illustrate the noises from the inverters with 2 different type of inverters.

http://www.youtube.com/watch?v=6Ucl6YoAocw&feature=fvwrel

http://www.youtube.com/watch?v=aQGOxxeSN38&feature=fvwrel

The first is older technology but this is the noise from the drive electronics. Bigger motors etc in a train so more noise compared to these bench models. Any other type of noise is traction motor blowers, compressors and auxiliary power sullies.
 

rail-britain

Established Member
Joined
12 Aug 2007
Messages
4,102
Do you think I should speak to a 334 driver about this and find out?
Why not send a letter to ScotRail Fleet Manager, and see if you can have it explained to you at Shields Road Depot?

I managed a visit when the Class 318 units were new and had just been delivered
 

Telcontar

Guest
Joined
19 Jan 2012
Messages
55
What's the reason for converting from AC to DC to AC instead of simply changing voltage with a transformer?

As for those two videos, for a second I thought that the second one sounded like the constant pitch traction system in Electrostars – they don't have rising or warbling pitch like other trains.
 

John55

Member
Joined
24 Jun 2011
Messages
800
Location
South East
What's the reason for converting from AC to DC to AC instead of simply changing voltage with a transformer?

As for those two videos, for a second I thought that the second one sounded like the constant pitch traction system in Electrostars – they don't have rising or warbling pitch like other trains.

The second one is an IGBT VVVF set up so that is about right. Each design will be slightly different depending on electrical and mechanical design differences.

An AC motor driven by a fixed frequency which is what comes out of the transformer is not very good for variable speed requirements i.e. a train. To drive a piece of machinery at a fixed speed like a ventilation fan they are fine.

Modern drives to AC motors vary the frequency of the drive current to maintain high efficiency in the motor as the speed increases. This is why the 25kV 50Hz supply is converted to DC so the inverter can generate the correct (and variable) voltage and frequency drive current to the motors.
 

Telcontar

Guest
Joined
19 Jan 2012
Messages
55
The range of sounds is so wide, though – from the "gear change" of the 323, 465 and LT1996, to the Desiro car burglar alarm and the sinister hum of Electrostars. Seemingly all serving the same purpose.
 
Status
Not open for further replies.

Top