brushes

[eabadger]

If they are slip rings they should be very smooth and shiny, are they copper colour under that?
Do the brush’s fit in that dip?
Ideally have them on the lathe, but cleaning the central contact area will be a massive improvement.

What engine, what problem?

steve

[billi]

Ok cleaned it, will see ......  looks more like brass colour  to me similar as this


But perhaps polished copper gets more  yellow



Ok my DC Generator  has a Hatz engine i would say  it is this one

and i think has a seizing of the piston  ,  was running without or little  engine oil  ( but refilled oil  about 20 running hours before )

Engine just stopped and cannot  turned  with the hand cranking thing

[camillitech]

Thanks 

I had a lovely   2 kw  DC  diesel charger ,but engine problem  and much more prefer  DC charging


 and  this AC one is  a rented one  from a friend ,so  you are  telling me that i should grind them flat ?

Yup, that's it Billi, though that brush holder on the left looks like it's squint too. What I do, and I've done it several times but would NEVER advise anyone else to do it is get a piece of wood that is perfectly flat at the end and fold a piece of emery paper around it. Then start the engine and push it hard and square against the slip rings one at a time until you've taken taken the worst of it off. That done and after counting all your fingers go to a fine 'wet or dry' then finish off with a cloth and some polish  Keep the cloth tight and don't blame me if it goes pear shaped on you.

Good luck, and I will not even mention Mr Lister 

[eabadger]

those old engines are prety tough, i heat siezed my big twin enfield, i was very upset.
anyway gave it a big whack on the starting handle and become free, has since ran fine 100+ hours.

meant to say brass, loosing it.

my charging set is a Lister, is great, can give the full rated 2.8kw without breaking in to a sweat, but need new air filter, cant get them here, awaiting the postman.

steve

[billi]

  hey Paul   i understand,will  be careful .........lost a part of a finger  surfing  waves   in Costa Rica  few  years back 

Steve will search for the  hammer and give it a try  , did  try  it gentle before ....

I think  i should be on holidays  every year in JAN and February 

[eabadger]

re holiday, you and me both, mppt stil not back.
amount of clout to unstick engine was large, i assumed it was dead, was amazed when it burst back in to life.
never forget to check coolent level now.

steve

[Philip R]

I had a problem with brushgear sparking in past. Big machine, 660MW with slipring fed rotor, slipring sparking looked pretty serious, like angle grinder in use. Keep that up and the ring would have been scrapped in two days!

Machine taken off load on the night shift, me and a colleague did some unofficial cleaning with crocus paper on scaffold board Very not the done thing, but done it a way that would not have eaten the board, or more importantly got me sent into earth orbit and killed!  with shaft running ~ 60 RPM, 5 minutes of this broke patina and with brushes replaced, unit run up and synchronised. Did the trick for 3 months, I then had some in situ machining organised for next unit outage.

When roughing the rings, do not use Silicon carbide as it can embed into soft rings like brass. Never use polish ( silicones), these destroy any patina before it forms. Avoid oily atmospheres ( difficult), sea ( salty) enviroments also and paint solvents. Moisture is good for patina formation, but not the  condensing variety as it causes low rotor IR and tracking.

PhilipR

[johnrae]

Would have thought at that sort of power level you'd have had a PMG and rotary rectifier assembly  ie no slip rings required.

[roys]

Philip R was it Longannet or Drax you worked at?  Just a wild shot in the dark, I remember measuring the brush length on the exciters with tufnel rulers and insulated gloves with the unit running.

[Philip R]

Later machines used PMG rotating exciter and rectifier, to overcome problems associated with brushgear.

The machines in question were the first of the GEC (AEI /EE) 660MW family to be built and located in Somerset. Other ideas touted at the time was a mercury pickup, similar to a oil scoop arangement for Babbitt metal pedestal bearings. Great idea but would have been a health and safety nightmare. Everybody would end up like a Luton Hatter.

You forgot to mention the insulated rubber mat!

PhilipR

[billi]

Where can i buy brushes ?  Or can i cut them my self ? out of a block ? Cause it is hard to find the right size online

[johnrae]

You need to find your "local" motor rewinding service and pay them a visit.  They will stock, or can "resize", all manner of brushes.   Alternatively, if your brushes are somewhere around the size of washing machine ones (smaller) you can rub them down on a file or sandpaper to fit their holders. 

[billi]

cheers, mine are about 6mmx9mm  and   can be an inch long   


washing machine  ? Will have a look .............hate that thing any how in winter ...just kidding

[Iain]

Hi billi
I have just found a small box of new brushes in the garage.
Found some 9mm x 6mm with the main body 22.5mm long. There is a wire within a spring about 40mm long on the end of the main body.
marked on the side of the brushes:-
ECP
M14

Not sure if that is the grade of carbon .
I think they were for DC motors on a boat.
Any use? You are welcome to a pair of them . Just PM me

Also:-  http://www.ekaton.ltd.uk/products.asp?catid=51&showProds=true
Any use?
Iain

[billi]

Thanks Iain for the offer  ,  that  helped a lot   

Never  looked into  brushes with  wire connections ..........and just cut the wires off ........will google


I need 8  minimum for my 2  left over AC$ generators 

Other investigation  on the bespoke  generator   is , that sometimes  after an hour runtime  or so  ,engine still runs  but no Volts  out of the 230 Volt socket any more ,  but 110 Volt still available from the 110 Volt socket (not much use  to me)


Can someone tell me why  110volt is working ,while 230Volt off  ?

Thaaanks