a simple approach to carbon brushes - mining electrical ·  · 2015-06-01a simple approach to...

BY

Robert W Karlheim

Technical Sales Support Manager

PH: 866-793-6742 Mobile: 214-477-0965

Email: robert.karlheim@helwigcarbon.com

A Simple Approachto

Carbon Brushes

We know what the brush does?

It Facilitates Transfer,

from a stationary part ,

to a moving part,

within an electrical circuit

COMMUTATOR / RING FILM

BRUSH

COMMUTATOR OR RING

GRAPHITE PARTICLES&

MOISTURE DROPLETS

OXIDE LAYER

We all want the following:• Long brush life

• Minimal commutator issues

• Good film/patina

• Them to work and be as hassle free as possibleunder every condition

• At a reasonable price

• This is not to much to ask for.. Right.. You shouldexpect this…. And we agree!

And we don’t want:• Any trouble with the brushes

• To pay what the mfg asks

• To wait for product

• To provide all the details so the mfg can supply asolution

• Long drawn out process

• And how does the story go…..

We want the cake and to eat it to!

The brush is most often NOT the problem!

Most of the time the brush gets blamed forall your brush related issues. It is most

often NOT the issue.

The brush acts like a fuse in the circuit. Ifthere is something wrong the brush will

show you there's a problem.

What do we do now !

How do we get there?

• When brushes are inspected it usually fallsunder 1 of 2 main categories:

– A routine brush inspection = PM plan, regularmotor inspection, shift change, or similar

– A non routine brush inspection = unit failure,unscheduled outage, quick brush change orsimilar

INSPECTION and AWARENESS

• INSPECTION - It is very important to have adocumented routine inspection regardless ofwhy you are inspecting the brush circuit

• AWARENESS – While inspecting be on the lookout for any early warning signs of trouble.Anything other than a nice smooth contactsurface, with a nice medium film, and a brushthat looks like new but worn down sayssomething may be going on

How does my brush look?

• Does it look like this or this

When inspecting brushes it isimportant to :

• Look at them through regular inspection

• Have a dedicated carbon brush plan – includes, theapplication, brushes, springs, and holders.

• Identify when something appears out of the norm asearly as possible

• Have a documented system so you can track progressor problems properly

• Not to jump to conclusion or judge the brush

• Gather as much information as possible beforegetting support

Here are some examples that tell youthere is a problem

Brush Issues

Mixed BrushesNever mix Brushes!!

ARE THERE ANYDEPOSITS IN THE HOLDER

Commutator Issues

Mixed SpringsNever mix Springs!!

Condition GUIDE – It is a guide only!

Carbon BrushPERFORMANCE

Carbon Brush PERFORMANCE!– There are a few factors to note about carbon

brush performance:

• Carbon Brushes do wear.

• In most cases excessive wear is not the brushes fault

• Most contact surface issues are not the result of a badbrush.

Carbon Brush PERFORMANCE!

– In most cases poor brush performance is not dueto the brush. Wait to form an opinion about thatbrush until you have worked with themanufacture to determine what is best for yourapplication. In most cases this will require athorough application review looking at all parts ofthe brush circuit.

What can cause poor brush performance?

– Oil, Dirt, Sand, Grease – any contamination

– Air flow – too little, cooled, dirty, etc

– Vibration

– Spring Force – too much/little, poor design, etc

– Amperage – running, nameplate, duty cycles

– # of brushes in circuit

– Contact surface

– Mixing of brushes – different grades, different mfg’s

– Brushholder issues – deposits, burrs, design, etc

– Brushes not properly seated

– Many more - Several various factors!

There can be can be many issues and manyvariables involved .

Contact your carbon brush manufacture tohelp solve your brush related problems.

It is best not to solve them on your own.

It may work now..Its only a matter on time

It’s time to call!And

When you do call.

CAN I HAVE A

HARDER OR SOFTERBRUSH?

BEFORE you call:

– DO NOT throw away the used samples

– Try to document as much of the issue as you can

– Clear pictures can help

– Be aware of any changes in your operation,equipment, environment, etc. – even simplechanges can make a world of difference.

CHOOSING THE RIGHT PRODUCTREQUIRES THE FOLLOWING

– Full Nameplate Information

– Running Amps & Trend Data

– # of Brushes in Circuit # per pole/# of poles

– Size of the brush

– Application

– Environment

AMPERAGE is important

– NAMEPLATE AMPS

– RUNNING AMPS

– DUTY CYCLES

– It is important we receive all 3 to best determinehow to provide the best possible solution

Sending a MOTOR for REPAIR

• YOU must be responsible for providing anoutline of what you want done on the motor.

• Provide a OUTLINE OF WORK to the MOTORSHOP with the motor. Many motor shopsrepair back to OEM spec – if your motor wassurveyed and changed to best suit yourapplication this could be lost.

• Have a survey done and have your motorrepair facility have a copy of that survey.

Be Proactive vs Reactive

• It starts with you

• Gather the correct information

• Your brush supplier is here to help you

• Contact us for more detailed information. Wehave more in-depth technical presentationsavailable at no cost to you.

THANK YOU!