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Contact Bouncing in Starter Motor Solenoid

09/16/2011 3:59 AM

Contact Bouncing In Automobile Starter motor Solenoid - When a moving contact is moved by solenoid to strike the fixed contacts, the moving contact will bounce in the opposite direction to the striking due to reaction force of the fixed contacts.

The striking & bouncing may repeat several times until the establishment of stable contact.

This phenomenae of unstability is refered as 'Contact Bounce'.

Can any one suggest the economical way of tackling the problem to provide a cost effective solution

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Guru
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#1

Re: Contact Bouncing in Starter Motor Solenoid

09/16/2011 6:07 AM

Replace the contactor with more modern equipment.

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#2

Re: Contact Bouncing in Starter Motor Solenoid

09/16/2011 6:13 AM

whats that modern equipment. can u elaborate. all starters till date use contactors also. can u suggest the alternative

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Guru
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#3
In reply to #2

Re: Contact Bouncing in Starter Motor Solenoid

09/16/2011 6:28 AM

Contactors where the conacts don't bounce....

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Guru
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#4

Re: Contact Bouncing in Starter Motor Solenoid

09/16/2011 7:01 AM

They should not bounce springs in the armature allow over travel and maintain contact force. The cause i have found is usually a loose connection to the coil. Either internal or external. The vibration of the contactor closing rattles the loose connection open and closed.

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#5

Re: Contact Bouncing in Starter Motor Solenoid

09/16/2011 7:23 AM

What type of contactors are those. can any one suggest any design modification that can be done to overcome the problem?

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Guru
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#6
In reply to #5

Re: Contact Bouncing in Starter Motor Solenoid

09/16/2011 8:08 AM

Replace them, as already stated.

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#7

Re: Contact Bouncing in Starter Motor Solenoid

09/16/2011 11:41 PM

With an automoblle starter, soleniod bouncing is seldom a problem. More often you are experiencing "Chattering". This is usually caused by a high resistence connection in the circuit. When the soleniod pulls in, contact is made to the starter motor. This causes a surge in current flow. This, in turn, causes a drop in the available voltage. This causes a drecrease in the current in the solenoid coil, causing it to drop out. Once this happens, the full voltage and current are again available and the cycle continues. At 12 volts, it does not take much resistance to have a huge effect in the current flow. Disassemble all of the connections, clean them thoroughly and reaffix them. Don't forget the ground connection at the starter flange. While you have the starter out (to clean the flange connection) take the solenoid off of the motor and inspect the contact disk for excessive pitting. Treat it and the contacts with emery paper if necessary. Resistance is futile but fixing it is not.

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Guru

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#8
In reply to #7

Re: Contact Bouncing in Starter Motor Solenoid

09/17/2011 12:02 AM

Can chattering occur due to low voltage in battery?. When you start a motor using a generator in across the line(DOL) method, chattering can occur due to VD during starting if size of generator is not selected properly for DOL starting.

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Guru
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#9

Re: Contact Bouncing in Starter Motor Solenoid

09/17/2011 12:09 AM

i have not studied automobile starter solenoids as such, but contact bounce is very much a fact of life in switchgear. A lot of research has been done in this field... here are some images which should be interesting for you...

1. Bifurcated contact - the two halves bounce differently, so one is always on, statistically speaking. Low current contactor relays.

2. Bell-crank system - >150A power contactors

3. Wiping contact - > 150A power contactors.

4. Leaf spring - can be used anywhere, but generally in larger power contactors.

Regrettably, unless you are a manufacturer of the starter motor, this knowledge is of no help to you. You will probably have to check the connection integrity and, if that is ok, replace the thing.

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#10

Re: Contact Bouncing in Starter Motor Solenoid

09/18/2011 5:57 AM

i've run across this problem a few times. it's caused by damaged winding in the solenoid. sorry, you have to replace it.

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#11

Re: Contact Bouncing in Starter Motor Solenoid

09/18/2011 7:53 PM

Go to the lectures and read the text you have been given.

Your other question about air conditioning sounded like homework too.

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