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Active Contributor

Join Date: Oct 2007
Posts: 24

### Urgent Answer Required. Electromagnet Design

08/09/2012 11:32 PM

Dear friends.

i need urgent answer. Pls Help me out.

i have to build a electromagnet in my project at following constraints.

1: I have core Ms grade 40.

2:Diameter is 30 mm not more then it.

3:Length have no constraint, can be more then 3 inches.

4:DC source 12 Volt 60Ah Car Battery.

5: Maximum Ampere not more then 2 A at 12 volt.

6: both poles are at opposite sides. through thickness of Core.

Kindly tell me coil data and length of core required to get Repel force of that electromagnet on N35 of 30mm * 30mm Piece should be 100 ponds. at 0.1 inches and at 38 mm more then 10 pounds.

I need to repel N35 of 30mm * 30mm Piece with that electromagnet. up to 38 mm distance. N35 magnet have repel force on same magnet at the distance 0.1 inches 75 pounds and at 38 mm distance it is 7 pounds.

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Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 5506
#1

### Re: Urgent answer required. Electromagnet design

08/10/2012 12:08 AM
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Active Contributor

Join Date: Oct 2007
Posts: 24
#2

### Re: Urgent answer required. Electromagnet design

08/11/2012 12:42 AM

thanks dear what i get is

B= (Mu*N*I)/Gap

Gap is in meter

I is in ampere

If i made a coil according to following formula r=V/I to get max resistance of coil.

at 12 vdc and I needed is 2 ampere so R=6 Ohm.

i use 24 gauge wire. resistance of 1000 feet is 25 ohm. thats mean at 12 vdc 1000feet of wire draw 0.48 amp.to get more currents and turns i make parallel winding. of 1000 feet and 500 feet. that gives me current of 1.48 Amp.

to find out how much gauss at 1 mm and 38 mm gaps i used B= (Mu*N*I)/Gap

B= (4*pi *10^-7 *1.5 A *1500)/1*10^-3m = 2.8 Tesla and 28000 gauss

at 38 mm it is 0.07 Tesla and 700 gauss.

is i did all calculations ok.

to reduce the dia of coil i should increase length of core because i can not reduce dia of core.

Power-User

Join Date: Jun 2010
Posts: 205
#3

### Re: Urgent answer required. Electromagnet design

08/11/2012 3:59 AM

At 1mm gap, it won't be 28000 Gauss. The steel will be close to saturation at about 14000 Gauss.

Active Contributor

Join Date: Oct 2007
Posts: 24
#6

### Re: Urgent answer required. Electromagnet design

08/14/2012 11:05 PM

thanks friend for information. this is calculation against no of turns, current and size of core.

can you tell me which material can give me this gausses ???

Power-User

Join Date: Nov 2006
Posts: 146
#4

### Re: Urgent answer required. Electromagnet design

08/11/2012 11:47 AM

If 1000 ft draws 0.48 A then 500 ft will draw 0.96 A, 250 ft will draw 1.92 A and 333-1/3 ft will draw 1.44 A. Why not use one 333 ft length of wire? It would be less bulky and keep the turns closer to the core.

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Active Contributor

Join Date: Oct 2007
Posts: 24
#5

### Re: Urgent answer required. Electromagnet design

08/14/2012 11:02 PM

it because, to increase magnetic field by increasing no of turns.