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Phase shift for multiable coils

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Andy

Thu Jan 08 2015, 06:33AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

Hi, im using the foumlas for Xc and Xl with phase shift =tan(Xl_Xc).
Was wondering if the first coil is 1H and a cap at 10uF should make it resonant at 50Hz, but for the next coil do I make it 1 degree shifted and the second coil 2 degrees shift, or is it just 1 degree on ever coil upto 90 degrees.

Cheers

Dr. Slack

Thu Jan 08 2015, 12:02PM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

As ever, post what you are trying to acheive, and post the circuit diagram you are considering. Without those, your OP is next to meaningless.

Andy

Thu Jan 08 2015, 03:47PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

Im trying to have a linear motor, with multiable electromagntics ,I would like the coils to reach there peak one after the other from the same voltage source, each coil will have a capacitor in series and each coil will be in series.

Sulaiman

Thu Jan 08 2015, 04:51PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Interresting idea, quite some maths involved,
but treat it as a delay-line filter and you can use online calculators
BUT
I foresee a problem,
the 'Q' of such things is usually >1,
which means that at any one time
more reactive (+/-j, +/-90degrees) power will be in the system than real power,
requiring much higher current and/or voltage rated components than a 'conventional' machine

Dr. Slack

Thu Jan 08 2015, 06:38PM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

Post a diagram.

If each coil is in series, and each coil has a series capacitor, then all components are in series, which means they all carry the same current, which means the magnetising force all all coils is in phase.

Unless I've got it wrong and a diagram would show which components are in parallel.

Andy

Thu Jan 08 2015, 07:36PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Thanks Sulaiman, checked out goggle images, which lead to the below image, is this what you meant?

1420745795 4266 FT168161 Img 20150109 083332

Sulaiman

Thu Jan 08 2015, 10:15PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

That's what I had in mind.
But I don't know if it's actually what you need.

Andy

Thu Jan 08 2015, 11:44PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

The idea is to have the below image, but replace the Neos with electromags, and the plates in phase with the electromags, the next block, is slight delayed phase that matchs the speed of water flow.
The reason for ac is to stop the plates wearing out.

1420760691 4266 FT168161 Img 20150109 122818

Sulaiman

Fri Jan 09 2015, 02:10PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

I have no experience in such motors
but I imagine that any current not in the magnetic field is wasted
so I'd try a larger magnetic field and smaller electrodes.

I suspect that to replace the magnetic field of NdFeB magnets with a similar field generated by electromagnets
will result in quite large and heavy electromagnet assemblies
and consume quite a bit of power.
With D.C and magnets you can use the steel structure(s) of the vessel as part of the magnetic circuit
you would have to use very low frequency ac to use solid steel as part of the magnetic structure
to avoid massive losses in the steel,
maybe not ac but use dc of alternating polarity with a low switching speed ?
(probably won't prevent corrosion though).

From memory, a pair of relevant thoughts;

1) the electrical power (real volts x amps) required for an electromagnet is proportional to
(total magnetic flux) x (effective magnetic path length)
which can be considered as (flux density)x(area) x (magnetic path length)
or just (magnetic flux density) x (volume of magnetic field)

2) the force on a current in a magnetic field is proportional to
(flux density) x (current) x (length of current path in magnetic field)

just random thoughts based on no direct experience, could be completely wrong!

Andy

Fri Jan 09 2015, 08:26PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

With 1&2 ,how much difference in power woul these two compare like

Compared to price, would it be better to get the large mag, at double the price.
Not sure weather to use 240 volt 10 amp recifered, or 24 volt car batterys for the plates.

I,ve checked out dc electromagntics, for 700 lb force cost about the same as the n52 above, but think a cap at resonace with the coil and try running it onac might work.

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