Saturation of a Magnetic Frame
Saturation of a Magnetic Frame
(OP)
Is it feasible to determine whether or not a magnetic frame is saturated by the following experiment?
Device: A small solenoid, approx 1.5inch by 2.0inch.
Method:
The solenoid is secured in a non-magnetic fixture.
The armature position is fixed half way along its stoke. [full stroke approx ¼ inch]
The armature is attached to a force gauge via a non-magnetic rod.
The coil power is increased at regular intervals whilst readings are recoded off the force gauge.
Prediction: The reading with the greatest magnitude is the point where the amp-turns are sufficient to saturate the magnetic circuit.
I appreciate that the efficiency of the magnetic circuit will be reduced by the air gap (approx 1/8 inch), but will this simple experiment provide me with sufficient information to determine if the coil frame is fully saturated? Thermal considerations negated.
I’d appreciate your comments:
Thanks & regards,
Device: A small solenoid, approx 1.5inch by 2.0inch.
Method:
The solenoid is secured in a non-magnetic fixture.
The armature position is fixed half way along its stoke. [full stroke approx ¼ inch]
The armature is attached to a force gauge via a non-magnetic rod.
The coil power is increased at regular intervals whilst readings are recoded off the force gauge.
Prediction: The reading with the greatest magnitude is the point where the amp-turns are sufficient to saturate the magnetic circuit.
I appreciate that the efficiency of the magnetic circuit will be reduced by the air gap (approx 1/8 inch), but will this simple experiment provide me with sufficient information to determine if the coil frame is fully saturated? Thermal considerations negated.
I’d appreciate your comments:
Thanks & regards,





RE: Saturation of a Magnetic Frame
If the amp-turns aren't sufficient to saturate the frame, then a max force reading is meaningless.
In addition, the solenoid may not have been desigend to operate near saturation. They are most efficient when operating in a region of high permeability which occurs before saturation.
RE: Saturation of a Magnetic Frame
I can confirm that I will be able to generate enough A-ts to saturate the frame. Also, to be clear, I should have mentioned that this is a DC solenoid.
I was hoping the exp will also show me how much power is required to fully saturate the frame, and to define the point on the curve where normal operation occurs. What i'm not sure about is (a) if this exp is feasible and (b) the best position for the armature e.g. fully open (max air gap), mid way, or just off its stop (min air gap).
RE: Saturation of a Magnetic Frame
If you have enough field then I would expect to see the curve come out looking just like a magnetization curve.
As you crank the field you will continue to get increased force, but it will increase very slowly once you are into a region of lower permiability, even if you haven't reached saturation.
You can easily test at different locations, this somewhat depends on design and leakage factors, but hte highest force should be with the smallest air gap.
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RE: Saturation of a Magnetic Frame
That's what I was thinking.
So, for this method, I have one vote for and one vote against.
Kind regards,
RE: Saturation of a Magnetic Frame
RE: Saturation of a Magnetic Frame
Be sure to measure actual current and not supply voltage because the resistance of your winding will go up as you increase power to the solenoid.