Transformer output indepedent of core permeability

In summary, the voltage is determined by the turns ratio and is independent of the mu of the core material.
  • #1
rutman
3
0
I am having trouble pinning down why the relative permeability of a transformer core will not directly affect the output voltage. In fact the voltage is determined by the turns ratio and is independent of mu of core material.

Given this where is the flaw in the following reasoning:
Induced field strength H is proportional to current in primary coil, H=k I (to be exact , integral H*dl = If+dD/dt)
Magnetic flux density in core is B=mu H
Voltage in single turn of secondary is proportional to rate of change of B; V=A dB/dt = A mu dH/dt = A mu k dI/dt

From this (apparently specious) reasoning, output voltage depends on mu.
 
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  • #2
It's because, in the normal way one uses a transformer, H decreases as µ increases, to keep B constant.

The point is that the primary winding sees B and the flux just as the secondary does. In a good transformer, the primary voltage makes the flux, with very little losses, and the secondary sees the same flux - except that they multiply it by their own numbers of turns.

Now if you have a very bad transformer which is inefficient at producing B and loses most primary voltage in the resistance of its copper windings, then H would be more constant than B, and µ would increase B and the secondary voltage.
 
  • #3
thanks that rings true. it opens the question why I am setting B instead of H; I've seen maxwell equation formulations with D, H instead of E, B but I suppose what you are saying is that the E,B form is 'basic' and the D,H forms are 'dependent' theron.
ie when i run current thru a wire i determine B, and if i bring a piece of iron or such near, the H is dependent on the extant B and mu of the material
 

What is "Transformer output independent of core permeability"?

Transformer output independent of core permeability refers to the principle that the output voltage and current of a transformer remain constant despite changes in the magnetic permeability of the transformer's core material.

Why is it important for transformer output to be independent of core permeability?

This is important because it ensures that the transformer's output remains stable and predictable, regardless of external factors that may affect the core's magnetic properties. This allows for reliable and consistent performance of the transformer.

How is transformer output independent of core permeability achieved?

This is achieved through careful design and selection of the core material and shape, as well as proper winding techniques. The core material should have a high saturation point and low hysteresis, and the windings should be evenly distributed and tightly coupled to minimize flux leakage.

What are the benefits of having transformer output independent of core permeability?

Having transformer output independent of core permeability allows for more efficient and accurate power distribution. It also reduces the risk of overheating and damage to the transformer, as well as improves its lifespan and reliability.

Are there any limitations to achieving transformer output independent of core permeability?

While careful design and construction can greatly reduce the impact of core permeability on transformer output, it is not possible to completely eliminate it. Changes in temperature, humidity, and other environmental factors can still affect the core's magnetic properties and therefore, to some extent, the transformer's output.

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