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Eddy Current Impedance Formula

This document discusses electrical impedance in eddy current testing. It defines impedance as the total opposition to alternating current, which includes resistance and inductive reactance. It provides an equation for calculating impedance using the Pythagorean theorem, where resistance is represented by the horizontal side of a right triangle and inductive reactance is the vertical side, with impedance as the hypotenuse. The document gives an example calculation of impedance when resistance is 0.6 ohms and inductive reactance is 0.4 ohms.

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Udhayakumar Venkataraman
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728 views4 pages

Eddy Current Impedance Formula

This document discusses electrical impedance in eddy current testing. It defines impedance as the total opposition to alternating current, which includes resistance and inductive reactance. It provides an equation for calculating impedance using the Pythagorean theorem, where resistance is represented by the horizontal side of a right triangle and inductive reactance is the vertical side, with impedance as the hypotenuse. The document gives an example calculation of impedance when resistance is 0.6 ohms and inductive reactance is 0.4 ohms.

Uploaded by

Udhayakumar Venkataraman
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOC, PDF, TXT or read online on Scribd
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Eddy Current Inspection Formula Impedance

Where:
Z = R = XL = Impedance (ohm) Resistance (ohm) Inductance Reactance(ohm)

Electrical Impedance (Z), is the total opposition that a circuit presents to alternating current. Impedance is measured in ohms and may include resistance (R), inductive reactance (XL), and capacitive reactance (XC). Capacitive reactance can usually not present in eddy current testing so this term is not included the equation. The total impedance is not simply the algebraic sum of resistance and inductive reactance. Since the inductive reactance is 90 degrees out of phase with the resistance and, therefore, their maximum values occur at different times, vector addition must be used to calculate impedance. This is illustrated in the image to the right. If the amount of resistance is represented by the length of the horizontal line and the amount of inductive reactance is represented by the length of the vertical line; then, the amount of impedance is represented by the length of the diagonal line. Since the lines form a right triangle, the Pythagorean theorem can be used to find the length (value) of the impedance line. The Pythagorean theorem is written: c2=a2+b2.
For this application the variable, a is equal to resistance, b is equal to inductive reactance, and c is equal to the impedance. So, the equation becomes:

Z2=R2+XL2 When this equation is rewritten to solve for Z, the impedance equation is produced in the form presented .

Example Calculation: Calculate the impedance when the resistance is 0.6 ohms and the inductive reactance is 0.4 ohms. Simply plug in the values and solve for Z.

Eddy Current Inspection Formula -

Ohm's Law

Impedance

Phase Angle

Magnetic Permeability

Where:
I = V = Z =

Where:

Where:

Where:
Magnetic Permeability (Henries/meter) Magnetic Flux Density (Tesla) Magnetizing Force (Am/meter)

= Z = Impedance (ohm) Current (amp) R = Resistance (ohm)XL = Voltage (volt) XL = Inductance R = Reactance(ohm) Impedance (ohm)

Phase Angle (deg) Inductance = Reactance(ohm) Resistance (ohm) B = H =

More Information Ohm's Law Calculator Relative Magnetic Permeability

More Information

More Information Phase Angle Calculator Electrical Conductivity (%IACS)


When resistivity is known

Conductivity & Resistivity

Electrical Conductivity (%IACS)


When conductivity in S/m or S/cm is known

Where: Where:
= =

or Where:

Relative Magnetic Permeability (dimensionless) Any Given Magnetic Permeability (H/m) Magnetic Permeability in Free Space (H/m), which is 1.257 x 10-6 H/m

Electrical = Conductivity Siemens/m = Electrical Resistivity (ohm-m)

Electrical = Conductivity %IACS (% IACS) Electrical = Resistivity ( ohm-cm) Electrical = Conductivity S/cm ( Siemens/cm)

Where:

More Information More Information Current Density Standard Depth of Penetration


When electrical

Electrical = Conductivity (% IACS) Electrical = Conductivity S/m (Siemens/meter) Electrical = Conductivity S/cm ( Siemens/cm)
%IAC

More Information Standard Depth of Penetration


When electrical

More Information

Standard Depth of Penetration


When electrical resistivity

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