Standard Inductor Values

3 Key excerpts on "Standard Inductor Values"

• 

  eBook - PDF

  Handbook of Power Management Circuits

  • Haruo Kobayashi, Takashi Nabeshima, Haruo Kobayashi, Takashi Nabeshima(Authors)
  • 2016(Publication Date)
  • Jenny Stanford Publishing

    (Publisher)

  6.1 Inductors and Transformers 6.1.1 Inductors 6.1.1.1 Definition of an inductor An inductor is a circuit element that is widely used in electronic circuits. Current flow through a conductive wire produces magnetic flux around the wire, following the Maxwell corkscrew (right-handed screw) rule. The main characteristic of an inductor is the magnetic flux that it produces when a current is passed through it. Although wire conductors also possess inductance components, the value is negligibly small. Chapter 6 Passive Components Yuya Tamai a and Yoshiyuki Ishihara b a Solution R & D Department, R & D Headquarters, Nippon Chemi-Con Corporation, 6-4, Osaki 5-Chome, Shinagawa-ku, Tokyo 141-8605, Japan b Electrical Engineering Department, Faculty of Science and Engineering, Doshisha University, Kyotanabe 610-0321, Japan [email protected], [email protected] Handbook of Power Management Circuits Edited by Haruo Kobayashi and Takashi Nabeshima Copyright © 2016 Pan Stanford Publishing Pte. Ltd. ISBN 978-981-4613-15-6 (Hardcover), 978-981-4613-16-3 (eBook) www.panstanford.com 136 Passive Components Inductance L (H) is the proportionality constant between the current flow I (A) through the wire and the linkage flux Φ , and the relation is expressed as follows: Φ = LI (Wb) (6.1) Here L is the value of inductance. When an inductor is used as a circuit component, it is usually constructed by winding a wire into a coil. This case, inductance is expressed as follows: L = n / R m (H) (6.2) Here, n is the number of turns and R m is the magnetic reluctance (A/Wb). Magnetic reluctance, R m , is given by R m = l /( μS ) (A/Wb) (6.3) Here, l is the average magnetic path length (m), μ is the permeability (H/m), and S is the cross-sectional area of the magnetic path (m 2 ).

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Electronics and Electronic Systems

  • George H. Olsen(Author)
  • 2013(Publication Date)
  • Butterworth-Heinemann

    (Publisher)

  The magnetic circuit is completed by a central cylindrical core. For a given inductor some variation of inductance is possible by adjusting the position of the central core or by varying the pressure at which the two ferrite cylinders are held together. Figure 2.9 Physical appearance of two forms of inductor: (a) Construction of an inductor for power frequencies. The shape of the laminations is shown on the left. Either combination may be used; (b) Essential parts of a 'pot-core' inductor Energy storage in inductors The process of establishing a current and associated magnetic field in an inductor involves the expenditure of energy. The total energy stored, / L , is measured by summing all the increments of work performed during the process of establishing the field, i.e. ni l j L = J V idt = J L ^-idt = | Liai (v is the instantaneous applied voltage, i.e. Ldi/dt.) Passive components 21 As the magnetic field collapses the energy is returned to the source. In a perfect inductor no energy is lost; like the capacitor, an inductor does not dissipate energy. Mutual inductance If two coils are placed close to each other so that a varying magnetic field in one coil induces an e.m.f. in the second coil, the two coils are said to be inductively coupled. The changing magnetic flux due to the current in the first or primary circuit must interlink the secondary circuit in order to induce an e.m.f. in the secondary coil. The phenomenon is called mutual induction. The mutual inductance, M, between the two coils is measured in henries and depends upon (a) the number of turns in the primary coil, (b) the number of turns in the secondary coil, (c) the relative position of the coils, and (d) the permeability of the medium between the coils. ., _ Induced voltage (e) in the secondary coil Rate of change of current in the primary When inductors are connected in series the total inductance is calculated in the same manner as that used for resistors in series.

  Sign up to read

  Learn more about book
• 

  eBook - PDF

  Newnes Circuit Calculations Pocket Book

  with Computer Programs

  • Thomas J. Davies(Author)
  • 2016(Publication Date)
  • Newnes

    (Publisher)

  8 Inductors 8.1 Introduction Inductors consist of coils of insulated wire wound on bobbins or formers. Inductance is the property of the coil which tends to prevent a change of current in a circuit. When current is flowing in a coil of wire, magnetic flux is produced which cuts the coil, and when this current is changing a voltage is induced in the coil. The induced voltage exactly balances the applied voltage which is producing the current. Inductance, L, is measured in henrys, which have unit symbol H, and a closed circuit has an inductance of one henry if an e.m.f. of one volt is induced when the current is varying at one ampere per second. 8.2 Units Inductance is expressed in henrys, and the subunits and the relationships between them are: 1 The millihenry where 1 mH = H or 1 0 -3 H 1 The microhenry where 1 |xH = H or 10 H Transposing these relationships shows that 10 3 mH = 1 H 10 6 u,H = 1 H and since 10 3 mH = 10 6 u.H then 1 mH = 10 3 jxH and 1 u,H = 10 3 mH Example 1 Express a 0.25-H inductor in millihenrys and micro-henrys. 0.25 H = 0.25 x 10 3 = 250 mH 0.25 H = 0.25 x 10 6 = 25 x 10 4 u,H or 2.5 x 10 5 u,H 10 PRINT PROG 95 20 PRINT CONVERSION OF HENRYS TO OTHER UNITS 30 INPUT ENTER HENRYS ; II 40 LET MH=H*10*3 50 LET UH=II*10*6 60 PRINT H HENRYS = MH MILLIHENRYS 70 PRINT H HENRYS = UH MICROHENRYS 126 Circuit calculations pocket book Example 2 An inductor has a value of 820 aH.

  Sign up to read

  Learn more about book