Snmek 1

Anglicky v odbornch pedmtech"Support of teaching technical subjects in EnglishTutorial: Mechanik - elektrotechnik

Topic: Basics of electrical engineeringthe 2nd. yearMeasuring inductancePrepared by: Ing. Ji Smlek

Projekt Anglicky v odbornch pedmtech, CZ.1.07/1.3.09/04.0002je spolufinancovn Evropskm socilnm fondem a sttnm rozpotem esk republiky.

Definition:

Measuring InductanceInductance is the ratio of the coupled induction flux to the current which passes through the coil.Coupled magnetic flux to the current that flows through the coilThe basic unit - 1 H (henry)L- inductance coilM - magnetic flux coupled coilsI current passing through the coilN number of turns in the coilsThe mutual inductance M of two close coils is the ratio of the induced emf in the first coil caused by a current in the second coil or vice versa - M1 = M2

Slovnk:induknost cvkymagnetick spaen tok cvkymagnetick tok cvkyproud protkajc cvkoupoet zvit cvkyZkladn jednotka Frazeologie:Induknost je pomr spaenho induknho toku k proudu, kter protk cvkou Vzjemn induknost M dvou blzkch cvek je pomr indukovanho elektromotorickho napt v prvn cvce vyvolan proudem druh cvky nebo opan2The used method:

Measuring inductanceDeviation method inductance is measured by an A-metre and V-metre to determine the value of the measured resistance deviation or determine the numeric value. Connection for the measurement of smaller inductance/ coils

Connection for the measurement of larger inductance/coils

Slovnk:

Frazeologie:Vchylkov metoda induknost se m A-metrem a V-metrem udvajcmi hodnotu namenho odporu vchylkou nebo selnm dajemZapojen pro men men induknosti / cvkyZapojen pro men vt induknosti / cvky

3Calculation:

Measuring inductanceSelf inductance can be determined from the definition of impedance:

Apparent power coils:

Coil impedance:

Coil resistance

Slovnk:Zdnliv vkon cvky:Impedance cvky:Odpor cvkyFrazeologie:Vlastn induknost urme z definice impedance4The measurement procedure:

Measuring inductionTo measure inductance using the indirect method we must know the voltage and the current calculate RX and ZLX calculate LXTo measure the resistance a DC current must flow in the circuitTo measure the inductance an AC current must flow in the circuit

Method suitable for measuring air coils in operation

Slovnk:

Frazeologie:Pro men induknosti nepmou metodou musme znt napt a proud vpoet RX a ZLX vpoet LXPi men odporu mus tct obvodem stejnosmrn proudPi men induknosti mus tct obvodem stdav proudMetoda vhodn pro men vzduchovch cvek v provozu

5The used method:

Measuring inductance with an iron coreDeviation method inductance is measured by an A-metre, V-metre and a W-metre - Inductance coils with an iron core are not constant because they depend on the magnetic flux, that is the current passing through the coil

Resistance Rreg adjusted current for example of 0.25 A and read current I, voltage U and power P (losses in the turns and the iron). From the measured values we calculate the coils impedance:

The measurement procedure:

Slovnk:ztrty ve vinut a v elezeFrazeologie:Vchylkov metoda induknost se m A-metrem, V-metrem a W-metrem - Induknost cvky se eleznm jdrem nen konstantn, protoe zvis na magnetickm toku ili na proudu prochzejcm cvkou.Odporem Rreg nastavujenme proud nap. po 0,25 A a teme proud I, napt U a pkon P.Z namench hodnot vypotme impedanci cvky:6Calculations:

Measuring inductance with an iron coreFrom the measured values we calculate:Coil impedance:

Active resistance:

Inductance:

Inductance can also be calculated from the relationship:

Of which

Slovnk:Impedance cvkyinn odporInduknostFrazeologie:Z namench hodnot vypotme:Induknost lze tak vypotat ze vztahu:z toho

7The used method:

Measurement of inductance bridgesBridge method inductance with a Maxwell-Wien bridge

The condition of the bridge balance:

After treatment and separation of real and imaginary members:

Slovnk:Mstkov metoda Frazeologie:Podmnka rovnovhy mstku:Po prav a oddlen relnch a imaginrnch len:8Describe how induction is defined Describe how mutual inductance is defined Write how you know the types of coils Write what methods can measure inductance direct

indirect

Activities for students - questions

Slovnk:Frazeologie:Popi jak je definovan induknost Popi jak je definovan vzjemn induknostNapi jak zn druhy cvek Napi jakmi metodami lze zmit induknost

9Explain why an inductance coil with an iron core is not constant Write a procedure to measure inductance with an iron core Write the procedure to calculate the inductance from the measured values Activities for students questions

Slovnk: Frazeologie:Vysvtli pro nen induknost cvky se eleznm jdrem konstantn Napi postup men induknosti se eleznm jdrem Napi postup vpotu induknosti z namench hodnot 10Muk, J. Management ve vzdlvn dosplch. Praha: EUROLEX BOHEMIA, 2000. ISBN 80-7361-269-7.Operan program Vzdlvn pro konkurenceschopnost, ESF 2007 2013.Dostupn na: http://www.msmt.cz/eu/provadeci-dokument-k-op-vzdelavani-pro-konkurenceschopnostUebnice Elektrick men Ing. Pavel Vylegala, SE Ostrava, 2006Uebnice Elektrick men SNTL, 1981Elektrotechnika - Laboratorn cvien pro bakalsk studium - Doc. Ing. Milo Hammer, CSc.

Bibliography