Disclosure to Promote the Right To Information

Transcription

1 इ टरन ट म नक Disclosure to Promote the Right To Information Whereas the Parliament of India has set out to provide a practical regime of right to information for citizens to secure access to information under the control of public authorities, in order to promote transparency and accountability in the working of every public authority, and whereas the attached publication of the Bureau of Indian Standards is of particular interest to the public, particularly disadvantaged communities and those engaged in the pursuit of education and knowledge, the attached public safety standard is made available to promote the timely dissemination of this information in an accurate manner to the public. ज न1 क अ+धक र, ज 1 क अ+धक र Mazdoor Kisan Shakti Sangathan The Right to Information, The Right to Live प0र 1 क छ ड न' 5 तरफ Jawaharlal Nehru Step Out From the Old to the New IS (1983): High voltage fuses, Part 4: Determination of short-circuit power factor for testing of high voltage fuses [ETD 39: Fuses]! न $ एक न' भ रत क +नम-ण Satyanarayan Gangaram Pitroda Invent a New India Using Knowledge! न एक ऐस खज न > ज कभ च0र य नहB ज सकत ह ह Bhartṛhari Nītiśatakam Knowledge is such a treasure which cannot be stolen

2

3

4

5 Indian Standard SPECIFICATION FOR HIGH VOLTAGE FUSES IS:9385(Part4) PART 4 DETERMINATION OF SHORT-CIRCUIT POWER FACTOR FOR TESTING HIGH VOLTAGE FUSES High Voltage Switchgear and Controlgear ETDC 58 Sectional Committee, Chair man SHRI H. M. PA1 Members Representing The Ahmedabad Electricity Co Ltd, Ahmadabad SHRI M. B. BAHULKAR ( Alternate to Shri H. M. Pai ) SHRI R. CHANDRAMOULI Tata Hydro-Electric Power Supply Co Ltd, Bombay SMT C. BAUGA ( Alternate ) CHIEF ENGINEER Calcutta Electric Supply Corporation Ltd, Calcutta SHRI T. K. GHO~E ( Alternate ) DIRECTOR Central Power Research Institute, Bangalore JOINT DIRECTOR, STDS ( Alternate ) SENIOR DEPUTY DIRECTOR (Alternate ) DIRECTOR,SUB-STATION Central Electricity Authority, New Delhi DIRECTORATE DEPUTY DIRBCTOR, SUB-STATION ( Alternate ) SHRI G. L. DUA Rural Electrification Corpn Ltd, New Delhi Sum S. C. KHURANA ( Alternate ) SHRI B. V. ESWAR ASEA Ltd, Nasik SHRI S. SUBRAMANIAN ( Alternate ) SHRI K. L. GARG Directo&;~neral of Supplies and Disposals, SBm R. V. NARAYANAN ( AIternate Copyright 1983 ( Continued on page 2 ) INDIAN STANDARDS INSTITUTION This publication is protected under the Indian Copyright Act ( XIV of 1957 ) and reproduction in whole or in part by any means except with written permission of the publisher shall be deemed to be an infringement of copyright under the said Act.

6 IS: 9389 (Part4)-1483 ( Continued from page 1 ). Members Representing SHRI B. N. GHOSH Bharat Heavy Electricals Ltd, Hyderabad SHRI A. RAJA RAO ( Alternate ) SHRI D. K. SINGLE ( Alternate ) SHRI Y. R. GODSE Bombay Electric SUPPlY and Transport Undertaking, Bombay SHRI D. SWAMINATHAN ( Alternate ) SHRI JAYANT N. GURJAR Kirloskar-Asea Ltd, Bangalore SHKI P.D. JAHAGIRDAR Maharashtra State Electricity Board, Bombay SHRI JAVEED AHMED NGEF Ltd, Bangalore SHRI K. P. SARATHY ( Alternate ) SHKJ P. M. JOSEPH Aluminium Industries Ltd, Kundara SHRI C. M. A. NAYAR ( Alfernate ) SHR~ G. K. KHEMANI Central Public Works Department, New Delhi SURVEYOR OF WORKS III ( Alternate ) SHRI B. N. KIS~ORE Crompton Greaves Ltd, Bombay SHRI A. N. VhNUGoPAL ( Alternate ) SHRI V. S. MANI Hindustan Brown Boveri Ltd, Vadodara SHKI S. R. POTNIS ( Alternate ) SHRI S. G. MENON Tata Consulting Engineers, Bombay SHRI C. S. KUMAR ( Alternate ) SHRI S. K. MUKHERJEE National Test House, Calcutta SHRI P. C. PRADHAN ( Alternate ) SHFZ B. S. NARASIMHAN Mysore Electrical Industries, Bangalore SHRI R. SATYANARAYANA SH~RMA ( Alternate ) SHRI J. S. NEGI Jyoti Limited, Vadodara SHRI R. M. NANAVATI ( Alternate > SHRI S. G. NEN~ Siemens India Ltd, Bombay SHRI T. C. NEELAKANTAN ( Alternate ) SHRI A. S. PINTO Delhi Electric Supply Undertaking, New Delhi SHR~ 0. P. ANAND ( Alternate ) THIRU T. E. B. SAMUEL Tamil Nadu Electricity Board, Madras THIRU T. SHEMB~HARAJAN ( Alternate ) REPRESENTATIVE Indian Institute of Technology, New Delhi REPRESENTATIVE Rese;x&,oI$esign & Standards Organization, SHR~ S. P. SACHDEV, Director General, ISI ( Ex-officio Member ) Director ( Elec tech ) Secretary SHRI K. GANESH Assistant Director ( Elec tech ), ISI

7 Indiun Standard SPECIFICATION FOR HIGH VOLTAGE FUSES PART 4 DETERMINATION OF SHORT-CIRCUIT POWER FACTOR FOR TESTING HIGH VOLTAGE FUSES 0. FOREWORD IS : 9385 ( Part 4 ) This Indian Standard ( Part 4 > was adopted by the Indian Standards Institution on 28 June 1983, after the draft finalized by the High Voltage Switchgear and Controlgear Sectional Committee had been approved by the Electrotechnical Division Council. 0.2 Requirements and tests for high voltage fuses of the current limiting and expulsion-type are covered in Parts 1 and 2 of this Indian standard. As a necessary adjunct to these standards a third part in the series was brought out covering guidelines on application of high voltage fuselinks. 0.3 For the breaking tests, there is no method by which the short-circuit power factor can be determined with precision, due to variation of resistance with frequency and current and of inductance with time and current. However, it had been possible to evolve methods by which the power factor of each phase of the test circuit may be determined with sufficient accuracy. 0.4 This standard ( Part 4 ) covers the following three methods of determining the short-circuit power factor appropriately: a) Method I is recommended for the determination of power factors higher than 0 3 ( for example, test duty 3 for currentlimiting fuses and test series 4 and 5 for expulsion fuses ) because it is generally not accurate for very low power factors due to difficulty in measurement of the resistance; b) Method II is recommended for the determination of power factors lower than 0 3 ( for example, test duties 1 and 2 for current-limiting fuses and test series 1, 2 and 3 for expulsion fuses ) because it is generally not accurate for power factors higher than 0 3 due to the short duration of the dc component and difficulty in determination of its time constant; and 3

8 .IS : 9385 ( Part 4 ) c) Method III is recommended for the determination of power factors higher than 0 5 ( for example, test series 5 for expulsion fuses ) because it is generally not accurate in the case of power factors below O S due to the necessary degree of accuracy with which phase displacements need to be measured. 0.5 In the preparation of this standard, considerable assistance has been derived from IEC Pub ( 1976) High voltage fuses: Part 3 Determination of short-circuit power factor for testing current-limiting fuses and expulsion and similar fuses issued by the International Electrotechnical Commission. This standard corresponds with IEC Pub ( 1976 ) and there are no major differences. 0.6 For the purpose of deciding whether a particular requirement of this standard is complied with, the final value, observed or calculated, expressing the result of a test or analysis, shall be rounded off in accordance with IS : *. The number of significant places retained in the rounded off value should be the same as that of the specified value in this standard. 1. SCOPE 1.1 This standard ( Part 4 > covers guidelines on methods of determination of short-circuit power factor for testing current-limiting fuses and expulsion and similar fuses. 1.2 The complete method of short-circuit tests on high voltage fuses are covered in Parts 1 and 2 of this standard. 2. TERMINOLOGY 2.1 For the purposes of this standard, the definitions given in Parts 1 and 2 of this standaid shall apply. 3. METHODS OF DETERMINKNG FACTOR SHORT-CLRCUIT POWER 3.1 Method I - Calculation from Circuit Constants - The power factor may be calculated as the cosine of an angle 4 where + = arc tan X/R, X *Rplqs for rounding off numerical values ( revised ). 4

9 Is : 9385 ( Part 4 ) - i983 and R being respectively the reactance while the short-circuit exists. and resistance of the test circuit R is measured in the test circuit with direct current; if the circuit includes a transformer, the resistance R1 of the primary circuit and the resistance Rz of the secondary circuit are measured separattly and the required value R is then given by the formula: R = Rz + R,r in which r is the ratio of transformation X is then obtained from the formula: X;=&E/I) -RR2 of the transformer. the ratio E/I ( circuit impedance) being obtained from the oscillogram as indicated in Fig. 1. Due to variation of generator reactance with current, the calibration test shall be at the bame excitation as the fuse test in each case. NOTE -Power factor can be obtained directly by this method by dividing resistance R by impedance E/I without reference to reactance cos d, = R T 3.2 Method II - Determination from dc Component The angel + may be determined from the curve of the dc component of the prospective asymmetrical current wave as follows ( see of IS : 9385 ( Part 1 )-1979* and of IS : 9385 ( Part 2 )-1980t The time constant L/R can be ascertained as.follows from the dc component: where *Specification id = Id0 e -RtlL id = value of the dc component at any instant; Ido = initial value of the dc component; for voltage fuses: Part 1 Current limiting fuses. tspecification for voltage fuses : Part 2 Expulsion and similar fuses.

10 IS : 9385 ( Part 4 ) CURRENT r CALIBRATION j?ecovery VOLTAGE TEST BREAKING TEST T = duration on first power frequency cycle following initiation of test. E h(v) Circuit impedance --=A1(A) I bl is obtained by extending the voltage envelope to the instant T/2 FIG. 1 DETERMINATION OF CIRCUIT IMPEDANCE FOR CALCULATION OF POWER FACTOR IN ACCORDANCE WITH METHOD I 6

11 L/R = time constant of the circuit, in seconds; t - time interval, in seconds, between ia and ZdO; e = base of Napierian logarithms; a) Measure the value of la0 at the instant of short-circuit and the value of ia at any other time t at which there is still a significant value of dc component; b) determine the value of emrtll by dividing id byz& c) from a table of values of e-, determine the value of -x corresponding to the ratio ia/zdo; d) The value x then represents Rt/L, from which L/R can be determined by dividing x by t Determine the angle $ or power factor from:. 4 = are tan wljr cos += I d 1 +(wl/r) where w is 2 x times the actual frequency. When current transformers are used for this method, attention should be paid to possible errors consequent upon ( a ) the time constant of the transformers and its burden in relation to that of the primary circuit and ( b ) magneticsaturation effects which can result from the transient flux conditions combined with possible remanence. NOTE - This method can be applicable also if the calibration test is made at reduced voltage and correspondingly lower current. 3.3 Method III - Determination with Pilot Generator When a pilot generator is used on the same shaft as the test generator, the voltage of the pilot generator on the oscillogram may be compared in phase first with the voltage of the test generator and then with the current of the test generator. The difference between the phase angles between pilot generator voltage and main generator voltage on the one hand, and pilot generator 7

12 is ( iart 4.) y 1985! voltage and test generator current on the other hand, gives the phase aqgle between the voltage and current of the test generator; from which the power factor can be determined. NOTE - Use of the wattmeter vibrator --ihis method may be. used as an alternative to the above methods to determine the power factor in test duty 3 for currentlimiting fuses according to IS : 9385 ( Part I)-J979* and in test series A and 5 for expulsion and similar fuses according to IS : 9385 ( Part 2 )-1980t. Specifications for high voltage fuses: Part t Current limiting fuses. tspecifications for high voltage fuses: Part 2 Expulsion and similar fuses. 8