AS 1018-1985

1 - AS 1018-1985 PARTIAL DISCHARGE MEASUREMENTS
4 - PREFACE
5 - CONTENTS
6 - 1. Scope
7 - 2. Object
7 - 3. Definitions
7 - 3.1 Partial discharge
7 - 3.2 Quantities related to partial discharges
7 - 3.2.1 General
7 - 3.2.2 Apparent charge q
8 - 3.2.3 Repetition rate n
8 - 3.2.4 Integrated quantities
8 - 3.3 Specified partial discharge magnitude
8 - 3.4 Voltages related to partial discharges
8 - 3.4.1 Partial discharge inception voltage Ui
8 - 3.4.2 Partial discharge extinction voltage Ue
9 - 3.4.3 Partial discharge test voltage
9 - 4. Test circuits and measuring instruments
9 - 4.1 General requirements
9 - 4.2 Test circuits
10 - 4.2.1 Measuring circuit characteristics
10 - 4.2.2 Scale factor of the test circuit kc
10 - 4.2.3 Measuring impedance
11 - 4.2.4 Coupling capacitor
11 - 4.3 Measuring instruments
11 - 4.3.1 Scale factor of the measuring instrument ki
11 - 4.3.2 Instruments for the measurement of apparent charge q
12 - 4.3.3 Instruments for the measurement of pulse repetition rate n
12 - 4.3.4 Instruments for the measurement of average discharge current I
12 - 4.3.5 Instruments for the measurement of quadratic rate D
12 - 4.3.6 Arrangements for the measurement of discharge power P
12 - 4.3.7 Use of radio interference meters for the measurement of partial discharges
13 - 4.4 Non-electrical methods of detection
13 - 4.4.1 Acoustic detection
13 - 4.4.2 Visual or optical detection
13 - 4.4.3 Observations of tracking
13 - 4.4.4 Dissolved gases in oil
13 - 5. Calibration
13 - 5.1 General
14 - 5.2 Determination of instrument characteristics
14 - 5.2.1 Calibration of instruments measuring apparent charge q
15 - 5.2.2 Calibration of instruments measuring integrated quantities
15 - 5.3 Calibration of the instrument in the complete test arrangement
16 - 6. Tests
16 - 6.1 General requirements
16 - 6.2 Conditioning of the test object
16 - 6.3 Requirements for the test voltage
16 - 6.4 Choice of test procedure
16 - 6.4.1 Determination of the partial discharge inception and extinction voltages
17 - 6.4.2 Determination of the partial discharge magnitude at a specified test voltage
17 - 6.5 Measurements on cables and on test objects with windings
17 - 7. Measuring accuracy and sensitivity
18 - 8. Disturbances
18 - 8.1 Sources of disturbances
18 - 8.2 Detecting disturbances
19 - 8.3 Reduction of disturbances
19 - 8.3.1 General
19 - 8.3.2 Balanced circuits
19 - 8.3.3 Electronic processing and recovering of signals
20 - 8.4 Disturbance levels
20 - 9. Special requirements for partial discharge measurements during tests with direct voltage
20 - 9.1 General
21 - 9.2 Quantities related to partial discharges
21 - 9.3 Voltages related to partial discharges
21 - 9.3.1 Partial discharge inception and extinction voltages
21 - 9.3.2 Partial discharge test voltage
21 - 9.4 Test circuits and measuring instruments
21 - 9.5 Tests
21 - 9.5.1 Requirements for the test voltage
21 - 9.5.2 Choice of test procedure
22 - 9.6 Disturbances
23 - APPENDIX A - TEST CIRCUITS
25 - APPENDIX B - INTEGRATED QUANTITIES
26 - APPENDIX C - MEASUREMENTS ON CABLES AND ON TEST OBJECTS WITH WINDINGS
27 - APPENDIX D - THE USE OF RADIO INTERFERENCE METERS FOR THE MEASUREMENT OF PARTIAL DISCHARGES

Describes types of measuring instruments, test circuits and methods of measurement of partial discharges in various types of electrical equipment. It is intended principally as a guide for use in the preparation of the relevant standard specifications for such equipment. Specifies requirements and test methods identical with those in IEC 270.

This standard applies to the measurement of partial discharges during tests with alternating voltage, but general terms, definitions and requirements are usually also applicable for measurement of partial discharges during tests with direct voltage. Some special characteristics of partial discharge measurements under direct voltage are given in a separate clause and necessary references are made throughout the text. This standard is intended principally as a general guide to the drafting of specifications for specific apparatus.Measurements of partial discharges are made for the following main purposes:- to verify that the test object does not exhibit partial discharges greater than a specified magnitude, at a specified voltage;- to determine the voltage amplitude at which partial discharges of a specified low magnitude commence with increasing voltage and cease with decreasing voltage;- to determine the magnitude of the specified discharge quantity at a specified voltage.The partial discharges which are considered in this standard are localized electrical discharges in insulating media, restricted to only a part of the dielectric under test and only partially bridging the insulation between conductors. Discharges mostly occur in the form of individual pulses, which can be detected as electrical pulses in the external circuit connected to the test object. However, a more continuous form may also occur, the so-called pulseless discharge. This form will normally not be detected by the measurement methods described in this standard.Partial discharges may occur in cavities in solid insulation, in gas bubbles in liquid insulation or between layers of insulation with different dielectric characteristics. They may also occur at sharp edges or points of metallic surfaces.Even though they involve only small amounts of energy, partial discharges may lead to progressive deterioration of the dielectric properties of insulating materials; the definition and evaluation of such deterioration, however, is beyond the scope of this standard.Partial discharge measurements on cables and on apparatus having windings, such as transformers, generators and motors, are complicated by attenuation, resonance and travelling wave phenomena. Special requirements for tests on these objects are only briefly dealt with.This standard deals mainly with electrical measurements of partial discharges, but some reference is also made to non-electrical methods.

Under Revision see DR 01020 CP