AS 2886-1986

1 - AS 2886-1986 VOLTAGE MEASUREMENT-SPHERE-GAP METHOD (ONE SPHERE EARTHED)
4 - PREFACE
5 - CONTENTS
6 - 1. SCOPE AND OBJECT
6 - 2. STANDARD SPHERE-GAP
6 - 2.1 Requirements for the spheres
6 - 2.1.1 Tolerances on size and shape
7 - 2.1.2 State of the surfaces
7 - 2.2 Construction of the shanks of the spheres
7 - 2.2.1 Vertical gap
8 - 2.2.2 Horizontal gap
8 - 2.3 Height of the spheres above the horizontal earth plane
8 - 2.4 Clearance round the spheres
8 - 2.5 Clearance round the spheres (table)
9 - 3. CONNECTION OF THE SPHERE-GAP
9 - 3.1 Earthing
9 - 3.2 High-voltage conductor
9 - 3.3 Protective series resistance in the measurement of alternating and direct voltages
10 - 3.4 Protective series resistance in the measurement of impulse voltages
10 - 4. THE USE OF THE SPHERE-GAP
10 - 4.1 Irradiation
10 - 4.2 Voltage measurements
11 - 4.2.1 Measurement of direct and alternating voltages
11 - 4.2.2 Measurement of impulse voltages
11 - 5. SPHERE-GAP DISRUPTIVE DISCHARGE VOLTAGES
11 - 5.1 Numerical values in the tables
12 - 5.2 Accuracy of the tables
12 - 5.2.1 Alternating and impulse voltages
12 - 5.2.2 Direct voltages
12 - 5.3 Influence of atmospheric conditions
12 - 5.3.1 Atmospheric conditions valid for the tabulated values
12 - 5.3.2 Correction for air density
13 - 5.3.3 Air density correction factor (table)
13 - 5.3.4 Humidity
14 - APPENDIX A - RANGE OF EXPERIMENTAL CALIBRATIONS
15 - APPENDIX B - PROCEDURE BY WHICH THE VALUES IN TABLES I AND II HAVE BEEN DERIVED FROM NATIONAL STANDARDS AND OTHER SOURCES

Adopts IEC 52:1960 which applies to the construction and use of sphere-gaps for measuring direct voltages and the peak value of alternating voltages and impulse voltages, both standard full wave and with longer tails. The peak values of the disruptive voltages in air are given in tabular form.

These recommendations concern the construction and use of sphere-gaps for voltage measurement. The rules apply to the measurement of the peak value of:a) alternating voltagesb) full standard impulses as defined in I.E.C. Publication 60 and impulses with longer tailsc) direct voltages.The peak values of the disruptive voltages in air for various spacings between the spheres are given in two tables.Appendix A gives the limits of voltage and frequency over which the tables have been derived from experiments and can be presumed to be accurate within the tolerances specified in Clause 5.2.Appendix B gives the procedure by which the values in the tables have been derived from previous National Standards and other sources.