IS 3070 : Part 3 : 1993 Lightning Arresters for Alternating Current Systems - Specification - Part 3 : Metal Oxide Lightning Arresters Without Gaps

1 Scope

This standard applies to non-linear metal oxide resistor typesurge arresters without spark gaps designed to limit voltage surgeson a.c, power circuits including low voltage type.

This standard basically applies to all metal oxide surgearresters; however, polymeric housed, gas insulated, liquidimmersed arresters may require special considerations in design,test and application.

This standard does not cover arresters/varistors required fortelecommunication and industrial electronic applications.

1.1 Service Conditions

1.1.1 Normal Service Conditions

Surge arresters which conform to this standard shall be suitablefor normal operation under This normal service conditions:

a) Ambient air temperature within the range of - 10°C to + 50°C

b) Solar radiation

Note - The effects of maximum solarr adiation (1.1 kW/m²) have been taken into account by pre-heating the testspecimen in the type tests. If there are other heat sources neatthe arrester, the application of the arrester shall be subjected toan agreement between the manufacturer and the purchaser.

c) Altitude not exceeding 1000 m

d) Frequency of the a.c. power supply not less than 48 Hz andnot exceeding 52 Hz.

e) Power frequency voltage applied continuously between theterminals of the arrester not exceeding its continuous operatingvoltage.

f) Mechanical conditions:

i) Maximum wind speed : 55 m/s

ii) Seismic acceleration : 0.3 g horizontal and 0.15 g vertical.

1.1.2 Abnormal Service Conditions

The use of this standard in case of abnormal service conditionsis subject to agreement between the manufacturer and the purchaser.

1.2 References

IS 2071 : Part 1 :1974 Methods of high voltage testing : Part 1Generaldefinitions and test requirements

IS 2070 : Part 2 : 1976 Part 2 test procedure

IS 5621 :1980Hollow insulators for use in electrical equipment

IS 6209 :1982Methods for partial discharge measure-merit