Common Question

The manufactured insulators are appropriate for what voltages?

The insulators manufactured by Afra Modern System Company have been designed for power cables of medium voltage, 20Kv, and 33 Kv

Do you produce multi-blade insulators and what are the criteria for choosing an insulator?

Number of blades is not important technically. Umbrella-shaped sections on the insulator are to create a long path, to create dry dots during rain, and also to make the surface of the insulator slippery to avoid rain stains forming on surface of the insulator. Creepage distance is a feature that should be taken into consideration for insulators. Creepage distance depends on the place and weather condition of the place where the insulator will be used in.

What is the difference between insulator’s type test and routine test?

Type test of insulator, which depends on insulator’s shape, material, dimensions, and generally on its design, is merely designed for studying electrical characteristics of an insulator.  This test is performed only once to verify the design of the insulators and to compare the results with the values determined by the standards. In routine test, Experiments are carried out on each insulator produced in the production line to exclude insulators that are likely to have a problem during their construction.

Why, in some cases, electrical ignition takes place on insulators?

Typically, if there is dust, moisture, or pollution between two points of the surface of an insulator with a potential difference (Regarding the fact that surface of the insulator is exposed to air and electrical resistance of the air is much less than the insulator), the surface of the insulator would be conductive and a residual current is placed on the surface of the insulator between the electrical conductor and its metal base. It lowers the insulating value of the insulator surface and creates a spark on the surface of the insulator prior to insulation breakdown.

What is the difference between long-base and short-base insulators?

The concept of a long or short base is the difference between the spark gap and the height of the insulator from the seating surface of the wire to insulators’ cross arm.

Afra Office

ADDRESS: Saman Building, Alley 3, Mahmoudieh street, Chamran Blvd. Shiraz, IRAN

PHONE:      +987136540838-41

Mobile:       +989175908969


Afra Factory

ADDRESS: AFRA MODERN SYSTEMS, Mokhaberat Blvd. East Tejarat Blvd. Shiraz Especial Economic Zone

POSTCODE: 715911-13958

PHONE:   +987137175281-2

PHONE:   +987137175292 -3