What is the creepage distance to the ground or specific creepage distance?

What is the creepage distance to the ground?

The creepage distance to the ground means the creepage distance of an insulator plus the height between an insulator and ground. (This is called overhead height.)

Some insulators should use the shelf when installed, some insulators use overhead steel pipe frame, such as aerial lightning arrester installed in power plant to use the steel pipe and then installed the insulation base. So the sum of the insulator creepage distance plus overhead height is creepage distance of the insulator to the ground.

composite insulator station post type-Orient Power

composite insulator station post type

What is the specific creepage distance of an insulator?

The specific creepage distance of an insulator refers to the ratio of the creepage distance of an insulator and the insulator’s highest running voltage; the ratio of the creepage distance (cm) and working voltage (KV) is called specific creepage distance.

For example: 3.1 cm/KV said above the ratio is 3.1.

Specific creepage distance is used to describe anti-pollution level. 3.1cm/kV is grade 4 anti-pollution. Insulators product if used on 10kv, the creepage distance is greater than 310 cm. 10kv is running voltage, and the voltage is typically calculated on the highest voltage (i.e., 12kv), so to meet 4 anti-pollution, namely the creepage distance can need up to 372 cm.

Specific creepage distance under the condition of 3.1cm/kV is IV filth level, and 2.5cm/kV is III filth level.