Electrical disc suspension insulators is used for high voltages (>33 kV), it is a usual practice to use suspension type insulators. Consist of a number of porcelain discs connected in series by metal links in the form of a string. The conductor is suspended at the bottom end of this string while the other end of the string is secured to the cross-arm of the tower. Each unit or disc for disc suspension insulator is designed for low voltage, say 11 kV. The number of discs in series would obviously depend upon the working voltage. For instance, if the working voltage is 66 kV, then six discs in series will be provided on the string.

Advantages of electrical disc suspension insulators:
1. Electrical disc suspension insulators are cheaper than pin type insulators for voltages beyond 33 kV.
2. Each unit or disc of suspension type insulator is designed for low voltage, usually 11 kV. Depending upon the working voltage, the desired number of discs can be connected in series.
3. If anyone disc is damaged, the whole string does not become useless because the damaged disc can be replaced.
4. The electrical disc suspension insulators arrangement provides greater flexibility to the line. The connection at the cross arm is such that electrical disc suspension insulators string is free to swing in any direction and can take up the position where mechanical stresses are minimum.

Relative Articles:
◆Suspension insulators,IEC U70C suspension insulators
◆Cap and pin type suspension insulators
◆Voltage distribution in suspension insulators
◆String efficiency of suspension insulators
◆suspension insulators.pdf
◆Ceramic Porcelain suspension insulators