Disc-shaped Suspended Porcelain Insulator
Cap and pin discs strung into insulator strings for overhead lines — standard and anti-pollution sheds, 40 kN and 70 kN.
- Rated load
- 40 kN and 70 kN
- Disc diameter
- 190–320 mm
- Creepage
- 200–550 mm
- Coupling
- Ball and socket / clevis
A suspension string carries the conductor and insulates it from the tower at the same time. Each unit is a porcelain disc cemented between a malleable iron cap and a steel pin; the number of units in the string sets the insulation level for the line.
Two shed families are made here: the standard profile, and anti-pollution profiles with a longer creepage path for polluted routes — double (D), triple (T) and mushroom (M).
Reading the Type Code
Each character in a type designation carries a meaning. Using the anti-pollution type as an example:
- U
- Disc-shaped suspended porcelain insulator
- 70
- Specified electromechanical failing load, kN
- B
- Ball-and-socket coupling; C for clevis
- P
- Anti-pollution shed; omitted on standard types
- 146
- Nominal spacing, mm
- D
- Shed profile: D double, T triple, M mushroom; omitted on standard types
Specifications
Electromechanical, dimensional and electrical values for every type made in this size range.
| Type | Nominal diametermm | Spacingmm | Creepagemm | Electromechanical failing loadkN | Routine tensile testkN | Coupling markmm | RIV at 10 kV, 1 MHzμV | Corona extinction, pin / capkV | Power-frequency arc test | Wet power-frequency withstandkV | Lightning impulse withstandkV | Power-frequency breakdownkV |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| U40 | 190 | 140 | 200 | 40 | 20 | 16 | 50 | 18 / 22 | / | 27 | 70 | 90 |
| U70B/146 | 255 | 146 | 320 | 70 | 35 | 16 | 50 | 18 / 22 | 0.12 s at 20 kA | 40 | 100 | 110 |
| U70C/146 | 255 | 146 | 320 | 70 | 35 | 16 | 50 | 18 / 22 | 0.12 s at 20 kA | 40 | 100 | 110 |
| U70BP/146D | 280 | 146 | 450 | 70 | 35 | 16 | 50 | 18 / 22 | 0.12 s at 20 kA | 42 | 120 | 120 |
| U70BP/155T | 320 | 155 | 550 | 70 | 35 | 16 | 50 | 18 / 22 | 0.12 s at 20 kA | 45 | 120 | 120 |
Values as published in the product catalogue. Power-frequency arc test applies to insulators for 220 kV and above.
Choosing a Type
Standard or Anti-pollution
At the same 70 kN rating, the anti-pollution sheds take creepage from 320 mm to 450–550 mm.
Ball and Socket, or Clevis
B types couple with ball-and-socket hardware, C types with clevis — match whichever the string uses.
40 kN or 70 kN
U40 is the distribution size; U70 is the standard rating for line strings.
Every unit is tensile-tested before it is packed, and each type is type-tested before it is offered for supply.
Ask about Disc-shaped Suspended Porcelain Insulator
Send the type designation, the quantity and the standard the project is working to. We reply with a price and a delivery date.
We usually reply within one working day.