115kV Long Rod Polymeric Insulator

Products Description

END FITTING

Why is 115kV commonly used abroad?

Historical reasons: Early US power grids used 110kV, 115kV, and 138kV series.
Many countries (Kenya, Tanzania, Nigeria, the Middle East, Southeast Asia) directly adopted this standard, building equipment and power grids according to 115kV.

Technical reasons:
115kV has a slightly larger transmission capacity and slightly lower losses than 110kV, suitable for transmission scenarios of 50–150km and 10–50MW.
It coordinates better with upstream and downstream voltage levels (such as 33kV and 230kV), resulting in a more balanced voltage gradient.

Four Core Reasons for Using Different Fittings with Composite Insulators:

1. Adapting to Line Voltage and Load (Most Crucial): Voltages like 115kV and 33kV have different rated mechanical loads (kN): 70kN, 100kN, 120kN, and 160kN tension forces correspond to different specifications of end fittings. Larger loads require larger fitting wall thickness, diameter, and steel component dimensions.

2. Different Connection Methods (Line Installation Structure):
Suspension string: Socket & Ball, for hanging on tower crossarms.
Tension string: Plate fittings/clamp fittings, for tensioning conductors.
Crossarm and jumper fittings: U-shaped hanging rings, trunnion fittings. Different installation points require different interface shapes.

3. Adapting to Conductor Diameter:
Conductors of 70mm²/120mm²/240mm² require different clamp hole diameters and clamp body sizes, necessitating the selection of matching insulator end fittings.

4. Differences in power grid standards among countries
Africa (Kenya, etc.) mostly uses ANSI American standard fitting dimensions. Domestically and in Southeast Asia, national standard/IEC dimensions are more common.
Even for the same 115kV insulator, the fitting interface specifications differ depending on the country of export.