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The use of strain type insulators is made where the conductors are
Dead End
Road Crossing
Intermediate anchor towers
All of the above
All of the above
Strain type insulators (also known as tension insulators) are designed to withstand high mechanical tensile stress where transmission lines undergo a change in direction, end, or cross obstacles. They are used in vertical or horizontal strings to keep the conductor at proper tension and clear of the tower structure.
Strain type insulators (also known as tension insulators) are designed to withstand high mechanical tensile stress where transmission lines undergo a change in direction, end, or cross obstacles. They are used in vertical or horizontal strings to keep the conductor at proper tension and clear of the tower structure.
TmaxтАЛ=nтЛЕTunitтАЛ тАФ where TmaxтАЛ is the total tension capacity and TunitтАЛ is the per-unit mechanical strength of the insulator disc.
IleakageтАЛ=RinsulatorтАЛVтАЛ тАФ where RinsulatorтАЛ is the high insulation resistance.
The strain insulator consists of a porcelain or glass assembly that acts as a mechanical link between the tower cross-arm and the conductor. By orienting the insulator string horizontally, the mechanical tension of the line is transferred directly to the tower, while the electrical insulation prevents leakage current from the line to the grounded tower structure.
Strain insulators are used when the line is subject to great mechanical tension.
For low voltage lines (< 11kV), shackle insulators are used as strain insulators.
For high voltage transmission lines, long strings of suspension insulators are used in a horizontal configuration to provide strain relief.
They are essential for maintaining sag and clearance requirements at anchor points.
High mechanical strength to handle line tension.
Provides flexibility in installation for different voltage levels.
Effective at breaking the span into smaller sections to limit mechanical damage.
Requires more space than pin-type insulators.
Higher installation cost due to the need for multiple discs for HV applications.
Dead-end towers where the line terminates.
Long spans and crossing points like rivers or roads.
Anchor towers where lines change direction significantly.
In practice, strain insulators for 33kV and above consist of multiple suspension discs connected in series to achieve the required insulation level and mechanical strength.
Option B (Road crossing) requires strain insulators to ensure the conductor does not sag or break, which could pose a safety hazard to traffic.
D is correct тАФ Strain type insulators are used wherever the line is subjected to significant mechanical tension, including dead ends, sharp curves, and crossings.
Always remember that while suspension insulators are used vertically for support, their usage changes to horizontal stringing to function as strain insulators in specific anchor scenarios.