Why are stones layed in switchyard?

Using stones in the switchyard provides protection against the entry of wildlife animals and snakes, lizards, rats etc in the substation area. Stone and gravels increase the resistance of soil which leads to reduce the limit of touch and step potential.

Why is there gravel in a substation?

So also, the purpose of filling gravel in switchyard is human safety first (i.e.) increase in the tolerable touch & step potentials. Any other reason, such as, drain of rain, avoiding vegetation growth, prevention of creeping of lizards & snakes, etc.

Why stones are used in substation to Mcq?

Stones in substations are provided so as to: Reduce step potential: The potential that is developed between two feet on the ground in case of short circuit. The potential between feet and body of power equipment when a person touches it. Stones stop the growth of weeds and grass inside the substation.

What is the difference between switchgear and switchyard?

A switchyard is a section of a substation where transmission or distribution lines are fed, which may contain switchgear, standalone circuit breakers, transfer switches, reclosers, etc. Switchgear refers to breaker and disconnect panels within the confines of the plant.

Why do we need substations?

Why do we have Substations? The purpose of a substation is to ‘step down’ high voltage electricity from the transmission system to lower voltage electricity so it can be easily supplied to homes and businesses through our distribution lines.

Is used in substations?

The Substations are mainly used to convert AC (alternating current) to DC (direct current). Some types of substations are tiny in size with an inbuilt transformer as well as related switches. Other types of substations are very huge with different types of transformers, equipment, circuit breakers, and switches.

Why are pole mounted substation very popular?

Pole Mounted Substation Such substations are used for supporting distribution transformers having the capacity up to 250 KVA. Lightning arresters are equipped over the high tension line for the protection of the transformers from the surges. Pole-Mounted substations are earthed at two or more places.

Why stones is used in Electrical switchyard & transformer yard?

Reasons for using Stones is used in Electrical Switchyard & Transformer Yard: Stones in the substation is provided to reduce the step potential and touch potential when operators work on switch yard. Step and touch potential occurs due to the short circuit current flows on the conductor.

Why are stones or gravel laid in the substation?

That’s why stones or gravel are laid in the substation to reduce the step potential and touch potential in case of maintenance or working on live equipment. The following table shows the resistivity of different materials such as stones and sand etc.

What is touch potential in switchyard?

When operating personnel touch an electrical equipment during short circuit condition, fault current flows through the human body. This is defined as touch potential. Gravel/Stones in the substation is provided to reduce the step potential and touch potential when operators work on switchyard. 2.

Why are there stones on top of power transformers?

Therefore to provide the high resistance for foot and ground, the stones are provided. It protects the moisture content evaporation and keeps the ground wet. Most in switchyard Power Transformers insulated with the insulation oil.