Table of Contents
What is the difference between electrical grid and substation?
An electrical power substation is a conversion point between transmission level voltages (such as 138 KV) and distribution level voltages (such as 11 KV). An electrical grid station is an interconnection point between two transmission ring circuits, often between two geographic regions.
What is primary grid substation?
Primary Grid Substations – This substation lowered the value of primary stepped up voltages. The output of the primary grid substation acts as the input of the secondary substations. The secondary substation is used for stepping down the input voltage to more lowered for further transmission.
Why stones are used in electrical substation instead of sand or grass?
Pebbles and stones are more shock resistant as compared to grass and sand therefore, it will reduce the vibration in the transformer (caused by Magnetostriction in core) and special cases like earthquakes etc. Stone and gravels increase the resistance of soil which leads to reduce the limit of touch and step potential.
What are the components of a substation?
Elements of a substation
- Primary power lines.
- Ground wire.
- Overhead lines.
- Transformer for measurement of electric voltage.
- Disconnect switch.
- Circuit breaker.
- Current transformer.
- Lightning arrester.
What is the resistance of grid station?
2. Maximum Permissible Resistance Of Earthing System
| Large power station | 0.5 ohms |
|---|---|
| Major sub-station | 1.0 ohms |
| Small sub-station | 2.0 ohms |
| In all other cases | 8.0 ohms |
| The earth continuity inside an installation | 1.0 ohms |
Why do electrical substations have gravel on the ground?
The main reason to lay gravel in the substation yard is to reduce Ground Potential Rise (GPR) AKA Step Voltage and Touch Voltage which may be defined as follow: Step Voltage (Es) is defined as the maximum potential difference that exists between the feet when a fault current flows in the body.
Why do we put gravel in substation?
Step and Touch Potential; Step Potential – It is the potential developed between the two feet on the ground of a man or animal when short circuit occurs. That is why substations uses gravel/stones to reduce the step potential and touch potential when operators work on switchyard.