Substation Grounding

In this section we will  introduce some of the basic principles behind faults and their effects on the currents and voltages of the electrical system, this knowledge will enable you to understand the impacts of faults on the power equipment.

Substation grounding is one of the most important elements of substation, as it keeps personnel and equipment safe during an electrical fault.

In the first lecture on this subject we will look in detail at how we use the grounding system to achieve these aims.

By the end of the lecture you will understand what causes ground faults and how we measure and use the transformer impedance to work out the magnitude of the current during a ground fault

In the second lecture on grounding we will look at various different substation configurations to try and establish how the magnitude and direction of the ground fault changes as the substation configuration changes

By the end of the lecture you will be able to identify which transformer neutral a ground fault will flow back to by looking at the circuit breaker arrangement, and be able to then calculate the maximum level of the ground fault current.

In the third lecture on grounding we will look at what effect the fault current has at it flows into the ground beneath the substation.

By the end of the lecture you will have learned what the soil resistivity is and how the current interacts with it to produce dangerous voltages, and also how the fault current flows back through the ground to the source substation

In the fourth lecture on grounding we will look at how the fault currents flowing into the ground beneath the substation can cause serious dangers to personnel working inside a substation.

By the end of this lecture you will understand how touch and step potentials are generated inside a substation that has gone faulty, and what measures we can take to reduce the dangers to personnel during a fault scenario.

In the fifth lecture on grounding we will look at the practical aspects of installing a grounding system inside a substation.

By the end of the lecture you will understand why grounding the substation fence is such a difficult procedure and what grounding materials we use to implement a safe and functional grounding system

Safety is the main priority for all electrical utilities and protecting personnel from the dangers of electricity, whilst they are working inside the substation is essential

To do this we use grounding equipment's to make sure that when equipment is being installed, modified or maintained the electrical energy is rendered harmless.

By the end of this lecture you will understand why we need to ground the equipment's and look at the equipment's that we can use to do this in a safe and controlled way.

In the previous lectures we have looked in detail what happens to the substation during a ground fault situation, and what affect the current has as it flows through the ground beneath the substation.

In this first lecture on grounding calculations we will start to look at how we can design a substation grounding system to make the substation safe for personnel under the worst case grounding fault scenarios.

By the end of the lecture you will have learned how to size the grounding conductor and how we define a high resistance surface material

In this second lecture on grounding calculations we will introduce some more calculations that will allow us to design a safe grounding system for any personnel working inside a substation that has gone faulty.

By the end of the lecture you will have learned how to calculate the tolerable touch and step potentials

In the lecture we will look at the grid resistance which is a key parameter in designing a safe substation grounding system.

By the end of the lecture you should understand all of the key parameters that go into defining the grid resistance and how we use them to calculate a design value, before going on to see how measure the actual resistance value to ensure that it is equal or lower to the one calculated using the formula.

In the fourth lecture we will introduce some more of the calculations that we use to design a safe substation grounding system.

In this lecture we will learn about the grid current and ground potential rise

By the end of the lecture you will understand what the ground potential rise is and how we protect the remote end substations from its dangerous effects, you will also understand what the current division factor is and how we use it to calculate the grid current.

In the fifth lecture we will introduce some more of the calculations that we use to design a safe substation grounding system.

In this lecture we will learn how to check if the substation grounding grid that you have proposed is safe

By the end of the lecture you will know how to calculate the actual touch and step potentials for your proposed grounding grid design and be able to use these values to check to see if your proposed grounding grid design is safe

In this sample calculation we will find out what impact adding ground rods to our substation grounding grid will have the main parameters

A short quiz to test your knowledge