Difference between Fault and Overload

You may see the 16 amps breaker in the distribution board in your power supply system. This 16 amp means the limit of current flow in the circuit is 16 amps. More than 16 amps current is not safe for this circuit, if it crosses the limit, there may be some problem and it must need control and heads the circuit to safe mode.

The above situation may happen due to fault and this increased current is called fault current. The fault is an abnormal situation for the circuit. Also, the current may be increased due to adding some extra load in the circuit which is called overload current.

It may also be considered an overload in that up to a certain level,  it may be say only 25 amps flowing on the 16 amps circuit. If the phase wire or hot wire and the neutral wire were to touch each other, currents as high as 10k amps may flow. This would be considered fault current.

What is the Fault Current?

Usually, the Fault Current refers to the current flow in an electrical circuit that is above normally expected levels. The fault current is the electrical current that flows through a circuit during an electrical fault condition. 

Fault currents are caused by very low-impedance short circuits. A fault condition occurs when one or more electrical conductors are short to each other or to the ground.

You may read to know the importance of the earthing system to save the life and property:

Why is Earthing Necessary in Electrical Systems?

So you have been told that it is an overload and not a fault. What actually is the difference?

Fault and overload are terms used in power supply. It is quite easy to understand the difference between these two terms.

We all make mistakes. The difference between fault and overload is the way you react to it.

When there is a fault or overload, the voltage across the load will go zero.

In this article, we will examine how a fault moves from one source to another, and what to do when an overload occurs.

Hi there, readers…As we all know that each of our applications is designed in a certain way, to provide different operations. But sometimes it becomes confusing what is a more suitable type of operation, Fault or Overload. This article will help you.

In an overloaded circuit, we don't give load to the lighting or heating appliances. It's also called a short circuit.

A fault occurs when the function that is called is not the right function for this call site and will never be the ...

When a point is overloaded, it should be firmed. Then we may detect whether the point is overloaded or faulty by this method: short the two terminals of the detection rod, then touch the end terminal to the main line and observe whether the sensation.

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In real life, we can observe that any fault or overload in Stations usually results in a shutdown. Therefore, it is better to alarm the station staff to attend to the fault/overload condition first, so that Train Controller or Engine Operator does

Types of electrical fault

These faults are classified into two types.

• Symmetrical Fault
• Unsymmetrical Fault

The symmetrical faults are classified into two types

• Line – Line – Line Fault
• Line – Line – Ground Fault

The unsymmetrical faults are classified into two types

• Single L – G (Line-to-Ground) Fault
• L – L (Line-to-Line) Fault
• Double L – G (Line-to-Ground) Fault

Open Circuit Faults

• Open Conductor Fault
• Two conductors Open Fault
• Three Conductors Open Fault.

What is overload current?

An electric overload occurs when too many current passes through electric wires.

The overload for a long time causes to damage the wires and control devices like circuit breakers.  The wires heat and can melt, with the risk of starting a fire.  

Avoid plugging several power-hungry items of equipment into the same line can prevent the circuit from overloaded and save the pieces of equipment.

What are the causes of fault currents?

1. Short Circuit: Touching two or more phase/earth cables to each other or any low-resistance connection between two points of an electrical circuit.
2. Ground Fault: Touching any phase conductor to the ground or breaking the phase conductor and touching the earth. 
3. Switching Load: If a large amount of load is switched to the system it acts like a fault due to large current flow like- the motor starting without control devices, switching new feeder, or a direct or indirect electrical discharge from a thunderstorm that can cause a fault current in electrical systems, etc.
4. Overvoltage/unstable Voltage: An abnormal increase in voltage in an electrical system may cause a fault. A piece of electrical equipment, such as transformers, switches, or generators may fail and cause this kind of fault.
5. Lighting Strike: A direct or indirect electrical discharge from a thunderstorm that can cause a fault current in electrical systems.

You may interrelated to read:

01. What is the Function of Earthing or Grounding Transformer?

02. Equipment Grounding for De-energized Construction and Maintenance.

What is the Ground fault in the electrical system?

A ground fault occurs when electricity takes an unplanned path to the ground, which means an electrical hot or live conductor touches the ground and abnormal current flows through the wires.