Transient Voltage Cause, Sources, Effects, Protection

In the field of electrical engineering, the term 'transient voltage' is very well known. You must know about transient voltage while you taking care of your electrical circuits, costly electrical machines, electronic devices, etc. Transient voltage may be very dangerous and can affect badly if protection not taken against it. But before that, you must know its sources and causes.

What is Transient Voltage?

Transient voltage is an unwanted temporary very high voltage suddenly occurs in an electrical circuit or power lines. Voltage surge or surge voltage differs from over-voltage, voltage swells, voltage fluctuations, voltage dip. Actually, this all are differing depends upon the magnitude and time duration. Voltage transient has the highest magnitude and very short time duration. That means in an electrical circuit or power line if the voltage rises to a very high level in a very short time duration then it can be called the voltage transient. Voltage transient is very similar to voltage spike because in both cases, voltage increases very high just the difference is voltage transient has a short time duration than voltage spike.

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Sources of Transient Voltage

In natural Lightning is the most common source of surge voltage. It raises the voltage to a very high level than other sources.

Natural capacitance effect in transmission line also a source of surge voltage. The capacitance effect in the transmission line stores the electrical energy and suddenly it releases the electrical through the power lines. Due to that voltage suddenly raises which known as the transient voltage.

Other sources of transient voltage are faulty contactors, tripped circuit breakers, reactive elements of electrical or electronic circuits.

Electrostatic Discharge or ESD also a natural source of surge voltage.

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Causes of Transient Voltage

Already we have known that the transient voltage sources from which transient voltage occurs naturally. Now we will know what are the common accidental causes due to which surge voltage occurs in the circuit.

The common causes or activities for the occurrence of surge voltage are frequent switching, the sudden disconnect of load from the power supply, improper operation of electrical motors with varying load, improper operation and handling of capacitor banks, improper handling, and operation of reactive devices.

So by handling and operating the reactive devices properly we can solve the 80 percent problem of the surge voltage. But to prevent the circuit and devices from natural sources we have to take the protection system.

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Effects of Transient Voltage

The transient voltage causes to flow of a very high current in electrical and electronic circuits. 

High current flow in any circuits can damage the conductors, burn the coil, cause to spark, fire. So transient voltage is very dangerous for your circuits as well as electrical and electronic devices.

Electronic components are mostly affected by transient voltage. Because they are designed to operate with a very low current and voltage. So rising in voltage can damage the conductive path of the electronic component, damage the internal circuit. Electronic ICs are facing these issues. Electronic components mostly affected due to surge voltage caused by ESD. That's why electronic manufacturing companies are used the ESD protection system.

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Transient Voltage Protection

The different ways for the transient voltage protection are,

• Limiting the voltage amplitude
• Limiting the current
• Shorten the transient time duration
• Bypassing the excess current

So there are different types of transient voltage protective devices are available which works in any one principle from the above.

Series Reactor(made of inductors) is a transient voltage protective device that works on the principle of current limiting. When transient voltage occurs, it limits the excess current.

A shunt Reactor(made of capacitors) is also a transient voltage protective that works on the principle of current bypassing. So when transient voltage occurs, it bypasses the excess current to the ground. 

Diode, thyristor, varistor are used for the protection of electronic circuits and components from the surge voltage.

Read Also: 

• Series and Shunt Reactor Difference, Applications, Use
• Difference between Earth Fault Relay and Earth Leakage Relay
• Ground Fault Causes, Effects, Example, Explanation
• The List of Faults RCCB can Protect and Can't Protect
• Different Types of Protection for Capacitor Bank Explained

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