Surge Absorber|3 Types Of Surge Absorbers

A surge absorber is a protective device which reduces the steepness of wave front of a surge by absorbing the surge energy. A surge absorber is a device to protect electrical equipment from over-voltage transients caused by external or internal events.

The travelling waves set up on the transmission lines by the surges may reach the terminals apparatus and cause damage to it.

The amount of damage caused not only depends upon the amplitude of the surge but also
upon the steepness of its wave front.

The steeper the wave front of the surge, the more the damage caused to the equipment.

Also Read: Lightning Arrester|ESE Lightning Arrester & Conventional Iightning Arrester

Contents

Surge Absorber

In order to reduce the steepness of the wave front of a surge, we generally use surge absorber.

A surge absorber is a protective device which reduces the steepness of wave front of a surge by absorbing surge energy.

The surge absorbers are used for protection against low – voltage high – frequency oscillations.

Although both surge diverter and surge absorber eliminate the surge, the manner in which it is done is different in the two devices.

The surge diverter diverts the surge to earth but the surge absorber absorbs the surge energy.

A few cases of surge absorption are discussed in this post.

Download & Install EEE Made Easy App

Condenser surge absorber

A condenser connected between the line and earth can act as a surge absorber.

The above fig shows how a capacitor acts as surge absorber to protect the transformer winding.

Since the reactance of a condenser is inversely proportional to frequency, it will be low at high frequency and high at low frequency.

Since the surges are of high frequency, the capacitor acts as a short circuit and passes them directly to earth.

However, for power frequency, the reactance of the capacitor is very high and practically no current flows to the ground.

parallel combination of choke and resistance

Another type of surge absorber consists of a parallel combination of choke and resistance
connected in series with the line as shown in Fig. gien below.

The choke offers high reactance to surge frequencies (XL = 2 π f L). The surges are, therefore, forced to flow through the resistance R where they are dissipated.