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The metal oxide lightning arrester or surge arrester is a surge protection device that limits the voltages in substations to a specific protection level. These devices protect both gas-insulated and conventional substations against temporary over-voltages, switching pulses, lightning impulses, and, to a limited extent, transient, very fast over-voltages.

Metal Oxide Lightning Arrester: How Do They Work?

The surge arrester acts as an open circuit and will resist surges under normal conditions.

The metal oxide surge arrester reacts quickly to a switching surge. This is in the order of one nanosecond. The surge arrester’s resistance decreases at the moment that the system surge switches, thereby allowing for the discharge of large currents to the earth.

The switching surge is diverted safely to the earth, and the arrester absorbs the energy. The system continues to operate at its normal voltage and the resistance property of the surge arrester increases. This allows it to act as an open circuit. This leaves the system voltage unchanged under normal conditions.

Advantages of Metal Oxide Lightning and Surge Arrester

The metal oxide lightning arrester offers the following advantages over other types of arresters:

• It eliminates the spark gap because of the nonlinearity of arrester resistance.
• It is easy to construct the arrester by reducing its size.
• Superior protective performance.
• Excellent durability for multiple operating duty cycles
• Quick response for steep discharge current.
• The absence of spark gaps means that the voltage grading system does not need to be used.
• Operation stability and energy absorption are high.
• The flow of leaked current is lower than other arresters when there is no surge voltage.

This post was written by Justin Tidd, Director at Swartz Engineering. For nearly half a century, Swartz Engineering has been at the forefront of industry safety. They are a family owned company specializing in power distribution for the electrical industry. They are the leading manufacturer of Surge Arrestors. The SWARTZ® Current Transducer is a high performance, solid-state unit specifically developed to meet requirements for supervisory control and data acquisition (SCA- DA) systems.