A varistor is essentially a transient voltage suppressor or a surge protector. They are used in a number of devices that need a consistent voltage across the system for reliable operation. In the power industry, varistors are used in high voltage transmission systems to protect the grid from line surges caused by things like lightning strikes.
Varistors are variable resistors that act as a shunt, allowing the flow of current under normal voltage but restricting current flow at or above the clamping voltage—the voltage required to trigger the sintering of the varistors zinc oxide and ceramic matrix. Varistors are vital in all electrical transmission applications, but new and better varistors are needed to protect extremely high voltage systems from line surges.
Varistor technology is one of the limiting agents on the maximum voltage of high voltage transmission systems. Using zinc-oxide nanoparticles in the varistor matrix will produce varistors with better performance characteristics, ultimately increasing reliability, more efficient transmission technologies and smaller vasristors. This technology will aid in the development of super high voltage transmission networks that operate at voltages as high as 1500kV while still maintaining grid stability.
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This technology has the potential benefit of allowing for better protection of transmission lines against line surges and overvoltages, allowing for infrastructure upgrades conducive to economic growth.
Zinc Oxide poses a potential risk to mammalian species due to its chemically unstable nature. Zinc oxide tends to oxidize within biological systems creating ions that can be toxic. While the potential toxicity of zinc oxide is has been studied, the risk lies in the potential for release. In metal oxide varistors, the potential for environmental release lies in the manufacturing and disposal stage, and potentially in the event of device failure.