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In thyrite lightning arrester the resistance
Varies linearly with the applied voltage
Increases with the applied voltage
Decreases with the applied voltage
Is high at low current and low at high current
Is high at low current and low at high current
Thyrite is a non-linear ceramic material used in lightning arresters. Its resistance is not constant; it follows the characteristic I=KV╬▒, where ╬▒ is high (typically 3 to 7), causing the material to behave as a high-resistance insulator at normal operating voltages and a low-resistance conductor during high-voltage surges.
Thyrite is a non-linear ceramic material used in lightning arresters. Its resistance is not constant; it follows the characteristic I=KV╬▒, where ╬▒ is high (typically 3 to 7), causing the material to behave as a high-resistance insulator at normal operating voltages and a low-resistance conductor during high-voltage surges.
I=KV╬▒ тАФ Represents the non-linear relationship between current and voltage for Thyrite material
R=IVтАЛ тАФ Represents the effective resistance which decreases as I increases
The non-linear nature of Thyrite allows it to discharge high-magnitude surge currents to the ground without significantly increasing the voltage across the arrester. At normal power frequency, the high resistance limits leakage current, but when a surge hits, the sharp reduction in resistance creates a low-impedance path to ground, effectively clamping the voltage at a safe level for protected equipment.
Thyrite is a trade name for silicon carbide (SiC) based ceramic material.
The exponent ╬▒ determines the degree of non-linearity; higher ╬▒ implies better clamping performance.
It acts as a valve, allowing only surge currents to pass while blocking normal system current.
Excellent non-linear behavior clamping overvoltage surges
High capability to discharge high-energy lightning impulses
Simple construction without moving parts
Non-linear characteristics can degrade over time due to repeated surges
Requires series spark gaps to prevent leakage current at normal operating voltages
Protection of high-voltage transmission lines
Substation transformer protection
Surge protection in electrical distribution networks
The term 'Thyrite' is a specific material formulation often used as a synonym for non-linear silicon carbide valve-type arresters.
Option A is incorrect because the relationship is exponential, not linear.
Option B is the inverse of the actual physical behavior observed in surge protection devices.
D is correct тАФ Thyrite material exhibits a non-linear resistance property where it maintains high resistance during normal operation but shifts to low resistance when subjected to high-current surge voltages.
Remember that Thyrite is a SiC-based material; in modern power systems, it is increasingly being replaced by Zinc Oxide (ZnO) arresters, which provide even better non-linear characteristics (higher ╬▒).