A "transformer overvoltage protection" device is designed to safeguard transformers and other sensitive electrical equipment from voltage surges, including those caused by lightning strikes. These voltage surges, often referred to as lightning surges or transient overvoltages, can cause significant damage to electrical systems if not properly controlled.
Here's how a typical transformer overvoltage protection device handles lightning surges:
Surge Detection: The device is equipped with sensors that can detect sudden increases in voltage, such as those caused by lightning strikes. These sensors are often designed to respond quickly to rapid changes in voltage levels.
Voltage Clamping: When a lightning surge is detected, the overvoltage protection device activates. It provides a low-impedance path for the surge current to flow, effectively "clamping" the voltage to a safe level. This prevents the surge from reaching the transformer or other protected equipment.
Diverting Surges: The overvoltage protection device typically consists of surge protection components like metal oxide varistors (MOVs) or transient voltage suppressors (TVS diodes). These components have nonlinear voltage-current characteristics, which means that they become highly conductive when the voltage exceeds a certain threshold. This behavior allows them to shunt the surge current away from the protected equipment and into the ground.
Absorption and Dissipation: The surge protection components absorb and dissipate the energy of the lightning surge. This prevents the excessive voltage from reaching the transformer or other equipment. The energy absorption capability of the protection device is a key factor in its effectiveness.
Recovery: After the surge has passed, the protection device should ideally return to its normal state and be ready to handle subsequent surges. Depending on the type of protection device, this recovery may be automatic or require manual intervention.
Coordination with Other Protection Devices: In a comprehensive electrical protection scheme, the transformer overvoltage protection device may be part of a larger system that includes other protective devices, such as lightning arrestors and circuit breakers. These devices work together to ensure that the electrical system remains operational and safe during and after a lightning event.
It's important to note that the effectiveness of a transformer overvoltage protection device depends on its design, the quality of its components, and how well it's integrated into the overall electrical system. Lightning surges can generate extremely high voltages and currents, so proper design, installation, and maintenance of protection devices are crucial to ensuring the safety and reliability of the electrical infrastructure.