Why is Overvoltage Protection necessary? Essentially, overvoltage protection shuts off or clamps the power supply when the voltage reaches a preset level. A circuit protects the electronic components from over-voltage damage in most power supplies. Circuit overvoltages have different effects on various components, ranging from damages to degraded components and circuit malfunctions. The power supply may experience an overvoltage condition due to faults inside the supply, or it could be caused externally, such as by faults in distribution lines. When designing an effective protection system, magnitude and duration of the overvoltage are important considerations. Basically, the protection is set to shut down the supply if a threshold voltage is exceeded, or divert the extra voltage to different circuit parts, such as a capacitor.
A protection circuit for over voltages should have the following characteristics:
- Make sure that the components are not subjected to excess voltage.
- There should be no interference between the circuit or system and the protection circuit. Power supply voltages should not drop when the protection circuit loads the power supply.
- Protection circuits should distinguish between normal voltage fluctuations and dangerous overvoltages.
- Be fast enough to prevent damage to downstream components and the power supply if transient events occur.
- It is important that the OVP method doesn’t generate false trips or fail to detect real overvoltage conditions. When there is a false trip, this can be a nuisance or potentially dangerous, especially if it is unable to see the real overvoltage condition.
Various types of overvoltage protection circuits have been built to address over voltage issues, such as discrete components, integrated circuits, mechanical devices, etc. Depending on the circuits involved, these can either be internally or externally connected. A variety of circuit protection designs are available, each with its own advantages, modes of operation, sensitivity, capabilities, and reliability. Power components can be protected by clamping, or shutting down, excess voltage.