The effect of voltage fluctuations on low-voltage electricity

High-voltage electrical equipment typically refers to power conversion devices such as high-voltage motors or transformers. The tripping of their load switches is subject to certain conditions, including instantaneous trip, overcurrent, undervoltage, etc. An instantaneous trip generally occurs without any delay; however, its set value is usually relatively high； The overcurrent setting value is smaller than that of instantaneous trip, but there is usually a time delay (generally within 1 second) ； The standard setting for low voltage is generally 7 kV, with no delay or only a short delay (a few tenths of a second). Moreover, there is also a time interval between the detection of parameters and the activation of the output; for conventional protective devices, it is possible to withstand brief power fluctuations ； Microprocessor-based protection should also include safeguards in the software to prevent misjudgments). As the name implies, voltage flicker is a short-term instability phenomenon; therefore, high-voltage equipment sometimes can avoid being triggered and remain inactive. For the power supply of low-voltage (motor) equipment, the load switch is generally a contactor. Its operating condition is typically when the voltage falls below 85% of the coil’s rated voltage; there is no time delay (unless a time-delay circuit is specifically designed), and it operates directly (high voltage involves electrical circuits and mechanical transmission). The above are my personal opinions.

The impact of voltage sags is unrelated to the voltage level; it is determined by the nature of the electrical load. The enterprise I work for is in the metal smelting and processing industry. I know that vibrations in iron-making blast furnaces may cause equipment accidents such as tuyere blockages. Steelmaking continuous casting mold solidification accidents, and so on.