Relationship Between Phase Voltage And Line Voltage

The standard AC voltage commonly used in our country is: phase voltage is 220v, line voltage is 380v, and the mathematical relationship between phase voltage and line voltage is: line voltage is √3 times of phase voltage.

Why can the surge protector work normally when the Uc value is less than the line voltage?

First, let's understand the working principle of the surge protector: the installation position of the surge protector is between the phase line and the neutral line, the phase line and the ground line, and the 3PN surge protector will also be installed between the neutral line and the ground line. In any case, the surge protector will not be installed between the two live wires. Therefore, when we select the surge protector and the Uc value, we only need to consider the phase voltage in the circuit.

Therefore, when everyone installs the surge protector, the circuit voltage seen is 380v, and the actual phase voltage is only 220v. Installing a lightning arrester with a Uc of 320v or 385v can fully achieve the lightning protection effect. If the line voltage is 440v, then its phase voltage is 254v, and installing a 320v or 385v surge protector can also meet the lightning protection requirements in this circuit system.

People often encounter many problems when selecting surge protectors, which is not surprising, as lightning protection is a relatively cold industry.