How Lightning Protection Rated Voltage Works in DC Surge Protectors

May 23, 2022

The maximum allowable power frequency voltage that the DC surge protector can work reliably and complete the expected action load test is called the lightning protection rated voltage. For the DC surge protector with a gap, my country, Germany and the Soviet Union once called this voltage as the arc extinguishing voltage, and now it is defined uniformly by the IEC standard. In order to ensure the normal operation of the DC surge protector, this voltage must be designed to be greater than the maximum short-term power frequency voltage that may be present at the installation site. The lightning impulse overvoltage between the live conductor and the ground on the power supply line cannot be eliminated or suppressed by the bonding wire, because doing so will cause the short circuit of the live conductor to the ground.

For this reason, a surge protector needs to be installed in between, which only turns on and leaks at the moment of overvoltage and reduces the overvoltage. At this time, the surge protector plays the role of equipotential bonding, but it is only transient rather than continuous and fixed equipotential bonding. In order to determine and calculate the rated voltage of the DC surge protector, it is necessary to analyze the change of the voltage of the power frequency surge protector where the DC surge protector is installed: In the system, there are three main reasons for the rise of the short-term power frequency voltage:

First, the speed of the generator increases after the sudden load shedding, which causes the bus voltage to rise;

The second is that due to the inductance-capacitance effect, the terminal voltage of the long-distance transmission line increases when there is no load;

Third, when a single-phase ground fault occurs, the sound phase voltage rises. Operational experience shows that it is very rare for the whole line to trip, load shedding and single-phase grounding faults at the same time, and the faults often appear locally in the line. Therefore, it is not necessary to consider the possibility that these three voltages increase simultaneously. In our country, the measured data on the busbar voltage rise caused by load rejection does not exceed 1.37 times the phase voltage.

What are power surges (aka surges) and peak voltages?

Surge and peak voltage (pulse) are increases in "regular" voltage, usually caused by drastic fluctuations or increased demand for electricity. Turning on high-powered appliances, vacuum cleaners, air conditioners, and washing machines can all cause surge protectors to cause surges and peak voltages. Any type of interference can damage electronic equipment. beyond the scope of actual maintenance. In addition, severe weather (lightning) and the daily shut-off and repair work of the power company can cause damaging surges to power lines.

How does a surge protector work?

Surge protectors act like a power sponge, capable of absorbing dangerous extra voltages, preventing most of them from reaching your sensitive equipment.

Surge-proof sockets with phone line protection can provide the most complete protection for your electrical equipment against harmful surges. Power surges and voltage spikes can damage or degrade the performance levels of your valuable electronic equipment through phones and power lines. Perfect surge protection function can protect such as computers, telephones, modems, televisions and other home electronic equipment and electrical appliances at any time. Anti-surge sockets can protect your electrical equipment and telephone equipment from lightning strikes, work stably, and prolong the service life of electrical appliances.