Surge protective suppliers tell you the difference between AC and DC surge protectors
What are the types of surge protectors?
(1) Power surge protector
Power surge protectors are divided into DC and AC. What are the differences between AC surge protectors and DC surge protectors?
Surge protective suppliers tell you that the biggest difference between the AC and DC systems is the frequency. The 50Hz cycle change of the AC system forms three important nodes of zero, positive peak, and negative peak (peak valley), which makes the SPD take turns in the positive and negative directions. Under the voltage of the positive peak or negative peak, plus the amplitude of positive and negative peak voltage, the cycle time is symmetrical, so that the positive and negative electrons in the SPD chip are also arranged equally and are in a relatively stable state.
The DC system has no frequency, and its comprehensive impedance lacks the last two items of the above formula (only the internal resistance and line resistance of the power supply itself), so the internal resistance of the DC system is lower than that of the AC system. The advantage of low DC internal resistance is high efficiency, and the disadvantage is The reason is that once the short circuit occurs, the discharge current will be very large, and because there is no zero-crossing feature, it is difficult to cut off, which can easily cause a fire accident, and this kind of fire is difficult to control, and the energy in it is often exhausted before it is turned off. Therefore, in the power supply system, the price of DC surge protectors, DC circuit breakers, and DC relays is higher than that of similar products in the AC system, which is also due to the difficulty of DC breaking, high production process and technical requirements, and high cost.
Surge protective supplier tells you the difference between AC surge protectors and DC surge protectors. In addition to the higher, more stable, and more uniform heat generation of the chip, the design of the disconnection mechanism of the DC surge protector is very important, and the disconnection mechanism is required to respond more quickly and the disconnection distance is larger. Not only is it required to be able to drive the disengagement mechanism to act under a small amount of heat, but also the creepage distance must be large enough to reduce the risk of accidents. In a word, the DC surge protector is required to operate before the chip breaks down, so as to ensure that the DC SPD does not catch fire. However, due to the limited internal space of the SPD, how to design the detachment mechanism is a test of the technical strength of a surge protector manufacturer.
(2) Signal surge protector
Because the electromagnetic interference (EMI) generated by the communication equipment has a certain impact on the surrounding environment, the surrounding electronic equipment cannot work normally.
The signal surge protector is a device used to suppress various transient overvoltages and pulses. It is mainly used in power supply systems of electric power, railway, aviation, transportation, and other systems and computer information system equipment.
How Signal Surge Protectors Work
The surge protector supplier will tell you that when there is a high-frequency peak pulse current passing through the input terminal (such as the moment of a lightning strike in the mains power grid), a large-amplitude impulse current Ip (Input Pulse Impedance) will be generated in the input circuit. ), this current will enter the constant current diode VDD2 (Current Detector Diode) after stepping down through the isolation transformer for absorption, filtering, amplification, and shaping, and then provide a stable DC voltage source Ie (Induction Power) to the load.
To sum up, the difference between AC surge protectors and DC surge protectors is quite large and cannot be used universally.