WRE-640 WRE-641 WRE-642 WRE-643 WRN-230 assembly thermocouple, in fact, when the power is turned on, the rectifier bridge is blown up under normal conditions not because the selected charging high-power resistor R is too small, but because R is too large to cause the rectifier bridge to blow up. After the inverter is turned on, the current is recharged through the charging resistor. When the charge is sufficient to assist the power supply (for example, 200V), the CPU will return the signal to the relay or thyristor to make it conductive. When the relay is turned on, the voltage at point b of the relay is very low (greater than 200V), and the voltage at point a is AC380V indirect rectification, which used to be about DC540V, so the voltage difference between the two terminals of a and b is very large. When triggering and turning on, the current is very large, just like a small resistance between a and b. When the voltage is several hundred volts, the current flowing through the rectifier bridge is much larger than the extra current of the rectifier bridge. The bridge blew up.
The larger the inverter power, the smaller the charging resistance. As the power of the inverter is higher, the capacity of the electrolytic capacitor is required to be larger, and the larger the capacitor capacity is, the longer the time required for charging is. RC decides the charging time. To make the charging time as short as possible, just make the charging resistance R small. Selection of ordinary charging metal film resistance: The maximum value should not exceed 300Ω, and the minimum value should be greater than or equal to 10Ω. For high-power inverters, choose a small charging resistance and small-power inverters have a large charging resistance.