What are the reasons for the breakdown of SCR
1. Over-voltage breakdown: overvoltage breakdown is one of the main causes of silicon controlled breakdown. The ability of SCR to withstand overvoltage is almost no time. Even in a few milliseconds, the overvoltage will be penetrated. Therefore, in the actual application circuit, the RC absorption loop must be attached to the two ends of the SCR to avoid any irregularity. The instantaneous overvoltage caused by the interference pulse. If thyristor breakdown occurs frequently, check whether the components of the absorption circuit are burned or failed.
2, overcurrent and overheat breakdown: in fact, overcurrent breakdown is one of the same as overheating breakdown. Over current breakdown is the heat effect of the current in the silicon controlled silicon chip, which makes the chip temperature rise. When the chip temperature reaches 125 C, the chip will fail and can not be recovered. Under normal operating conditions, this thermal breakdown will not occur as long as the working current does not exceed the rated current of the thyristor, because the over current breakdown principle is caused by the increase of temperature, and the process of temperature rise is required for a certain time, so in a short time (hundreds of milliseconds to several seconds) is generally not. It will be worn out.
3, overheat breakdown: the overheat breakdown described here refers to the thermal breakdown that occurs when the working current does not exceed the rated current of the silicon controlled silicon. The main reason for this breakdown is the poor working of the silicon controlled auxiliary heat dissipation device, which causes the high temperature induced breakdown of the silicon controlled silicon chip.