Causes of damage of rectifier diodes and reasons for replacement and selection

Causes of damage of rectifier diodes and reasons for replacement and selection.
(1) the measures of lightning protection and overvoltage protection are not effective. The rectifier device is not equipped with lightning protection and overvoltage protection device, even if it is equipped with lightning protection and overvoltage protection device, but its work is not reliable and the rectifier diodee is damaged due to lightning strike or overvoltage.
(2) the operating conditions are bad. For the generator set with indirect transmission, because the calculation of the speed ratio is incorrect or the diameter ratio of the two belt discs does not meet the requirements of the speed ratio, the generator operates at high speed for a long time, and the rectifier diodee works at a higher voltage for a long time. Accelerate the aging of the rectifier diodee and be damaged prematurely.
(3) the operation and management is poor. The operator on duty is irresponsible and does not understand the change of external load (especially between midnight and 6 am the next day), or when a load rejection fault occurs in the outside world, the operator fails to deal with it in time, causing overvoltage and breaking down the rectifier diodee.
(4) the quality of equipment installation or manufacture is not up to standard. Because the generator set is running in a large vibration for a long time, the rectifier diodee is also under the interference of the external force of this vibration; at the same time, because the rotational speed of the generator set is high and low, the working voltage of the rectifier diodee varies from high to low, which greatly accelerates the aging and damage of the rectifier diodee.
(5) the specification and model of rectifier diodee is not in conformity with each other. When replacing the new rectifier diodee, the pipe whose working parameters do not meet the requirements is replaced or the wiring is wrong, resulting in breakdown damage of the rectifier diodee.
(6) the safety margin of rectifier diodee is small. The safety margin of overvoltage and overcurrent of the rectifier diodee is too small, so that the rectifier diodee can not bear the attack of the peak value of overvoltage or overcurrent transient process in the generator excitation circuit.
Folding.
Inspection method.
First of all, all the rectifier diodes in the rectifier are removed, and the two lead wires of the rectifier diodes are measured with the 100xR or 1000 × R ohms of the multimeter. If the resistance values measured by the two times are very different, for example, the resistance value is as high as several hundred K Ω to infinity, while the resistance value is only a few hundred Ω or less, it shows that the diode is good (except for the diode with soft breakdown). If the two measured resistance values are almost the same, and the resistance value is very small, it means that the diode has been broken down and can not be used. If the resistance value of both measurements is infinite, it means that the diode has been internally disconnected and cannot be used.
Substitution.
After the rectifier diode is damaged, it can be replaced by the same type of rectifier diode or other type of rectifier diode with the same parameters.
In general, the rectifier diode with high voltage withstand value (reverse voltage) can replace the rectifier diode with low voltage withstand value, while the rectifier diode with low voltage withstand value cannot replace the rectifier diode with high voltage withstand value. Diodes with high rectifying current value can replace diodes with low rectifying current value, while diodes with low rectifying current value cannot replace diodes with high rectifying current value.