Fault phenomenon: there is no response when the equipment is started. After observation, the phase loss indicator on the control circuit board is on.

Fault cause: the quick fuse is burnt out. Generally, the quick fuse has a fusing indication, and the indication can be observed to judge whether the fuse is burnt out. However, sometimes, due to the long service time or quality reasons of the quick fuse, the indication is not indicated or the indication is unclear, so it is necessary to cut off the power or measure with a multimeter.

Treatment method: replace the quick fuse and analyze the cause of burning out. Generally, there are four reasons for burning out the fast fuse:

(1). The equipment operates under the conditions of high power and high current for a long time, resulting in the heating of the fast fuse and the hot melting of the fusible core;

(2). Short circuit of rectifier load or medium frequency load, resulting in instantaneous high current impact, burn out the fast fuse, and check its load circuit;

(3). If the fault of rectifier control circuit causes instantaneous high current impact, the rectifier circuit shall be checked;

(4). If the contact of the master switch is burnt out or there is a phase failure in the front stage power supply system, measure the line voltage of each stage with the AC voltage gear of the multimeter to judge the fault position.