中频信号取样回路有开路或极性错误现象――这种原因多在采用交角法的线路中，中频电压信号开路或在维修其它故障时将中频电压信号的极性接反，均会造成此故障现象
2.
If there is an open circuit or polarity error in the sampling circuit
of the intermediate frequency signal - this is often the case in
circuits using the intersection method. If the intermediate frequency
voltage signal is open circuit or if the polarity of the intermediate
frequency voltage signal is reversed when repairing other faults, it can
cause this fault phenomenon
3.逆变引前角移向电路出现故障――中频电源的负载是呈容性的，即：电流超前于电压。在取样控制电路中，都设计有移相电路，如果移相电路出现故障也会造成此故障现象
3.
The inverter leads to a fault in the forward angle shift circuit - the
load of the intermediate frequency power supply is capacitive, that is,
the current leads the voltage. In sampling control circuits,
phase-shifting circuits are designed, and if the phase-shifting circuit
fails, it can also cause this fault phenomenon
三.启动困难，启动后直流电压最高只能升到400V，且电抗器震动大，声音沉闷
3、
Difficult to start, the maximum DC voltage can only rise to 400V after
starting, and the reactor vibrates heavily with a dull sound
故障分析及处理：这种故障是三相全控整流桥故障，其主要原因是：
Fault
analysis and handling: This type of fault is a three-phase fully
controlled rectifier bridge fault, which is mainly caused by:
1.整流可控硅开路、击穿、软击穿或电参数性能下降――用示波器观察各整流可控硅的管压降波形，查找损坏的可控硅后更换。当损坏的可控硅击穿时，其管压降波形为一条直线；软击穿时电压升到一定时为一条直线，电参数下降时电压升到一定值时波形发生变化。如果出现上述现象，直流电流就会出现断流现象，造成电抗器震动
1.
Open circuit, breakdown, soft breakdown, or decrease in electrical
parameter performance of rectifier thyristor - observe the voltage drop
waveform of each rectifier thyristor with an oscilloscope, find the
damaged thyristor, and replace it. When the damaged thyristor breaks
down, its voltage drop waveform is a straight line; When the voltage
rises to a certain value during soft breakdown, it becomes a straight
line, and when the electrical parameters decrease, the waveform changes
when the voltage rises to a certain value. If the above phenomenon
occurs, the DC current will be cut off, causing the reactor to vibrate
2.缺少一组整流触发脉冲――用示波器分别检查各路触发脉冲（最好在可控硅上检查），检查出没有脉冲的回路时，用倒推法确定故障位置，更换其损坏器件。当出现这种现象时，直流电压的输出波头就会缺少一个波头，造成电流断流，产生此故障现象
2.
Lack of a set of rectifier trigger pulses - Use an oscilloscope to
check each trigger pulse separately (preferably on a thyristor). When a
circuit without a pulse is detected, use the reverse method to determine
the fault location and replace the damaged components. When this
phenomenon occurs, the output wave head of the DC voltage will lack one
wave head, causing current interruption and generating this fault
phenomenon