一.装置无法启动，启动时只有直流电流表有指示，直流电压、中频电压表均无指示。
1、 The equipment cannot be started, and only the DC Ammeter has indication when starting, while the DC voltage and intermediate frequency Voltmeter have no indication.
故障分析及处理：这是一种最常见的故障现象，造成的原因可能是：
Fault analysis and handling: This is the most common fault phenomenon, which may be caused by:
1.逆变触发脉冲有缺脉冲现象――用示波器检查逆变脉冲（最好在可控硅的AK上检查），如发现有缺脉冲现象，检查连线是否有接触不良或开路，前级是否有脉冲输出。
1. Inverter trigger pulse has missing pulse phenomenon - use an oscilloscope to check the inverter pulse (preferably on the AK of the thyristor). If missing pulse phenomenon is found, check the wiring for poor contact or open circuit, and whether there is pulse output in the front stage.
2.逆变可控硅击穿――更换可控硅，并检查可控硅损坏原因（有关可控硅损坏原因参见后面的可控硅损坏原因分析）
2. Inverter thyristor breakdown - replace the thyristor and check the cause of thyristor damage (refer to the analysis of thyristor damage causes later)
3.电容器击穿――拆除损坏的电容器极柱
3. Capacitor breakdown - removing damaged capacitor poles
4.负载有短路、接地现象――排除短路点和接地点
4. There is a short circuit or grounding phenomenon in the load - eliminate the short circuit point and grounding point
5.中频信号取样回路有开路或短路现象――用示波器观察各信号取样点的波形，或在不通电的情况下用万用表测量各信号取样回路的电阻值，查找开路点或短路点
5. If there is an open circuit or short circuit in the intermediate frequency signal sampling circuit - use an oscilloscope to observe the waveform of each signal sampling point, or use a multimeter to measure the resistance value of each signal sampling circuit without power, and find the open or short circuit point
二.启动较困难，启动后中频电压高出直流电压的一倍，且直流电流过大。
2、 It is difficult to start, and the intermediate frequency voltage is twice as high as the DC voltage after starting, and the DC current is too large.
故障分析及处理：造成这种故障的原因有：
Fault analysis and handling: The reasons for this fault include:
1.逆变回路有一只可控硅损坏――当逆变回路有一只可控硅损坏时，装置有时也可启动，但启动后会出现上述故障现象，更换损坏的可控硅，并检查损坏原因
1. One thyristor in the inverter circuit is damaged - when one thyristor in the inverter circuit is damaged, the equipment can sometimes be started, but the above fault phenomenon may occur after starting. Replace the damaged thyristor and check the cause of the damage
2.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