1) Fault phenomenon: the equipment cannot be started. During startup, only the DC ammeter has indication, and there is no indication of DC voltage and intermediate frequency voltage
analysis
a. The inverter trigger pulse is missing
b. Inverter thyristor breakdown;
c. If signal sampling circuit has open circuit or wrong polarity;
d. Short circuit and grounding of load;
e. If signal sampling circuit has open circuit or short circuit.
2) Fault phenomenon: it is difficult to start. After starting, the intermediate frequency voltage is more than twice the DC voltage, and the DC current is too large.
analysis
a. One thyristor of the inverter circuit is damaged
b. One of the inverter thyristors does not turn on, that is, the "three legs" work;
C. If signal sampling circuit has open circuit or wrong polarity;
d. The inverter leading forward angle phase-shifting circuit is faulty;
3) Fault phenomenon: it is difficult to start, the DC voltage after start is difficult to reach full load or close to full load, and the reactor vibrates greatly and the sound is dull.
analysis
a. Open circuit, breakdown, soft breakdown or electrical parameter performance degradation of rectifier thyristor
b. A set of rectifier pulses is missing
c. Rectifier thyristor gate open circuit or short circuit
4) Fault phenomenon: it can be started, but it stops immediately after starting, and the equipment is in the state of repeated starting.
analysis
a. The leading front angle is too small;
b. The load oscillation frequency is at the edge of its excitation frequency
5) Fault phenomenon: after the equipment is started, when the power rises to a certain value, it is prone to overcurrent protection. Sometimes the thyristor is burned out before it is restarted. The phenomenon remains the same
analysis:
a. If overcurrent occurs at low voltage just after startup, the front angle of the inverter is too small to turn off the thyristor reliably
b. The cooling effect of inverter thyristor water-cooling jacket decreases
c. Poor contact of groove connecting wire
6) Fault phenomenon: when the equipment is running, the DC current has reached the rated value, but the DC voltage and intermediate frequency voltage are low.
Analysis: this phenomenon is not caused by the failure of intermediate frequency power supply, but due to the low load impedance
a. The series capacitor is damaged
b. The inductor has inter turn short circuit