11) Fault phenomenon: Frequent burnout of the thyristor original, after replacement, burned out

Analysis:

Refer to fault E) for additional introductions as follows:

a. When the thyristor is turned off in reverse, the instantaneous glitch voltage subjected to the reverse voltage is too high, and the RC absorption is checked.

b. The load is reduced to ground insulation, and the ground is fired, or high voltage is formed at both ends of the thyristor

c. Pulse trigger loop fault, sudden loss of trigger pulse causes open thyristor

d. Load open circuit when the device is running

e. Load short circuit when the device is running

f. Protection system failure (protection failure)

g. Thyristor cooling water system failure

h. Reactor failure, causing current interruption on the inverter side, burning the thyristor due to magnetic saturation of the reactor and loss of current limiting

i. The inductance of the commutating inductor is too large, or the insulation is reduced to cause current instability.

12) Fault phenomenon: When the device is started, when the IF start switch is turned on, the main circuit switch protection trip or overcurrent protection

Analysis:

a. The power adjustment knob is at the highest position, and the instantaneous current impact is too large.

b. The current regulator is faulty, especially if the current transformer is damaged or the wiring is open, the current feedback suppression is started, and the current impact is too large.

13) Fault phenomenon: The intermediate frequency transformer burns out, and the starting device is still burned out after replacement.

Analysis:

This phenomenon generally occurs on the boost load device, mainly due to the open circuit of the snorkeling discharge. The two sets of capacitor voltages in the boost mode are inconsistent. The high voltage discharge is slow during discharge. When it is not discharged, it starts to charge and will accumulate on the capacitor. The DC charge is released by the discharge and discharge, and the open circuit is discharged through the intermediate frequency transformer. The capacity of the intermediate frequency transformer is small and burned out.

14) Fault phenomenon: bleed and discharge in the booster circuit, heat or burnout

Analysis:

a. Small discharge and discharge

b. Inverted pulse asymmetry

c. When the inverter thyristor has a burnout condition, the output voltage of the intermediate frequency is fluctuating, causing a large current flowing through the discharge and causing heat or burnout.

15) Symptom: The device can be started, the startup frequency is much higher than the original, sometimes it is not good to start.

Analysis:

a. There is a short circuit between the load coils

b. The load capacitor column has an open circuit

16) Fault phenomenon: easy to start, but the voltage is easy to overvoltage when boosting, sometimes overvoltage and overcurrent appear simultaneously

Analysis:

a. The inverter lead angle is too large, causing the inverter glitch voltage to be too high

b. The main circuit inside the power cabinet has virtual connection, insulation reduction, and sparking

c. The load coil or capacitor has a virtual connection, insulation reduction, and sparking

d. Inverter thyristor trigger has a problem, the connection is loose or the door is open

17) Fault phenomenon: The device can be started, but the voltage rise is not high, the reactor sound is loud and dull, the voltage rises when it is unstable, sometimes overcurrent and overvoltage protection, sometimes burns the thyristor, but the rectifier is good.

Analysis:

a. The reactor has a large inductance and magnetic saturation, which does not filter.

b. Reactor insulation is not good