In the process of designing the intermediate frequency power supply, how to select the appropriate inverter thyristor according to the actual application can follow the following principles:
1. According to the working frequency range of the intermediate frequency power supply:
a) KK-type thyristors with a frequency of 100HZ---500HZ with a selected turn-off time of 20μs-45μs.
b) KK-type thyristors with a frequency of 500HZ---1000HZ with a selected turn-off time of 18μs-25μs.
c) KK-type thyristors with a frequency of between 1000 Hz and -2500 Hz with a selected turn-off time of 12 μs to 18 μs.
d) The selected off-time of the frequency at 2500HZ---4000HZ is controllable at KKG type of 10μs-14μs.
e) KA type thyristor with a frequency of 4000HZ---8000HZ with a selected off-time of 6μs - 9μs.
2. According to the output power of the intermediate frequency power supply:
According to the theoretical calculation of the parallel bridge inverter circuit, the current flowing through each thyristor is 0.455 times of the total current. Considering that there is sufficient margin, the thyristor of the same size as the rated current is usually selected.
a) The thyristor with a power of 50 kW----100 kW with a selected current of 300 A/1400 V. (380V phase-in phase voltage)
b) The thyristor with a selected current of 500A/1400V with a power of 100KW--250KW. (380V phase-in phase voltage)
c) The thyristor with a selected current of 800A/1600V with a power of 350KW-400KW. (380V phase-in phase voltage)
d) The thyristor with a selected current of 1500A/1600V with a power of 500KW--750KW. (380V phase-in phase voltage)
e) A thyristor with a selected current of 1500A/2500V with a power of 800 KW to 1000 KW. (660V phase-in voltage)
f) The thyristor with a selected current of 2000A/2500V with a power of 1200KW-1600KW. (660V phase-in voltage)
g) A thyristor with a current of 2500A/3000V with a power of 1800KW-2500KW. (1250V phase voltage)
