East EA990G5, Руководство по обслуживанию

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Step 3: Use the diode gear of the multimeter to detect the PIN1(+)-PIN3(-) and PIN2(+)-PIN3(-) of the boost
IGBT and the inverter outer/inner bridge IGBT. If the multimeter shows that the voltage drop is too low (less than
0.1V), you need to replace the corresponding IGBT.
Note: When replacing the IGBT, it is necessary to apply heat dissipation paste on the back of the IGBT. If the
corresponding insulating gasket is blackened, burned, burned through, burned, etc., it should also be replaced
together.
Step 4: Use the multimeter diode gear to detect the Zenner diode of IGBT driver. If the multimeter shows that
the voltage drop is too low (less than 0.1V), the corresponding Zener diode needs to be replaced.
Note: If the IGBT is found to be damaged in step 3, the corresponding driving Zener diode will also be
damaged.
Step 5: Use the diode gear of the multimeter to test the input rectifier diode and Boost diode. If the forward
voltage drop is too low (less than 0.1V) or there is also a reverse voltage drop, the diode may be damaged and
needs to be replaced.
Step 6: Measure the resistance of the battery thyristor (SCR) with a multimeter in the ohm range. The normal
resistance should be around 20Ω. If not, it needs to be replaced.
After completing the inspection work in steps 1-6, replace the damaged device; after replacing the device,
use the shorting cap to short-circuit J2 of the rectifier control board CT1 and J2 of the inverter control board CT2,
and then follow the steps shown in Figure 6-6. Connection method Connect the main power board to the input and
output board (only connect the signal cable, not the copper bus), and carry out the drive test. The test waveforms
of each key device are shown in Table 6-6.
Fig.6-4 The connection of drive test circuit of 20kVA power board
Table 6-4 The driver test description of 20kVA power board
Component and its tag number Waveform Remark