East EA990G5, Руководство по обслуживанию

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Step 1: Check whether the copper foil is corroded and rusted on the entire I/O board. You can use a
multimeter to assist in the inspection. If there is corrosion, the copper foil needs to be re-soldered.
Step 2: Visually inspect the entire I/O board for obvious burns or explosions, and replace if necessary.
Step 3: Measure the resistance of the bypass thyristor (SCR) with the ohm gear of the multimeter. The normal
resistance should be around 20 Ω . If not, it needs to be replaced.
Note: When replacing the SCR, it is necessary to apply thermal paste on the back of the device. If the
corresponding insulating gasket is blackened, burned, burned through, burned, etc., it needs to be replaced
together.
After completing the inspection work in steps 1-3, 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 6-20. Connection method for drive test. The test waveforms of each key
device are shown in Table 6-20.
Fig.6-20 The connection of drive test circuit of 15/20kVA bypass board
Table 6-20 The driver test description of 15/20kVA bypass board
Component and its tag number Waveform Remark
Bypass SCR
Q1,Q2,Q3,Q4,Q5,Q6
High level
1V-1.5V
；
Low level
0V
；
If it is found that the individual SCR is abnormally driven during the drive test, please re-check whether the
device is replaced, and check whether the corresponding drive module is damaged.
6.3.3 Maintenance of 30kVA bypass board
The 30kVA bypass board mainly includes bypass output circuit and output current sampling circuit. Among
them, the forgile component is bypass SCR, which is shown in Table 6-21, and its position in the board is shown
in Fig.6-21.