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  1. #1
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    Danfoss AquaDrive 202 DC-Bus Over-voltage

    Hi,

    I'm a control system technician and need to fix a 440Vac, 600HP Danfoss AquaDrive 202. After a storm this drive starts but after some seconds it trips with alarm 7 DC-Bus over-voltage. I made some voltage measurements and realize that when the motor is stopped the bus voltage is 640Vcc but when I start the motor this voltage increase to 880Vcc and the drive trips!!!!! How this is possible, using my multimeter all power semiconductors like IGBTs, SCRs, and diodes are all ok, can someone help me?

    P.S. There are two bank of capacitors of 8 4700uF x 450V each in series or 8 x 4700 x 450V = 18800 x 900V each bank x 2 = 37600uF x 900V.
    According to my capacitance meter they are with approximately 16200 uF each bank so this may be the cause of the defect?

    Regards,

    Fernando - Brazil

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  2. #2
    Super Moderator
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    Re: Danfoss AquaDrive 202 DC-Bus Over-voltage

    Does the motor have a load attached as it starts up? Does it turn slowly, possibly drawing excessive Amperes (which is common with many types of motors when running slower than normal)?

    Would it help if you were to start the motor with no load and let it run for a few seconds? Then attach the load?



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