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fuse falure

Dear sir,

we are useing 4Q dc drive SSD make for 700 hp rolling mill application .This motor for mill.We are faceing problem when ever power dip occured incomming fuses of 3 phase fuses falure freqently and alarm showing in drive speed feedback.we are useing incomming thyrestor fuses. how to eleminate this problem?

Reply to
harivv17
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  1. You may need an isolation xformer for the drive from the mains. You could have a problem with your motor shorting in the armature to ground.
  2. The alarm in the drive is indicating you have a stall out. this could be due to a machine jam up or, like I said, armature shorting in the motor when it gets hot, or could be a bad encoder that is allowing the mill to run away and over currents. This could also mean in proper set of the drive allowing high currents above the fuse protection.

Check the motor with a megga meter for shorts. it should be well above 2 megs when the motor is hot.

  1. You have a bad bridge in the drive that is shorting when hot or, you have a miss fire in the firing circuit and could be due to buss shorting.

measure your 3 phase voltage from each leg to ground to start with.

Make sure the current limiting in the drive is set below the fuse ratings and do not have the drive ignore the error.

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Reply to
Jamie

Power dips. Fuses blow (expectedly). Motor stops. Drive speed drops to zero. Alarm indicates drop to zero. Is that what you are saying, and if so, where's the 'problem'?

If you want to eliminate the blowing fuses, you need to either get a more reliable power source, or find a different protection scheme that can handle power dips.

Or I'm totally mis-reading your (Google translated?) post...

Reply to
PeterD

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