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tjwork

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• Aug 15, 2011

• #1

why would a siemens micromaster 440 sometimes fail to power up when energised

 

KalleOlsen

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• Aug 15, 2011

• #2

tjwork said:

why would a siemens micromaster 440 sometimes fail to power up when energised

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Do you have a BOP / AOP connected?

K

 

tjwork

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• Aug 15, 2011

• #3

KalleOlsen said:

Do you have a BOP / AOP connected?

K

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yes

 

KalleOlsen

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• Aug 15, 2011

• #4

Don't you get warning or error indication? Would be like Axxx, where xxx=a number code that you can find in the manual.

 

tjwork

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• Aug 15, 2011

• #5

KalleOlsen said:

Don't you get warning or error indication? Would be like Axxx, where xxx=a number code that you can find in the manual.

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noerror code the bop doesnt power up
no previous warning

 

KalleOlsen

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• Aug 15, 2011

• #6

I'd say if the BOP is dark, the MM isn't energized. What did you do to find the error? Did you measure on the power terminals, the DC circuit? The MM4 is more like a pile of cheap plastic, is it properly fitted?

 

KalleOlsen

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• Aug 15, 2011

• #7

You could power the BOP from the 24V terminals on the IO card. Maybe you can see an error code then?

Edit: ..... or am I messing? Maybe it is the Profibus card that has 24V external supply.

 

Last edited: Aug 15, 2011

sthompson

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• Aug 15, 2011

• #8

I have seen this occur when there are problems in the Precharge circuitry. There is usually an SCR or Relay that bypasses a Current Limiting Resistor that limits the Inrush to the Filter Capacitors at Power Up. I don't know if the MMs have Precharge, but most modern VFDs do these days.

Stu....

 

KalleOlsen

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• Aug 15, 2011

• #9

On a plant I'm often visiting there are apx 300(!) MM440's. The oldest are 10+ years. Never seen or heard of anything like this. What I've seen fail, are some Proficards - they seem not to like the good and warm closets.

Kalle