help

[tjwork]

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

 

[KalleOlsen]

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

Do you have a BOP / AOP connected?

K

 

[tjwork]

Do you have a BOP / AOP connected?

K

yes

 

[KalleOlsen]

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]

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

noerror code the bop doesnt power up
no previous warning

 

[KalleOlsen]

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]

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.

 

[sthompson]

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]

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