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Mark covered with high merit the high-damage problem of switching transients with star delta starter and jraef mentioned in one of his previous post the damage caused to the fan blades on a 700HP compressor. I am looking for snaps on mechanical damage caused by the open transition.






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Hi Bob


I've seen plenty of examples, but never actually photographed any.

Star delta starting is now becoming more rare in this country, so probably not too many opportunities to take photographs in the future.

Good luck!!


Best regards,


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Hi Bob,


Been a while. Hope life is treating you well. In a similar thread I wrote that torque (worst case condition) would be equal to 4 times that which was being developed by the motor just prior to the transition from star to delta, clearly much greater than that which is delivered under DOL or Full Voltage start conditions.


Like Mark, I have never photographed damaged caused by such transients but have seen the end result very often. Examples include:


Thrown or displaced belt couplings

Stripped gear belts

Stretched and damaged chain & sprocket couplings

Damaged pump, fan and compressor (chiller) impellors

Broken mounting feet on motors


Yet there are still many sold into industry each year because they are cheap. Educating installers is achievable but invariably the decision makers are financial people who appear to look at everything in 12 month blocks!





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Yeah, sorry. All of the ones I have seen were in the days before digital cameras so taking pictures was something you had to plan out in advance (camera, film, light etc.) I rarely did. Broken shafts are not something that typically happens with advanced warning...
"He's not dead, he's just pinin' for the fjords!"
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