Motor load 50%of nameplate data

[Sofistioelevib]

Hello guys,
i have a very strange fact.
i have 7 fan vertical motor-pulley-fan in a steam condensation field and for every motor i collected phase-phase voltage, phase-neutral voltage, and phase current.
All the motor are mechanically and electrically equal and have 380V, 88A, cosfi=0,82 data but during data acquisition i found some with very low cosfi (until 0,6) and very low load (until 53A).
In attachment you found data acquired. I don't know how many time this problem is present.

None have idea about this issue? or can instruct me to find the way to solve it?

PS: There are no problem on belt and the pitch angle for every blade is locked on the main shaft and with correct angle (from constructor)!!

 

[waross]

A simple calculation shows that a motor running at 0.8 pF at 100% load will drop to a PF of 0.64 at 50% load.
The motor current will drop to about 78%.
The simple calculation ignores the change in magnetizing current with a change in load but it makes the point.


Bill
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"Why not the best?"
Jimmy Carter