What’s the Matter?!?! (Take the Quiz)

While providing witness inspection services as a utilities owner engineer on a new motor they had ordered which was undergoing testing, the motor manufacturer reported a problem with the ventilation. It was an open ventilated machine with air inlets at both ends. However, it was noticed that all the air appeared to be entering only one end. Furthermore, when that air was blocked as expected all the air then entered the other end. What was surprising was that when the blocking was removed the air continued entering the second end. What was wrong?

(a) Blowers not working properly.
(b) Internal baffles not properly assembled.
(c) Rotor design issues.
(d) The window near the test station was not propped open


The manufacturer chose (a) and (b) and their accountant (d). The EME representative asked to review the rotor drawings being suspicious that the problem appeared similar to ones occurred on vertical hydro-generators. The manufacturer installed new blowers which they claimed to be more efficient and made changes to the internal anti-recirculating end bells. This effort provided no improvement for the ventilation problem.
Upon reviewing the rotor design the EME representative noted that there was no partition in the center of the rotor spider. Installation of such a partition at this stage in a rotating component was viewed as risky in that it had to be able to sustain the centrifugal forces to which it would be subjected. EME suggested a partition design that could be adequately supported and at the same time readily installed.
The suggested partition was manufactured and installed. The results upon testing showed that the motor was ventilated with air entering at both ends as intended – an example of an ENGINEERED SOLUTION by EME.