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1. Which one of the following device using the analog signal?
A. VFD. B. start/stop button. C. Occupancy sensor


2.how to reduce VFD harmonic current?
A.rectifiler b.lower the load
C.raise the load
D. Change the power factor


3.split phase Dc motor ,when centrifugal switch cannot close ,what will happen?
A.motor not start ,but hum
B.motor running at low speed.
C. Run winding will overheat
D.the start windings will bum out


4.split phase DC motor ,when centrifugal switch is stuck close by corrosion on the slides of switch, what will this probably cause?
A.the motor may not start,but hum
B.the motor will not reach full speed
C.the run windings will burn out
D. The start windings will bum out


5.a new overload relay keeps tripping ,what should be done?
A.replace the relay
B. adjust the relay
C.adjust voltage
D. Replace over load with VFD
 
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