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Discussion Starter · #1 ·
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




Thanks
 

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fysnh said:
If u know it, please help
I know them all. The most helpful thing you could do for yourself is read the chapters and see what you missed
 

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Pool Shark
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For first question I'd guess the occupancy sensor is analog and I'll explain why. Digital is like FrunkSlammer said, 1s and 0s. The occupancy even though runs off 120v AC, the sensor part uses analog detection, ie. Infrared.

2. Lowering the load is the only reasonable answer.
3. No idea
4. No idea
5. Adjust Relay
 

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Discussion Starter · #20 ·
For first question I'd guess the occupancy sensor is analog and I'll explain why. Digital is like FrunkSlammer said, 1s and 0s. The occupancy even though runs off 120v AC, the sensor part uses analog detection, ie. Infrared.

2. Lowering the load is the only reasonable answer.
3. No idea
4. No idea
5. Adjust Relay
thanks
 
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