A single phase motor question here where Ive been stumped on the configuration of the power supply.
I recently came across a 220V single-phase fan motor. It had a 16 uF (400V) cap installed and had 3 wires connected to the terminals.
From my lack of experience with single-phase motors, I always thought that single-phase motors needed 2 supply wires and not 3, so you can see where I am stumped.
It didnt help that the cables were not labelled so I disconnected the 3 wires from the motor and measured the supply between them. Cable 1-2 = 220V, Cable 2-3 = 220V, Cable 1-3 = 0V, however when I measured the supply with respect to earth, each wire had a potential of around 120V. Meaning Cable 1-3 were the same phase, but I tested this by turning off the power and checking the continuity between Cable 1-3, much to my surprise there was no continuity. Wondering what is happening here.
I have attached some pics of motor details and the final connections I made to the motor to get it running at the rated speed.
I was curious to see the behaviour of the motor with only 2 supply wires connected so I connected Cable 1 = U1 and Cable 2 = U2 with the links up and down. The motor turned however not at the rated speed. I finally connected the motor as I first came across it, with Cable 1 = U1, Cable 2 =U2, Cable 3 = Z1 with the links up and down and voila back to rated speed.
Its been awhile since I have been in class and the fundamentals of single-phase motor with a start-cap, has faded from my memory a bit. If someone can lend me there expertise I will definitely be grateful and pass on the knowledge.
I recently came across a 220V single-phase fan motor. It had a 16 uF (400V) cap installed and had 3 wires connected to the terminals.
From my lack of experience with single-phase motors, I always thought that single-phase motors needed 2 supply wires and not 3, so you can see where I am stumped.
It didnt help that the cables were not labelled so I disconnected the 3 wires from the motor and measured the supply between them. Cable 1-2 = 220V, Cable 2-3 = 220V, Cable 1-3 = 0V, however when I measured the supply with respect to earth, each wire had a potential of around 120V. Meaning Cable 1-3 were the same phase, but I tested this by turning off the power and checking the continuity between Cable 1-3, much to my surprise there was no continuity. Wondering what is happening here.
I have attached some pics of motor details and the final connections I made to the motor to get it running at the rated speed.
I was curious to see the behaviour of the motor with only 2 supply wires connected so I connected Cable 1 = U1 and Cable 2 = U2 with the links up and down. The motor turned however not at the rated speed. I finally connected the motor as I first came across it, with Cable 1 = U1, Cable 2 =U2, Cable 3 = Z1 with the links up and down and voila back to rated speed.
Its been awhile since I have been in class and the fundamentals of single-phase motor with a start-cap, has faded from my memory a bit. If someone can lend me there expertise I will definitely be grateful and pass on the knowledge.
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