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commonly for motors we use 20% impedance..
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∙ 13y ago
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What is meant by apparent impedance?
You may be mixing up 'impedance' with 'apparent power'.Impedance is the vector sum of an a.c. load's resistance and reactance, and is expressed in ohms. Apparent power is the vector sum of true power and reactive power, and is expressed in volt amperes.Apparent power is also the product of the square of the load current and the impedance of the load.
What is impedance protection for a motor?
A motor that relies solely upon the impedance of the windings to prevent overheating.
What is meant by apparent?
You may be mixing up 'impedance' with 'apparent power'.Impedance is the vector sum of an a.c. load's resistance and reactance, and is expressed in ohms. Apparent power is the vector sum of true power and reactive power, and is expressed in volt amperes.Apparent power is also the product of the square of the load current and the impedance of the load.
What is the ratio of apparent power to true power?
The ratio of apparent power to true power is called 'admittance', expressed in siemens. Admittance is the inverse of impedance.
How do you convert percent impedance of transformer to impedance value?
The apparent impedance looking into a transformer from one side will not be the same as looking in it from the other, which is why percent impedance is used. If you are looking from the high voltage winding (I'm labeling #1) to the low voltage winding (#2), you must scale the percent impedance as follows: (% impedance) x (Winding #1 nominal voltage)^2 / (transformer base VA)
What is FCMA Soft Starter?
At start the equivalent impedance of the FCMA is constant and maximum, done by the Main winding and the motor current through it. When the motor speed increase, the cemf of the motor increase the flux in the feedback winding, as this winding is in opposition with the Main winding the total flux, so the total equivalent impedance in the module, is decreasing with the motor speed. The design of our module, fonction of the motor data, is such as the starting current is keeping constant and the voltage at the motor terminal is continiously increasing during the motor start .
What is the current to an induction motor at 90 percent voltage?
It depends on the impedance of the induction motor. By rearranging ohms law, I=V/R where V would be 90% of Vmax
Which is better high input impedance or low input impedance and why?
That depends on the output impedance. In electronic we use voltage bridging, that is a relative low output impedance to a higher input impedance. Usualy the input impedance is more than ten times higher then the output impedance. An input impedance is called also a load impedance or an external impedance. An output impedance is called also a source impedance or an internal impedance.
How to distinguish between characteristic impedance and input impedance?
The characteristic impedance or surge impedance belongs to uniform transmission lines.In electronic gears we use voltage bridging, that is a relative low output impedance to a higher input impedance. Usualy the input impedance is more than ten times higher then the output impedance.An input impedance is called also a load impedance or an external impedance.An output impedance is called also a source impedance or an internal impedance.
Does it matter if the voltage leads the current or the current leads the voltage?
Yes. If voltage leads the current, the impedance is inductive (this would be the case if the load is a motor). If current leads the voltage, the impedance is capacitive (this would be the case for a CFL light bulb).
When the motor stops for no apparent reason the first thing to do is?
Check the fuse of the power supply.
Input impedance is greater than to load impedance?
In electronic gears we use voltage bridging, that is a relative low output impedance to a higher input impedance. Usualy the input impedance is more than ten times higher then the output impedance.An input impedance is called also a load impedance or an external impedance.An output impedance is called also a source impedance or an internal impedance.
