The stator current is calculated by dividing the phase voltage by the equivalent complex impedance of the entire circuit shown. The speed of the stator magnetic field in radians per second is 4xPixf/poles.
How to calculate stator current?
What is the speed of a rotor?
What is no load in motors?
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Analysis of stator current of induction motor used in transport system ...
found in [23]. Stator winding fault diagnosis in three-phase synchronous and asynchronous motors has been performed by extended Park’s vector approach [24, 25] and then
How to find the power of a three phase system?
Easy enough. To find the power given current, multiply by the voltage and then the power factor to convert to W. For a three phase system multiply by three to get the total power.
How to solve a three phase problem?
the easiest way to solve three phase problems is to convert them to a single phase problem. Take a three phase motor (with three windings, each identical) consuming a given kW. The kW per winding (single phase) has to be the total divided by 3. Similarly a transformer (with three windings, each identical) supplying a given kVA will have each winding supplying a third of the total power. To convert a three phase problem to a single phase problem take the total kW (or kVA) and divide by three.
Can a single phase load be unbalanced?
Often where single-phase loads are involved, residential and commercial premises, for example, the system can be unbalanced with each phase have a different current and delivering or consuming a differing amount of power.
How to calculate kVA from kW?
By remembering that a three phase power (kW or kVA) is simply three times the single phase power, any three phase problem can be simplified. Divide kW by the power factor to get the kVA. VA is simply the current times the voltage, so knowing this and the voltage can give the current. When calculating the current use the phase voltage which is related to the line voltage by the square root of three. Using these rules it is possible to work out any three phase problem without the need to remember and/or resort to formulas.
What to consider when carrying out calculations?
Other things to consider while carrying out calculations may include the efficiency of equipment . Knowing that efficiency of power consuming equipment is the output power divided by the input power, again this can easily accounted.for Reactive power is not discussed in the article and more details can be found in other notes (just use the site search).
What is the relationship between kVA and kW?
The relationship between kVA and kW is the power factor (pf): which can also be expressed as: Single phase system - this is the easiest to deal with. Given the kW and power factor the kVA can be easily worked out. The current is simply the kVA divided by the voltage.
Can a single phase load be unbalanced?
Often where single phase loads are involved, residential and commercial premises for example, the system can be unbalanced with each phase have a different current and delivering or consuming a differing amount of power.
What is the formula for the power consumed by the load?
The formula for the power consumed by the load is a derivative of both the P=VI and V=IR formulas.
How to calculate electrical energy consumption?
So if you want to calculate electrical energy consumed, just multiply wattage rating of your appliance with the time for which it is in operation .
How does torque change with speed?
Motor torque changes with the speed. At no load you have maximum speed and zero torque. Load adds mechanical resistance. The motor starts to consume more current to overcome this resistance and the speed decreases. If you increase the load at some point motor stops (this is called stall). When it occurs the torque is at maximum and it is called stall torque. While it is hard to measure stall torque without special tools you can find this value by plotting speed-torque graph. You need to take at least two measurements with different loads to find the stall torque.
How accurate is torque calculation?
How accurate is the torque calculation? While voltage, current and speed could be accurately measured, efficiency of the motor may not be correct. It depends on the accuracy of your assembly, sensor position, friction, alignment of the motor and generator axles etc. If you want to get meaningful numbers you might use a second generator kit as explained in Torque and Efficiency Calculation section.
What are the two important values that determine how powerful a motor is?
Motors supposed to do some work and two important values define how powerful the motor is. It is motor speed and torque – the turning force of the motor. Output mechanical power of the motor could be calculated by using the following formula:
How much torque is in a N•M?
As the result is small usually it is expressed in milliNewton meters (mN•m). There is 1000 mN•m in 1 N•m, so the calculated torque is 1.26 mN•m. It could be also converted further to still common gram force centimeters (g-cm) by multiplying the result by 10.2, i.e. the torque is 12.86 g-cm.
How many watts per horsepower is a 575 volt motor?
40 years ago we used to estimate, on a 575 volt 3 phase industrial system, 1 amp per motor horsepower. That worked out to 995 va, or 1 kva per horsepower. At a motor power factor of 80% that would be 800 watts per horsepower. At a real 745 watts per horsepower, that anticipated an efficiency of the motor of 93.1%, probably still a fair estimate.
How to tell if a motor is starting current?
just attacth the clamp meter to your wire which is connected to the motors mains now when you starts the motors it shows the starting current its so simple method dont worry about formulass
How much current should a lock rotor have?
Rule of thumb for starting current or lock rotor current 6 X full load current .
How much is rotor current locked?
locked rotor current is calculated during design.It depends upon so many factors like rotor bar configuration,Induct ance of windings on stator ,Flux density and so on.It is approximately 6 times the Full load current of the motor on DOL starting.The satrting current values are subject to tolerance of 20%.You can peruse any catalogue of motor manufcaturer and see the starting current given in performance chart .
Why is the rotor current called lock current?
(1) The measured current is at a time (0 sec) ie when the rotor is at standstill,thus the rotor is considered "LOCKED" and thus the term LOCK ROTOR AMPS.
Why is a rotor considered a transformer?
Because the rotor is not turning, it is considered as a transformer, of which the secondary winding is shorted.
Which rotor amps have the highest current draw?
This lock rotor amps is the highest current draw of the motor because when the rotor is locked impedance is the lowest.
How much more current does a locked motor draw?
It is not always correct, the locked motor draws 6 times more current than it's nominal current. This is only an estimation.
How to calculate stator current?
The stator current is calculated by dividing the phase voltage by the equivalent complex impedance of the entire circuit shown.
What is the speed of a rotor?
The speed of the rotor (mechanical speed) is the speed of the stator magnetic field minus the slip. The speed of the rotor magnetic field is the same as the speed of the stator magnetic field. In the other problem, I believe that the stator omega is the frequency of the power and the mechanical speed is the speed of the magnetic field.
What is no load in motors?
In analyzing motor performance, "no-load" is assumed to be operation with nothing connected to the shaft. Except for that special condition the speed of the rotor = speed of load. The torque developed in the rotor = torque of load plus mechanical losses in the motor consisting of bearing friction and aerodynamic drag on the rotor (windage). In this problem, mechanical losses seem to be considered to be part of the load or considered to be negligible. Stator speed = field speed = synchronous speed.
