The rated voltage U of a motor is 220 V, the rated current I is 20 A, and the efficiency of the motor is 80%

The rated voltage U of a motor is 220 V, the rated current I is 20 A, and the efficiency of the motor is 80%

For AC motor, only rated voltage U = 220 V, rated current I = 20 A, input active power can not be obtained and power factor is missing
In the case of DC motor, the motor loss can be calculated
Heat loss of motor coil when passing current (including two groups of coils if there is excitation winding);
Mechanical friction loss of rotor rotation;
Loss of tail cooling fan
 
In case of permanent magnet DC motor, the latter two losses are not included
Rated power & nbsp; 220 * 20 = 4400w
Loss & nbsp; & nbsp; 4400 (1-80%) = 880W
Resistance of motor coil = 880 / (20 * 20) = 2.2 Ω

How to adjust the speed of AC 220 V motor

DC motor can control speed by controlling current, AC motor can only adjust speed by changing the frequency of AC. now the frequency conversion air conditioner changes the speed of compressor by changing the frequency of AC

May I ask what method single-phase 220 V AC motor can be used for speed regulation? If there is a significant change in speed, can it be adjusted by the governor of household electric fan? Thank you

Spend a few dollars to buy a speed switch installed on it

How to adjust the speed of 220 V single phase motor

Can use step-down speed regulation, can buy a ceiling fan stepless governor... Pressure speed regulation, its power is also relatively reduced

How to connect single phase 220 V inverter with single phase motor

I have used many single-phase inverter, but I have never used single-phase motor. Under the same power index, three-phase motor is cheap and easy to use, why use single-phase motor speed? Ordinary three-phase motor can be used for single-phase inverter through the link transformation of terminal. General single-phase motor uses capacitor split phase circuit, can't be used for frequency control

The line voltage of star connection is 380V, so what is the line voltage after changing to triangle connection?
If the line voltage of star connection is 380V, what is the line voltage after changing to triangle connection?
In the step-down start-up, the relationship between the root 3 of the line voltage of the star triangle has nothing to do with their phase voltage?

You mean high-power three-phase motor. This kind of motor is star start triangle operation, triangle direct start will burn the motor or seriously affect the quality of the power grid. Star has a common zero point, coil terminal voltage is 220 V, triangle is 380 v. but the coil connection is different, instantaneous switching by AC contactor

When a three-phase generator is connected to a triangle, the voltage of each phase is 380V. When it is connected to a star, the line voltage provided to the outside is a.127v and b.220v
C.380V D.660V

When the three-phase generator is connected into a triangle, there is only line voltage, but no phase voltage. The line voltage should be 380V
When connected in star shape, there are phase voltage and line voltage. The line voltage is d 660V and the phase voltage is C 380V

The formula of current, voltage and power!
Just know. For example: voltage 24 V 36 V 48 V 110 V... Power 1 kW equal to how much current!

Power P = UI, i.e. the product of voltage and current, when 1kW, it is 24V 41.67a, 36V 27.78a, 48V 20.83a, 110V 9.09a

What is the formula for calculating the electrical power of triangle connection

P = 1.732 * u * I * power factor times efficiency
Three phase: 0.85 (compensated to 0.95)
Single phase: 0.75

Calculation formula of steel bar weight

The calculation is simple
Weight = volume × weight
Volume = sectional area × length
Therefore, if you know the type and diameter of a batch of steel bars, you can use the above formula to calculate the weight
But the reinforcement is generally ribbed, and there is a little error between the cross-sectional area and the circular area. You can refer to the code for design of concrete structures to get the area and weight. For bridges, you can refer to the code for design of highway reinforced concrete and prestressed concrete bridges and culverts