Problems of motor power calculation, motor power calculation method

The technicians of the motor factory were not entirely right.

In the three-phase three-wire system, only two voltages and two currents are needed to calculate the three-phase power, and this measurement method is called the two-watt meter.

Suppose the midpoint of the motor is n (although it is not led out).

Then the instantaneous power of the motor.

p=uan*ia+ubn*ib+ucn*icSince it is a three-phase three-wire system, according to Kirchhoff's current law, the sum of the currents flowing into the node is equal to the sum of the currents flowing out of the node.

Therefore. ia+ib+ic=0

In addition, according to the definition of voltage (the difference between the potential of two points).

uab=uan-ubn

ucb=ucn-ubn

Using Eq. (2), (3), and (4), transform Eq. (1) with P=uan*ia-ubn*ia+ubn*ia

ubn*ib+ucn*ic

uab*ia+ubn(ia+ib)+ucn*icuab*ia+ubn(-ic)+ucn*icuab*ia+ucb*ic

Eq. (5) is an instantaneous value expression.

If it is expressed as a valid value.

p=uab*ia*cos ab+ucb*ic*cos cb: p1=uab*ia*cos ab

p2=ucb*ic*cosφcb

p=p1+p2

This is the principle and expression of the two-watt meter.

Equation 1 selects the motor power according to the force, and equation 2 selects the motor power according to the torque.

The choice of this formula is not based on the motor itself, but according to the way the load moves.

For example, the belt conveyor is dragged by force, and the material above is moving in a straight line or tending to a straight line, so choose formula 1, and the f in the formula is the force required for load movement;

Fans, on the other hand, are rotary movements, so the required motor power is calculated according to the required torque.

1) The power calculation formula of single-phase motor: p=u*i*cos, if the power factor is, the voltage is 220V, and the current is 2A, then the power p=.

2) Three-phase motor power calculation formula: p = is the power factor, U is the load line voltage, i is the load line current).

Materials** on the Internet, invaded and deleted!

Actual power p = actual * u actual * actual power factor * efficiency, whether the power factor can be measured, if it cannot be measured, use the nameplate (the power factor is smaller than the rated power factor at low load).

How to calculate the actual power of the motor.

w=pt√3uicosφηt

u Rated voltage.

i Actual execution current.

The power factor of the COS motor.

The efficiency of the electric motor.

t Execution time.

The result is active power consumption, which should be slightly larger because the motor is often not at maximum efficiency during actual execution.

How to calculate the motor power.

w = torque * speed * negative to the third power.

How to calculate the electrical power consumed by an electric motor?

The circuit of the motor is a non-pure resistance circuit, so the electrical energy consumed, that is, the work done by the current (w=uit), is mainly converted into mechanical energy, and only a part of it is converted into thermal energy (q=i rt), so w q, i.e., uit i rt. Therefore, the electric power consumed by the nailing motor can be calculated by P=W T or P=UI, and cannot be calculated by P=I R or P=U R.

The difference between the rated power and the actual power of the motor.

The rated power refers to the power marked on the nameplate of the motor, which indicates the maximum power that the motor is allowed to carry in a safe state;

The actual power refers to the power dragged by the motor when it is actually executed, and the magnitude is determined by the load, which is equal to the product of the actual current and the actual voltage (the AC motor also contains the power factor); The actual power should be less than the rated power, and the motor execution is safe.

The actual power calculation of the motor is how much power is actually consumed?

w=pt√3uicosφηt

u Rated voltage.

i Actual execution current.

The power factor of the COS motor.

The efficiency of the electric motor.

t Execution time.

The result is active power consumption, which should be slightly larger because the motor is often not at maximum efficiency during actual execution.

How to calculate the actual power of an AC motor 10 points.

p=power factor un rated voltage in operating current.

Power factor = power apparent work. You can also check the power factor table of the distribution screen and choose it directly, and the power factor of the motor used in the general pump is low. Hereinafter.

Summary. Hello dear, happy to answer for you, according to the question you described: the formula for calculating motor power is:

Power (W) = Voltage (V) Current (A) Power Factor Among them, the power factor is a parameter that reflects the load nature of the motor, and in general, the power factor of the industrial motor is around. In addition, the power rating of the motor can also be found on the rating plate of the motor. If you need to calculate the actual output power of the motor, you also need to consider the efficiency of the motor, which is generally more than 85%.

Therefore, the actual output power of the motor can be calculated by multiplying the rated power of the motor by the efficiency of the motor.

Hello, I am happy to answer for you, according to the question you described: the calculation formula of motor power is: power (w) = voltage (v) current (a) power factor Among them, the power factor is a parameter that reflects the load nature of the motor.

In addition, the power rating of the motor can also be found on the rating plate of the motor. If you need to calculate the actual output power of the motor, you also need to consider the efficiency of the motor, which is generally more than 85%. Therefore, the actual output power of the motor can be calculated by multiplying the rated power of the motor by the efficiency of the motor.

Hello, I want to know how to calculate the rated power of the 72V2000W motor, thank you.

Pro, according to the information you provided, the rated power of the 72V2000W motor is 2000W, which means that under the rated working conditions of the motor, the output power of the motor is 2000W. The specific calculation formula is as follows: rated power (w) = voltage (v) current (a) power factor Since the rated power of the motor is known, and the power factor of the motor is assumed, the rated current of the motor can be calculated by the following formula:

Rated current (a) premature defeat = rated power (w) (voltage (v) power factor) substituting the data, obtains: rated current (a) = 2000w (72v Therefore, the rated current of the 72V2000W motor is.

There are formulas for your problem to refer to and analyze:

Motor power: p=

Motor torque: t=9549 p n;

Motor power Torque = 9550 * Output power Output speed torque = 9550 * Beam loser leakage power Output speed.

p = t*n/9550

Formula derivation. The relationship between motor power, torque, and speed.

Power = Force * Velocity.

p=f*v--- Equation 1

Torque (t) = torque (f) * radius of action (r) Push out f = t r -- Equation 2 linear speed (v) = 2 r * speed per second (n seconds) = 2 r * speed per minute (n minutes) 60 = r * n minutes 30 --- Equation 3

Substituting the formula into Equation 1 yields:

p=f*v=t r* r*n points 30 = 30*t*n points.

-p=power only rate unit w, t = torque unit nm, n minutes = speed per minute unit revolution.

If the unit of p is replaced by kw, then the rubberized formula is as follows:

p*1000=π/30*t*n 30000/π*p=t*n 30000/

The formula for calculating motor power is: p=f v 60.

The formula for calculating motor power is: p=f v 60. In the formula, p power (kw), f traction force (kn), v speed (m min), and the efficiency of the transmission machinery are generally left and right.

When running at a constant speed, the traction force f is equal to the friction force when the trolley moves on the track, f = g, is the friction coefficient, which is related to the state of the wheel and the rental guide rail; g = 400kN (40 tons).

Relationship between power and voltage:

The work done by an electric current per unit of time is called electrical power. It is a physical quantity used to express the speed of consuming electrical energy, expressed by p, its unit is watts, referred to as watts, and the symbol is w. Electric current refers to the flow of a group of electric charges.

The magnitude of the current is called the current intensity, which refers to the amount of charge passing through a certain section of the wire per unit time, and the amount of electricity passing through one coulomb per second is called one amperere.

The power of a pure resistive circuit is p = ui, and when the current is constant, the power is proportional to the voltage. That is, the higher the voltage, the higher the power. Power is the amount of work done per unit time or the large power of energy conversion.

Voltage, also known as potential difference or potential difference, is a physical quantity that measures the difference in energy between a unit charge in an electrostatic field due to different potentials.

Electrical power is a physical quantity that indicates how fast or slow the work of an electric current is, and the magnitude of the power of an electrical appliance is numerically equal to the amount of electrical energy it consumes in 1 second. If the electrical energy W is consumed over a long period of time in such a way that t is so bad, then the electrical power of the appliance is p=w t, and the electrical power is equal to the product of the voltage at both ends of the conductor and the current passing through the conductor. <>

Transformer power and motor calculations.

The formula for calculating electrical power, multiplying voltage by current, is the definition of electrical power, which is always correct and applicable to any situation.

For purely resistive circuits, such as resistance wires, lamps, etc., they can be calculated using the formulas of "square of current multiplied by resistance" and "square of voltage divided by resistance", which is derived from Ohm's law.

However, for non-purely resistive circuits, such as electric motors, the formula "voltage multiplied by current" can only be used, because Ohm's law does not apply to electric motors, etc., that is, voltage and current are not proportional. This is because the electric motor generates a "back electromotive force" when it is runningFor example, if the external voltage is 8 volts, the resistance is 2 ohms, and the back EMF is 6 volts, the current is (8 6) 2 1 (amps) instead of 4 amps.

So the power is 8 1 8 (watts).

In addition, Joule's law is the formula for resistive heating, and the heating power is "the square of the current multiplied by the resistance", which is also always true.

Take the above example as an example, the power of the motor is 1 1 2 2 (watts), that is, the total power of the motor is 8 watts, the heating power is 2 watts, and the remaining 6 watts are used to do mechanical work.

p=iu, commonly known as the universal formula, that is, it can be used at any time;

p=i 2*r, the current in the circuit is equal or used to calculate electric heat;

p=U2 r, used when the voltages in the circuit are equal.

The motor power can be solved by the following formula:

p = v × i × cos(θ)

where p represents the power output of the motor in watts (W);

v represents the voltage of the motor in volts (v);

i represents the current of the motor in amperes (a);

cos( ) denotes the power factor of the motor, which is the phase angle difference between the current and voltage of the motor.

The specific solution steps are:

1.The voltage and current of the motor are measured, and their product is calculated, i.e., v i.

2.The phase angle difference between the motor current and the voltage is measured, and the remaining chord values cos( )3Multiply V i by cos( ) to get the output power p of the motor.

It should be noted that the power of the motor is usually divided into rated power and actual output power, the rated power is the maximum power rate of the motor that can be continuously output under the condition of trembling and trembling, and the actual output power is affected by the load of the motor, power supply voltage and other factors.

According to the conservation of energy in the second year of high school, the energy conservation solution is as follows:

Do the rough work = fs

Suppose the motor rotates once, and the work done on the motor side f=ta(torque) r(radius) makes one revolution, s=2 r

fs=（ta/r）*2πr=2πta

The axial work of the screw is FS=FA (axial load) * i (the distance between the motor and the group touching the separation s is the lead i of the screw rod).

Motor work * efficiency (n1) = axial work of the screw 2 ta*n1=fa*i, so ta=(fa*i) (2*