The power of the servo motor should be selected according to the power required by the production machine. Try to make the servo motor run under the rated load. Pay attention to the following two points when selecting:

1 If the power of the servo motor is too small, the phenomenon of "small horse-drawn carriage" will occur, causing the servo motor overloaded for a long time, and the insulation damaged due to heat, and even the servo motor being burned.

2 If the power of the servo motor is too large, the phenomenon of "large horse-drawn car" will appear, and the output mechanical power cannot be fully utilized. The power factor and efficiency are not high, which is not only bad for the user and the power grid, but also causes electric energy waste.

To properly select the power of the servo motor, the following calculations or comparisons must be made:

P = F*V/1000 (P = calculated power KW, F = required pull N, V = linear speed M/S)

For the continuous working mode with constant load, the required power of servo motor can be calculated according to the following formula:

P1(kw):P=P/n1n2

N1 is the efficiency of production machinery; N2 is the efficiency of servo motor, that is, transmission efficiency.

The power P1 calculated according to the above formula is not necessarily the same as the product power. Therefore, the rated power of the selected servo motor should be equal to or slightly greater than the calculated power.

In addition, the most commonly used method is analogy to select the power of servo motor. The so-called analogy method is to compare the power of servo motor used in similar production machinery.

The specific method is to know how high power servo motors are used by similar production machinery in our unit or other nearby units, and then to select similar power servo motors for testing. The purpose of testing is to verify whether the selected servo motors match the production machinery.

The method of verification is:

The servo motor drives the production machinery to operate, the working current of the motor is measured by a clamp-type ammeter, and the measured current is compared with the rated current marked on the nameplate of the servo motor.

If the actual operating current of the servo motor is not much different from the rated current indicated on the spleen, the power of the selected servo motor is appropriate.

If the actual operating current of the servo motor is about 70%, lower than the rated current indicated on the nameplate, which means that the power of the servo motor is too large, and the servo motor with smaller power should be exchanged.

If the measured servo motor operating current is more than 40%, larger than the rated current indicated on the nameplate, which means that the servo motor's power is too small, and the servo motor with higher power should be replaced.

In fact, it should be considered the torque (torque), servo motor power and torque calculation formula.

That is T = 9550P/n

In the formula:

P — power, kw

n — rated speed of the servo motor, r/min

T — torque, N.m

The output torque of the servo motor must be greater than the torque required by the working machine. Generally, a safety factor is required.

Mechanical power formula: P=TxN/97500

P: power unit W

T: torque, in grams per cm

N: speed, unit r/min