Answer the reason why the motor speed is slow when starting the motor?

Answer the reason why the motor speed is slow when starting the motor?

If it is only slow at start, it will be normal after starting. It may be that the starting capacitor does not match, or the motor design is originally such (according to the design of the place), or it may be that the starting time is too long due to factors such as excessive load resistance.

If the speed is slow after starting, the problem may be insufficient voltage, mismatched capacitance, and high rotational resistance.

How to choose the brush of the rotor of the winding type asynchronous motor rotor?

It is mainly determined according to whether the working condition of the brush satisfies the current density (A/cm2) and the linear velocity (m/s) of the circumferential edge of the collector ring.

Determine the formula:

Brush current carrying capacity (A) = brush current density (A / cm2) × brush width L (cm) × brush thickness b (cm) ≥ motor rotor rated current (A);

The linear velocity (m/s) of the peripheral edge of the collector ring = rated motor speed (r/m) / 60 (s) × circumference of the collector ring (m) ≤ the specified range (m / s) applicable to the brush.

The commonly used brushes are three types: non-ink brush, electrochemical graphite brush and metal graphite brush. During use, care should be taken to check the brush activity, brush pressure and wear level. The brush should be able to move up and down freely in the brush holder without jamming. When the card is brushed, smooth both sides of the brush on the abrasive cloth. The pressure of the brush should be adjusted according to the type and model of the brush. At present, the brush pressing spring attached to the brush holder is mostly a tension compression spring, and the pressure thereof gradually decreases with the wear of the brush, so the brush pressure should be adjusted at any time during the running of the motor.