Why can the current from a rotating motor not power up another motor to rotate?

The current of the rotating motor usually has the potential to drive another motor to rotate, but in some cases it may not be driven, mainly for the following reasons:

1. Electrical parameters do not match

Voltage mismatch

Different motors may have different voltage rating requirements. If the voltage corresponding to the current output of the rotating motor is significantly different from the rated voltage of the other motor, it may not be able to drive the motor to rotate. For example, if the current generated by a 220V rated rotating motor tries to drive a 380V rated motor, it may not be able to start and run the motor normally due to insufficient voltage.

Even if the voltage gap is not very large, it may cause the motor to not work properly. For example, the rated voltage of a motor is 110V, and the rated voltage of another motor is 120V, although the difference is small, it may cause the motor speed to drop, the torque is insufficient, and even can not start.

Current mismatch

The current output of the rotating motor may not be sufficient to meet the start-up and operation requirements of another motor. Each motor has its own specific current rating, and if the input current is less than this value, it may not be able to generate enough magnetic field and torque to drive the motor to rotate. For example, the output current of a small rotating motor may be only a few amps, while another large motor may require tens of amps of current to start, at which time the current of the small motor cannot drive the large motor.

Too much current may also cause damage to the motor and cannot be driven normally. If the current output of the rotating motor is far more than the capacity of the other motor, it may burn the winding of the motor, making the motor unable to rotate.

Second, mechanical and load factors

Insufficient torque

Even if the current appears to drive another motor in terms of electrical parameters, it cannot spin the motor if the torque generated by the rotating motor is not enough to overcome the load torque of the driven motor. For example, if the driven motor is attached to a heavy mechanical load, and the rotating motor has less power and cannot provide enough torque to start and drive this load, then the driven motor cannot rotate.

Torque is also affected by the speed of the motor. In some cases, as the speed increases, so does the torque required. If the rotating motor cannot provide enough torque at a certain speed, then the driven motor cannot rotate properly.

Mechanical failure

The driven motor itself may have mechanical faults, such as damaged bearings, stuck rotors, etc., even if there is a suitable current input, it cannot be rotated. For example, the motor bearing wear is serious, will cause the rotor rotation is not flexible, increase friction resistance, even if there is a current drive, the motor may not be able to start normally.

Transmission problems can also affect the rotation of the motor. If the two motors are connected through the belt, gear and other transmission devices, and the transmission device fails, such as belt breakage, gear damage, etc., it will also cause the driven motor to be unable to rotate.

Control and protection mechanisms

Protective device action

Modern motors are usually equipped with various protective devices, such as overload protection and short circuit protection. If the current output of the rotating motor triggers the protective device of the driven motor, the motor may be automatically cut off from the power supply and cannot rotate. For example, when the current is too high, the overload protection device of the driven motor may trip to prevent the motor from burning out.

Some motors also have electronic protection systems, such as inverter controlled motors. If the input current frequency, phase and other parameters do not meet the requirements, the protection system may prevent the motor from starting, in order to protect the safety of the motor and control system.

Incompatible control mode

Different types of motors may require different controls to operate properly. If the control mode of the rotating motor is not compatible with the driven motor, even if there is a current input, the motor cannot be driven to rotate. For example, some motors require specific speed control signals, and the current output of the rotating motor cannot provide these signals, so the driven motor cannot operate in the expected way.

For DC motors and AC motors, their control methods are very different. If you try to drive an AC motor with the current of a DC motor, or vice versa, it is usually not successful because of their different working principles and control requirements.