Dc motor starting
Date:2022-08-03 Click:940
Because the resistance and inductance of the motor armature circuit are small, and the rotating body has a certain mechanical inertia, so when the motor is connected to the power supply, the armature speed and the corresponding back electromotive force are small at the beginning of the starting stage, and the starting current is large. Up to 15 ~ 20 times of rated current. This current will cause the grid to be disturbed, the unit to be mechanical impact, commutator spark. Therefore, direct closing starting is only suitable for motors with power no more than 4 kW (starting current is 6 ~ 8 times of rated current).
Working principle of DC motor
In ORDER TO LIMIT THE STARTING current, a specially designed variable resistor is USUALLY connected in the ARmature loop, and its principle wiring is shown in Figure 1. In the starting process, with the constant increase of the speed, the resistance of each section is short-connected step by step in time, so that the starting current is limited within a certain allowable value. This starting method is called series resistance starting, very simple, portable equipment, widely used in all kinds of small and medium DC motor. However, because of the high energy consumption in the starting process, it is not suitable for the motor and the medium and large DC motor. However, for some special needs, for example, although the city trolley is often started, in order to simplify the equipment, reduce the weight and convenient operation and maintenance, the series resistance starting method is usually adopted.
For DC motor with large capacity, voltage drop starting is usually adopted. That is, the armature of the motor is supplied by a separate adjustable voltage DC power supply, and the control of the power supply voltage can not only make the motor start smoothly, but also achieve speed regulation. The power supply equipment of this method is more complex.
Working principle of DC motor
In ORDER TO LIMIT THE STARTING current, a specially designed variable resistor is USUALLY connected in the ARmature loop, and its principle wiring is shown in Figure 1. In the starting process, with the constant increase of the speed, the resistance of each section is short-connected step by step in time, so that the starting current is limited within a certain allowable value. This starting method is called series resistance starting, very simple, portable equipment, widely used in all kinds of small and medium DC motor. However, because of the high energy consumption in the starting process, it is not suitable for the motor and the medium and large DC motor. However, for some special needs, for example, although the city trolley is often started, in order to simplify the equipment, reduce the weight and convenient operation and maintenance, the series resistance starting method is usually adopted.
For DC motor with large capacity, voltage drop starting is usually adopted. That is, the armature of the motor is supplied by a separate adjustable voltage DC power supply, and the control of the power supply voltage can not only make the motor start smoothly, but also achieve speed regulation. The power supply equipment of this method is more complex.
