March 14, 2025

DC motors have a wide range of applications and are often used in harsh environments, such as humid, high temperature, dusty, corrosive, etc. Therefore, in addition to the proper use, the protection link of it is an indispensable part of the electrical control system, and proper protection can extend its life. Its protection is to ensure the normal operation of the motor, prevent damage to the motor or mechanical equipment, and protect personal safety. Here, Leili will tell you in detail. 1. DC motor operating precautions (1) Check whether the commutator’s appearance can be bright before use, there should be no mechanical damage and spark burn marks. (2) Check whether the brush has been worn too short, whether brush grip pressure is appropriate (usually the pressure should be 150-200 g/cm?), check whether the brush holder orientation is by following per under the specified symbol. (3) The spark on the commutator during operation should not be greater than 1/4-1/2 level. 2. DC motor protection time (1) Monthly protection: check the carbon brushes and rectifiers, do a good job of cleaning, replace the fan screen if necessary. Check whether all collector rings, DC motors, and collectors can work correctly, and check the thickness of wiring on terminals and parts. Check whether there is water inside the main electric cabinet and DC motor. (2) Protection of each quarter: check the bearings (temperature, boo,m and noise). Check the insulation to the ground with a shaking table (not less than 2 megohms) (3) Every six months of protection: dry airflow to clean the rectifier and windings. Check the electrical articulation and all the screws. In winter time, in order to adhere to the temperature of the motor, the following voltage (30-50V) can be supplied to the excitation. 3. Protection measures of DC motor (1) Short-circuit protection When the short-circuit fault is caused by insulation damage of the motor winding and wire, damage to the control appliance and line, or the misoperation of touching the line, the measure of using the protection appliance to cut off the power quickly is short-circuited protection. Commonly used short-circuit protection appliances are fuses and automatic air circuit breakers. (2) Undervoltage protection When the grid voltage decreases, the motor will run under undervoltage. Since the motor load is not changed, the motor torque decreases, and the stator winding current increases, which affects the normal operation of the motor and even damages the motor. Under-voltage protection is achieved by contactors and electromagnetic voltage relays. The fuse and thermal relay can’t protect the under-voltage, because when the motor is running under the under-voltage, the stator winding will increase. The magnitude of the stator winding increase is not enough to make the fuse and thermal relay operate, so these two appliances can’t carry out the under-voltage protection. (3) Loss of voltage protection When the production machinery is working, for some reason, the power grid suddenly stops, when the power supply is restored, the protection apparatus should ensure that the production machinery can run after restarting, so as not to cause personal and equipment accidents, this protection is loss of voltage (zero voltage) protection. The electrical appliances to achieve the loss of voltage (zero voltage) protection are contractors and intermediate relays. (4) Weak magnetic protection The protection apparatus is used to ensure that the DC motor works under a certain strength of the magnetic field. So that the magnetic field will not be weakened or disappear. The motor speed will not be increased rapidly, and even the flying phenomenon will occur. In the excitation circuit of DC motor, a weak magnetic relay (i.e. under-magnetization relay) is connected to the DC motor. The weak magnetic protection can be realized by adding a weak magnetic relay (i.e. under the current relay) in series. Working principle of under current relay: in the process of DC motor starting and running, when the excitation current value reaches the action value of under current relay, the relay will absorb and make the normally open contacts in the control circuit close, allowing the motor to start or maintain normal operation. But when the excitation current decreases a lot or disappears, the undercurrent relay will release and the normally open contacts will break, cutting off the control circuit and the contactor coil will be de-energized and the motor will stop. When the excitation current decreases a lot or disappears, the under-current relay will be released and its normally open contact will be broken to cut off the control circuit. (5) Overload protection When the motor load is too large and the starting operation is frequent or the phase is not running, the motor current will exceed its rated current for a long time, which will shorten the motor life or damage it. When the motor is overloaded, the measure to cut off the power with the protection apparatus is overload protection. (6) Over-current protection The protection apparatus is used to limit the starting current or braking current of the motor so that the motor will run under the safe current value, which will not cause damage to the motor or mechanical equipment. Generally, an electromagnetic over-current relay is used to achieve over-current protection. Easy to generate overcurrent situation: additional resistors are strung into the armature winding of DC motor and rotor winding of the three-phase AC wire-wound rotor asynchronous motor to limit the motor starting or braking current. If the additional resistors are shorted during starting or braking, it will cause a large starting current or braking current. In this case, overcurrent is easy to occur. The method of implementing overcurrent protection: the coil of the electromagnetic overcurrent relay is connected in series in the main circuit and its normally closed contact is connected in series in the control circuit. When the overcurrent value of the motor reaches the auction value of the overcurrent relay, its normally closed contact disconnects the control circuit and stops the motor from a power supply, thus realizing the overcurrent protection. The difference between overload protection and

Geared Stepper Motor Structure: A geared stepper motor is a standard stepper motor with an output shaft connected to a gear box. The gearbox provides high torque and low speed output through reduction gear transmission. Features: Provides high torque, low speed and precise positioning. With a reduction gear drive, higher output torque can be achieved for applications requiring precise position control and larger loads. Applications: Robotics: Micro geared stepper motor is often used in robot joints and actuators. Since the robot requires precise position control and stable motion, these motors provide high torque through gearing to cope with mechanical loads while maintaining precise stepping resolution for accurate attitude and motion control. Numerical Control Machine tools (CNC): In CNC machine tools, gear-type stepper motors are used to control the position of the tool, tables, and other moving parts. They provide enough torque to handle cutting and machining operations, and they ensure that the workpiece remains in a precise position during machining. Conveyor systems: In automated conveyor systems, a stepper motor with a gear box can be used to control the movement and stopping of conveyor belts, as well as to position objects when needed. Since delivery systems often require precise object positioning and fast stop/start operations, the high torque characteristics of these motors are very valuable in these applications. Medical devices: Stepper gearbox has a wide range of applications in medical devices, such as motion control for X-ray robotic arms, joint control for surgical robots, and precision positioning tasks in drug distribution devices. Laser cutting and engraving machines: In equipment where laser tools need to be precisely positioned for cutting and engraving, geared stepper motors can provide the precise control required to ensure high-quality cutting and engraving results.   Hybrid Stepper Motor Structure: The hybrid stepper motor combines the two principles of permanent magnet and variable reluctance. The rotor usually consists of a permanent magnet and a winding on the stator. Features: Delivers high torque and speed performance, as well as relatively high step resolution. More flexible than permanent magnet stepper motors for applications where torque, speed and precision need to be balanced. Applications: Numerical Control Machine tools (CNC): In CNC machines, a hybrid servo stepper motor is used to control the position of the tool and the table. Because these motors can provide high-precision position control and smooth motion, they are essential for the control of machining processes such as engraving, cutting, milling, etc. Medical equipment: Hybrid type stepper motor plays a key role in medical equipment, such as moving parts in medical imaging equipment, positioning of drug distribution equipment, joint control of surgical robots, etc. In these applications, high-precision and reliable motion control is essential for patient safety and therapeutic outcomes. Automation and robotics: In the field of industrial automation and robotics, hybrid synchronous stepper is often used in robot joints and actuators, as well as in automation systems that require highly precise control. These motors offer good dynamic performance and positioning accuracy. Experimental equipment and scientific research instruments: In scientific research and experimental equipment, the need for high-precision motion control is very common. Hybrid stepper motors are used for sample movement and adjustment in equipment such as microscope platforms and experimental platforms for various tests and observations. Precision instruments and optical equipment: High-precision position control is essential to the performance of precision instruments and optical equipment. Hybrid stepper motors are used in telescopes, laser equipment, spectrometers, and other equipment to ensure stable movement and accurate positioning of the equipment. 3D printing and rapid prototyping: In the field of 3D printing and rapid prototyping, hybrid stepper motors are used to control the position of print heads and tables to enable complex printing and manufacturing processes. Permanent Magnet Stepper Motor Structure: PM stepper motor has a permanent magnet on the rotor and an electromagnetic coil on the stator. When energized, the electromagnetic coil generates a magnetic field that interacts with the permanent magnet on the rotor, which drives the stepping motion. Features: Relatively simple and low cost, suitable for applications requiring moderate torque and low speeds. However, performance may be limited at high speeds and high loads. Applications: Printers and plotters: Permanent magnet stepper motors are often used in printers and plotters to control the position of the print head. These motors provide enough precision to ensure fine print or drawing while being suitable for relatively low speed and load requirements. Automation small tasks: In some small automation tasks, such as automatic doors, vending machines, automatic display stands, etc., permanent magnet stepper motors can provide moderate positioning control and motion functions. Household appliances: Permanent stepper motor is widely used in some household appliances, such as the rotating plate of a microwave oven, the washing bucket control of a washing machine, and the bread rack rise in a toaster. Medical equipment: In some medical equipment requiring lower costs, permanent magnet type stepper motor can be used to control the moving parts of medical equipment, such as bed position adjustment, drug distribution devices, etc. Mechanical instruments: In some medium-precision mechanical instruments, such as test equipment, small machine tools, etc., permanent magnet stepper motors can provide sufficient positioning accuracy and motion control. Small robots: In some small robots that require simple position control, permanent magnet stepper motors can provide basic motion control capabilities.