DC motors are widely used in many fields such as smart devices, household appliances, and medical instruments due to their compact size, high efficiency, and flexible control. However, during use, if the positive and negative terminals of a DC motor are reversed, it can not only affect normal operation but also cause safety hazards.
This article explains the consequences of reversing the polarity of a DC motor and shares three practical methods to help you correctly identify the positive and negative terminals, thereby avoiding wiring errors.
Motor reversal causes malfunction
The rotation direction of a DC motor depends on the direction of the current. If the power supply polarity is reversed, the motor will rotate in the opposite direction, which may cause equipment malfunction or even damage.
Reduced conversion efficiency and motor performance degradation
Reversed polarity causes the magnetic field and current direction to be misaligned, reducing energy conversion efficiency. This can lead to motor overheating, decreased power output, and over time, shortened motor lifespan.
Potential electrical hazards
In some circuits, reversed polarity may cause short circuits or overcurrent, damaging the driver or burning out the motor. In severe cases, it may even cause fire hazards.
Check motor markings
Most DC motors are marked at the factory with polarity indicators. The positive terminal is usually marked with a red wire or a “+” sign, while the negative terminal is marked with a black wire or a “−” sign.
Use a multimeter to measure
Set the multimeter to DC voltage mode. Connect the red and black probes to the two motor terminals respectively. If the reading is positive, the red probe is on the positive terminal; if negative, the black probe is on the positive terminal.
Observe the motor rotation direction
Connect the power supply and observe the rotation direction. Then reverse the polarity and test again. If the rotation direction changes, the initial connection corresponds to the correct polarity.
Always disconnect the power before wiring.
Avoid direct contact with exposed wires or terminals.
If unsure, seek assistance from a professional.
Extended Reading Recommendation:
Common Types of Micro DC Motors and Their Applications
Methods to Reduce Current in Micro DC Motors
Comprehensive Guide to Micro Dc Motor Selection: From Basic Parameters to Customized Solutions
Guangdong Lihua Mechatronics Co., Ltd.
With 20 years of experience specializing in micro DC motors, our products are widely used in smart homes, medical devices, automotive parts, beauty care, and other fields.
Annual output value exceeds 130 million RMB
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Jailyne (Ms.)
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Guangdong Lihua Mechatronics Co., Ltd.
Address: No. 66, Chigang Road, Humen Town, Dongguan City, Guangdong Province, China
