To understand the difference between explosion-proof and standard servomotors, it’s important to understand their design and application. Standard servomotors can generate sparks during operation, making them unsafe for use in environments where flammable or explosive substances are present. For example, in coal mines, petrochemical plants, or the chemical industry, even a small spark can have catastrophic consequences. Explosion-proof servomotors solve this problem because their design eliminates the possibility of sparks, making them indispensable in hazardous environments.
Key Features of Explosion-Proof Servomotors
Explosion-Proof Motor Design
Explosion-proof servomotors are equipped with a special explosion-proof junction box and bushing, preventing the possibility of fire.
The motor housing is made of high-strength, corrosion-resistant, explosion-resistant materials.
Ingress Protection (IP)
Explosion-proof servomotors have a minimum IP55 rating, but can also be IP64 or IP65.
Normal servomotors typically have IP23, IP44, IP54, IP55, or IP56 ratings.
Explosion-Proof Marking
The housing of an explosion-proof servomotor is marked with a marking indicating the explosion protection type, equipment category, gas group, and temperature class. For example, Ex d IIB T4.
This marking indicates the motor’s suitability for use in environments with flammable gases or dust.
Casing Materials
The casing of explosion-proof motors is made of materials with a limited content of light metals, such as aluminum, titanium, and magnesium.
The magnesium content must not exceed 6%, and the combined titanium and magnesium content must not exceed 15%.
Safety Clearances and Temperature Classes
Explosion-proof servomotors are tested for maximum safety clearances (A, B, C) and temperature classes (T1–T6).
The permissible motor surface temperature ranges from 85°C to 450°C, depending on the class.
Temperature Sensors
A PTC thermistor is built into the motor stator, which signals overheating, preventing accidents.
Cost of Explosion-Proof Servomotors
The price of explosion-proof servomotors is significantly higher than that of standard motors and can range from several thousand to tens of thousands of dollars. This is due to the use of specialized materials, complex design, and strict certification requirements.
Selection Recommendations
When selecting explosion-proof servomotors, it is important to:
Research the characteristics and applications of various motor types.
Choose products from trusted manufacturers to ensure quality and safety.
Consider the requirements for the protection level, temperature class, and housing materials.
Conclusion
Explosion-proof servomotors are specialized equipment designed for operation in hazardous environments. Their design eliminates the possibility of sparks and overheating, making them indispensable in the oil and gas, chemical, and mining industries. When selecting these motors, it is important to consider their characteristics and purchase products from reputable manufacturers to ensure safe and reliable operation.
