Industrial manufacturing processing environments are frequently subjected to hazards arising from flammable gases, vapors, and combustible dust. Protecting workforce assets and high-value physical infrastructure requires the application of specialized explosion-protected machinery. As an authorized global distributor of Wolong Electric Drive Group Co., Ltd, Shaanxi Nanfang Motor Technology Co., Ltd. provides certified system solutions that meet the requirements of international safety standards.
This technical whitepaper analyzes the mechanical, electrical, and thermal properties of Ex ec (increased safety "ec" for Zone 2 gas areas) and Ex tc (protection by enclosure "tc" for Zone 22 dust areas) electric motors. Understanding these design methods is essential for design engineers, procurement specialists, and safety officers operating within the oil & gas, chemical processing, coal mining, and marine sectors.
The safety protection principles for hazardous area equipment have transitioned to align with IEC standards. Specifically, the former "Ex nA" non-sparking designation has been updated to Ex ec under IEC 60079-7 (increased safety). Similarly, Ex tc is defined under IEC 60079-31, providing explosion prevention through the use of robust dust-tight enclosures. These designs are suited for environments where combustible dust is present in normal operations, yet explosive mixtures are unlikely to persist.
The demand for certified explosion-proof motors is driven by global environmental policies, demanding energy efficiency requirements, and occupational safety mandates. Across Europe, North America, and the Asia-Pacific region, heavy industries are replacing legacy equipment with higher-efficiency motors (such as IE4 and IE5 designs) to reduce carbon emissions while maintaining plant safety.
By coordinating with Wolong's worldwide operations, Shaanxi Nanfang Motor Technology delivers complete drive systems suited to different regions:
Founded in 1984 and listed on the Shanghai Stock Exchange in 2002 (code SH600580), Wolong has grown to become a major manufacturer of electric motors and drive control systems. Operating 3 key R&D bases, 39 manufacturing centers, and 3 global R&D divisions, Wolong's global reach is supported by strategic international acquisitions:
This integration of engineering history brings valuable technical capabilities:
• ATB (Austrian Motor Group): Acquired in 2011, establishing a strong presence in European industrial markets.
• Morley: Brings 130 years of history in coal mining applications.
• Laurence Scott: Known for low starting current designs, supplying marine vessels and power stations.
• Brook Crompton: Known for developing energy-efficient motor lines, including the "W" and "10" series.
• Schorch: Since 1882, providing heavy-duty drive systems for oil, gas, and power generation.
• OLI: A provider of industrial vibration motors and sensors.
• General Electric (GE Industrial Motors): Integrated in 2018, expanding capabilities in North American NEMA-standard heavy industries.
The construction of Ex ec and Ex tc motors is designed to meet strict safety and durability standards. Wolong utilizes high-quality raw materials and precision manufacturing processes:
Features a squirrel cage design using cast aluminum, produced by centrifugal casting or high-pressure die-casting. This creates a solid component with integrated rotor bars and end rings, ensuring reliable torque characteristics. For high-output applications, copper bar rotors are used, featuring welded end rings and retention rings to support high-speed operation.
The coils are wound with polyester film and glass-reinforced conductors, insulated with high-mica tape. The entire assembly undergoes a Vacuum Pressure Impregnation (VPI) process. This creates a solid, moisture-resistant insulation system with high thermal stability and mechanical strength, preventing electrical discharge in hazardous environments.
Designed using multi-physics computer simulations, the high-strength cast iron (or structural steel) frames provide good heat dissipation and structural rigidity. The frame design limits vibration and resists mechanical impact, keeping the motor's operating temperatures within safe limits.
Consists of an air guide cylinder, protective screen, and acoustic damping plates. The side-entry air inlet reduces noise and prevents blockage behind the motor. The fan cover provides IP22 finger safety protection while maintaining optimal cooling airflow.
Our motors are tested and certified to comply with various international standards, allowing import into strict regulatory markets.
Nemko / ATEX
CSA Group
CE Certification
CCC Ex
SABS Approved
TESTSAFE
Wolong motors undergo a series of mechanical and thermal tests, including insulation resistance testing, starting current/torque tests, durability tests, and vibration evaluations to verify safety:
Our capabilities are built upon decades of industrial engineering experience, supported by the integration of global brands.
By bringing together global motor manufacturers, Wolong has acquired a range of technologies and patents, forming a comprehensive product portfolio:
• In 2011, Wolong acquired the ATB Group (including Morley and Laurence Scott), expanding its technology base and industrial presence in Europe.
• The integration of Brook Crompton brought expertise in the design of energy-efficient electric motors, such as the "W" series.
• The addition of Schorch in 2011 enhanced our ability to build high-capacity driving systems for oil, gas, and power generation.
• The addition of Nanyang Explosion Protection Group (CNE) in 2015 created a large production base for explosion-proof motors in China.
• The acquisition of GE's Commercial and Industrial Motors business in 2018 strengthened our design capabilities and sales networks in the Americas.
Combining Wolong's global manufacturing footprint with localized engineering support.
Wolong operates design and control R&D centers in China, Europe, and Japan, with a central institute in Shanghai focused on developing motor efficiency and control technologies.
Featuring established domestic and international brands like Nanyang Explosion, Brook Crompton, Morley, Laurence Scott, Schorch, and ATB, recognized across global processing industries.
Our motors are built to operate in hazardous environments like oil, chemical plants, and coal mines, verified by ATEX, IECEx, and CU-TR explosion-proof certifications.
The industrial landscape is moving toward higher digitalization and efficiency. Future developments in Ex ec and Ex tc motors focus on key technical areas:
Wolong motors are used in various sectors including oil and gas extraction, petrochemical refining, marine shipping, ventilation systems, water management, metallurgy, and industrial automation.
Common technical questions answered by our application engineers.
NANFANG
