Browse our premier catalog of low-voltage and high-voltage explosion-proof motors, optimized for hazardous zone classifications worldwide.
In hazardous industrial processes, explosive atmospheres are an ever-present risk. An Ex Dii Ct4 Motor is a highly specialized piece of electrical machinery meticulously engineered to safely operate inside these explosive environments without acting as an ignition source. Understanding this alphanumeric code is critical for safety-first procurement directors:
The flamepath is the path where mating surfaces of the motor frame meet. If an internal ignition happens, the burning gases escape through these gaps. As they pass through the gap, they are cooled below the ignition temperature of the outside atmosphere. An Ex d IIC motor features exceptionally tight tolerances compared to standard industrial motors, maintaining structural integrity even when internal pressures surge.
Heavy industries are evolving towards high reliability, environmental stewardship, and safety compliance. Procurement directors are focusing their engineering strategies on three key priorities:
International environmental frameworks mandate a shift from IE3 towards IE4 and IE5 super-premium efficiency ratings. By sourcing high-efficiency flameproof motors, businesses achieve a lower carbon footprint and drop operational expenses over the motor lifecycle.
Operating internationally requires equipment that conforms to regional regulations. Procurement agents prioritize suppliers providing dual or triple certifications (ATEX for Europe, IECEx for global markets, UL/CSA for North America, and EAC for the Eurasian customs union).
Modern process control relies on variable frequency drives (VFD/VSD). Standard explosion-proof motors running on VFDs risk excessive heat buildup. Modern Ex d IIC motors feature reinforced insulation systems (like Wolong's VPI process) to tolerate high-frequency voltage spikes.
Shaanxi Nanfang Motor Technology Co., Ltd. is the authorized global distributor of Wolong. Wolong Electric Drive Group Co., Ltd. was established in 1984 and listed on the Shanghai Stock Exchange in 2002 (code SH600580). Over three decades of growth has established Wolong as a premier force in electric motor manufacturing and drive systems.
Today, Wolong operates 3 global manufacturing bases, 39 advanced factories, and 3 global R&D centers. Dedicated to a comprehensive global brand strategy, Wolong delivers cutting-edge technology, process innovation, and sales support worldwide.
Through strategic acquisitions and technology integration, Wolong has incorporated several century-old brands, bringing together premier expertise in heavy industrial drive design:
In 2011, Wolong acquired 97.94% of the Austrian ATB Group, one of Europe's top three motor manufacturers. This acquisition included:
Morley: Possessing nearly 130 years of history in underground coal mining drives, Morley is synonymous with heavy-duty reliability.
Laurence Scott: Known for low starting current designs, Laurence Scott serves British nuclear installations and naval vessels.
Brook Crompton: Pioneers in energy-efficient motor design, providing low, medium, and high-voltage AC motors like the premium "W" and "10" series for harsh industrial environments.
Schorch: Established in 1882 in Germany, setting standards for high-output driving systems in oil, gas, power generation, and steel processing.
OLI: A joint venture initiated in 1999, OLI is a leading global brand in industrial vibration motors and sensors.
CNE (Nanyang Explosion-Proof Group): Joined Wolong in 2015, serving as China's largest scientific research and production base for explosion-proof drives.
General Electric (GE) Commercial & Industrial Division: Partnered in 2018, bringing over a century of North American commercial and industrial engineering experience to heavy applications.
In an era of volatile supply chains, Wolong maintains production consistency and timely deliveries through an integrated Factory 4.0 infrastructure. This digitalization coordinates engineering, logistics, and quality assurance processes:
1. Digital Twin Simulation: Before production, motors undergo structural and fluid multi-physics field simulations. This optimizes heat dissipation, balances frame resonance, and minimizes mechanical vibrations under extreme loads.
2. Automated Stator & Rotor Core Manufacture: High-speed progressive punching presses construct laminations with high dimensional consistency. This step reduces eddy current losses and ensures dynamic stability.
3. End-to-End Traceability: Every raw material batch—from high-grade copper wire to silicon steel sheets—is tracked through digital identification codes. Real-time logging of the VPI varnish viscosity, curing temperatures, and winding tension maintains consistent quality standards.
Wolong explosion-proof motors are designed to ensure safety, durability, and reliable mechanical output.
The rotor features a squirrel cage design. Cast aluminum rotors are produced using centrifugal casting or high-pressure die-casting, where molten pure aluminum is poured into the rotor core slots. This forms a single-piece construction integrating the rotor bars and end rings, delivering outstanding starting torque. For larger high-voltage motors, copper bar rotors are used. These feature robust bar securing and end-ring welding, coupled with high-speed protective retaining rings, to ensure reliable operation under extreme loads.
The coils are crafted from premium copper wire, wrapped with polyester film, glass cloth, and high-mica-content tape. Following the VPI (Vacuum Pressure Impregnation) process, the assembly is cured to form a void-free insulation barrier. This meticulously engineered insulation provides electrical performance, mechanical strength, moisture resistance, and thermal stability under continuous thermal cycles.
Using digital multi-physics simulation platforms, our motor frames are cast from high-strength iron or steel. This structure provides generous mechanical redundancy, excellent heat dissipation, and vibration isolation margins. The rugged frame is engineered to endure mechanical shocks and hostile environments while maintaining low vibration levels and a minimal temperature rise.
The cooling system comprises an optimized fan cover body, an air guide cylinder, a protective window, and a silencer plate. The side-entry air inlet optimizes airflow around rear obstacles, minimizing turbulence and reducing noise. Integrated sound-absorbing materials help damp high-frequency sounds. The system holds an IP22 safety rating, preventing external contact with the fan blades.
Wolong Ex d IIB and IIC motors provide reliable operation across diverse industrial installations, including:
In atmospheres where hydrogen and ethylene are processed, Ex d IIC T4 motors run high-pressure compressors, pipeline pumps, and process air fans. Flameproof enclosures isolate internal electrical faults, safeguarding the wider refinery.
Our DNV-certified marine motors operate in damp, saline atmospheres. They power offshore drilling systems, ballast pumps, winches, and vessel thrusters. They offer protection against salt spray corrosion and gas ingress.
For methane-laden underground mines, Wolong Nanyang CNE and Morley brands supply flameproof coal shearer cutting motors and scraper conveyor drives. These are designed to withstand structural shocks and high dust exposure.
We maintain a rigorous quality assurance program. Our products are certified by international testing agencies to ensure compliance with regional safety frameworks:
Nemko / ATEX
CSA
CE
CCC
SABS
TESTSAFE
ISO 9001 Ex compliance: Wolong maintains an ISO 9001 certified quality system for manufacturing explosion-proof motors. Meeting these standards is essential for supplying global industrial contracts.
NEMA Standards: For North American projects, we verify mechanical and electrical performance specifications (starting torque, current draw, and vibration limits) through testing. Testing certifies compliance with UL and CSA standards.
TESTSAFE certification: This certification permits Wolong to supply coal mining equipment to Australia and other international mining markets, aligning with regional underground safety codes.
Gas Group IIB covers gases like ethylene, ether, and butadiene. Gas Group IIC is the most volatile category, encompassing gases like hydrogen and acetylene. An Ex d IIC motor features tighter flamepath tolerances and smaller gaps to prevent hydrogen explosions from propagating. A Group IIC certified motor can safely operate in both IIB and IIA environments, offering wide chemical compatibility.
The Vacuum Pressure Impregnation (VPI) process places the wound stator into a vacuum chamber. Air and moisture are extracted, and a solventless resin is introduced under pressure. This ensures the varnish fully penetrates the stator coil windings, creating a solid, void-free insulation barrier. This system provides mechanical rigidity, excellent heat transfer, and protection against moisture and chemical attack.
Yes, provided they are certified for VFD operation. Operating a flameproof motor on a VFD can cause additional rotor/stator heating due to harmonic content and voltage spikes. Wolong motors designed for VFD applications feature class F/H insulation systems, premium bearings, and built-in thermal sensors (like RTDs or thermistors) to monitor winding temperature and prevent overheating.
Under the IEC/EN standards, a T4 rating limits the motor's maximum outer surface temperature to 135°C (275°F) under worst-case operating conditions. This class is suitable for environments containing gases with ignition points above 135°C, providing a safety margin for process applications.
Through Shaanxi Nanfang Motor and Wolong's international network of 39 factories, 3 R&D centers, and regional hubs, we support projects in over 58 countries. We supply standard and custom drives with full documentation, certification records, test certificates, and local commissioning support.
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