Explore our high-performance low and high voltage industrial motors optimized for hazardous environments and severe starting conditions.
Shaanxi Nanfang Motor Technology Co., Ltd is the authorized distributor of Wolong. Wolong Electric Drive Group Co., Ltd was founded in 1984 and successfully listed in 2002 (code SH600580). After more than 30 years of development, Wolong has 3 manufacturing bases, 39 factories, and 3 R&D centers worldwide now. Wolong has always focused on the manufacture of motors and control systems, committed to a global brand strategy, making Wolong a leader in R&D, technology, process, manufacturing, and sales in the global market.
Three-phase wound rotor induction motors, also widely known as slip ring motors, are critical equipment for heavy industries. Unlike standard squirrel cage motors, wound rotor induction motors are designed to support high inertia loads by adjusting the external resistance connected via carbon brushes. This capability is crucial for global procurement agencies seeking to optimize initial startup currents while maintaining maximum starting torque.
| Procurement Criteria | Industrial Challenges | Wound Rotor Motor Solutions | System Impact |
|---|---|---|---|
| High Starting Torque | Heavy conveyor system starting under full load | Adjustable external rotor resistance control | Prevents belt damage, guarantees smooth acceleration |
| Inrush Current Control | Weak power supply grids in remote mine areas | Low starting current profile during ignition phase | Reduces grid voltage sag, prevents local blackouts |
| Thermal Dissipation | Continuous slow starts causing thermal stress | External starting resistors dissipate secondary heat | Extends stator and rotor winding lifespan |
| Regulatory Compliance | Explosive atmospheres and mining hazards | ATEX, IECEx, and MSHA flameproof configurations | Guarantees operations safety in coal dust/gaseous zones |
To serve heavy industries worldwide, Wolong Group has strategically consolidated leading international motor legacy brands under its portfolio. This integration combines decades of Western European and North American engineering with highly efficient Asian manufacturing bases.
Acquired in 2011, ATB (comprising Morley and Laurence Scott) delivers specialized heavy-duty electric motors. Morley brings nearly 130 years of underground coal mining expertise, representing quality, power, and extreme reliability globally. Laurence Scott stands out as a pioneer in low starting current systems, famously supplying British nuclear facilities and naval fleets.
Brook Crompton features over a century of electric motor design expertise, pioneering high-efficiency low, medium, and high-voltage motors (W and 10 series). Schorch, established in 1882, designs specialized driving packages for critical applications including oil, gas, power generation, wastewater, and infrastructure tunnels worldwide.
In 2015, CNE, China's largest ex-proof motor scientific base, joined Wolong to supply the oil and nuclear sectors. In 2018, GE Industrial Motors joined Wolong, strengthening heavy industry applications (materials processing, mining, cement) with decades of high-grade engineering support.
Every OEM 3 Phase Wound Rotor Motor constructed under Shaanxi Nanfang Motor and Wolong Electric uses high-grade metallurgy, sophisticated fluid dynamics simulations, and class-leading winding insulation systems.
Our rotors feature advanced designs. Cast aluminum rotors are produced using centrifugal or die-casting techniques, integrating the rotor bars and end rings into a single-piece construction for optimized torque. For larger-capacity motors, copper bar rotors are utilized, which benefit from reliable bar securing and end ring welding procedures. The protective ring design of high-speed motors ensures stable operation for the copper bar rotor under heavy loads.
The coil is crafted from polyester film and reinforced with glass cloth, using high-mica content or medium-powdered mica tapes. Following the VPI (Vacuum Pressure Impregnation) process, a clean white coil emerges from production. After winding, the assembly goes through the VPI process to transform into a solid unit. The stator layout is engineered to provide exceptional electrical performance, mechanical strength, moisture resistance, and thermal stability.
The motor frame utilizes a digital design platform for structural and fluid multi-physics simulations. Keeping the core patents' structures, the frame uses high-strength cast iron (or steel alternatives). It offers structural redundancy, heat dissipation, and frequency isolation margins. This design helps the motor endure mechanical shocks, maintain low vibrations, and keep internal temperatures low.
This system consists of a fan cover body, air guide cylinder, protective window, and silencer plate. Its compact structure and lightweight design minimize vibrations. The side air inlet optimizes airflow around obstacles, reducing noise caused by pressure drops. Sound-absorbing materials inside lower the overall motor noise. The cover is rated IP22, keeping operators safe from contact with the fan.
To support global supply chains, Wolong has obtained the major international product certifications, eliminating trading barriers across the Americas, Europe, Africa, and APAC.
Nemko/ATEX
CSA
CE
CC
SABS
TESTSAFE
Compliance Standards & Testing Specifications:
The next generation of 3-phase wound rotor induction motors focus on efficiency, smart diagnostics, and reduced maintenance costs.
Deploying wireless vibration sensors and thermal monitoring systems directly onto the slip ring housing. This enables real-time predictions of brush wear and rotor winding temperatures, preventing unplanned shutdowns.
Developing advanced synthetic carbon-metal composites that reduce friction, spark emission, and carbon dust formation, doubling the lifespan of wear components in harsh environments.
Developing hybrid topologies that integrate Variable Frequency Drives (VFD) with liquid resistance starters, allowing speed control over wider operational ranges with high system efficiency.
As a globally esteemed manufacturer of motors and drive solutions, WOLONG boasts 39 manufacturing facilities and 4 research and development centers (R&D center) across various countries including China, Vietnam, the United Kingdom, Germany, Austria, Italy, Serbia, Mexico, India, and so forth.
WOLONG's diverse range of motors finds application across a multitude of industrial sectors, serving equipment such as fans, water pumps, compressors, and engineering machinery. These motors are integral to various industries, including ventilation and refrigeration, construction, oil and gas, petrochemicals, coal chemistry, metallurgy, electric and nuclear power, maritime, and industrial automation, to name a few. WOLONG's mission is to deliver optimal solutions and services to our customers.
Ball mills, sag mills, heavy crushers, and overland transport conveyors.
Flameproof pump systems, heavy air compressors, and mixers.
High capacity municipal water pumps, sewage aerators, and thrusters.
Tunnel boring cutter heads, exhaust ventilation fan setups, and hoists.
Shaanxi Nanfang Motor and Wolong Electric supply more than just industrial hardware. We provide engineering support across global project lifecycles to ensure high operational efficiency and regulatory compliance.
Our engineers support system configuration, customized mechanical shafts, customized slip rings, and electrical protection panels.
Field services include alignment, startup current adjustments, setting up liquid resistance control panels, and vibration testing.
Helping old plants upgrade their equipment to meet IE3/IE4 standards, and retrofitting motors to comply with newer ATEX safety standards.
A: The main advantage is the ability to adjust speed and torque characteristics by inserting external resistance into the rotor circuit through slip rings. This allows the motor to develop maximum starting torque with minimum starting current, making it ideal for high-inertia startup applications.
A: Resistor sizing depends on starting torque requirements, load inertia (GD²), startup duration, and the allowed starting current limit of the grid. Our engineering team calculates the step values or liquid resistance profile based on these parameters.
A: Regular maintenance focuses on the slip ring assembly. This includes checking carbon brush wear, brush pressure, cleaning accumulated carbon dust, and resurfacing the slip rings when wear grooves occur.
A: Yes. By short-circuiting the rotor winding slip rings externally, these motors can operate under modern VFD control. We also offer specialized dual-mode setups for redundant systems.
Explore the second tier of our high-capacity range, designed for mineral conveyors, pumps, and demanding environments.
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