Explore our advanced range of explosion-proof, low voltage, and variable frequency motors engineered for high-performance star-delta configurations and direct-on-line operational setups.
In global industrial systems, the three-phase AC induction motor acts as the workhorse of heavy operations. However, starting these high-power machines directly on full voltage (Direct-On-Line or DOL starting) creates significant electrical and mechanical challenges. The massive initial current inrush—often 5 to 8 times the nominal full-load current—can cause severe voltage drops in localized power grids, impacting adjacent equipment and putting extreme thermal stress on motor windings.
As a leading China Motor 3 Phase Star Delta Supplier, Shaanxi Nanfang Motor Technology Co., Ltd (an authorized distributor of Wolong Electric Drive Group) delivers state-of-the-art motor systems optimized for Star-Delta (Wye-Delta) starting configurations. Star-delta starting is a highly effective, cost-efficient method to reduce starting current draw. By initially wiring the motor stator winding in a Star (Wye) configuration, the phase voltage applied to each winding is reduced to 57.7% of the line voltage, which drops the starting torque and current to approximately one-third of the DOL values. Once the rotor reaches approximately 80% to 90% of its operating speed, the motor windings are switched to the Delta configuration, allowing it to run at full voltage and design speed.
Reducing starting currents to 1/3 of typical values prevents transient voltage dips, satisfying strict local utility regulations and keeping high-precision industrial systems operating without disruption.
By lowering the initial startup torque spike, star-delta starting minimizes mechanical shocks on drive shafts, gearboxes, couplings, and belts, leading to longer component life and less maintenance.
Utilizing high-efficiency motors (IE3, IE4, and IE5) configured for star-delta operation reduces overall plant energy footprint and guarantees compliance with global environmental standards.
Advanced Production Lines
Export Countries & Regions
Global Engineering Patents
Mega Industrial Projects Completed
Today's industrial landscape is shaped by the transition to carbon neutrality, the integration of smart manufacturing, and the need for resilient equipment. High-voltage and low-voltage three-phase motors represent over 60% of all industrial electricity consumption. Consequently, updates to regulatory frameworks (such as the EU Ecodesign Directive and NEMA Premium standards) demand higher minimum efficiencies (IE3 and IE4, transitioning rapidly toward IE5 permanent magnet types).
Procurement directors face the challenge of balancing equipment costs with operational efficiency. In continuous industries like oil and gas, petrochemicals, mining, and maritime applications, a single hour of motor failure can cost hundreds of thousands of dollars. The choice of a 3-phase motor supplier is no longer just about the unit price; it requires evaluating the manufacturer's R&D capabilities, certification portfolio, global technical support network, and supply chain security.
China's smart manufacturing infrastructure (Industry 4.0) has evolved from simple assembly lines into a fully integrated, digitized ecosystem. Shaanxi Nanfang Motor Technology Co., Ltd., through its close integration with the Wolong Electric Drive Group, utilizes some of the most advanced manufacturing technologies in the world. With 3 R&D centers and 39 factories globally, our production lines employ real-time industrial IoT tracking, automated winding machinery, digital twin quality simulations, and automated VPI (Vacuum Pressure Impregnation) testing.
This localized cluster efficiency guarantees that raw material sourcing, stator winding, rotor dynamics matching, frame casting, and safety certifications are managed under a single unified standard. This integration yields shorter lead times, consistent quality, and a robust supply chain capable of handling global disruptions.
A detailed look at the precision engineering, structural integrity, and acoustic design that make our three-phase motors the most reliable in harsh environments.
The rotor features a rugged squirrel cage design, with cast aluminum rotors being widely utilized. These rotors are produced using either centrifugal aluminum casting or die-casting techniques, where molten pure aluminum is poured into the slots of the rotor core, resulting in a single-piece construction that integrates the rotor bars and end rings. The structural integrity and manufacturing process of cast aluminum rotors guarantee the motor rotor's reliability, and also endow the motor with outstanding torque properties.
For larger capacity motors, copper bar rotors are employed, which benefit from dependable bar securing and end ring welding procedures. Additionally, the protective ring design of high-speed motors further ensures the reliable operation of the copper bar rotor under continuous high-torque demand.
The coil is crafted from polyester film and reinforced with glass cloth, utilizing either low-powder mica tape with a high mica content or medium-powdered mica tape with an abundance of mica. Following the VPI (Vacuum Pressure Impregnation) process, a pristine white coil emerges from the production line. After the billet is extracted from the wire, it proceeds through the VPI process to transform into a finished unit.
This premium insulation system is engineered to provide exceptional electrical performance, high dielectric strength, mechanical stability, resistance to moisture, and long-term thermal durability (meeting Class F and Class H parameters).
The motor frame employs a fully digital platform for structural and fluid multi-physics field simulations. This simulation platform retains the original patent's structure and design, utilizing mature, high-strength cast iron (or steel as an alternative).
The frame boasts exceptional structural redundancy, outstanding heat dissipation properties, and ample inherent frequency isolation margins for the entire machine. It is engineered to endure significant mechanical shocks, maintain a superior vibration level, and ensure a lower temperature increase in the motor, safeguarding internal components from fatigue.
The low-noise fan cover system comprises a fan cover body, an air guide cylinder, a protective window, and a silencer plate. Its compact structure and lightweight design facilitate vibration reduction.
The air inlet is situated on the side, which optimizes the avoidance of obstacles behind the motor, minimizing adverse effects on ventilation and reducing noise caused by energy loss during propagation path changes. The system also incorporates sound-absorbing materials that absorb noise, thereby lowering the overall motor noise. Additionally, the fan cover is rated IP22, ensuring that hands cannot come into contact with the fan.
Shaanxi Nanfang Motor Technology Co., Ltd. operates with the backing of Wolong's global network. Founded in 1984 and listed in 2002, Wolong has executed several strategic acquisitions, building a portfolio of legendary electric motor brands.
In 2011, WOLONG company acquired strong technical and technological supports. WOLONG's holdings group successfully acquired 97.94% of the Austrian ATB Group (ATB motor), one of the three major European motor manufacturers, becoming the actual controller of the ATB Group. This acquisition integrated Morley (a mining motor brand with a 130-year history) and Laurence Scott (renowned for low starting current designs and nuclear power applications) into the group.
Brook Crompton Motors brought over a century of experience in motor design and energy efficiency, offering premium low, medium, and high-voltage AC motors. Schorch (established in 1882) brought its heritage of high-quality drive systems for oil & gas and water management. Additionally, the joint venture with OLI Brand (established in 1999) secured our leadership in vibration motors and Ex vibration sensors.
In 2015, China's largest explosion-proof motor scientific research and production base, Nanyang Explosion-Proof Group (CNE), officially joined Wolong. In 2018, General Electric (GE) Industrial Motors joined our ranks, strengthening our capacity to supply commercial and industrial electrical equipment to heavy industries worldwide.
To operate in critical hazardous zones and heavy commercial domains, our three-phase motors are built to meet and exceed local and international trade standards.
Fully compliant with European Union Directives for equipment intended for use in potentially explosive atmospheres.
Certified by the Canadian Standards Association for electric safety and operational reliability across North American networks.
Affirms conformity with health, safety, and environmental protection standards for products sold within the EEA.
Mandatory China Compulsory Certificate guaranteeing electrical insulation and operational safety compliance.
Certified by the South African Bureau of Standards, meeting the strict requirements of African mining and industrial sectors.
Authorized by the premier mining product certification body, facilitating direct import channels into the Australian market.
By adhering to a global certification framework, Wolong and Shaanxi Nanfang Motor simplify international procurement processes:
As a global manufacturer of motors and drive solutions, Wolong operates 39 manufacturing facilities and 4 R&D centers across China, Vietnam, the United Kingdom, Germany, Austria, Italy, Serbia, Mexico, and India. This network supports local industrial projects with targeted technical assistance.
Our star-delta configured motors are used in large-scale municipal water treatment, desalination plants, and agricultural irrigation, protecting pumping systems from water hammer and structural stress.
For demanding applications like conveyor belts, crushers, and tunnel boring machines, our explosion-proof Morley and Nanyang motors deliver high torque under harsh operating conditions.
In hazardous environments where explosive gases may be present, our ATEX and IECEx-certified explosion-proof motors run safely and reliably in key refinery units.
Our motors drive large tunnel ventilation fans and commercial HVAC systems, with star-delta starters helping to manage current draws in municipal building grids.
With DNV Type Approvals, our low-voltage marine motors power thrusters, cargo winches, and onboard pumps, standing up to corrosive salt-spray environments.
Integrating motors with advanced control packages ensures precise speed adjustment and system safety in continuous process lines like pulp & paper and steel mills.
Common technical and procurement questions regarding 3-phase star-delta configurations and sourcing from China.
In a Star (Wye) configuration, the ends of the three stator windings are connected together at a common neutral point, meaning each winding receives the phase voltage (line voltage divided by 1.732). In a Delta configuration, the windings are connected end-to-end in a closed loop, exposing each winding to the full line-to-line voltage. This difference allows Star wiring to start the motor with lower current, while Delta wiring provides full power during running.
DOL starting applies full voltage immediately, creating a current surge that can drop localized grid voltages and damage mechanical components. Star-delta starting reduces this initial current draw and torque shock to approximately 33% of DOL levels, protecting both the electrical grid and downstream mechanical equipment.
No. A motor must have all six terminals of its three stator windings brought out to the terminal box (often labeled U1-U2, V1-V2, W1-W2). Additionally, the motor's rated voltage for Delta connection must match the supply line voltage. For example, a 400V Delta motor can be started with a Star-Delta starter on a 400V supply.
The transition time is the delay between opening the Star contactor and closing the Delta contactor (typically 50 to 100 milliseconds). If this transition occurs too quickly or without proper alignment, it can cause transient current spikes that trip circuit breakers. Our motor systems are designed with mechanical and electrical characteristics that ease this transition.
As an authorized distributor, we provide direct access to Wolong's 39 global manufacturing facilities and technical R&D resources. Every motor is backed by Wolong's testing protocols and carries authentic global certifications (ATEX, IECEx, UL, CSA, CE), supported by our local engineering and logistics teams.
Typically, if a VFD is installed, a star-delta starter is not required because the VFD manages the motor's acceleration profile to prevent current spikes. However, some systems use star-delta bypass configurations for emergency backup operation if the VFD fails.
Browse our selection of specialized high-voltage, non-sparking, variable frequency, and marine-approved motors designed for heavy industrial applications.
NANFANG
