In modern industrial power transmission, Asynchronous Slip Ring Motors (also classified as Wound Rotor Induction Motors - WRIM) represent the gold standard for applications requiring immense inertia startup, strict starting current constraints, and variable speed regulation under full load conditions. Unlike standard squirrel cage induction motors where rotor resistance is fixed by die-cast aluminum or copper bars, a slip ring motor features a three-phase insulated winding brought out to external slip rings mounted on the rotor shaft.
By connecting carbon brushes riding on these rotating metallic rings to an external starter—such as a Liquid Resistance Starter (LRS) or multi-stage grid resistor—plant engineers gain total control over the motor's speed-torque characteristic curve. This engineering dynamic yields crucial benefits for power utilities and heavy industry manufacturers in Thailand:
Reduces starting current spikes from typical 600-800% FLI (Full Load Current) down to 120-150% FLI. This eliminates line voltage dips across regional Thai PEA (Provincial Electricity Authority) and MEA power networks.
Achieves breakdown torque (up to 250% FLT) right at zero RPM (standstill). Ideal for heavy cement ball mills, jaw crushers, and fully loaded sugar cane diffusers without thermal overload.
During heavy acceleration, heat generated by rotor current is absorbed primarily in the external LRS tank, protecting stator insulation from premature thermal degradation in humid tropical climates.
| Motor Series | Voltage Rating (V / kV) | Power Range (kW / MW) | Enclosure & Cooling (IEC 60034-6) | Protection Class | Typical Industrial Load |
|---|---|---|---|---|---|
| YR / YRKK Series | 380V / 400V / 690V / 3.3kV | 160 kW – 4,000 kW | IC411 (Surface Air) / IC611 (Air-to-Air) | IP54 / IP55 | Cement Mills, Slurry Pumps, Sugar Crushers |
| YRKS / YKS Series | 6.6 kV / 10 kV / 11 kV | 500 kW – 12,000 kW | IC81W (Air-to-Water Cooled) | IP55 / IP56 | Power Plant ID/FD Fans, Mine Hoists |
| YXR Heavy Duty | 380V – 660V Low Voltage | 30 kW – 1,000 kW | IC01 (Open Drip Proof) / IC411 | IP23 / IP55 | Steel Rolling Mills, Crane Drives |
| Custom OEM Replicas | Customized to legacy footprint | Up to 25,000 kW | IC616 / IC86W / Custom Modular | IP65 / IP67 Special | Retrofit replacements for obsolete brands |
As a dedicated manufacturing exporter serving Thailand and international markets, our factory does not merely build off-the-shelf motors. We specialize in tailored OEM (Original Equipment Manufacturer) and ODM (Original Design Manufacturer) electrical and mechanical integration. Whether your plant requires a 100% mechanical drop-in duplicate for a legacy 1980s European motor or a custom high-voltage motor for modern greenfield sites, our engineering office executes complete 3D FEA (Finite Element Analysis) structural validation.
Full dimensional flexibility for mounting foot positions, shaft extension diameter, keyway design, flange configuration (V1, B3, B5, B35), and terminal box orientation (Top, Right, Left) to match existing foundations seamlessly.
Vacuum Pressure Impregnation using resin chemistry engineered specifically to resist 95%+ relative ambient humidity, corrosive tropical air, and aggressive industrial airborne contaminants found in agricultural processing.
Optional motorized automatic brush lifting device (Short-Circuiting Device). Once startup is complete, the mechanism lifts the carbon brushes and short-circuits the slip rings, eliminating brush wear and maintenance overhead.
Thailand’s industrial heartland—spanning from the Eastern Seaboard industrial estates to the agricultural processing hubs in the Northeast and Central plains—relies heavily on robust asynchronous drives. Our OEM/ODM motors are field-proven across Thailand’s most critical production lines:
Location Hubs: Suphan Buri, Khon Kaen, Udon Thani, Nakhon Sawan.
Drive Challenge: Heavy cane shredders, knives, and heavy-duty roller mills require massive starting torque under dense organic load. High ambient fiber dust (bagasse) requires specialized IP55 IP65 sealing.
OEM Solution: YRKK Air-to-Air Cooled Medium Voltage Slip Ring Motors (1000kW – 3500kW) with reinforced copper rotor bars and anti-corrosive winding insulation.
Location Hubs: Saraburi (Kaeng Khoi), Phetchaburi, Lampang.
Drive Challenge: Raw material ball mills, sag mills, and primary jaw crushers demand smooth startup without grid distortion while enduring harsh abrasives and dust.
OEM Solution: Heavy-duty YRKK 6.6kV 2500kW Slip Ring Motors integrated with automated Liquid Resistance Starters (LRS) and heavy bearings (SKF/FAG) with circulating oil systems.
Location Hubs: Surat Thani, Songkhla, Rayong, Chonburi.
Drive Challenge: Banbury mixers, rubber kneaders, and palm fruit digesters face extreme load fluctuations, high thermal stress, and chemical vapours.
OEM Solution: Custom Low Voltage YR Series 380V/400V (250kW - 630kW) IP55 Slip Ring Motors fitted with PT100 bearing and winding temperature sensors.
Thailand’s industrial landscape is undergoing a rapid evolution driven by the Eastern Economic Corridor (EEC) Initiative and the National "Thailand 4.0" Policy. Industrial facilities are modernizing aging drive infrastructure to meet strict energy consumption metrics while ensuring compliance with PEA/MEA electrical grid codes.
Thai power distribution agencies enforce strict penalties for reactive power surges and voltage sags during large motor starting. Our custom wound rotor motors paired with LRS provide near-unity power factor during acceleration, eliminating penalty fees for manufacturing facilities.
With Thailand's average annual relative humidity exceeding 80-95% during monsoon cycles, standard motor insulation degrades rapidly. Our ODM motors incorporate dual-vacuum pressure impregnation, space heaters, and tropical-grade anti-fungal varnishes as baseline standards.
Thousands of older plants across Thailand utilize legacy German, Japanese, or Eastern European slip ring motors whose original manufacturers no longer produce spare parts. Our factory provides 100% mechanical and electrical dimensional replication, avoiding costly foundation rebuilds.
With decades of deep specialized expertise in heavy-duty rotating machinery, our factory combines European-influenced design methodologies with lean production efficiency. Every motor exported to Thailand undergoes rigorous multi-stage quality inspections:
Our state-of-the-art testing facility supports full-load, no-load, temperature rise, vibration (ISO 10816-1), and partial discharge tests up to 13.8kV and 15MW prior to shipment.
Seamless export services directly to Bangkok Port (Klong Toey) and Laem Chabang Port, including Form E Certificate of Origin documentation for ASEAN duty benefits.
Direct consultation with senior electrical drive engineers for starter matching, rotor resistance calculation, installation guidance, and rapid spare parts dispatch.
A slip ring motor has a three-phase wound rotor connected via slip rings to external resistors (or LRS), enabling ultra-high starting torque (up to 250%) with low starting current (1.2 to 1.5x FLI). A squirrel cage motor has a fixed rotor cage and typically draws 6 to 8 times full-load current during direct-on-line (DOL) startup, which can cause severe voltage drop on restricted Thai utility grids.
Yes. Our OEM/ODM reverse engineering team routinely produces exact drop-in duplicates. We match shaft centerline height, shaft extension dimensions, foot mounting hole pitch, terminal box placement, and electrical parameters so that the new motor drops onto existing foundations without civil modifications.
All motors shipped to Thailand receive tropicalized Class H or Class F insulation with Vacuum Pressure Impregnation (VPI). Stator and rotor windings are treated with moisture-proof anti-fungal varnish, slip ring enclosures are sealed up to IP55/IP66, and internal anti-condensation space heaters are fitted as standard.
We strongly recommend pairing our YRKK series medium/high-voltage slip ring motors with a Liquid Resistance Starter (LRS). The LRS provides smooth, stepless resistance reduction as the motor accelerates, guaranteeing zero torque shock to mechanical gearboxes and minimal electrical shock to the grid.
Standard manufacturing lead times range from 6 to 10 weeks depending on power rating and voltage. For emergency plant shutdown replacements, our factory offers expedited 3 to 4-week production schedules, followed by direct sea freight to Laem Chabang Port (approx. 7-10 days transit).
Yes. As a certified exporter, we provide Form E Certificates of Origin under the China-ASEAN Free Trade Agreement, allowing Thai importers to benefit from zero or significantly reduced import tariffs.
Absolustely. Our motors can be equipped with PT100 RTDs for stator windings and bearings, SPM vibration monitoring studs, anti-condensation space heaters, and digital brush wear limit switches connected to your plant's SCADA system.
Simply click the Get Catalog button on any product card above or click our technical support link to connect directly with our engineering sales department. Provide your motor nameplate data, required voltage, power rating, and driven machine details for a comprehensive quotation within 24 hours.
Contact our senior electrical drive engineering office today for customized OEM/ODM design engineering, legacy replacement matching, and fast quotation services for Thailand.
