The “Flow Stabilizer” for Bulk Material Handling – How Wheatstone ExplosionProof Mining Servo Motors Handle HeavyLoad Starts and MultiMotor Power Sharing

In coal preparation plants, mineral processing facilities, cement plants, chemical plants, and port terminals, equipment such as vibrating feeders, belt conveyors, bucket elevators, tripper cars, large screens, grinding mills, and screw conveyors are the core machinery for material transfer, screening, and elevating. These devices face complex load characteristics: material flow fluctuates, inertia shocks during startstop are high, and uneven torque sharing among multiple drive motors can cause belt misalignment, chain overload, motor overheating, and even burnout. Standard motors may stall during heavyload starts, struggle to achieve precise torque sharing in multidrive configurations, and cannot adapt to rapid changes in material flow. Jiangsu Wheatstone has developed a full series of explosionproof mininggrade servo motors for industrial and port applications, combining 3× peak overload capacity, 13000 rpm wide speed range, masterslave power sharing, and IP66 high ingress protection – delivering smooth starts, precise speed regulation, and balanced output for bulk material handling systems.

I. Five Core Requirements for Material Handling Drive Motors

Heavyload smooth starting: Vibrating feeders and screw conveyors must overcome static friction and inertia when starting under full load, requiring starting torque ≥2× rated torque.

Wide speed range to match material flow: Belt conveyors and bucket elevators need to adjust speed according to incoming material flow to avoid energy waste at light loads or blockages at heavy loads.

Automatic power sharing for multimotor drives: Long belt conveyors and tripper cars often use multiple motors driving the same load. Output torque must be shared automatically to prevent individual motor overload.

High overload capacity for shock loads: Impact loads occur during screen startstop and mill feed fluctuations, requiring high shortterm overload capability.

Explosion protection and high ingress protection (chemical plants, dusty areas): Where flammable gases or combustible dusts may be present, motors must carry appropriate explosion protection certifications (Ex d IIB T4 Gb / Ex tb IIIC T130℃ Db) and high ingress protection (IP65/IP66).

II. Core Advantages of Wheatstone ExplosionProof Mining Servo Motors

1. 3× Peak overload capacity – handling heavy starts and shocks: Peak torque up to 3× rated torque. When a vibrating feeder starts under full load, the motor instantly delivers ample torque for smooth, jerkfree starting. In a coal preparation plant, the start success rate increased from 85 % to 99.5 % after upgrading to Wheatstone motors.

2. 13000 rpm wide speed range – precisely matching material flow: Motors operate stably from 1 rpm to 3000 rpm, delivering rated torque even at low speeds. With VFDs, belt conveyors can adjust speed based on weigh feeder signals (“faster for more material, slower for less”), achieving overall energy savings of 1525 %.

3. Masterslave control and automatic power sharing: For long belt conveyors or multiple screw conveyors driven in parallel, Wheatstone drives support masterslave control. The master runs in speed control mode, while slaves follow in torque control mode, automatically balancing load with current deviation within ±3 %, eliminating individual motor overload.

4. 23bit absolute encoder – precise position and speed feedback: Standard 23bit absolute encoder provides speed accuracy of ±0.1 % and positioning error better than ±0.01°, ideal for tripper car precise stopping and bucket elevator bucket positioning.

5. Ex d IIB T4 Gb / Ex tb IIIC T130℃ Db explosion protection: Suitable for Zone 1/Zone 2 gas and Zone 21/Zone 22 dust hazardous areas. Ingress protection IP65/IP66, optional 316L stainless steel housing.

6. Permanent magnet high efficiency: Motor efficiency >95 %, 58 percentage points higher than conventional induction motors, delivering significant energy savings on continuously running conveyors.

III. RealWorld Application Cases

Case 1 – Coal preparation plant belt conveyor masterslave control retrofit (Hebei, China): A 1.2 km raw coal belt conveyor was driven by two induction motors; current deviation during starting reached 25 %, causing frequent overcurrent trips. After retrofitting with Wheatstone 110EXM explosionproof servo motors with masterslave control, starting current deviation was reduced to 3 %, belt operation became stable, and unplanned stops decreased by 8 per year.

Case 2 – Cement plant bucket elevator VFD upgrade (Shandong, China): The elevator originally ran at fixed speed, leading to frequent blockages when material flow varied. After upgrading to a Wheatstone 90EXM servo motor with VFD, speed was automatically adjusted based on motor current, blockages reduced by 90 %, and winding temperature dropped by 12 °C.

Case 3 – Port terminal tripper car precise positioning (Jiangsu, China): The tripper car required accurate stopping over storage bins. Original mechanical limit switches gave large positioning errors. After retrofitting with a Wheatstone servo motor and 23bit absolute encoder in closedloop control, positioning accuracy reached ±2 mm, unloading efficiency increased by 20 %, and the motor has run for 24 months without failure.

IV. Selection Guide

• All series customisable for voltage AC 380 V / 660 V / 1140 V; explosionproof versions available with Ex d IIB T4 Gb or Ex tb IIIC T130℃ Db certification.*

V. Conclusion

From raw coal belts in preparation plants to bucket elevators in cement works, from tripper cars at port terminals to screw conveyors in chemical plants, the smooth operation of material handling equipment depends on drive motors that deliver stability, precision, and balance. Jiangsu Wheatstone explosionproof mining servo motors – with 3× overload capacity, wide speed range, masterslave power sharing, and high ingress protection – provide efficient, reliable, energysaving power solutions for bulk material handling systems.