Changsha Zoomlian Pump Co., Ltd. 长沙中联泵业股份有限公司

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    Technical Solution for Difficult Startup of MDP-Type Wear-Resistant Self-Balancing Multistage Mine Pumps

    Publication Date:

    2026-04-24

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    MDP-type mining wear-resistant Self-balancing multistage pump Starting up is difficult, which poses a very serious safety risk in mining operations. If underground water inflows are not drained promptly, the mine tunnels are at risk of collapse; therefore, timely troubleshooting is crucial. In this article, a manufacturer of multistage pumps Changsha Zoomlion Pump Industry Conduct a systematic analysis and troubleshooting of the fault causes for reference by the user organization.

     

    MDP-type Wear-Resistant Self-Balancing Multistage Pump for Mining

     

    I. Core Fault Diagnosis

    1. Power Supply System: Verify that the supply voltage is within the rated range of 380 V ± 5%; use a multimeter to measure the voltage drop at startup (a drop of ≤7% of the rated value is considered acceptable). Inspect the cable cross-sectional area to ensure it matches the requirements (≥4 mm² for copper-core conductors), and eliminate excessive contact resistance caused by oxidation or loosening of connections.

    2. Motor System: Perform insulation resistance testing on the motor (using a 500 V megohmmeter, with a reading of ≥10 MΩ); prioritize detection of inter-turn short circuits in the windings (using a double-arm bridge to measure DC resistance, with a deviation ≤2%). For self-balancing multistage pump motors, additionally inspect bearing clearance (≤0.1 mm) to prevent jamming that could cause the starting torque to exceed the specified limit.

    3. Load System: Conduct blind flange pressure testing on the inlet and outlet pipelines (at ≥1.5 times the working pressure) to identify and eliminate blockages caused by foreign objects (installation of a Y-type strainer is recommended). Measure the pressure differential across the pump chamber at the inlet and outlet (normal value ≤0.05 MPa); if the differential exceeds this limit, disassemble the impeller to inspect the wear on the balance disc (the safety threshold is ≤0.2 mm).

    4. Control System: For the PLC control cabinet, verify that the circuit breaker’s breaking capacity is ≥1.25 times the motor’s rated current, and ensure that the contact erosion area of the contactor does not exceed 20% of its rated area. Set the current-limiting parameters of the soft starter to ≤2.5 times the rated current to prevent voltage dips during startup from triggering protective shutdown.

     

    II. Fault Repair Specifications

    1. Power supply issues: Replace the regulated power supply module (response time ≤ 10 ms) and install a surge protector (Imax ≥ 5 kA).

    2. Motor Repair: The windings are rewound using a vacuum impregnation process, with Class F insulation (temperature rating of 155°C). SKF 6308/C3 bearings are used.

    3. Load Optimization: Replace the 100-mesh filter screen, chrome-plate the impeller (hardness ≥ HRC55), and use Hastelloy C276 for the balance disc.

    4. Control System Upgrade: Upgraded to an intelligent control cabinet with an integrated RS485 communication interface, supporting remote monitoring of the inrush current curve.

     

    III. Preventive Maintenance Plan

    1. Monthly inspection: Measure motor vibration (≤4.5 mm/s), check bearing temperature (≤70°C), and record the axial displacement of the balance disc (≤0.15 mm).

    2. Quarterly Maintenance: Disassemble and inspect the back vanes of the impeller for wear (≤0.5 mm); clean scale buildup in the guide vane passages; replace the rotating ring of the mechanical seal (recommended interval: 6 months).

    3. Annual Overhaul: Conduct a hydrostatic pressure test on the pump casing (operating pressure of 1.6 MPa, held for 30 minutes with no leakage), and verify the coupling concentricity (radial deviation ≤ 0.05 mm).

     

    Changsha Zoomlion Pump Industry recommends: If the above troubleshooting steps still fail to resolve the issue, vibration spectrum analysis (vibration frequency ≤ 1000 Hz) or motor torque measurement should be conducted, followed by diagnosis by a qualified engineer.

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    Analysis of the Causes of Aging and Failure of Bearings in High-Pressure Centrifugal Pumps and Corresponding Solutions

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    Technical Troubleshooting and Solutions for Multistage Centrifugal Pumps That Fail to Prime

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