Application of Warrenson Electric's Intelligent Online Insulation Monitoring System for High-Voltage Motors in the Coal Industry

Industry Operation Background

I. Case Overview
This client is a coal mining company located in Shanxi Province, specializing in highly hazardous coal mining operations. Their primary requirement was to establish an intelligent online insulation monitoring, analysis, and control system to monitor critical equipment of high-voltage motors, such as the main/auxiliary shaft hoists, main air compressors, main ventilation fans, and gas drainage pumps. The purpose of this system is to replace the traditional manual insulation testing method using meggers, addressing the lag in insulation degradation warnings, reducing risks in explosion-proof zone operations, and integrating scattered data. The project utilized WARENSEN's WRS-MTS3 series high-voltage 10kV motor insulation online monitoring devices as the core technology, enabling real-time monitoring of motor insulation conditions and pre-fault warnings, thereby ensuring the continuity and safety of mine production.

II. Core Customer Pain Points

Monitoring Lag: Traditional manual offline testing conducted weekly cannot capture dynamic degradation processes such as winding aging or moisture absorption. A previous insulation breakdown caused a main ventilation fan to shut down for 4 hours, compromising underground safety;
Difficulty Adapting to Explosion-Proof Scenarios: The gas drainage pump room is an explosion-proof area. Manual cabinet disassembly for testing is cumbersome and poses risks of gas concentration exceeding limits;
Lack of Data Support: Manually recorded data cannot form continuous trends, missing key indicators such as polarization index and absorption ratio, leading to盲目运维决策 (blind maintenance decisions);
Complex Multi-Scenario Installation: The equipment layouts across six major engine rooms vary significantly. Some rooms require additional cabinets, while others need integration into existing control panels, creating conflicts between space and safety requirements.

III. WARENSEN Solution

1. Core Product Configuration
Centered on "precise monitoring + explosion-proof adaptation," the configuration includes WRS-MTS31 high-voltage motor insulation online monitoring devices (15 units, including 6 explosion-proof boxes), WRS-MTS3X high-voltage couplers (45 units, 3 per motor), LXK (C)-φ120 zero-sequence current transformers (15 units), paired with custom cabinets of 800×1500×2300mm/800×1000×2300mm (gas engine room cabinets equipped with explosion-proof glass doors) to meet diverse scenario needs.

2. Key Technical Advantages

During motor operation, insulation degradation trends are monitored via zero-sequence current monitoring of ground current; during motor shutdown, the DC high-voltage injection method is used, where a 2500VDC signal is injected into the motor windings via couplers to measure insulation resistance (1-9999MΩ, error ≤5%), simultaneously calculating polarization index and absorption ratio; triple safety protection: mechanical interlocking of circuit breakers, electrical detection of voltage and current, and current limiting via 10MΩ high-voltage resistors, ensuring the monitoring system automatically withdraws when the motor is powered and initiates detection immediately after power-off, eliminating high-voltage risks.

3. Scenario-Specific Implementation

Hoist Room: Added 800×1500×2300mm cabinets for main/auxiliary shafts, spaced 1.5m from frequency converter cabinets, with verticality calibrated using a level (error ≤2mm/m);
Voltage and Current Sampling Wiring: Collected voltage (from PT cabinet) and current (from motor outlet cabinet) signals (cabinet located next to the frequency converter cabinet); Transformer Installation:
Transformer Installation: Zero-sequence transformers placed around three-phase cables to collect zero-sequence current signals.

Coupler Installation: WRS-MTS3X high-voltage couplers connected to motor windings to achieve high-low voltage isolation; three-phase used for motor stator windings in Y-connection. Three couplers installed with insulating plates at the bottom of the motor switchgear cabinet, high-voltage sides of couplers connected in parallel with outlets; image shows rear of cabinet:

Gas Drainage Pump Room Installation as shown:

Note: The front glass door of the control panel is explosion-proof glass, with an explosion-proof shield inside the cabinet;

1. Material Shaft Engine Room: WRS-MTS31 high-voltage motor intelligent insulation monitoring device embedded into the rear panel of the control screen (150mm×76mm opening), connected to power (AC220V) and communication lines (RS485); added VBG-12P 630A high-voltage circuit breaker with custom bracket to adapt to on-site space, as shown:

< p>Wiring strictly adhered to coal mine standards: voltage/current signal cables (RVV-450/750V 4×1.5mm²) laid along existing wire ducts, spaced ≥100mm from power cables to prevent interference; RS485 communication cable shielding layer single-end grounded, 433MHz wireless transmission used in explosion-proof areas to avoid compromising explosion-proof structure with wiring.

IV. Installed Product Images:

V. Project Outcomes

Monitoring Efficiency Leap: Upgraded from "weekly manual checks" to "real-time online monitoring," with data sampling intervals ≤1s. When a gas drainage pump motor's insulation resistance dropped from 800MΩ to 500MΩ, the system issued a warning 7 days in advance, preventing failure and downtime;
Safety Risks Eliminated: Achieved contactless monitoring in explosion-proof areas, with zero safety incidents during construction; the system passed coal industry safety acceptance;
Optimized Maintenance Costs: Reduced manual inspection time by 60%, avoiding unplanned downtime losses (based on main ventilation fan shutdown impacting 500 tons of raw coal per hour, annual cost savings exceed 2 million RMB);
Data-Driven Maintenance: Integrated with the coal industry's PLC/DCS system, generating insulation trend charts and fault records, providing data support for full-lifecycle motor management.
WARENSEN's customized solution precisely addresses the challenges of medium-voltage motor insulation monitoring in coal mines, offering a replicable model for intelligent maintenance of electrical equipment in high-risk industries.