SEG MRR1D

Core Technical Specifications

• Monitoring Objects: Rotor insulation resistance, excitation overcurrent, excitation undercurrent, rectifier diode ripple voltage fault
• Two-Stage Protection Logic: Warning stage (alarm only), trip stage (cut excitation circuit)
• Output Relays: 5 groups of isolated relay contacts for alarm, trip, fault signal
• Communication: RS485 Modbus RTU, support remote parameter setting and data upload
• Mounting: Standard 19-inch cabinet panel mount
• Operating Temperature: -20 °C ~ +70 °C
• Adjustable Parameter Range: Insulation resistance threshold 0.1 kΩ ~ 100 kΩ; excitation current threshold 5% ~ 150% rated excitation current

Function & Performance Features

1. Rotor earth fault insulation resistance real-time monitoring, two-stage alarm/trip grading protection
2. Excitation overcurrent & undercurrent dual protection, prevent rotor winding burnout caused by abnormal excitation
3. Rectifier bridge diode failure detection via ripple voltage sampling, early warning of excitation rectifier damage
4. Front panel digital display shows real-time rotor insulation resistance and excitation current value
5. Built-in fault memory storage, record fault type, action time and pre-fault operating parameters
6. Anti-interference hardware filtering design, stable operation under high electromagnetic interference environment of power plant main control room

Working Principle

1. Low-frequency measuring signal injected into rotor winding to calculate insulation resistance between rotor and ground
2. Current sampling transformer collects excitation loop DC current signal for over/under current judgment
3. Ripple voltage sampling circuit detects AC ripple component in excitation DC to judge rectifier diode open/short circuit fault
4. MCU processes all sampling signals, compares with user setting values to trigger alarm or trip relay action
5. All operating data and fault logs are transmitted to power station SCADA system through Modbus bus

Material Composition & Structural Characteristics

• Housing: Metal shielded cabinet structure, built-in EMC anti-interference partition
• Operation Panel: Blue background membrane key panel, red digital LED display, fault indicator light matrix
• Internal Circuit: Isolated sampling circuit, optocoupler isolation between strong and weak current circuits
• Enclosure Protection: IP30 dust-proof grade for indoor cabinet installation

Installation Requirements

1. Install in generator excitation control cabinet, separate from high-voltage switch cabinet to avoid strong electromagnetic interference
2. Rotor insulation measuring signal wire adopts dedicated shielded twisted pair, single-point grounding of shielding layer
3. Excitation current sampling transformer wiring must ensure correct polarity, reverse connection will lead to protection misoperation
4. Cabinet ventilation gap must be reserved to avoid long-term high temperature accelerating internal component aging

Application Scenarios

• Thermal power plant synchronous generator rotor protection
• Hydropower station large hydro generator excitation monitoring
• Industrial self-owned synchronous generator set fault protection
• Gas turbine generator unit excitation loop safety monitoring

Usage Precautions

1. Regularly test rotor insulation measurement function every half year to ensure sampling circuit normal
2. Adjust excitation current threshold according to actual generator rated excitation current parameters
3. Do not short-circuit rotor measuring signal terminals during generator maintenance, will damage internal measurement circuit
4. After power station high-voltage equipment maintenance, recheck wiring polarity of MRR1D sampling lines