Frequency Inverter Overvoltage Trip (OV Fault) Troubleshooting Guide

Fault Cause Analysis

Common Causes:

1. Excessively short deceleration time (typically < 3 seconds)
   • Motor operates in generating mode, energy cannot be consumed in time
   • Excess energy causes DC bus voltage to rise
2. Grid voltage fluctuations
   • Input voltage exceeds ±15% of rated value
   • Voltage surge caused by external factors such as lightning strikes
3. Regenerative braking energy
   • Frequent braking generates large amounts of regenerative energy
   • Brake resistor aging or improper selection
4. Incorrect parameter settings
   • Overvoltage protection threshold set too low
   • Inappropriate deceleration time parameter configuration

Step-by-Step Troubleshooting Process

Step 1: Emergency Response

1. Immediate shutdown: Stop the equipment immediately and disconnect power supply
2. Fault documentation: Record the exact fault code and operating conditions
3. Voltage verification: Check if grid voltage is within normal range

Step 2: Systematic Diagnosis

Power Supply Assessment

① Measure grid input voltage (normal range: 380V±15%)
② Check power supply stability and identify any fluctuations
③ Verify if simultaneous starting/stopping of other equipment causes interference

Parameter Configuration Check

• Deceleration time: Extend to appropriate range (10-30 seconds)
• Overvoltage protection: Adjust threshold to reasonable levels
• Braking parameters: Verify brake resistor configuration settings

Hardware Inspection

• Brake resistor: Check for signs of aging, damage, or overheating
• Capacitor bank: Inspect DC bus capacitors for bulging or leakage
• Connection terminals: Ensure all electrical connections are tight and secure

Step 3: Resolution Strategies

For Excessive Deceleration Issues:

• Extend deceleration time parameters appropriately
• Enable “deceleration overvoltage stall prevention” function
• Implement S-curve deceleration profile for smoother operation

For Grid-related Problems:

• Install voltage stabilizer or line reactor
• Implement surge protection devices
• Adjust overvoltage protection thresholds based on actual grid conditions

For Braking Energy Management:

• Upgrade to higher capacity brake resistor
• Install additional braking unit if necessary
• Consider four-quadrant inverter for frequent regenerative applications

For Parameter Configuration Errors:

• Reset to factory default settings and reconfigure
• Perform automatic parameter tuning function
• Consult manufacturer’s technical support for optimal settings

Preventive Maintenance Framework

Regular Maintenance Schedule

1. Monthly inspections:
   • Check brake resistor temperature and condition
   • Verify parameter settings and backup configuration
   • Monitor DC bus voltage during normal operation
2. Quarterly maintenance:
   • Inspect cooling system and clean heat sinks
   • Check capacitor bank for signs of deterioration
   • Test overvoltage protection functions
3. Annual servicing:
   • Comprehensive electrical insulation testing
   • Brake resistor resistance measurement
   • Software and firmware updates if available

System Optimization

• Configure parameters based on specific application requirements
• Implement appropriate energy management strategies
• Set up voltage monitoring and logging systems
• Establish regular preventive maintenance protocols

Protection Enhancement

• Install proper surge protection devices
• Implement voltage regulation equipment
• Configure appropriate protection thresholds
• Regularly test all safety systems

Safety Precautions

1. Electrical safety:
   • Always disconnect power before performing maintenance
   • Allow sufficient time for capacitors to discharge (minimum 5 minutes)
   • Use appropriate personal protective equipment
   • Follow established lockout/tagout procedures
2. Professional requirements:
   • Complex faults should be handled by qualified technicians
   • Ensure proper training and certification for maintenance personnel
   • Follow manufacturer’s safety guidelines and recommendations
3. Documentation practices:
   • Maintain detailed records of all fault occurrences
   • Document maintenance activities and parameter changes
   • Keep accurate inventory of spare parts
   • Establish comprehensive equipment history records

Conclusion