Maintenance and repair of inverters and soft starters - Database & Sql Blog Articles

Maintenance and inspection of inverters and soft starters are essential practices to prevent unexpected failures. To ensure effective maintenance, it's important to prepare a detailed checklist that records changes in the device’s characteristics and component stability. This helps in identifying potential issues early and facilitates troubleshooting when problems occur. Maintenance is typically divided into daily checks and periodic inspections. At the initial installation stage, more frequent inspections should be conducted to avoid early failures. As the equipment runs longer, regular checks on component degradation become necessary.

1. Preparation Steps for Inspection and Maintenance

• Turn off the device
• Switch off the main power supply
• Turn off the control power supply
• Confirm that the main circuit has fully discharged
• Perform a voltage check

2. Daily Inspection

2.1 Inspection Frequency: Once per month

2.2 Key Items to Check:

• Verify the installation environment — temperature, humidity, presence of special gases, and dust levels
• Listen for abnormal noises from components like reactors, transformers, and cooling fans
• Check for unusual smells, such as burning insulation or other circuit components
• Inspect internal contamination and adjust cleaning frequency based on dirt levels

Visual checks are the primary method, and any abnormalities must be addressed immediately.

3. Periodic Inspection

3.1 Inspection Frequency: Based on the unit's minor repair schedule

3.2 Key Inspection Items:

• Clean the cabinet and internal components
• Check for discoloration, deformation, or leakage in circuit parts (capacitors, reactors, transformers, etc.)
• Inspect the board for discoloration, deformation, contamination, or aging solder joints
• Check wiring for discoloration or heat-related corrosion
• Ensure all fastening components (nuts, bolts, screws) are secure

When inspecting the main circuit, wait at least 5 minutes after power is turned off. Capacitors may still hold a charge, so always take precautions against electric shocks. Never open the equipment while it is running.

4. Focus Areas for Maintenance

4.1 Cleaning and Maintenance of Main and Control Circuits

The first step is cleaning. Ensure the power is disconnected and confirm no voltage is present before removing dust using suction or compressed air. Avoid high-pressure air to prevent damage. Use a cloth for hard-to-remove debris. Start cleaning from the top down to avoid missing falling particles.

4.2 Cabinet and Structural Components

• Cooling Fan (Checked at All Times): Monitor airflow and noise levels. Be cautious during reinstallation to avoid vibration damage due to loose bolts.
• Main Circuit Components (Checked Monthly to Annually): Inspect for dust, reactor status, fuse integrity, capacitor condition, resistor performance, and wiring connections.

4.3 Printed Circuit Boards

PCBs with integrated circuits and electronic components require protection from dust, corrosive gases, and extreme temperatures. Regular cleaning and proper environmental control help reduce malfunctions. When cleaning, use a brush or similar tool. Always handle PCBs carefully to avoid damage.

4.3.1 Precautions for PCB Maintenance:

• Wait at least 5 minutes before working on the PCB
• Disconnect all cables and remove fixing screws before removal
• Handle PCBs and screws with care to avoid dropping them
• Reinstall in reverse order of removal
• Store PCBs with the aluminum frame down to prevent short circuits

5. Step-by-Step Inspection and Maintenance Process

5.1 Preparation Steps:

• Stop the unit and confirm the motor has completely stopped
• Press the stop button on the operator panel
• Disconnect the external main power supply (low-voltage drawer)
• Ensure the control panel indicator is off
• Turn off the control power switch
• Wait at least 5 minutes
• Open the inverter (soft starter) door and confirm LEDs are off
• Check for voltage on external cables
• Ground the main circuit input

5.2 Recovery Steps:

• Remove the grounding wire
• Turn on the control power and close the door
• Power up the external main supply (low-voltage drawer)
• Confirm the control panel indicator is lit
• Complete safety checks and prepare for operation

When replacing an inverter or soft starter, always follow the manufacturer’s instruction manual.