DC electronic load is the core equipment for power testing, battery aging screening, and electronic component performance verification. Its stability and accuracy directly affect the reliability of experimental results. To ensure the long-term efficient operation of the equipment, systematic maintenance is required from the dimensions of environmental control, daily maintenance, calibration and commissioning, mechanical and electrical system maintenance, and operating standards. The following is a detailed operation guide:
1、 Environmental Management and Preventive Maintenance
（1） Environmental parameter monitoring
1. Temperature and humidity control: The temperature in the work area should be maintained at 20-25 ℃, and the humidity should be ≤ 60% RH. A constant temperature and humidity machine should be equipped and data should be recorded daily. High temperatures can easily cause semiconductor components to overheat and fail, while high humidity may lead to condensation and short circuits on circuit boards.
2. Dust prevention measures: Install an air filtration device (recommended EN 1822 H13 HEPA filter element), replace the filter screen monthly, and regularly clean the dust accumulation in the heat dissipation holes with an air blow tank.
3. Electromagnetic shielding: Keep away from strong interference sources such as frequency converters and motors. The grounding resistance of the equipment should be ≤ 4 Ω to avoid signal acquisition distortion.
2、 Mechanical Structure and Electrical System Maintenance
（1） Maintenance of cooling system
1. Air cooling module: Disassemble the cooling fan every quarter, clean the dust on the blades with a vacuum cleaner, apply high-temperature resistant silicone grease (such as Dow Corning SE4700), reinstall and test the speed deviation to be less than 5%.
2. Water cooling system (if any): Check the coolant level weekly, replace deionized water once a year, clean the scale on the inner wall of the pipeline, and monitor the inlet and outlet water temperature difference to be ≤ 3 ℃.
（2） Electrical connection management
1. Wiring port: After each test, check whether the banana plug and aviation socket are oxidized. Use electronic cleaner (such as CRC 05-06) to wipe the gold plating layer to ensure that the contact resistance is less than 10m Ω.
2. Relay maintenance: Test the conduction voltage drop of solid-state relays annually. If it exceeds the nominal value by 20%, it needs to be replaced to avoid PCB warping caused by heating.
3、 Calibration and Accuracy Assurance
（1） Core parameter calibration
1. Voltage measurement calibration: Connect to a standard voltage source (such as Agilent E3631A), set typical values such as 5V/10V/20V, adjust the internal potentiometer of the device to make the displayed value deviate from the standard source by ≤± 0.1%+20mV.
2. Current measurement calibration: Using the shunt method, connect a standard resistor (0.01% accuracy) in series with the test load, and correct the gain error by comparing theoretical calculations with actual measurements.
3. Dynamic response test: Input square wave load command (such as 0-100% full load jump), the oscilloscope should monitor the current rise time to be ≤ 100 μ s, and adjust the PID control parameters when exceeding the tolerance.
（2） Special function verification
1. CV curve test: Simulate the load of lithium batteries, set 0.05V step charging, and verify that the capacity integration error is less than 1%.
2. Ripple suppression test: Inject a ripple current of 1kHz/peak to peak value of 10% in constant current mode, and the equipment should automatically filter out noise>40dB.
4、 Software and Data Management
1. Firmware upgrade: Check the manufacturer's updates every quarter and upgrade the control algorithm (such as upgrading from PID V1.2 to V2.0 to enhance dynamic response).
2. Data backup: The test data adopts NAS network storage and local hard drive dual backup, and exports log files to encrypted mobile hard drives every month.
3. User permission management: Set multi-level operation permissions (such as administrator/engineer/operator) to prohibit unauthorized personnel from modifying test scripts.
5、 Periodic major maintenance standards
Perform comprehensive disassembly and maintenance every two years:
1. Disassemble the power module and replace it when the IGBT junction capacitance deviation is greater than 20%.
2. Clean the solder joints of the PCB board and solder the severely oxidized connector pads.
3. Replace aging electrolytic capacitors (such as Rubycon ZL series models with a lifespan of 105 ℃/2000 hours).
4. Re calibrate the temperature control probe (accuracy ± 0.5 ℃) to ensure that the intelligent speed regulation function of the cooling system is normal.