The Danfoss FC-302 series is a versatile frequency converter, capable of controlling the entire operation of any machine or production line, from standard to servo speeds, using a single unit. It features a compact form factor, various package options, a safe stop function, an intelligent cooling system, a wealth of built-in components, and standard communication configurations. It is widely used in various industries, such as food, beverage, printing, papermaking, petrochemicals, textiles, steel, machinery, hoisting, elevators, building materials, and HVAC systems.
Shanghai Jinxin Inverter Technical Service Center received an FC-302P1K5T5E20 inverter. The customer reported that it was displaying a W66 fault during operation, which would occur whenever the inverter was powered on.
Inspection process:
The FC0302P1K5T5E20 frequency inverter is a 1.5KW unit with an IP20 rating, making disassembly and assembly very simple. Based on the customer's feedback, we immediately began inspecting the inverter. First, we removed the control panel, then the top cover, revealing the inverter's control card. After removing the control card, we removed the side panel to access the cooling fan, allowing us to remove the power supply card. Testing the power supply card revealed that the rectifier module, inverter module, electrolytic capacitors, switching power supply, and drive circuitry were all functioning normally. However, upon powering on, a W66 fault was displayed. The W66 fault indicates low heatsink temperature. The inverter's heatsink temperature was displayed as 0 degrees Celsius.
Fault Cause Analysis:
According to the W 66 fault explanation, there are two possible causes for the inverter displaying a fault: 1. The temperature sensor; 2. The temperature sensor's detection circuit. Checking the temperature sensor, which is integrated inside the IGBT module, is simple; just measure the resistance value. The temperature sensor was found to be good. Therefore, the fault lies in the detection circuit.
Why did the frequency converter suffer such damage? The repair personnel immediately inquired about the customer's on-site environment, and the customer stated that the area had been dusty and humid recently. The repair personnel immediately inspected the fan and found a lot of oil on the frequency converter's cooling fan, thus determining that the oil was the cause of the frequency converter's damage.
Repair process:
Replace the damaged components in the inverter's temperature detection circuit. Reinstall the inverter's power supply card, base plate, side plate, control card, top cover, and operation panel in sequence. Check the inverter's diode characteristics and insulation to ground to ensure they meet power-on standards. Power on the inverter; after passing the self-test, measure the input power supply voltage; ensure the output voltage is balanced upon startup. Measure the input and output currents under load to ensure they are balanced. The inverter is now repaired.
Summary of experience: When using frequency converters, pay close attention to the surrounding environment. In areas with poor environmental conditions, the frequency converter can be installed inside a control cabinet. Regular maintenance is also essential.
