Before repairing Emerson series inverters, it is crucial to understand the fault code first. Without knowing the specific error, you may not be able to proceed with the repair process effectively.
Fault Code and Fault Type:
POFF - Input undervoltage
E008 - Input phase loss
E001 - Accelerated overcurrent
E009 - Output phase loss
E002 - Deceleration overcurrent
E010 - Module protection
E003 - Constant speed overcurrent
E011 - Inverter overheating
E004 - Accelerated overvoltage
E012 - Rectification overheating
E005 - Deceleration overvoltage
E016 - Read/write fault
E006 - Constant speed overpressure
E018 - Contactor not sucking
E007 - Control power supply overvoltage
E019 - Current detection circuit failure
1. Current Detection Fault (e.g., E019, E001):
(1) The control board Q1 (15050026) may be faulty.
(2) The 7840 chip could be damaged. When the inverter is powered on, use a DC meter: connect black to pin 5, red to pins 6, 7, and 8 respectively. If the readings are 2.5, 2.5, and 5, it's normal. Otherwise, the 7840 is bad.
(3) The small board might be faulty. When powered on, measure from pin 5 of the 7840 to the small board. If the values are incorrect (e.g., 2.5, 2.5, 3.4, 1.5, 0, 1.6), the small board is likely bad. Replace the three ICs (39030024 LMV393) on the small board if needed. If not fixed, replace the entire small board.
2. Display POFF:
The drive board is likely at fault. Check the CVD voltage; it should be between 2.6–2.7 V. If it reads 1.9 V, one of R51, R52, C36, or C37 may be faulty, especially the electrolytic capacitor. POFF is only reported when the motor is running, so check for possible damage to the driver board transformer.
3. Bad Buffer Resistor:
A faulty buffer resistor often correlates with a faulty filter capacitor. A bad snubber resistor can also result from a relay that fails to engage (bad relay, control board, or related components). For single-phase input inverters (220V), pay attention: if there's no display or alarm, it may indicate the user connected it to a three-phase power source (380V). Check the control board’s bus voltage—310V changed to 540V suggests the IPM rectifier bridge is damaged, as well as the filter capacitor. Replacing the IPM without replacing the capacitor can cause repeated failures. If the capacitor is swollen or hardened, it must be replaced immediately.
4. Unstable Display:
First, the display appears, then disappears, and the fan stops, with a voltage of only 12V. This usually indicates a faulty U1 thick film. If E015 is reported, the power-on indicator is on, but the keyboard is off, and the fan is just spinning—this may suggest a short-circuited fan. For braking issues, check the brake tubes (01180100, 01180113, 01180114) inside the IPM. After replacing the IPM, verify the brake circuit quality: optocoupler, brake tube (measure its series freewheeling diode, which should read around 0.37V), and gate resistance (should be around 100 ohms). After repair, set TD900 F093 to 150. If the voltage between P(+) and PB is 17–30V, the brake is working properly. For TD3200, F133=150 and DC voltage between 270–350V means the brake works.
5. Damaged Rectifier Bridge:
If some rectifier bridges are damaged but the inverter bridges are fine, it may be due to arcing between the positive and negative busbars. High humidity is a common cause, with water droplets causing shorts between terminals. Insulation deterioration requires replacement. Another reason could be a shorted filter capacitor (swollen or hardened), which should be replaced immediately.
6. Machine Hiccup:
When the fan runs fast and slow, and there's no display, it typically indicates a short-circuit on the control board. Remove the control board and power it on again. If the issue persists, the thick film or nearby components may be faulty. For example, a high resistance value on R56 (27 ohms) on the TD1000 large-volume board suggests a problem with the snoring protection circuit. If the switching power supply doesn’t work, check for voltage fluctuations or short circuits in the rear circuit (e.g., solder bridging, filter capacitor touching). If no voltage is present, the switching power supply isn’t starting, possibly due to a faulty thick film or 2844 chip.
7. Weak Fan Speed:
For EV1000 D6 breakdown, check the FECDF21U1 board’s U8. It may be damaged with small cracks. For models like 01180128, under load, a "8888" error may occur due to poor transformer inductance or insufficient insulation between primary and secondary coils of PC9.
8. Fault Report 8888:
This may indicate a short-circuited drive optocoupler.
9. EV1000 Large Volume:
Original fault was a blown component. After running, no output or E019. Often, U9 is the culprit. No output can also be caused by a faulty Q2.
10. EV1000 Small Volume:
After repair, no output is common. R13 is often the issue. During repairs, ensure R13 is not 10 ohms.
11. General Tips:
The inverter consists of the main circuit, power circuit, IPM drive and protection circuit, cooling fan, etc. Its structure is mostly modular. Due to improper use or environmental factors, the inverter may malfunction. To prevent issues, it's important to analyze potential causes before they occur.
1.1 Main Circuit Fault Analysis:
The main circuit includes rectifier bridges, smoothing capacitors, filter capacitors, IPM inverter bridges, current limiting resistors, contactors, etc. Many faults are caused by electrolytic capacitors. Their lifespan depends on applied DC voltage and internal temperature. Capacitor design determines their life, and temperature significantly affects performance. Every 10°C increase halves the life. Ensure proper ambient temperature during installation and reduce pulsating current using reactors. In maintenance, electrolytic capacitors are judged by electrostatic capacity. If below 80% of rated value or insulation resistance less than 5 MΩ, replace them.
1.2 Typical Main Circuit Failure Analysis:
Symptom: Overcurrent during acceleration, deceleration, or normal operation. First, determine if it's load or inverter-related. If the inverter trips, check the current at the time. If it exceeds the rated current or electronic thermal relay setting, consider overload or sudden changes like motor stall. Extend acceleration time if inertia is high. If the current is within limits, the IPM module or related part is likely faulty. Test the resistance between main output terminals (U, V, W) and DC side (P, N). If the module is fine, the drive circuit is faulty. If overcurrent occurs during deceleration, the upper half of the IPM is likely at fault; during acceleration, the lower half. External dust or humidity often causes such issues.
1.3 Control Loop Fault Analysis:
The control loop includes the power supply, smoothing capacitor, and snubber capacitor on the IPM board. These capacitors are affected by temperature and power-on time. Since they are soldered, measuring electrostatic capacity is difficult. Estimate based on temperature and usage time. The power supply board powers the control loop, IPM drive, display, and fan. If a power supply is shorted, it may affect other parts. For example, a control power short may damage the switching power supply. Logic control boards contain large-scale ICs like CPU, MPU, RAM, EEPROM. Though reliable, EEPROM faults can occur due to simultaneous power-on. Resetting the EEPROM can resolve the issue. IPM boards include drive and buffer circuits, as well as protection circuits. Measure optocouplers while testing IPM modules.
1.4 Cooling System:
The cooling system includes a heat sink and fan. Fans have a limited life, typically 10,000–35,000 hours. As they age, vibration increases, noise rises, and eventually, the fan stops. This leads to IPM overheating. Some products operate fans only when the drive is running, not when powered on, to extend fan life.
1.5 External Electromagnetic Interference:
Interference sources near the inverter can enter through radiation or power lines, causing control circuit malfunctions, abnormal operation, or even damage. Reduce interference by adding absorption devices to relays and contactors, keeping control wiring short and separated from the main circuit. Maintain a minimum distance of 15mm between twisted joints and 10cm from the main circuit. If the inverter is far from the motor (>100m), increase wire cross-section and install an output reactor. Ground the inverter properly, avoiding mixing with welding or power grounding. Install radio noise filters at input and output to reduce harmonic and line noise.
1.6 Installation Environment:
Inverters require strict installation environments. Follow the manual guidelines. If not met, take preventive measures: vibration can damage electronics, so use shock-absorbing measures. Moisture, corrosion, and dust cause rust, poor contact, and low insulation. Treat control boards with anti-corrosion and dust-proof coatings. Temperature is critical for reliability, especially for semiconductors. Avoid direct sunlight. Regularly check air filters and cooling fans. In cold areas, use air heaters to ensure microprocessors function correctly.
1.7 Power Supply Anomalies:
Power anomalies include phase loss, low voltage, and power failure. Causes may be weather events or short circuits. Voltage fluctuations and frequency variations can occur in self-generated power systems. To protect equipment, separate the inverter’s power from other devices. For continuous operation, use an automatic uninterruptible power supply. Even if a diode-input inverter continues to run during phase loss, excessive rectifier current and capacitor pulse current can harm longevity, requiring prompt inspection.
1.8 Lightning Strike and Induced Lightning:
Lightning or induced lightning can cause surge voltages, damaging the inverter. Vacuum circuit breakers may generate high surges during switching. Prevent overvoltage by installing varistors at the inverter’s input. Add surge absorbers to vacuum circuit breakers. If a vacuum circuit breaker is on the transformer’s primary side, disconnect the inverter before operating it.
2. Inverter Self-Diagnosis and Prevention Function:
Older transistor inverters had issues like frequent tripping and low overload capability. With IGBT and CPU advancements, modern inverters now feature improved self-diagnosis and fault prevention, greatly enhancing reliability. Using vector control functions like “all-area automatic torque compensation†helps overcome issues like insufficient starting torque or reduced output due to environmental conditions. The inverter calculates required torque in real-time and adjusts output voltage to maintain performance under changing conditions.
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