Author: baiyuzhan

Introduction

Variable Frequency Drives (VFDs), commonly known as inverters, are essential components in modern industrial control systems. They regulate motor speed and performance to achieve energy efficiency and precise control. However, their complexity can lead to faults, which are often indicated by error codes on the inverter’s display. In the SUNYE CM530 and CM530H series inverters, ERR24 is a frequently encountered fault code, typically associated with an “output side phase error” or “output phase loss.” This article provides a comprehensive guide to understanding ERR24, identifying its causes, troubleshooting the issue, and implementing preventive measures to ensure reliable operation.

Understanding ERR24

The ERR24 fault code likely indicates that the inverter has detected an issue with the output side, specifically a phase sequence error or a missing phase in the three-phase output (U, V, W) to the motor. This disruption can prevent the motor from operating correctly, potentially causing equipment downtime or damage. The error suggests an imbalance in the current or voltage output, which is critical for maintaining stable motor performance. Addressing ERR24 promptly is vital to minimizing disruptions in industrial processes.

Possible Causes of ERR24

Several factors may trigger the ERR24 fault code. Based on common inverter issues and general electrical engineering principles, the following are the most likely causes:

1. Output Cable Issues
   • Cables connecting the inverter to the motor may become loose, damaged, or disconnected due to vibration, aging, or external factors, resulting in phase loss.
   • Insulation damage in cables can cause short circuits between phases or to ground, disrupting the phase sequence.
2. Motor-Related Problems
   • Internal motor windings may develop open circuits or short circuits due to overheating, aging, or voltage imbalances, leading to unbalanced phases.
   • Loose or disconnected motor terminal connections can also trigger ERR24.
3. Inverter Internal Faults
   • Internal components, such as Insulated Gate Bipolar Transistors (IGBTs) in the inverter’s output module, may fail due to overload or wear, causing phase sequence errors.
   • Faults in the control circuit or power board can also contribute to ERR24.
4. Environmental Factors
   • High dV/dt (voltage change rate) from Pulse Width Modulation (PWM) outputs can stress cable or motor insulation, leading to phase loss.
   • Long cable runs (over 50 meters) may require dV/dt or sine wave filters to mitigate voltage spikes.
5. System Configuration Issues
   • A mismatch between the inverter’s output capacity and the motor’s rated power can destabilize the phase sequence.
   • Excessive motor load or frequent start/stop cycles may also induce ERR24.

Troubleshooting ERR24

To resolve the ERR24 fault, follow these systematic steps to identify and address the root cause:

1. Inspect Output Cables
   • Verify that the U, V, W three-phase cables are securely connected, free from wear, breaks, or burn marks.
   • Use a multimeter to test cable continuity and check for open circuits or short circuits.
   • For cable runs exceeding 50 meters, consider installing dV/dt or sine wave filters to reduce voltage spikes.
2. Examine Motor Connections
   • Check that motor terminal connections are tight and secure, tightening them if necessary.
   • Measure the resistance of the motor’s three-phase windings (U1-V1, V1-W1, W1-U1) with a multimeter to ensure consistent values. Inconsistent readings may indicate a need for motor repair or replacement.
3. Check Inverter Internals
   • If cables and motor are intact, the issue may lie within the inverter, such as a faulty IGBT module or control circuit.
   • Contact SUNYE’s official after-sales service or a qualified technician to inspect internal components using specialized diagnostic tools.
4. Verify System Configuration
   • Ensure the inverter’s output capacity matches the motor’s rated power to prevent phase sequence issues.
   • Check for excessive motor load and adjust operating parameters or reduce start/stop frequency as needed.
5. Assess Environmental Factors
   • Confirm that cables meet VFD standards, such as XLPE insulation, and are properly grounded in metal conduits.
   • Evaluate the operating environment for high temperatures, humidity, or corrosive gases that could degrade cable or motor insulation.

Troubleshooting Steps Table

Preventive Measures

To minimize the occurrence of ERR24 faults, implement the following preventive strategies:

1. Regular Maintenance
   • Conduct routine inspections of output cables and motor connections to detect and address wear or looseness.
   • Perform preventive motor maintenance, including insulation testing, to identify potential issues early.
2. Proper Equipment Selection
   • Select an inverter with a capacity that matches the motor’s rated power to avoid compatibility issues.
   • Install dV/dt or sine wave filters for long cable runs to protect against voltage spikes.
3. Environmental Protection
   • Shield cables and motors from high temperatures, humidity, or corrosive environments.
   • Use VFD-compliant cables, such as XLPE-insulated cables, and ensure proper grounding.
4. Operational Monitoring
   • Leverage the inverter’s monitoring features to regularly check output current and voltage balance.
   • Address any detected anomalies promptly by adjusting parameters or seeking technical support.

Case Studies

The following real-world examples illustrate how ERR24 faults were diagnosed and resolved:

1. Case Study: Cable Insulation Failure
   In a manufacturing facility, a CM530H inverter displayed ERR24, and the motor failed to start. Technicians discovered that the cables connecting the inverter to the motor had deteriorated insulation due to prolonged use, causing a short circuit in one phase. Replacing the cables with new, properly grounded ones resolved the ERR24 fault, and the system resumed normal operation.
2. Case Study: Inverter Component Failure
   Another user reported persistent ERR24 errors despite normal cable and motor checks. A professional technician used diagnostic tools to identify a damaged IGBT module in the inverter, caused by overloading. Replacing the module and optimizing the load configuration eliminated the fault.

Conclusion

The ERR24 fault code on SUNYE CM530 and CM530H inverters likely indicates an output side phase sequence error or phase loss, potentially caused by issues with cables, motor windings, internal inverter components, or improper system configuration. By systematically inspecting cables, motor connections, inverter internals, and system settings, users can effectively diagnose and resolve the issue. Preventive measures, including regular maintenance, proper equipment selection, environmental protection, and operational monitoring, are essential to reducing ERR24 occurrences. For complex issues, refer to the SUNYE user manual, particularly Chapter 7, “Fault Diagnosis and Countermeasures,” or contact SUNYE’s official after-sales service for professional assistance. Addressing ERR24 promptly ensures equipment reliability and enhances industrial production efficiency.

Introduction

In the field of industrial automation, Variable Frequency Drives (VFDs) are essential for controlling motor speed and torque. The Shihlin SS2 series inverter is widely recognized for its efficiency and reliability across various industrial applications. However, like any electronic device, it may encounter faults, one of which is the “ou0” fault—a common issue that can lead to downtime and affect productivity. This article provides an in-depth analysis of the “ou0” fault, its causes, and detailed solutions to help users restore normal operation swiftly.

What Is the “ou0” Fault?

The “ou0” fault code typically indicates that the inverter has detected an excessively high DC bus voltage, a condition known as overvoltage. The DC bus is a critical component in the inverter that converts AC input into DC before inversion. When the DC bus voltage exceeds the safety threshold, the inverter triggers a protective mechanism, displaying “ou0” and halting operation to prevent damage to internal components like the IGBT module. On the Shihlin SS2 inverter’s control panel, “ou0” is usually shown in red, accompanied by an abnormal status of the operation indicator light.

Common Causes of the “ou0” Fault

Overvoltage faults can stem from multiple factors, with the following being the most prevalent:

1. High Input Voltage
   If the AC input voltage exceeds the inverter’s rated range (typically 380V ±15%), the DC bus voltage rises accordingly. Grid fluctuations, poor power quality, or external disturbances like lightning strikes can contribute to this issue.
2. Regenerative Energy Feedback
   During motor deceleration, especially with high-inertia loads (e.g., CNC machines or heavy machinery), the motor can act as a generator, feeding energy back to the inverter. If the deceleration time is too short or there is no mechanism to dissipate this energy, the DC bus voltage spikes.
3. Component Aging or Failure
   DC bus capacitors play a vital role in absorbing and stabilizing voltage. Aging or damaged capacitors may fail to perform, leading to voltage fluctuations. Additionally, faults in the rectifier or inverter modules can also cause overvoltage.
4. Improper Parameter Settings
   A deceleration time set too short is a frequent misconfiguration, causing regenerative energy to accumulate rapidly. Other parameters, such as voltage regulation settings, may also impact voltage stability.
5. External Factors
   • Excessively long cables or degraded insulation can introduce voltage interference or leakage.
   • Environmental conditions like high temperatures or dust accumulation may affect the inverter’s cooling and performance.

Diagnosing the “ou0” Fault

To accurately identify the cause of the “ou0” fault, a systematic diagnostic approach is recommended:

1. Check Input Voltage
   Use a multimeter to measure the three-phase input voltage of the inverter, ensuring it falls within the Shihlin SS2 series’ rated range (typically 380V ±15%). If the voltage is too high or fluctuates significantly, investigate grid stability or external interference.
2. Review Deceleration Time Settings
   Access the inverter’s parameter settings through the control panel and check the deceleration time parameter (possibly P.02, as per the manual). If the deceleration time is too short (e.g., 2 seconds), consider extending it to 5 seconds or more to reduce regenerative energy buildup.
3. Inspect DC Bus Capacitors
   If possible, use a capacitance tester to measure the DC bus capacitors’ capacitance and equivalent series resistance (ESR). Aging capacitors may show reduced capacitance or physical damage (e.g., bulging or leakage). Replace them if necessary.
4. Evaluate Load Characteristics
   Determine if the load is high-inertia (e.g., heavy machinery or fans). High-inertia loads generate significant regenerative energy during deceleration, potentially requiring additional braking equipment.
5. Inspect Cables and Grounding
   Ensure the output cable length does not exceed the recommended limit (typically 50 meters) and check the cable insulation for integrity. Verify that the inverter is properly grounded to avoid electrical noise or static interference.
6. Use Diagnostic Tools
   If the inverter supports communication features, connect diagnostic software to view detailed fault logs. Record the operating condition during the fault (e.g., acceleration, deceleration, or constant speed) for further analysis.

Solutions

Based on the diagnosis, the following measures can resolve the “ou0” fault:

1. Adjust Deceleration Time
   Extending the deceleration time is a simple and effective way to address regenerative energy issues. Access the parameter settings via the control panel and adjust the deceleration time (e.g., P.02) from a short duration (like 2 seconds) to 5 seconds or longer, depending on the load characteristics.
2. Install a Braking System
   For high-inertia loads, installing a braking resistor and braking unit is highly recommended. The braking resistor dissipates excess regenerative energy as heat, preventing the DC bus voltage from rising beyond the protection threshold. Ensure the resistor matches the inverter model, as specified in the Shihlin SS2 manual.
3. Stabilize Input Voltage
   If the grid voltage is unstable, consider installing a voltage regulator or reactive power compensation device. A line reactor can also help filter high-order harmonics, improving power quality.
4. Replace Faulty Components
   If the capacitors or other internal components are damaged, they should be replaced by a qualified technician. Ensure the power is disconnected and safety protocols are followed during replacement.
5. Optimize Environmental Conditions
   Ensure the inverter is installed in a well-ventilated, temperature-controlled environment. Regularly clean the heat sink and fan to prevent dust buildup that could impair cooling.
6. Reset Parameters
   If parameter settings may be incorrect, reset the inverter to factory defaults (often by holding the “STOP/RESET” key while powering on, as per the manual). Reconfigure the necessary parameters afterward.

Preventive Measures

To prevent the recurrence of the “ou0” fault, consider the following:

• Regular Maintenance: Inspect the inverter’s capacitors, connectors, and cooling system every 6-12 months to ensure optimal condition.
• Monitor Power Quality: Use a power quality analyzer to periodically check the input voltage stability and address potential issues early.
• Optimize Parameter Settings: Adjust acceleration and deceleration times to match the load characteristics, ensuring compatibility with the application.
• Install Protective Equipment: In lightning-prone areas, install surge protection devices to safeguard the inverter from transient overvoltage.

Case Study

In a manufacturing plant, a Shihlin SS2 inverter controlling a CNC machine frequently reported the “ou0” fault during rapid deceleration. Technicians first measured the input voltage, confirming it was within 380V ±10%, ruling out power supply issues. They then reviewed the parameters and found the deceleration time set to 2 seconds, which was too short. After extending it to 5 seconds, the fault ceased. To further enhance reliability, the plant installed a braking resistor, effectively managing the regenerative energy from the high-inertia load. This case highlights the importance of proper parameter adjustments and hardware upgrades in resolving the “ou0” fault.

Conclusion

The “ou0” fault in the Shihlin SS2 inverter is typically an overvoltage issue caused by factors like input voltage anomalies, regenerative energy buildup, or component failure. Through systematic diagnosis (e.g., checking voltage, adjusting parameters, installing braking systems), users can effectively address the issue. Regular maintenance and optimized settings are key to preventing future faults. If the problem persists, professional technical support is advised to ensure safe and reliable operation.

Common Overvoltage Fault Codes and Solutions

Below is a summary of typical overvoltage faults in inverters for reference:

Note: The Shihlin SS2 may use “ou0” to denote overvoltage, which should be confirmed with the specific manual.

In the field of industrial automation control, inverters, as the core equipment for motor speed regulation, are widely used in various scenarios requiring graded speed regulation, such as fans, pumps, and conveyor belts. This article will take the ZK880-N positive control inverter as an example, combined with official technical documentation and practical application scenarios, to elaborate in detail on how to achieve three-stage speed control through DI digital input terminals, providing systematic guidance from hardware wiring to parameter settings.

I. Technical Principles of Three-Stage Speed Control

The essence of three-stage speed control is to preset the motor operating frequency into three different levels through the multi-stage speed instruction function of the inverter. Users can select the corresponding frequency band through external switch signals to realize the graded regulation of motor speed. The ZK880-N inverter uses digital input terminals (DI) as the trigger signal source, combined with function code parameter settings, to build a flexible and reliable multi-stage speed control system.

II. Hardware Wiring Implementation Steps

1. Terminal Function Definition

According to control requirements, the DI1-DI3 digital input terminals need to be configured as multi-stage speed control ports. Refer to the inverter terminal distribution diagram, with standard wiring terminals located in the control circuit interface area.

2. Wiring Specifications

• Power Connection: Ensure that the main circuit power supply (R/S/T) and control circuit power supply (usually +24V) of the inverter are correctly connected.
• DI Terminal Wiring:
  • DI1: As the first-stage speed trigger terminal, it is recommended to connect a normally open contact switch.
  • DI2: As the second-stage speed trigger terminal.
  • DI3: As the third-stage speed trigger terminal.
  • Common Terminal (COM): The signal common terminal for all DI terminals, which should be connected to the other end of the switch.

3. Wiring Precautions

• The switch signal voltage range must comply with the DI terminal input specifications (5-30V DC).
• It is recommended to use shielded twisted pair cables for signal transmission to avoid electromagnetic interference.
• After wiring, use a multimeter to detect the insulation resistance between terminals to ensure there is no short circuit.

III. Detailed Explanation of Core Parameter Settings

The following function codes need to be configured through the operation panel or dedicated software:

1. DI Terminal Function Mapping

2. Multi-Stage Speed Frequency Settings

3. Operating Parameter Configuration

IV. Realization of Three-Stage Speed Control Logic

1. Single Terminal Single-Stage Speed Mode

• Only DI1 is closed: The motor operates at the frequency set by FC-00 (20Hz).
• Only DI2 is closed: The motor operates at the frequency set by FC-01 (35Hz).
• Only DI3 is closed: The motor operates at the frequency set by FC-02 (50Hz).

2. Combined Control Mode (Advanced Application)

Through function codes FC-03 to FC-07, combined stage speeds can be set:

• DI1+DI2 closed: Execute the frequency set by FC-03 (reserved for extended stage speed).
• DI2+DI3 closed: Execute the frequency set by FC-04 (reserved for extended stage speed).
• Special application scenarios: Realize automatic stage speed switching logic through PLC programming.

V. Commissioning and Verification Process

1. No-Load Test Stage

1. Disconnect the motor load and only retain the inverter and dummy load.
2. Close the DI1-DI3 switches in turn to observe whether the output frequency is consistent with the set value.
3. Use an oscilloscope to detect the output voltage waveform and confirm there is no distortion.

2. Load Commissioning Stage

1. Gradually load to the rated load.
2. Test the current impact during stage speed switching (should be less than 1.5 times the rated current).
3. Verify whether the acceleration/deceleration time meets the process requirements.

3. Abnormal Handling Test

1. Simulate DI terminal signal adhesion fault.
2. Verify the effectiveness of the FC-17 fault reset function.
3. Test the reliability of overload protection (OL) action.

VI. Typical Application Cases

In a certain water plant’s constant pressure water supply system, the three-stage speed control of the ZK880-N inverter is adopted:

• First-stage speed (25Hz): Maintain the basic pressure of the pipe network during night low-peak periods.
• Second-stage speed (40Hz): Meet normal water demand during daytime water supply.
• Third-stage speed (50Hz): Quickly supplement the pipe network pressure during peak water consumption periods.

Through the automatic switching of stage speeds by pressure sensor signals, an energy-saving rate of 32% is achieved, and the pressure fluctuation range is controlled within ±0.02MPa.

VII. Maintenance and Optimization Suggestions

1. Regularly check the reliability of DI terminal wiring, and recommend tightening every six months.
2. Recheck the FC-00 to FC-02 parameter settings every quarter according to load characteristics.
3. Upgrade to the latest firmware version (currently V2.13) to obtain an optimized stage speed switching algorithm.
4. For impact loads, it is recommended to add an input reactor to improve power quality.

By following the above systematic implementation steps, users can efficiently achieve the three-stage speed control function of the ZK880-N inverter. In practical applications, it is necessary to combine specific process requirements and optimize parameters to achieve the best control effect. With the development of Industry 4.0, this inverter supports the Modbus-RTU communication protocol and can be integrated with the host computer system to achieve more intelligent stage speed scheduling management.