Category: Industrial control technology

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.

Introduction

Inverters are vital components in industrial automation, enabling precise control over motor speed and torque across various sectors, including manufacturing and energy. The Shihlin SS2 series inverter, manufactured by Shihlin Electric, is widely recognized for its reliability and performance. However, like any complex equipment, it may encounter faults during operation. One such issue is the E0 fault, which can be perplexing for users due to its specific triggering conditions. This article provides a comprehensive analysis of the E0 fault in the Shihlin SS2 inverter, detailing its meaning, causes, solutions, and preventive measures to assist users in restoring normal operation efficiently.

1. Meaning of the E0 Fault

According to the Shihlin SS2 Series Inverter Manual (version V1.07), the E0 fault is triggered under specific conditions related to the inverter’s parameter settings and operation mode. Specifically, when parameter P.75 (stop function setting) is set to 1, and the inverter is operating in a mode other than PU (panel operation mode) or H2 (high-frequency mode), pressing the stop button (labeled as “(20) key” in the manual) for 1.0 second causes the inverter to stop. The display shows “E0,” and all functions are disabled or reset. This behavior acts as a protective mechanism to prevent unintended operation or potential damage under these conditions.

Interestingly, the manual also lists E0 in the fault code table under “00(H00)” as “no fault” (无异常), which may indicate a different context, such as a default or reset state in fault logging. This dual reference suggests that E0’s meaning depends on the operational context, but the primary focus here is its association with the stop function and parameter P.75.

2. Causes of the E0 Fault

To effectively resolve the E0 fault, understanding its causes is essential. Based on the manual and related information, the following are the primary reasons for the E0 fault:

• Parameter P.75 Configuration: Parameter P.75 governs the inverter’s stop behavior. When set to 1, it enables a deceleration stop function. In non-PU or non-H2 modes, pressing the stop button for 1 second triggers the E0 fault, as the inverter interprets this as an invalid operation under the current settings.
• Operation Mode Restrictions: The E0 fault is specific to non-PU and non-H2 modes. PU mode allows direct control via the inverter’s control panel, while H2 mode may relate to specific high-frequency applications. Operating in external control mode (e.g., via external signals) with P.75 set to 1 increases the likelihood of triggering E0.
• External STE/STR Command Interference: External start/stop commands (STE/STR) can conflict with the inverter’s settings. The manual notes that when E0 occurs, these external commands are canceled, suggesting that signal interference may contribute to the fault.
• Operator Error: Inadvertently pressing the stop button for more than 1 second in an incompatible mode can trigger the E0 fault. This is particularly common during initial setup, debugging, or when operators are unfamiliar with the inverter’s operation.

It’s worth noting that earlier versions of the Shihlin SS2 manual (e.g., V1.01) describe E0 as a communication error related to parity check issues. This discrepancy indicates that fault code definitions may have evolved across manual versions, with V1.07 providing the most relevant information for modern SS2 inverters.

3. Solutions for the E0 Fault

Resolving the E0 fault involves a systematic approach to eliminate its triggers and restore normal operation. The following steps, derived from the manual (version V1.07), are recommended:

1. Cancel External STE/STR Commands:
   • Inspect the inverter for any external start/stop (STE/STR) signals that may be interfering with its operation.
   • Cancel these inputs to ensure no external commands conflict with the inverter’s settings. In program operation mode, manual signals typically do not require clearing, but verifying the absence of interference is critical.
2. Reset the Inverter:
   • Locate the stop button (labeled “(20) key”) on the control panel.
   • Press and hold it for at least 1.0 second to clear the E0 fault and reset the inverter to an operational state. This is a direct method recommended in the manual.
3. Check and Adjust Parameter P.75:
   • Access the inverter’s parameter setting menu to review the value of P.75.
   • If P.75 is set to 1 and this is not suitable for your application, change it to 0 (the factory default) or another appropriate value. Refer to section 5.33 of the manual for detailed guidance on adjusting P.75.
4. Verify Operation Mode:
   • Ensure the inverter is operating in the correct mode (PU or H2, if required for your application).
   • Switch to the appropriate mode to prevent the fault from recurring.
5. Perform a Parameter Reset:
   • If the above steps do not resolve the issue, use parameters P.996 or P.997 to reset the inverter. These parameters can clear fault records or restore factory settings, as outlined in sections 5.78 and 5.80 of the manual.
6. Seek Professional Assistance:
   • Persistent faults may indicate hardware issues (e.g., faulty motherboard or wiring errors) or complex configuration problems.
   • Contact Shihlin Electric’s technical support team via their official website or arrange for the inverter to be inspected by the manufacturer.

The following table summarizes the causes and solutions for the E0 fault:

4. Preventive Measures for E0 Fault

To minimize the occurrence of E0 faults and ensure reliable inverter operation, consider the following preventive measures:

• Proper Parameter Configuration:
  • During installation and commissioning, thoroughly review the Shihlin SS2 Series Inverter Manual (version V1.07) to ensure parameters like P.75 are correctly set for your application.
  • Avoid modifying parameters without understanding their functions to prevent unintended faults.
• Regular Maintenance:
  • Conduct periodic inspections of the inverter’s wiring, cooling system, and control panel to check for loose connections, dust buildup, or overheating.
  • Regular maintenance reduces the risk of faults caused by environmental or mechanical issues.
• Operator Training:
  • Train all personnel operating the SS2 inverter on its proper use and fault-handling procedures.
  • Ensure the manual is readily available for quick reference during operation or troubleshooting.
• Power Supply Stability:
  • Use voltage stabilizers or surge protectors to protect the inverter from power fluctuations, which can contribute to faults.
  • A stable power supply is essential for long-term reliability.
• Fault Monitoring and Logging:
  • Maintain a record of all fault occurrences, including their conditions and resolutions.
  • Regularly monitor the inverter’s performance to identify and address potential issues early.

5. Conclusion

The E0 fault in the Shihlin SS2 inverter, while initially confusing, can be effectively managed by understanding its association with parameter P.75 and specific operation modes. By following the outlined steps—canceling external STE/STR commands, resetting the inverter, adjusting P.75, and verifying the operation mode—users can typically resolve the fault quickly. Additionally, adopting preventive measures such as proper parameter setup, regular maintenance, operator training, power protection, and fault monitoring can significantly reduce the likelihood of E0 faults. For persistent issues, contacting Shihlin Electric’s technical support or arranging professional inspection is advisable. By implementing these strategies, users can ensure the stable and efficient operation of their SS2 inverters, maximizing performance in industrial applications.

Key Citations

1. System Overview

Constant pressure water supply technology is widely used in modern industrial and civil water systems for efficient and energy-saving operation. This project uses the Milan M5000 inverter as the control core, combined with the YTZ-150 potentiometric remote pressure gauge, to construct a closed-loop constant pressure control system. It enables automatic adjustment of a single water pump to ensure the outlet pressure remains stable within the set range.

The system features low cost, easy maintenance, and fast response, making it suitable for small water supply systems, factory cooling water circulation, boiler water replenishment, and more.

2. Main Hardware and Functional Modules

1. Inverter: Milan M5000 Series

• Built-in PID controller
• Supports multiple analog inputs (0-10V, 0-5V, 4-20mA)
• Provides +10V power output terminal for sensor power supply

2. Pressure Sensor: YTZ-150 Potentiometric Remote Pressure Gauge

• Resistive output with a range of approx. 3–400Ω
• Rated working voltage ≤6V, but 10VDC tested in practice with stable long-term operation
• Outputs a voltage signal (typically 0–5V) varying with pressure via a voltage divider principle

3. Control Objective

• Adjust pump speed using the inverter to maintain constant pipe pressure
• Increase frequency when pressure drops, and decrease when pressure exceeds the setpoint to save energy

3. Wiring and Jumper Settings

1. 3-Wire Sensor Wiring (Tested with 10V)

2. Analog Input Jumper JP8

• Default: 1–2 connected, indicating 0–10V input
• Keep the default setting in this project (no need to switch to 2–3)

4. PID Parameter Settings (Based on Field Use)

5. Sleep Function Configuration

To enable energy saving when there is no pressure demand, the inverter can be configured to sleep:

6. PID Tuning Guidelines

1. After starting the system, observe pressure fluctuations:
   • If large oscillations, reduce P7.11 (proportional gain)
   • If sluggish response, reduce P7.12 (integral time)
2. Aim to maintain output pressure within ±2% of the P7.05 set value
3. Ensure return pipes have damping to prevent sudden pressure spikes

7. Key Considerations

1. Keep JP8 jumper at default 1–2 for 0–10V input
2. YTZ-150 sensor has been tested with 10V power supply and works stably
3. Ensure proper grounding (PE terminal) to avoid PID interference from common-mode noise
4. If feedback signal is noisy, add a filter capacitor (0.1–0.47μF) between VC1 and GND

8. Conclusion

With this design, the Milan M5000 inverter combined with the YTZ-150 pressure sensor delivers a cost-effective and reliable constant pressure control solution for water systems. The inverter’s built-in PID control simplifies implementation compared to external PLCs and offers strong performance with minimal tuning. As long as power supply, signal matching, and grounding are properly managed, the system achieves excellent closed-loop control stability.

Introduction

The Delixi EM60 series inverter is a robust variable frequency drive (VFD) designed to regulate the speed and torque of AC motors in industrial applications. Engineered for reliability, it features advanced protective mechanisms to safeguard both the inverter and the connected motor. One such protection is the “quick current limit,” which prevents damage from sudden overcurrent conditions. However, when this limit is exceeded for too long, the inverter triggers the ERR34 fault code, known as “quick current limit timeout” (快速限流超时). This article explores the meaning of the ERR34 fault, its potential causes, and provides a detailed guide on how to troubleshoot and repair this issue, drawing on the Delixi EM60 series user manual and practical VFD maintenance principles.

What Does ERR34 Mean?

The ERR34 fault code indicates that the inverter’s output current has surpassed the quick current limit threshold for a duration exceeding the specified timeout period. In the Delixi EM60 series, this protective feature is part of the motor control strategy, managed through parameters in the P1 group (pages 31-73 of the user manual). The quick current limit activates during transient overcurrent events—such as sudden load spikes or short circuits—by reducing the output frequency or voltage to stabilize the current. If the current remains high beyond the timeout threshold (typically a few seconds), the inverter halts operation and displays ERR34 to prevent damage.

This fault serves as a critical alert, signaling that the system could not resolve an overcurrent condition within the allotted time. Understanding its implications is key to diagnosing whether the issue lies in the motor, wiring, parameters, or the inverter itself.

Potential Causes of ERR34

Several factors can trigger the ERR34 fault. Based on the manual’s fault diagnosis section (pages 191-199) and general VFD operation, the following are the most likely culprits:

1. Motor Overload
   Excessive mechanical load, such as a jammed rotor or heavy machinery, forces the motor to draw more current than the inverter can safely handle, activating the current limit.
2. Incorrect Parameter Settings
   Misconfigured settings in the P1 group (motor control parameters, pages 31-73) or P3 group (programmable functions, pages 47-117), such as a low current limit or short timeout period, can cause the fault to trigger prematurely.
3. Power Supply Instability
   Voltage fluctuations, harmonics, or transients in the input power can disrupt the inverter’s ability to regulate current, as emphasized in the safety guidelines (pages 6-7).
4. Wiring Issues
   Loose connections, damaged cables, or short circuits between the inverter and motor can lead to abnormal current spikes. The manual’s installation section (page 213) highlights the importance of secure wiring.
5. Motor or Inverter Faults
   Internal motor issues (e.g., shorted windings) or inverter hardware failures (e.g., damaged IGBT modules or current sensors) can sustain overcurrent conditions.
6. Environmental Factors
   Dust accumulation or poor ventilation, as observed in the image of an EM60G0R7S2 inverter, can overheat the unit, exacerbating current-related problems.

Troubleshooting the ERR34 Fault

Diagnosing the ERR34 fault requires a systematic approach. The following steps, inspired by the manual’s troubleshooting sections (pages 56-128) and practical experience, will help identify the root cause:

1. Ensure Safety
   Disconnect the power supply and verify with a multimeter that the system is de-energized, adhering to the caution label warning against live servicing.
2. Check Motor Load
   Inspect the motor and driven equipment for mechanical issues like binding or overloading. Measure the current draw with a clamp meter and compare it to the motor’s rated capacity.
3. Review Parameter Settings
   Use the inverter’s keypad (featuring “MODE,” “ENTER,” and arrow buttons) to access the P1 group. Verify the current limit (e.g., P1-03) and acceleration/deceleration times (P1-09, P1-10, page 159). Adjust if they are too restrictive for the application.
4. Inspect Wiring
   Examine all connections between the inverter and motor for looseness, fraying, or burn marks. Test for continuity and insulation resistance to rule out shorts.
5. Assess Power Supply
   Measure the input voltage to ensure it’s within the specified range (e.g., 380V ± 15% for three-phase models). Use a power quality analyzer to detect noise or surges.
6. Monitor Environmental Conditions
   Check the inverter’s surroundings for dust or high temperatures (recommended range: 0-40°C). Clean the unit and ensure proper ventilation.
7. Reset and Test
   After addressing potential issues, reset the fault via the “STOP” button or power cycle (page 128). Run the system at a low speed to observe if ERR34 reoccurs.

Solutions and Repairs

Once the cause is pinpointed, apply these solutions:

1. Reduce Overload
   Lighten the mechanical load or upgrade to a higher-capacity motor and inverter if the demand exceeds specifications.
2. Adjust Parameters
   Increase the current limit or extend the timeout period in the P1 group to accommodate normal operation. For example, lengthening acceleration time (P1-09) can reduce startup current spikes.
3. Stabilize Power
   Install a voltage stabilizer or harmonic filter to ensure consistent input power.
4. Repair Wiring
   Tighten connections or replace faulty cables, ensuring compliance with the manual’s wiring guidelines (page 213).
5. Fix Hardware
   • Motor: Test windings with an insulation tester; repair or replace if defective.
   • Inverter: If internal components are suspected (e.g., IGBTs), consult Delixi support for repair, as detailed diagnostics may require proprietary tools (P8 group, page 66).
6. Improve Environment
   Relocate the inverter to a cleaner, cooler area or add cooling fans to mitigate thermal stress.

Preventive Measures

To avoid future ERR34 faults:

• Conduct regular maintenance on the motor and machinery to prevent overloads.
• Periodically review P1 and P3 group settings, adjusting for changes in load or application (pages 31-117).
• Install surge protectors to safeguard against power issues.
• Clean the inverter routinely to remove dust, as recommended in the safety sections (pages 6-7).
• Train staff on parameter configuration and fault handling, leveraging the manual’s application cases (pages 180-183).

Conclusion

The ERR34 fault code in the Delixi EM60 series inverter is a vital safeguard against prolonged overcurrent conditions. Whether caused by overload, parameter errors, wiring faults, or environmental factors, this issue can be resolved through careful troubleshooting and targeted repairs. By following the steps outlined and adhering to the user manual’s guidance, users can restore functionality and enhance system reliability. For complex hardware failures, professional assistance from Delixi or a certified technician ensures long-term performance and safety.