1. Overcurrent Trip and Cause Analysis The inverter's overcurrent trip can be categorized into three main types: short-circuit faults, trips during operation, and trips that occur when the speed is increasing or decreasing. 1.1 Short-Circuit Faults (1) Fault Characteristics - The first trip may happen during operation, but after resetting, it often trips again at a certain speed. - There is a large inrush current, but most inverters are designed to trip quickly before any damage occurs. Due to the fast response time, it can be difficult to measure the actual current value. (2) Diagnosis and Resolution The first step is to determine if the fault is due to a short circuit. To do this, connect a voltmeter to the input side before restarting. Slowly increase the potentiometer from zero and observe the voltmeter. If the output frequency rises immediately and the inverter trips, with the voltmeter pointer returning to zero instantly, this indicates a short circuit on the output side. Next, check whether the short circuit is internal or external. Disconnect the inverter’s output wiring and gradually increase the frequency. If the inverter still trips, it suggests an internal fault. If not, the issue lies in the wiring between the device and motor, or the motor itself. 1.2 Light Load Overcurrent This phenomenon is common in variable frequency drives. In V/F control mode, instability in the motor’s magnetic circuit can cause overcurrent trips, especially under low-frequency and light-load conditions. This is due to varying saturation levels of the motor’s magnetic circuit depending on the load. Solution: Adjust the U/f ratio appropriately to stabilize the magnetic circuit. 1.3 Heavy Load Overcurrent (1) Fault Phenomenon During operation, if the load suddenly increases or becomes stuck, the motor speed drops rapidly, causing a sharp rise in current. If the overload protection fails, this leads to an overcurrent trip. (2) Solutions - First, check if the machine has a fault and repair it if necessary. - If the overload is a normal part of the process, consider increasing the transmission ratio between the motor and the load. This reduces the resistance torque on the motor shaft and prevents stalling. If this isn’t possible, consider upgrading the motor and inverter capacity. 1.4 Overcurrent During Speed Changes This occurs when the acceleration or deceleration rate is too high. Solutions include: - Extending the acceleration/deceleration time if allowed by the production process. - Using the inverter’s built-in anti-stall function. When the current exceeds the set limit, the speed change is paused until the current decreases. 2. Inverter Overload Trip and Cause Analysis When the motor rotates but the running current exceeds its rated value, it’s considered an overload. Unlike overcurrent, the excess current is usually moderate and doesn’t result in a large surge. 2.1 Main Causes of Overload (1) Excessive mechanical load – the motor overheats, and this can be identified by checking the displayed current. (2) Unbalanced three-phase voltage – one phase may have a higher current, leading to an overload. This can be hard to detect as the display shows only one phase. (3) Internal fault in the inverter – faulty current detection can cause unnecessary tripping. 2.2 Inspection Methods - Check if the motor is hot. If it’s not, verify the inverter’s thermal protection settings and adjust them if needed. - If the motor is overheating, it may indicate a heavy load. Increase the gear ratio or upgrade the motor and inverter. - Check the balance of the three-phase voltage. If unbalanced, inspect the inverter output and connections for issues like loose terminals or faulty contacts. - If the voltage is balanced, check the operating frequency at the time of tripping. For low frequencies and non-vector control, reduce the U/f ratio. If the load remains stable, the original setting was too high. Otherwise, consider increasing the inverter capacity. If vector control is available, switch to that mode for better performance.
Yuhai company develop and produce of various rings sizes, bearing variety of electrode and metallisation configurations. This variety of Rings is fabricated from various material formulations for applications such as high power, sensitivity, stability.
Features
· • electrode type on request
· • Surface roughness on request, for specific demanding application
· • Thickness/Radial frequency tuning available on request
• Wide choice of PZT formulations
Applications include
• Sensors
• Welding
• Ultrasonic cleaning
• Precise Measurement
• Ultrasonic scalpel
• Cauterisation
• Phacoemulsification
• Therapeutic ultrasound
• Accelerometers
Dimension range
|
Outer diameter |
3-180mm |
|
Inner diameter |
1-150mm |
|
Thickness |
0.2-25mm |
Piezo Ring,Pzt Ring,Piezoelectric Ceramic Ring,Piezo Ceramic Ring
Zibo Yuhai Electronic Ceramic Co., Ltd. , https://www.yhpiezo.com