Regarding the issue of inverter tripping
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An incident occurred in our company involving a frequency converter tripping. The inverters that tripped were all over 110KW, with the faults indicated as overvoltage during acceleration and overcurrent during acceleration. But no actions were taken at that time, and the system voltage was relatively stable. I would like to ask the masters at Haichuan, what is the reason? I would appreciate your advice.
Please tell me the brand of the frequency converter. Possible causes include issues with the acceleration/deceleration time settings, changes in load, or problems with the coupling. If it operates normally when started up next time, it’s necessary to check whether the parameters are appropriate.
The frequency converter is from Emerson. The parameters are set correctly.
What is the speed control method of inverters? It is preliminarily judged to be caused by surge interference in the power grid.
The frequency-defined channel is: CCI analog defined； The command execution channel is: terminal command execution channel ； The start-up operation mode is: speed-tracking start-up ； The acceleration and deceleration pattern is: S-curve acceleration and deceleration ； Operation mode: three-wire operation ； The analog output range is: 4--20mA.
When a frequency converter trips due to protection during operation, its terminal voltage rises instantaneously, resulting in a surge voltage.
How can one determine if it’s a surge? At that time, according to the historical curves, there was no overvoltage phenomenon nor any changes in load; everything was quite normal. It’s really frustrating when 5 inverters trip at the same time. A web expert, please help solve this.
The duration of surge voltage is very short, and historical curves are generally not recorded due to limitations related to the time over which they are measured. Power systems use specialized recorders for logging. However, this situation can occur with frequency converters, especially high-power ones, if no input reactor is installed, and if the power distribution system does not have appropriate surge protectors in place; this is particularly true in areas prone to thunderstorms. It is recommended to install a incoming line reactor, as well as 2–3 levels of surge protectors in the low-voltage distribution network. If the poster is located in an area with frequent lightning strikes, the above measures can also protect the frequency converter from being damaged by lightning.
It is caused by surge voltage; transmission paths: 1. External transmission lines of the building. (Including power supply cables, communication cables, network cables, antenna feed cables that come from outside the city, or the metal coatings of such cables, as well as metal items such as water pipes and gas pipes.) 2. Ground wire counterattack. 3. Line surges. 4. Static electricity and electromagnetic induction.
A reactor should be installed; it doesn’t cost much, so there’s no need to skimp on it
All the input and output reactors are installed, as well as the DC reactor. Is it necessary to install surge protection devices? May I ask everyone, what is the general price of surge protectors? Also, how is the surge protection device installed, and where should it be installed? Thank you all for your active contributions.
Why isn’t anyone participating? I hope all the experts can give me some guidance! Moderator, could you mark this as pinned? Thank you!
Your question is too profound. I don’t have much on-site experience. No comment. Surge protectors are generally installed in the incoming circuit; a simple parallel connection is sufficient. Its function is to exhibit high resistance under normal conditions, and to conduct current when there are high voltages (surges), thereby protecting the normal electrical circuits. It’s likely to be quite expensive; however, in my many years of experience in design, I’ve hardly ever used it. During training, I heard that the technology and quality of such devices aren’t yet perfect :( I’m referring to international brands here. Domestic ones, as usual, not to mention! ) This post was last edited by ZJYSSF on 2009-3-21 19:26 ]
I agree with the view from Floor 8: historical curves are limited by the sampling time, and thus cannot fully capture voltage fluctuations over short periods. Surges are typically measured in milliseconds, which is usually much shorter than the sampling time period.
Based on everyone’s analysis, it seems that the main cause is surges. What is the price of surge protection devices? How are they installed, and where should they be installed? I haven’t worked with surge protection devices before; I hope those who know about them can explain as in detail as possible. Thank you!
It is said that Mitsubishi frequency converters are good, especially in harsh pumping environments; however, if the parameter settings are too restrictive, this phenomenon can still occur. Do we still use electric or diesel generators?
If all five fail at the same time, it must be a problem with the power grid.
After reading the responses from everyone above, I feel like I need to say something: 1. If 5 frequency converters fail simultaneously, it can be determined that it is a problem with the power grid. 2. Does this phenomenon occur frequently? If it does, it requires close attention. 3. The key is to see if there are any changes in other loads on the same network segment as the transformer in question Has an impact load been added? 4. If impact loads are added, considering adding an FC compensation or RC absorption circuit is advisable.
Please, the original poster, explain what type of load the frequency converter is connected to. In the case of a load with high inertia, the startup mode of the inverter in question is \"speed-tracking start\", which constitutes a runaway start. During this process, since the motor is in a power-generation mode, the voltage on the inverter’s DC bus rises suddenly, triggering the inverter’s overvoltage protection mechanism. Additionally, the simultaneous tripping of the five frequency converters mentioned by the poster is likely due to a power grid issue. It’s not clear whether the inverter owned by the poster has had its low-voltage protection setting disabled; if so, when the grid voltage drops suddenly, the inverter tends to trigger an overcurrent protection response.
Note: Our company has more than 30 other frequency converters that are on the same network as those 5 frequency converters mentioned above, and none of them tripped. It was only these 5 that tripped at the same time. The key parameters set for them have been provided. Additionally, there were no significant fluctuations in the power grid before or after the tripping, nor were any impact-loaded devices activated.