Question: Can the input current of the inverter be used to calculate the load?
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One of my colleagues said that it’s not possible to calculate the load using the current at the input side of the inverter. He said that an inverter is essentially a power supply. However, in my understanding, anything that is not a source of power generation constitutes a load. I’m not sure why this is the case; I would appreciate some guidance! Thank you!
I think it’s fine; feel free to upvote the post.
You are right when it comes to the electrical load. It is calculated using the input current and input voltage of the frequency converter. A frequency converter is equivalent to a controller that can adjust the output voltage and frequency.
The inverter itself consumes electrical power; if the load is calculated based on the current at the inverter’s input terminal, the resulting value for the load will be incorrect. The power consumed by the inverter itself must be taken into account.
This post was last edited by lushengbin on 2012-2-21 23:10. I’m sorry; I was wrong. What my colleague meant was that \"the load power cannot be calculated using the input current of the inverter.\" That’s what happened at the time: the production department suspected that the impeller had fallen to the bottom of the tank (we used instantaneous power to monitor the condition of the impeller). After checking, it was found that the impeller was fine; the suspicion then shifted to the power transmitter. However, by using a clamp meter to measure the current in the wiring connected to the transmitter (which has a range of 4–20 mA, 0–150 A and is installed at the wiring inlet), the measurements turned out to be correct. Could it be that there was an error in the calculation formula in the PLC? It is shown as P=1.732UIcosΦ, but the calculated power is very low (less than 1 kW); in my opinion, it shouldn’t be that low (the motor’s rated power is 37 kW). Given such a large load from the impeller, I ended up using the current coming out of the inverter (the motor current) for the calculations. What’s the explanation for this? Everyone, please help out. Thank you all! ! :(