I have a general question on the theory of a vfd.
I understand that when set to V/hz, the drive will bring the volts and hz up together when speeding up.
My question is, when running a motor over 60hz, when does the output voltage equal base voltage or max output voltage?
For example, if I had a vfd on a 480V line and had it set to a max hz of 75hz. Would the output voltage be at 480V at 60hz, then just increase the hz up to 75 or would the drive scale the whole curve so that it would not hit 480V until it was at 75hz?
The reason I prompted this question. I had a customer today that told me that he had a vfd that has 495V incoming. He claimed that he was getting 795,800 output voltage. First, I do not think that is electrically possible (please correct me if I am wrong). Second, I don't know if he had an RMS meter or not.
He said they were running this motor at 120hz.
So I am trying to understand this and I want to make sure I am right. That even over 60hz even on a standard v/hz pattern, there is no way he could have had more than 495V out??
The motor failed after only a few months which is why he called us and trying to figure it out.
I understand that when set to V/hz, the drive will bring the volts and hz up together when speeding up.
My question is, when running a motor over 60hz, when does the output voltage equal base voltage or max output voltage?
For example, if I had a vfd on a 480V line and had it set to a max hz of 75hz. Would the output voltage be at 480V at 60hz, then just increase the hz up to 75 or would the drive scale the whole curve so that it would not hit 480V until it was at 75hz?
The reason I prompted this question. I had a customer today that told me that he had a vfd that has 495V incoming. He claimed that he was getting 795,800 output voltage. First, I do not think that is electrically possible (please correct me if I am wrong). Second, I don't know if he had an RMS meter or not.
He said they were running this motor at 120hz.
So I am trying to understand this and I want to make sure I am right. That even over 60hz even on a standard v/hz pattern, there is no way he could have had more than 495V out??
The motor failed after only a few months which is why he called us and trying to figure it out.