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Posted: **Thu Nov 10, 2022 12:52 pm**

Hello,

this might be a quick and easy one, but I played with the rev limiter and was surprised by the fmax limit and then measured rpm:

I expected (either/or):
Hz * 60 == maxrpm
Hz * 60 * 4 == maxrpm

I measured:
Hz * 14.6 == maxrpm.

Where is my thinking wrong?

Firmware is 5.18 on the inverter I tested.
Disclaimer: I haven't read the inverter firmware (yet).

Code: Select all

21 Hz == 300 rpm
30 Hz == 424 rpm
40 Hz == 583 rpm

67 Hz == 981 rpm

376 Hz presumed 5500
369 Hz presumed 5400

EDIT:
Oh god just typing it out made me realise:
60 / 4 == 15
~ 14.6.

Posted: **Thu Nov 10, 2022 1:00 pm**

The speed of the motor is Hz divided by poles. So in your case, RPM is Hz * 60 / 4. Assuming this is an induction motor with slip, the shaft will be slightly slower then the electrical signal, hence 14.6 rather than 15.

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surprising relation between fmax and speed rpm? ~14.6

surprising relation between fmax and speed rpm? ~14.6

Re: surprising relation between fmax and speed rpm? ~14.6 [SOLVED]