A Motor runs @ 2980rpm = 50Hz....

Now if I get a peak @ 100Hz, than is this the 2X or is it the 2Lf, as our plants Line Frequency is 50Hz.

Is it exactly running on 50hz? Be sure of that. If it is the 2LF you can test it by switching off the motor and look in "Monitor Mode" to the peak on 100hz. If it is directly gone after switching off, it is the 2LF. I think it is an indication of softfoot. This is what I have learned but wait for an answer from the experts here

Cormatech,

Cant switch off the motor as it is running a blower, which is cooling the turbine compartment.

Ambient temp is 47 deg C. So that is not helping either.

Motor speed 2980rpm = 49.66Hz
Supply frequency = 50hz

Difference = 0.34 Hz

Take another reading with higher resolution (more lines over a shorter frequency span) to be able to indentify the difference

Try 200Hz at 3200 or 6400 lines. Laws of physics apply here and data collection will require quite a long time.

Buzz is right
You simply need better resolution or zoom function to seperate the peaks to see which is dominant

I agree if it is EXACTLY 100.0 HZ then it is 2X line. I have it on just about all of my motors its just 120.0 here.On some I have 120.0 and a sideband of 119.5 well that is 2xline AND 2x speed.

Mike

I'm with you Buzz,
Resolution is the key here. One high resolution reading that requires additional time on site saves you a massive amount of time in the future.

Hooch

That's why I asked "Is it exactly running on 50hz?"