Clamp meters This topic contains 3 replies, has 2 voices, and was last updated by John C 7 months, 1 week ago. Author Posts February 16, 2017 at 2:52 pm #8464 Doug FitzgeraldParticipant Hi I have a clamp meter I use to measure motor amps and it is pretty good at that. Why doesn’t it measure the output frequency correctly? Just gives me random readings. February 16, 2017 at 2:55 pm #8465 John CGalco Representative Hello Doug, thanks for asking Galco today. Let me guess, the motor you are trying to measure is on a VFD? February 16, 2017 at 2:57 pm #8466 Doug FitzgeraldParticipant Yes it is. The only time it seems to work at all is when the drive is at full speed, but then I know what the output frequency is. So why can’t I see lower frequencies? February 16, 2017 at 3:01 pm #8467 John CGalco Representative I know what you mean Doug, I’ve had this problem myself. Usually it is because the motor is lightly loaded or is just a small HP and the meter can’t tell the difference between the Carrier frequency and the motor operating frequency. Author Posts You must be logged in to reply to this topic.