VFD Voltage Output Measurement. AC Drive Filtered vs Unfiltered vs Wrong
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- Опубликовано: 13 сен 2024
- The measurement you get on the output of an AC drive will vary depending on the meter you have.
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I made a mistake in this video. I didn't press the low pass filter (yellow button). I realized it later but didn't insert the fixed clip.
ruclips.net/video/qdVcGO8QFIo/видео.html
Of course Tim please. I think anything you are willing to show us would either be a great video for beginners in the field and a great refresher to any of the experienced technicians. Loved the video and owned both of the Fluke meters mentioned here and they are always nice and dependable.
You got it!
How to tell if a motor is burned up? Yes please!
OK, let me see if I can get some equipment.
Smells like burning, then it’s burnt up.
@LordNiakon Unfortunately not always.
Thanks for the great noldge their is a life being saved with information.always use good tools
@@darthenx2585What if it smells and tastes like burning?
I have always liked those t6 meters for a tool pouch meter or technicians meter. The only drawBack is the proprietary leads they use. Thanks for the vid
I picked one up. I like it a lot.
T6-1000 is my go to everyday carry meter
Mine too now. I did this video on it.
ruclips.net/video/pZFvdSQuEF8/видео.html
Have a look at the fluke 325, its nice because the clamp meter uses standard multimeter test leads.
Need to enable the low pass filter with the yellow button.
👍
HF noise from the drive making meters read off; a decent dual-display will show voltage and frequency. My FLIR CM275 shows something like 1.5kHz with the motor voltage, once you put it in VFD mode you get a true reading.
Nice!
Thanks for this. So at 30hz should I read 1/2 the voltage ? I guess meters have came a long way, I thought you needed a meter with a pwm function to read the output.
That is correct. All decent meters can make a general representation of the voltage but one item accidentally got clipped out of this video was the low pass filter. With it, you get the most accurate reading. See link below.
ruclips.net/video/qdVcGO8QFIo/видео.html
I would love to see a motor troubleshooting video!!!
OK, let me see if I can get some equipment.
The LoZ filter. Love my 289!
I learned a lot about while playing with these
Great meter! But the LoZ (impedance) and low-pass filter (frequency) are two different things. And yeah, the 289 does have both.
Video with low pass clarification.
ruclips.net/video/qdVcGO8QFIo/видео.html
Does the T1000 have a decimal on DCV? The T600 does not and for that I cannot recommend that meter for low voltages.
No, and before this series, I would agree with you but the T6-1000 has too much else going for it with the auto voltage sensing to knock it for that. The key is to think of it as a general purpose voltage meter, not a meter for process measurements such as analog. In that case, if I check for 24V, I don't really care if it is 22 or 26 V. I think too many of us think that we should have one meter to cover all of our needs. Here is a video I did on my thoughts on the T6-1000.
ruclips.net/video/pZFvdSQuEF8/видео.html
@@TimWilborne fair points, besides, who doesn't want another meter anyway!?
😁
Of course make a motor video.... and where is he link to the Fluke article?
OK, let me see if I can get some equipment. Here is the article on the Fluke CAT ratings.
www.fluke.com/en-us/learn/blog/safety/multimeter-guide#multimeter-cat-ratings
@@TimWilborne Sure you enabled the low-pass filter on the 87V? Didn't look like it on the display, voltage should have been closer to what the VFD display indicated, according to Fluke's document on it.
No and I didn't catch it till later and didn't proof the video good enough. Maybe a part 2 :)
@@TimWilborne Yeah, a part two would be cool. See how much difference the low-pass actually makes.
I'll see what I can do.
Hooray EECO!!
Yes, I couldn't have make this video without their help.
I don’t think that Brand X meter is Cat IV rated. VFD uses a PWM output which is a square wave and not a sine wave. The T6-1000 processes the information and calculates what that voltage would be if it was a sine wave. The 87B is actually reading the VFD output correctly. That’s why I tell people to NEVER use their meter on VFD outputs unless it is 1000V rated. I have PD pumps that when they shutoff they have a braking resistor to absorb the generation load from cycling off. I was blowing up 755 VFDs from PD liquid pumps when the pumps would shutoff and the load would push through the pump and keep the pump spinning at a substantial amount of generation. We would see 700V bus spikes on the VFD.
The DC bus is something I had not thought about before this series. Here is a video I did on it and the CAT rating of the Brand X meter.
ruclips.net/video/7pmS_we4uDI/видео.html
@@TimWilborne I just watched it. I will say if you don’t see the rating being showcased like the manufacturer is proud of it then it isn’t worth risking it. If something is rated it cost that manufacturer money to get that rating and showcasing that added security is going to be their primary focus for consumers investing in their equipment. The only time I suggest checking voltage on a secondary of a VFD is if you suspect a phase loss and the VFD isn’t smart enough to communicate that error. I have seen VFDs, a 753 with a 20-Comm-E card, display the drive was accelerating while it was actually dropping motor rpm. The frequency output was the same but it lost leg V/T2. The VFD comm output said everything was fine, the vfd 20-him-a6 was also giving me the same information. The rpm of the motor was dropping, the frequency was rising to the frequency limit, the amps were rising. I watched the VFD and speculated the problem while it slowed down. I calculated the output speed of the motor with a phase loss, roughly 60% of what it should be with all 3 working phases, reported my findings because a 20G11ND096 isn’t cheap. Drove 8 hours to the facility with the new drive. Replaced the 20-Comm-E with a 750-ENETR. Logged diagnostic codes and got a phase loss diagnostic code. Reported those back to management and got the OK to swap out the 20F11ND096 and install an additional 20-750-1132C-2R module for analog support. FYI a 20F with a 750-ENETR card does not assemble in Rockwell with the Ethernet module well at all. It’s a known anomaly where the drive won’t let you select you port. You have to back cycle the version to add it to the assembly with the port you want then update to the version you need.
Looks like there is enough demand that I'll probably do some more motor checking videos...once I get some test equipment. My machine trainer can simulate several different bad motor scenarios but I only use them to show how the Powerflex 525 reacts..
Isn't the brand x just reading the DC bus voltage?
No, the drive is 120VAC powered, rectifying it would be 120 x 1.414 = 170 VDC
@@TimWilborne Ah my bad. Too used to working with the 480 stuff. Got a video in the works on why the brand x meter reads that?
More importantly, here is a video on if you should use a brand X meter or not.
ruclips.net/video/vbV9cujm3Ec/видео.html
@@TimWilborne I was already convinced not to use Brand X. Fluke still cream of the crop.
However, this teardown comparison video is interesting. Seems like there are good alternatives out there. ruclips.net/video/3Hlmq57FQQk/видео.html
I am still curious about what is actually going on as to why brand x is reading what it is though.
I'm sure it has to do with the PWM that simulates the AC SINE waveform. There is no good explanation for it.
Yes motor burnt up would be good.
OK, let me see if I can get some equipment.
I do want to see
👍
I must say, I'm extremely disappointed that the video cuts off when it does. It seems entirely pointless to put out a video like this and not even really begin to address WHY they are different. Perhaps some very brief off-hand references are given. But, I'd wager most people watching this video could not point to the actual causes because they aren't clearly mentioned. It's pretty likely that the crappy meter is merely seeing the peaks from PWM but it would have been pretty nice to explain that and also explain why two fluke meters could have such different results. You mentioned a PDF that Fluke sent to you but it doesn't seem like you actually linked to that. I just wish you had taken a few minutes more to explain things rather than have 4 minutes of - this is what happens, guess why!
Understood, where is your video on it so I can learn how to do it better?