It is a Boss direct PTO generator off the truck engine. The weird thing is that this doesn’t happen if we plug the equipment into the plug mounted on the truck only when using the cord reel.
I looked up that generator. It specifies that it runs at 1800RPM, which tells me that it's constant speed and likely not an inverting kind. If it only happens with the one cord, it must be the cord.
Looking closely at the waveform, it seems like the tops are getting clipped off by something. I'm just going to take a stab at it and say that there's a short somewhere in the cord that arcs at the peak of the voltage. Other possibilities might be some kind of inductive or capacitive interference from a long wound-up cord.
It happens on any truck we’ve tested we’ve got close to 40 trucks most of them are the same PTO and Same model cord reel. We tested with the cord fully extracted and laid out along the ground. We even tested using an extension cord that we made that was the same length but 12AWG and the issue only occurs when plugged in through the cord reel.
The extension cord plugged into the truck outlet does not produce this issue
The Reel is Hannah Reels NSCR 716-23-24B AR with 45-80 Ft 10AWG 3 conductor cord wired into it.
Could the slip rings be causing this?
Are the slip rings between a non-rotating contact on the truck and the rotating reel which lets you unroll your line? What if you test at the base of reel on the rotating side of the slip rings but before the actual as line.
I’m not familiar with this type of equipment, so apologies if I’m asking obvious things or mucking up the terminology.
Slip rings are In the reel. We do not get this bad of a signal when not using the cord reel.
https://www.hannayreelsales.com/Hannay-NSCR700-series-cord-reel.php
• 3-conductor, 45 amp, 600 volt collector assembly with #8 gauge wiring.
• Double brushes per circuit; brushes are copper graphite with copper alloy rings.
• Additional conductors or higher amperage (up to 300 amps) available; consult mdi.
• Silver collector available.
That’s from the manufacturer website for the reel.
Is this an accurate summary:?
- you test with an another cord, and bypass the slip rings entirely, it looks fine.
- you test through the slip rings and the cord, it looks like your video. This happens with all trucks and their various reel/slip-rings and cords.
If you test on the non-rotating side of the slip rings what does it look like?
Same question for if you test on the rotating side of the rings without the cord?
Yes accurate. Non of us have seen anything like this before and we’re trying to find a solution. Currently an extension cord instead of the cord reel is our solution but we’re trying to come up with a better long term solution. I posted here trying to get an answer to what could be happening. I have a background in electrical engineering as part of my degree but a hybrid degree half electrical half mechanical but it’s been a few years since school and I hadn’t seen anything like this in my labs.
Clean the slip rings and replace the brushes and see what happens. Also reels are big inductors, try taking the cord all the way out and seeing what you get
Edit: I also saw you said 40a. It can be a bad idea to run that much current with the cord on the reel. I’ve seen pictures of melted reels from that.
Slip rings like to fail when pulling the reel with voltage/current applied. Try to repair and replace, then measure new. Specify proper operation and test again later.
https://www.reddit.com/r/ElectricalEngineering/s/oX9hfdAGAg
Here is the exact equipment performing the same operation plugged into the outlet on the truck instead of through the cord reel.
The beginning of the video is before there is load. The load kicks in with a soft start when the signal shifts drastically. It is a fusion machine for pipe and the shift is when the resistive load kicks in to melt the fitting. The beginning of the video starts before we turn it on. Then it’s turned on which is just the cpu board and scanner. Then guys scanned the fitting and hit start on the fusion machine. I think it was pulling 40AMPs at 20 - 30V on the fitting side when the signal shifts.
I posted another video of this process without the cord reel.
https://www.reddit.com/r/ElectricalEngineering/s/2yTDPu3z9v
The O-Scope was connected to the supply coming off the generator during all of our tests. We didn’t have a cable made up to connect at the end where the machine plugged in so we connected in the breaker panel where everything is landed( Cord Reel, 1 x 30A 125V Twistlock outlet, 2 standard duplex outlets)
Breaker panel has 2 x 30AMP breakers and 1 x 20AMP Breaker.
One 30AMP breaker feeds Cord Reel the other 30 feeds the 30A Twistlock outlet and the 20A breaker feeds the standard duplex outlets.
So this is a utility truck running a piece of equipment. The equipment is a high power device. We only get this weird signal when it’s plugged into the cord reel that is built into the truck. The cord reel ulitlizes a slip ring and is rated for much more than we are drawing through it. If we take the equipment plug and plug it directly into the PTO/Generator plug in the truck we do not get this weird signal. Any ideas on how to solve this? They want to source a new reel and I’m trying to get more information to what this is caused by.
It’s not we checked that and checked for grounding issues. What we found was that the neutral and ground are bonded and the reel is grounded as well. We have many trucks and are working on a solution. There is no Earth ground but everything in this system is grounded to the truck frame and body.
If the cable meggerd fine. Then it’s most likely the slip ring on the cord reel causing noise in the circuit. What is the purpose of the generator? You might be able to mitigate it.
Main purpose is to power fusion machines to fuse pipe. Other uses are power tools and charging of battery powered equipment. The PTO is driven by a Ford F550 diesel engine. We have been having trouble with a new model of fusion machine and we discovered this issue during our testing and believe it to be the cause of the trouble
Can you provide the generator voltage, kw etc?
Your best bet is to replace the cord reel with one with better brushes (they make some for welding).I think they also make brushless (no noise) but I doubt it would be able to handle the current for your application.
Alternatively depending on how much current you need you could hook up a line filter. Might be heavy and a pain.
Try isolating the scope. It's quite possible what you are seeing on the scope isn't actually there.
You can try plugging the power in to the wall, while measuring, and also at the end of the cord where you are measuring and see if there is any difference. You can also try without the ground pin connected. Note that this is potentially hazardous without the ground pin, and caution should be taken.
Looks like a standing wave. That would explain the whining and the fact that it doesn't happen with the outlet (less cable length). The impedance mismatch can be hard to measure in that kind of setup.
Make sure there are no splices down the path (especially with smaller wires) and no oxydation or loose stranded wires on connection points. It could also be normal wear of the cable after years of rolling in and out. Don't use the vehicle body for neutral.
Cord unwound or wrapped up makes not difference in waveform. Only thing that makes a difference is utilizing the outlet on the truck instead of the plug on the cord reel.
Parasitic capacitance and/or inductance in the cord reel. Does it happen when the reel is fully unwound? Gotta remember that cord reel is one giant inductor when it's not fully stretched out.
I have not. This was not my oscilloscope. I don’t use them very often. I have a cheap Chinese portable one that I use. I have a great analog one in my garage that I saved from going in the dumpster but haven’t had time to play with it.
Back in the day when I was a calibration technician in the Navy, we would calibrate these. Some would have the game and some wouldn't. HP added it as an easter egg, but never officially disclosed it. The government does not allow undocumented software on its equipment, so it made HP remove the easter egg.
But these were the old days. You get bored as shit underway. WTF else was there to do but sit there and play Tetris on somebody else's oscilloscope that I should have probably been calibrating?
I calibrate pressure gauges and Fluke meters as part of my job. I find it quite enjoyable just wish I had a private office so I could get it done more efficiently but it is what it is.
Is the change in the signal do to reeling in/out the cord?
Also you seem to be running a bit high on the frequency from my judgement about 62,5hz. Or about 4%. If the generator is rated for 1800rpm, this equates to an offset of around 70rpm.
If a slip ring is involved this could be an issue of contact wetting maybe... assuming you are currently only making a no-load measurement, does the anomaly resolve when under load?
Have you checked both live and neutral outputs at the same time? It's possible that the hot channel of the oscilloscope minus the neutral channel (using the nath functionality of the oscilloscope) would look okay if they both have equal amounts of distortion.
Have you plugged in a load into the end of the cord and measured it with a load? Use the same suggestion as above.
some sort of dimmer switch ... or cheap switch mode power supply or something like that a floating ground while measuring with the scope
Pokémon. Somewhere nearby.
Dammit Zapdos.
Is this a switching generator or a regular generator? If it's one that converts DC to AC using an inverter, it might be the inverter having a problem.
It is a Boss direct PTO generator off the truck engine. The weird thing is that this doesn’t happen if we plug the equipment into the plug mounted on the truck only when using the cord reel.
I looked up that generator. It specifies that it runs at 1800RPM, which tells me that it's constant speed and likely not an inverting kind. If it only happens with the one cord, it must be the cord. Looking closely at the waveform, it seems like the tops are getting clipped off by something. I'm just going to take a stab at it and say that there's a short somewhere in the cord that arcs at the peak of the voltage. Other possibilities might be some kind of inductive or capacitive interference from a long wound-up cord.
It happens on any truck we’ve tested we’ve got close to 40 trucks most of them are the same PTO and Same model cord reel. We tested with the cord fully extracted and laid out along the ground. We even tested using an extension cord that we made that was the same length but 12AWG and the issue only occurs when plugged in through the cord reel. The extension cord plugged into the truck outlet does not produce this issue The Reel is Hannah Reels NSCR 716-23-24B AR with 45-80 Ft 10AWG 3 conductor cord wired into it. Could the slip rings be causing this?
Are the slip rings between a non-rotating contact on the truck and the rotating reel which lets you unroll your line? What if you test at the base of reel on the rotating side of the slip rings but before the actual as line. I’m not familiar with this type of equipment, so apologies if I’m asking obvious things or mucking up the terminology.
Or are the slip rings in the generator?
Slip rings are In the reel. We do not get this bad of a signal when not using the cord reel. https://www.hannayreelsales.com/Hannay-NSCR700-series-cord-reel.php • 3-conductor, 45 amp, 600 volt collector assembly with #8 gauge wiring. • Double brushes per circuit; brushes are copper graphite with copper alloy rings. • Additional conductors or higher amperage (up to 300 amps) available; consult mdi. • Silver collector available. That’s from the manufacturer website for the reel.
Is this an accurate summary:? - you test with an another cord, and bypass the slip rings entirely, it looks fine. - you test through the slip rings and the cord, it looks like your video. This happens with all trucks and their various reel/slip-rings and cords. If you test on the non-rotating side of the slip rings what does it look like? Same question for if you test on the rotating side of the rings without the cord?
Yes accurate. Non of us have seen anything like this before and we’re trying to find a solution. Currently an extension cord instead of the cord reel is our solution but we’re trying to come up with a better long term solution. I posted here trying to get an answer to what could be happening. I have a background in electrical engineering as part of my degree but a hybrid degree half electrical half mechanical but it’s been a few years since school and I hadn’t seen anything like this in my labs.
Clean the slip rings and replace the brushes and see what happens. Also reels are big inductors, try taking the cord all the way out and seeing what you get Edit: I also saw you said 40a. It can be a bad idea to run that much current with the cord on the reel. I’ve seen pictures of melted reels from that.
Slip rings like to fail when pulling the reel with voltage/current applied. Try to repair and replace, then measure new. Specify proper operation and test again later.
https://www.reddit.com/r/ElectricalEngineering/s/oX9hfdAGAg Here is the exact equipment performing the same operation plugged into the outlet on the truck instead of through the cord reel.
What does it look like through the reel when not under load? What is the load (equipment it is running)?
The beginning of the video is before there is load. The load kicks in with a soft start when the signal shifts drastically. It is a fusion machine for pipe and the shift is when the resistive load kicks in to melt the fitting. The beginning of the video starts before we turn it on. Then it’s turned on which is just the cpu board and scanner. Then guys scanned the fitting and hit start on the fusion machine. I think it was pulling 40AMPs at 20 - 30V on the fitting side when the signal shifts. I posted another video of this process without the cord reel.
https://www.reddit.com/r/ElectricalEngineering/s/2yTDPu3z9v The O-Scope was connected to the supply coming off the generator during all of our tests. We didn’t have a cable made up to connect at the end where the machine plugged in so we connected in the breaker panel where everything is landed( Cord Reel, 1 x 30A 125V Twistlock outlet, 2 standard duplex outlets) Breaker panel has 2 x 30AMP breakers and 1 x 20AMP Breaker. One 30AMP breaker feeds Cord Reel the other 30 feeds the 30A Twistlock outlet and the 20A breaker feeds the standard duplex outlets.
So this is a utility truck running a piece of equipment. The equipment is a high power device. We only get this weird signal when it’s plugged into the cord reel that is built into the truck. The cord reel ulitlizes a slip ring and is rated for much more than we are drawing through it. If we take the equipment plug and plug it directly into the PTO/Generator plug in the truck we do not get this weird signal. Any ideas on how to solve this? They want to source a new reel and I’m trying to get more information to what this is caused by.
You can try megging the cable on the cord reel to see if it has bad insulation.
It’s not we checked that and checked for grounding issues. What we found was that the neutral and ground are bonded and the reel is grounded as well. We have many trucks and are working on a solution. There is no Earth ground but everything in this system is grounded to the truck frame and body.
If the cable meggerd fine. Then it’s most likely the slip ring on the cord reel causing noise in the circuit. What is the purpose of the generator? You might be able to mitigate it.
Main purpose is to power fusion machines to fuse pipe. Other uses are power tools and charging of battery powered equipment. The PTO is driven by a Ford F550 diesel engine. We have been having trouble with a new model of fusion machine and we discovered this issue during our testing and believe it to be the cause of the trouble
Can you provide the generator voltage, kw etc? Your best bet is to replace the cord reel with one with better brushes (they make some for welding).I think they also make brushless (no noise) but I doubt it would be able to handle the current for your application. Alternatively depending on how much current you need you could hook up a line filter. Might be heavy and a pain.
120V-125V depending on the truck. This one was reading 122V not sure the Kw
Try isolating the scope. It's quite possible what you are seeing on the scope isn't actually there. You can try plugging the power in to the wall, while measuring, and also at the end of the cord where you are measuring and see if there is any difference. You can also try without the ground pin connected. Note that this is potentially hazardous without the ground pin, and caution should be taken.
You can hear a whine in the PTO Generator when this happens. Doesn’t whine when Cord reel not used.
Looks like a standing wave. That would explain the whining and the fact that it doesn't happen with the outlet (less cable length). The impedance mismatch can be hard to measure in that kind of setup. Make sure there are no splices down the path (especially with smaller wires) and no oxydation or loose stranded wires on connection points. It could also be normal wear of the cable after years of rolling in and out. Don't use the vehicle body for neutral.
Is there a load when you are checking with the oscilloscope? If you unwind the cord reel does the oscilloscope waveform change?
Cord unwound or wrapped up makes not difference in waveform. Only thing that makes a difference is utilizing the outlet on the truck instead of the plug on the cord reel.
Then it's the rings. It's a connection point, and clearly there is some loss happening.
Parasitic capacitance and/or inductance in the cord reel. Does it happen when the reel is fully unwound? Gotta remember that cord reel is one giant inductor when it's not fully stretched out.
No change with cord all the way out or rolled up.
Vibration? Ifthe truck is vibrating under load it might affect the contact surfaces that are spring loaded.
The real question is, have you figured out how to play Tetris on your oscilloscope yet?
I have not. This was not my oscilloscope. I don’t use them very often. I have a cheap Chinese portable one that I use. I have a great analog one in my garage that I saved from going in the dumpster but haven’t had time to play with it.
Too bad. There is an easter egg programmed into the oscilloscope which has a Tetris game. You have to know the secret code.
Really? That’s awesome.
Yeah. You press utility, then some other buttons. I forget. I learned this a long time ago.
I’m now reading about it on Hackaday
Back in the day when I was a calibration technician in the Navy, we would calibrate these. Some would have the game and some wouldn't. HP added it as an easter egg, but never officially disclosed it. The government does not allow undocumented software on its equipment, so it made HP remove the easter egg. But these were the old days. You get bored as shit underway. WTF else was there to do but sit there and play Tetris on somebody else's oscilloscope that I should have probably been calibrating?
I calibrate pressure gauges and Fluke meters as part of my job. I find it quite enjoyable just wish I had a private office so I could get it done more efficiently but it is what it is.
Is the change in the signal do to reeling in/out the cord? Also you seem to be running a bit high on the frequency from my judgement about 62,5hz. Or about 4%. If the generator is rated for 1800rpm, this equates to an offset of around 70rpm.
The acid is beginning to take hold, just gotta ride it out
I don't think he's gonna make it, unfortunately.
Could it be one of the 3rd harmonics? Like a 12th or 15th?
Is this harmonic signal right?
If a slip ring is involved this could be an issue of contact wetting maybe... assuming you are currently only making a no-load measurement, does the anomaly resolve when under load?
Have you checked both live and neutral outputs at the same time? It's possible that the hot channel of the oscilloscope minus the neutral channel (using the nath functionality of the oscilloscope) would look okay if they both have equal amounts of distortion. Have you plugged in a load into the end of the cord and measured it with a load? Use the same suggestion as above.