View Full Version : Hot on the trail!
OK, it won't be long now and I should actually get to USE my dyno! It's only been ready since Dec 24th (yes I broke my biggest and best toy Xmas eve) but I've been fighting electrical gremlins ever since.
Last night I had it operating smoothly in the static load test (no vehicle) which is something I haven't been able to do on wall current. Generator yes, wall current no. Basically, if I switched off a particular circuit in the house which feeds from the same service as the dyno, it would work. I found that by switching the feed to the house off and on, I could shift the point at which things went wacky and could repeat the shifts pretty much at will.
If I shut the main breaker off in the house panel, itgets better, but if I shut the feed to the house off at the other panel (essentially eliminating 100' of dead end line, it gets worse... Anybody with specialized knowledge in line current harmonics etc ?
How is your service laid out?
Main panel in house, how many amp?
subfeed to garage from there?
Garage have it's own service?
Joey,
I'd prefer not to consume bandwidth here, so I'll drop you a line.
Suffice to say, it's looking like either:
1) weak neutral
2) Harmonics/resonance
3) ground issues
Thinking we may be trying an isolation transformer, as the harmonics thing seems to be prevailing thought. Switching different lines on and off seem to affect operation.
My boiler's draft fan (solid state) also surges even though there is no call for heat when the dyno load changes...
On edit: This thing has been consuming my life for nearly 2 months. At this point, the best solution that I see is to call in an industrial electrician to come in and evaluate the situation and try to measure what is going on when this is in operation. That way HOPEFULLY a finger can be pointed one way or another...
[ 02-16-2004, 01:09 PM: Message edited by: kennedy ]
LanduytG
02-17-2004, 03:44
John
Someteimes the power company will get involed in cases like this. It might be worth asking. A good commercial electrition should be able to help as well.
Gerg
A proper grounding system requires two ground rods eight feet in length ,located a distance apart (6 ft.)?.I have also been told not to put them under the overhang of the roof,they get better contact in moist soil.As Greg said,contact your power company.I am on COOPERTIVE lines and they are helpful in situations like yours.
I doubt the electric company will be much help unless you have a tremendous electric bill. Have you checked for voltage drop? Or something wired incorrectly. After years of living in my house, I found a wire on a receptacle wired to the wrong terminal and everything down from that was backwards. You could even have a loose connection somewhere. This can cause all sorts of wacky problems. Especially since many outlets and such are feed through and you could have a problem anywhere along the line. A partial connection somewhere can be fine until a load is put on it. Have you tried coming straight from the panel to eliminate a wiring issue? It could even be a breaker going bad.
I would think a bad ground could be the culprit. I doubt harmonics. Harmonics have to be generated somewhere and are usually only a problem when they get to be a certain percentage of the load. I don't think the power company would be giving you that bad of a problem. If you switched off your other items such as computers that have switching power supplies and contribute to the harmonics, then I don't think this would be a problem. If your dyno is generating harmonics, it would most likely be a bigger problem on the generator unless you have some humongous generator.
It could be in the dyno itself. Does it convert AC to DC to operate? It could be a power supply issue. I would contact the manufacturer and see if they have a recommendation.
I would check for voltage drop. Since you said you were ok on a static test, the increased load may cause the problem. Check the incoming voltage with no load and with a load.
Of course, you didn't mention anything about specs of the dyno. I'm not a dyno expert. Is it single phase, three phase, voltage, current draw, etc.
Good Luck!!
Quick overview:
Single phase service.
Panel A Bldg 1 200amp main feed Ground tested 25 ohms to ground. Neutral bonded to ground.
Panel B Bldg 2 (New bldg with dyno) 100amp fed from panel A. 4 wire system, neutral/ground seperate. I added a ground rod at the dyno driven through the sump basin as an added ground source.
Panel C 60amp (residence) fed from panel B. 4 wire system, neutral/ground seperate. I understand that by code, I need a ground rod for this building which I am lacking.
Superflow has been here, and logged approx 30 hrs on this case.
Power Co has set recorders, but see nothing outstanding. We never even exceeded 66 amps at peak draw. Planning to set another recorder again today. Power Co ends it's troubleshooting when it is determined that they are providing proper volts and amps.
Dyno converts AC to DC to field the absorbers. First issue was blowing breaker. Found to be shorting the diode bridge to ground. Fought this for quite a while, and finally have a controller that works, but absorber "warbles" at a certain percentage of load. I can shift the point at which this occurs around pretty consistently.
I have found that by turning the feed to the house off/on, I can alter shift the problem zone, AND if I shut down most/all of the house load on one particular leg, I can now get it to load smoothly top to bottom. Even with panel C main switched off, I can affect the point of trouble by switching the feed off and on. Better with lines connected than not.
Tried to swap in replacement controllers (supposedly tested at SF) and BOTH blew breakers again, so back to the one controller that was working.
Generator will run the unit without issue. Bear in mind I am only working with one contraooler and one absorber until we get SOMETHING to work.
Fit to be tied... :mad:
[ 02-17-2004, 09:49 AM: Message edited by: kennedy ]
The obvious may have already been tried, but have you "borrowed" a load isolation transformer and stuck it in after the generator/main power switch?
Sneaks,
That has been a common suggestion. I've been torn between buying one, or paying to have system tested.
At this point I figure I'll have system tested if I can get a tech out here soon. That way I know where to send the bill... ;)
May prove to be my problem, but you never know. System requirements are stated at 220-240v 40 amps service at 60hz.
John'
You might want to check and see how your neutral was connected in the sub panel if that is where you are making your connection. Normally sub panels do not ground the neutral. If the sub panel neutral is grounded you could have a ground loop problem. Should be easy to try it both ways. Grounding and neutrals is not something the local power company crews are very knowledgable about.
Earl
More detail edited into my system overview post.
At what panel is the power company testing? All three? If not have you checked the voltage at each panel and at the point of power to the dyno?
Did breaker trip instantaneously or after a period of time.
Panel a feeding panel b with a 100 amp circuit--but is this the size of the breaker feeding the dyno?
Sounds like you have an inrush/surge problem. Just because it is a 40 amp circuit, doesn't mean it can handle the inrush. How big is the breaker on your generator? Wire size and distance between panels could be a consideration as well.If your voltage is low, it could be causing the problem.
I don't think ground loops would cause it to trip out on start up, unless you have a short somewhere, but they can definitely cause problems while running.
Another thought is that when you are switching the panels on and off, you are not switching the neutral or ground, so they are still in play.
I would check the voltage, breaker size and isolate the system and try it.--disconnect the neutrals and grounds going elsewhere. This is basically what you are doing when running on the generator.
You may want to check and see if the power supply in the dyno is a switching type or linear.
If you get to the point you think you need an isolation transformer or want to try something else, let me know what you are looking for. I might be able to help you out on the price. At this point, I just don't think thats its though.
It gets pretty complicated, but basically, we have 2 large power absorber units aka eddy currents. They are DC powered by a control unit with a diode bridge/rectifier etc.
We have basically ceased testing with vehicles, and gone to manually fielding one absorber in static state. The controller outputs DC voltage and varies amperage based on percentage of load ranging 0-15 amps over 0-100% load.
The problem is, that when it "warbles" it is outputting too much amperage. The warble point can be shifted as stated above. When it clears the "warble, the output amperage gets back on track and things seem back to normal.
Ex.
50% output is approx 8 amps.
55% warble 12 amps
60% warble 12 amps
65% clear 10.8 amps
Minn-kota
02-17-2004, 16:58
Is it possible to run the unit on 3-phase or 1-phase?
If so, could it be wired for 3-phase but running on the single phase you are providing?
Just thought I'd throw something out there. Sometimes the most obvious is the most overlooked. I see the specs are for 208-250VAC that's why I'm asking.
autocrosser
02-17-2004, 17:53
John,
You should only ground your neutral at the main entrance panel. If I remember correctly you don't generate a second ground at the sub panel. You can generate more troubles by installing a second ground due to ground loops which will have current flowing on the ground lines.
Also make sure that you haven't swapped grounds and neutral as it will function but not correctly.
I don't know how you measured your ground resistance but it takes a special setup to do that properly such as a Biddle ground resistance tester and about 5oo' of wire that you string out to a stake and another long wire to probe the resistance along the path to find the lowest resistance. A ohm meter won't do it. You also have to isolate the system from the incomming power systems ground as it's a long path ground and won't be a good effective ground path due to the distance it travels to ground.
Single phase machine on single phase power.
Power Co checked ground with their gizmo and stated 25ohms.
Ground/neutral ONLY bonded in first panel. Wire difference eliminates swapping potential.
Looks like we'll definitely need tech out here to test everything power related.
A suggestion to add capacitors to the feed lines has also been made. This is supposed to help clean up the line noise and is apparently what generators use.
Again, Superflow was here for about 30hrs, and Power Co has checked out all of the obvious basics along with recording 24 hrs of VA readings.
I will add that they tested Neutral by applying a 20 amp unblanaced load to either leg of the service. I watched this test, and saw the load leg go to 116ish, and non load go to 124ish from 120 normal. While in spec, it seemed kinda extreme for a 20amp load...
Minn-kota
02-18-2004, 08:30
Capacitors were another thought I had as well.
We have a customer that uses extremely high DC voltages to produce a plasma that will melt down engine blocks and cars to a rock the size of a baseball. This AC-DC change causes some ugly harmonics and the capacitor idea has been thrown around to help that. We have them on a single feed with no other customers because of their particular situation.
The changing of loads or opening up feeds to your home affecting the dyno is interesting/odd. If I understood correctly, with the mains open at the house breaker and just the line between the new shop and the house energized, it worked better?
I'm not sure how to take it, but switching different circuits on/off seems to be adding to the capacitance of the system???
Switching things definitely causes changes, but sometimes the effect is different.
Last night if I shut down the house, it ran fine. Last time I did this it warbled at 35% load.
One thing consistent is my boiler in bldg A will flare (draft fan tries to start) when the load is stepped.
Keep in mind we are manually fielding the load in 5% increments by pushing the load button on the controller.
I spoke with the troubleshhoter from the Elctrician.
He seems very sharp, and basically feels that it is nothing exotic, usually something simple etc etc.
I have a pretty good feeling about this...
Minn-kota, are you talking about Northstar in Newport?
John, did you get the optional tire drier? You'll get this thing all tuned up and ready to run and won't be able to pour the coals to it driving in with wet tires. :D
Minn-kota
02-18-2004, 20:11
No, their name is Phoenix Solutions. Quite the facility. The main purpose of the device is to reduce waste (medical mostly) into rock and pebbles. Looks like volcanic rock when they are done. They "melted" a 55gal drum of concrete to just a chunk of rock for a demo.
If the issues cannot be resolved at some point, maybe your better off taking another approach. From my perspective, that would be to run a separate utility drop to just your dyno building. Not sure what the cost would be for this and you would have two bills to pay but at least it might get you going.
Dewey Faircloth
02-20-2004, 05:59
Maybe you should check for a unbalanced load.Sound like one leg or phase may be
pulling you down.If it is working with
other panels turned off.
Dewey Faircloth
02-20-2004, 06:04
Maybe you should check for a unbalanced load.Sound like one leg or phase may be
pulling you down.If it is working with
other panels turned off.
Not really good at explaining but:
Looks like for whatever reason, the one circuit in my house somehow affects
the "gating" of the SCR that is driving the unit.
For whatever reason, the machine is taking a larger portion of the positive
side of the sine wave than the negative when it acts up. I'm hoping to have
a better written description of the findings, and possibly a screenshot of
the actual waveforms.
The control board synchronizes to the sine wave of the electrcity feeding it and controls the "gating" of the SCR. For whatever reason, it gets off course, and doesn't control properly as described above. The current plan is to discuss isolation, OR even constant voltage transformers for this application.
Electrician found no signs of harmonics or anything funky.
I'm working on getting the explanation of the findings straight from the horses mouth, along with a screen shot of the good and bad waveforms.
John, when I built my shop, I had the power company put in a separate 400A service to it.
All I had to do was to provide the ditch and the PVC conduit at the building, along with a pair of grounding rods.
They provided the meter base and the cables. So my cost was limited to renting a baby backhoe @$170 for the day and about $20 worth of PVC piping and something like $10 for a pair of rods.
I now get two bills every month, one for the 400A service at the house, and another for the 400A service at the shop. Btw, both feeds come off the same transformer, which is located midway between my two buildings.
Anyway, not sure how much you're in for at this point, but my point is that having a separate service installed isn't necessarily all that expensive.
The eventual plan is to have a seperate service for the residence, but not until the new house is built. It just made sense to power the first building and branch from there. I'm hoping that the electrical contractor has a transformer laying around that we can try without risk, and this should hopefully resolve the issue
Update:
Looks like we are going to try an isolation transformer. It sounds like
what I need, and I need to try SOMETHING...
Not in a very good mood for the new year...
I have some captured waveforms as .bmp images if anyone who understands them wants to see them...
Mayb, could be, cautious optimism...
Passed static testing tonight, dynamic testing TOMORROW!
Keep your fingers crossed!!! Good luck. smile.gif
Did you get an isolation transformer yet?
If not, email me. I probably have one that will work.
whatnot@ureach.com
Yes I already have one. No thanks to the electrical supplier. I put in for a quote, and they never responded, so I ordered it from the contractor who did the testing. Transformer came from the supplier who did not quote. Nothing like paying semi retail for something you could have bought wholesale....
That and sending Elaine for an hour plus trip to pick up something that would have came on the route and been here earlier...
Thanks for the offer though!
What did it cost?
I wish I had read this thread earlier.
I could have probably saved you a pile of money.
Just shy of $500, PLUS about 8 hrs troubleshooting/testing labor, and countless hours of my time...
mark45678
02-25-2004, 17:08
Hey Jk! did the isolation xfmr solve the problem? are you back to makeing testing runs with your truck ? smile.gif
I made some runs today, and am still getting things set up.
I get a sense that it is still not right, but need to do some more testing and setup. In the upper speeds, it seems to have trouble regulating, and the test plots get more "ripple" than I think they should...
GMCHORSHAM
02-27-2004, 16:47
Congratulations JK.
Firstly; "Please excuse my ignorance !"
Not understanding all of the Tech/Terminology of the details that you supplied in you original post.(But still interested).
Am I right in assuming that the Isolation Transformer, sepperated the main power supply to your residence and workshop.
Thus providing a continuity of power to your workshop without any impeeding draw.
Hence arresting the potential gremins that presented ??
Have Fun, Safely.
Rod.
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