Issues Operating on a generator

[Guest guest]

Here is a strange problem. I have lights set up on a yacht and the system works perfectly when connected to shore power. When I fire up the diesel generator (large 20KW unit), all of the lights (on two controllers) go to about 1/3 intensity and stay there regardless of whether the controllers are coonected to the PC or not. The program will drive the lights more or less properly, but the intensity nevers drops below about 1/3 on. I have put surge protecters in line and fairly sophisticated line power filters and nothing changes. My next step is to put an oscilliscope on the line and look for anomalies. Anyone have an idea for a cause/rememdy?

[Guest guest]

You need to have a generator that cleans up the power coming from the unit. Youneed to have a generator that is rated for computer use. If you dont you get power surges and lulls. you are operating a mini computer with your controller boards so they need clean power.

[Guest guest]

Thanx for the hint. I spoke with Dan at LOR and he feels that the frequency might be the culprit. The controller is very fussy about having exactly the right frequency of AC power applied. Otherwise, the generator has been filtered and all other computers and electronic gear work fine.



Jerry

[Guest guest]

For those interested......

The problem has been resolved. Indeed, the units are quite sensitive to frequency. My generator was running a bit fast; probably 62 hertz or so. I adjusted the governor on the generator and the problem all but went away. As the load changes on the generator, the frequency varies which does create some artifacts, but in general it works pretty well. If you plan on using a generator, make sure it can hold frequency within about 1% (0.6 Hertz). Runing the system from an inverter (non-sinusoidal) will probably have similar problems or worse. Dan and I discussed some techniques for improving frequency tracking capability; hopefully these can be implemented over time to provide a more robust tolerance for less than perfect power.



Jerry

[Guest guest]

JerryB wrote:

For those interested......

The problem has been resolved. Indeed, the units are quite sensitive to frequency. My generator was running a bit fast; probably 62 hertz or so. I adjusted the governor on the generator and the problem all but went away. As the load changes on the generator, the frequency varies which does create some artifacts, but in general it works pretty well. If you plan on using a generator, make sure it can hold frequency within about 1% (0.6 Hertz). Runing the system from an inverter (non-sinusoidal) will probably have similar problems or worse. Dan and I discussed some techniques for improving frequency tracking capability; hopefully these can be implemented over time to provide a more robust tolerance for less than perfect power.



Jerry

NIce info to know....For non frequency issues maybe a line stabilizer would help

http://www.accuphase.com/pdf/ps-1210_e.pdf

I dont know what you can do about frequency drift. Nothing I've seen corrects for that. It would have to decouple the input to the output completely.

[Guest guest]

kb9nvh wrote:

JerryB wrote:
NIce info to know....For non frequency issues maybe a line stabilizer would help

http://www.accuphase.com/pdf/ps-1210_e.pdf

I dont know what you can do about frequency drift. Nothing I've seen corrects for that. It would have to decouple the input to the output completely.

Ok.. My guys want to run LOR next year on a series of parade floats with Generators. Has anyone fed a generator input to a LOR through a UPS system? Would that filter it enough to be happy? Most of our floats have little Honda type generators. From what I know about UPS's, they convert AC to DC, to the Battery backup and then back to AC. Filtered? I don't know.. any ideas?

[Guest guest]

You have to watch your ups system. some simply pass the line through until there is ina interuption. The expensive ones actually run off batteries all the time and use the line to keep them charged.

investigate closely what you buym but I dont think it will be cheap.

[Guest guest]

Hi Folks,



You have two issues with inverters, which is essentially what a UPS system is. The first is frequency, but most decent inverters should be carefully controlled since it is so cheap to do this (crystal control) and the LOR controller has some lattidude for absolute frequency as long as it doesn't "jitter" from cycle to cycle. Therein lies the second issue. Most inexpensive inverters use what is called a "modified sine wave" waveform. This is essentially a square wave with some "dead time" at the nominal zero crossing period. The dead time varies with load to provide a voltage regulation function. This is likely to drive LOR nuts.



Soooo.... my advice for a parade is to use a pure sine wave inverter which is likely to have excellent frequency control and shouldn't exhibit the jitter issue noted above. In any event, watch the surge rating for the inverter since incandencent lamps have a LARGE inrush current which may cause a fault in the inverter. Most of all....test it before you buy a unit."If it ain't tested, it's broke" and you can quote me. :}



Jerry

[Guest guest]

I have a few inverters laying around. A 1000watt mod-sine wave and a 300 watt pure sine wave as well as an APC SUMRNET 3000VA sinewave UPS. I really have no need to do anything mobile but after the holidays I plan on doing some testing just to try and help figure out this solution. One thing I'm planning on trying is powering the LOR logic side with the pure sine inverter to see how it reacts and maybe then add the modified sine to the left side of the controller. After that maybe try the beast(APC3000). I just wish I hadn't sold my oscilloscope.