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| Generator Auto Start - When to Stop Cranking |
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| frostheave:
--- Quote from: schmitt trigger on February 08, 2019, 05:30:40 pm ---There are many "clamp on" current sensors available on Amazon and Ebay, which should be minimally invasive if you decide to follow this route. --- End quote --- Yes, that would be a possible alternative if the relay method does not work. Thanks. |
| frostheave:
--- Quote from: fourtytwo42 on February 08, 2019, 05:40:03 pm ---I feel I have to share a funny story regarding this! .... --- End quote --- Yeah, those glow plugs are important to use when it's cold. Your point is well taken. I want to make the system as idiot proof as possible! |
| frostheave:
--- Quote from: NorthGuy on February 08, 2019, 06:46:25 pm --- --- Quote from: frostheave on February 08, 2019, 05:03:27 pm ---5) Trying to measure a tacho signal from the charging coil for the starting battery may be possible with no special sensors? 6) Measure AC output frequency. Once the alternator is producing ~35+Hz, stop cranking. Requires measuring Hi Voltage frequency. --- End quote --- Unless you have a fancy variable speed inverter generator, the AC frequency is the tachometer. As soon as a threshold frequency is achieved, you stop cranking. But also run a timer - don't crank for too long if there's no AC, and if this is the case, shut down the generator and disable automatic starts until a human inspects it. After the start I wait some time to let the generator warm up without a load, then I turn on the load relay. --- End quote --- Thanks NorthGuy. Nothing fancy about the gen. I will be using an Arduino for the controls. Is there some advantage to monitoring frequency vs. voltage? |
| frostheave:
--- Quote from: ejeffrey on February 08, 2019, 07:39:05 pm --- --- Quote from: frostheave on February 08, 2019, 05:03:27 pm ---6) Measure AC output frequency. Once the alternator is producing ~35+Hz, stop cranking. Requires measuring Hi Voltage frequency. --- End quote --- Easy enough to do with a small transformer. A standard 12V power transformer will allow you to get the voltage and frequency with an isolated measurement. This will also let you monitor while running. Does your generator have built-in load switch that only connects the output once at the target RPM? That would make sense to avoid loading the generator at startup and to avoid producing too low voltage/frequency during startup. If so, then your simple relay solution is probably the best. --- End quote --- Thanks a lot ejeffrey. I have a separate transfer switch that will be controlled by the Arduino in order to transfer between commercial and generator power. Yes, the programming will include a generator warmup and cool down period as well as only transferring loads when the generator is running and warmed up. I was wondering how I could sense the frequency and your transformer solution is so simple! If my voltage/relay method does not pan out, I'll definitely give this a try. Bob |
| Bratster:
--- Quote from: frostheave on February 08, 2019, 09:59:11 pm --- --- Quote from: NorthGuy on February 08, 2019, 06:46:25 pm --- --- Quote from: frostheave on February 08, 2019, 05:03:27 pm ---5) Trying to measure a tacho signal from the charging coil for the starting battery may be possible with no special sensors? 6) Measure AC output frequency. Once the alternator is producing ~35+Hz, stop cranking. Requires measuring Hi Voltage frequency. --- End quote --- Unless you have a fancy variable speed inverter generator, the AC frequency is the tachometer. As soon as a threshold frequency is achieved, you stop cranking. But also run a timer - don't crank for too long if there's no AC, and if this is the case, shut down the generator and disable automatic starts until a human inspects it. After the start I wait some time to let the generator warm up without a load, then I turn on the load relay. --- End quote --- Thanks NorthGuy. Nothing fancy about the gen. I will be using an Arduino for the controls. Is there some advantage to monitoring frequency vs. voltage? --- End quote --- If this is a basic generator, frequency will be very strictly tied in with RPM. I'm guessing the generator running RPM will probably be 3600 for 60 Hertz. That's what the ones that I have installed at various sites are. Sent from my Fi Moto x4 using Tapatalk |
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