Electronics > Projects, Designs, and Technical Stuff
Generator Auto Start - When to Stop Cranking
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.
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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! ....
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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.
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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.
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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.
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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.
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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.
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