Lister Engines > Original Lister Cs Engines
rpm limit
38ac:
--- Quote from: vegoil on October 12, 2021, 10:00:55 PM ---thanks for the reply, your way over my head.
regards
John
--- End quote ---
Don't feel alone! When Bruce talks engine and power management I get lost right after he says hello! I can only wish that I had his electrical knowledge!
There are tachometers that work from the injector line pulses. I used to own one . Maybe you could integrate one with a control to pull the rack? But that's in Bruce's territory for sure.
veggie:
Usually if the engine overspeeds, then the voltage goes up as well. (Depending on the generator head you are using)
Perhaps check for a voltage sensing relay (Ebay ??)
EG: If the voltage on a 240VAC generator raises to =>250 VAC, then trip the relay which energizes a kill solenoid on the fuel rack.
Just a thought
vegoil:
Hello Bruce,
I am not sure what part of the world you stay but there must be a time difference between us I am in the far north of the UK.
I am generating 220Volt 50 hz it is a old type BKB start o matic
Do you think that the photos I sent of the voltage cut out will work on the AC 220volt
I could get one for the 24 volt charging side and set it to trip at 28 volt (that's a guesstimate). you could please advise on the upper voltage trip setting.
the reason that I believe that the 220 volt side wont work as well is because I have one of that device that plugs into a socket then you plug in a load IE: light or heater into it. it has a screen that reads the voltage, amps, hertz . when the unit is plugged in on its own the engine dose not start. then the heater is switched on the engine starts when the heater is switched off but still plugged into the device the engine still runs until the device is switched off. if this makes sense. I only use this plug to test check the volts amps hertz
I am unable to run the engine over rev at the moment because when she over reved she brunt out the charging resistor. I have sent for 0.8mm wire to rewind the resistor.
Regards
John
BruceM:
Very helpful info, John. I'm surprised that the minimal power of a voltage and power monitoring circuit would keep the SOM running once the larger load is removed. Yes, sensing on the 24V side might be a good solution to avoid messing with the SOM start circuit. There are DC voltage controlled relays which could then do the job.
If you can connect on the DC generator side so that the relay is only powered when the generator is running that would avoid a load on your batteries. (Upstream of a diode between DC generator and battery would do this.) I'm not familiar with the SOM 24V charger circuitry so if you have a schematic/wiring diagram I can look at, that would be helpful. Ideally we'd like 24VDC to power your overspeed sensing that is only present when the engine is running.
You'll have to test and monitor via VOM to see if DC sensing will reliably detect engine overspeed, once you've repaired your charge current limiting resistor.
If a rise in DC volts with overspeed doesn't look viable in testing, then we might look for an AC over frequency sensing relay powered by 24VDC to avoid the SOM start circuit troubles. Frequency sensing relays are quite pricey, so I'd look at voltage sensing first.
AC frequency sensing via Arduino is readily available, and the Arduino 5V could be powered from the 24V side, but hopefully we can avoid that approach.
I'm in central eastern Arizona, USA.
Best Wishes,
Bruce
mikenash:
--- Quote from: vegoil on October 13, 2021, 05:03:09 PM ---Hello Bruce,
I am not sure what part of the world you stay but there must be a time difference between us I am in the far north of the UK.
I am generating 220Volt 50 hz it is a old type BKB start o matic
Do you think that the photos I sent of the voltage cut out will work on the AC 220volt
I could get one for the 24 volt charging side and set it to trip at 28 volt (that's a guesstimate). you could please advise on the upper voltage trip setting.
the reason that I believe that the 220 volt side wont work as well is because I have one of that device that plugs into a socket then you plug in a load IE: light or heater into it. it has a screen that reads the voltage, amps, hertz . when the unit is plugged in on its own the engine dose not start. then the heater is switched on the engine starts when the heater is switched off but still plugged into the device the engine still runs until the device is switched off. if this makes sense. I only use this plug to test check the volts amps hertz
I am unable to run the engine over rev at the moment because when she over reved she brunt out the charging resistor. I have sent for 0.8mm wire to rewind the resistor.
Regards
John
--- End quote ---
John in my industry we have simple diesel engine controllers in use out on farms all over the place. They're made from off-the-shelf components. They just do simple stuff like track revs and oil temp & pressure and start/stop on a signal. Several of them use the Hz signal off the diesel engine's alternator to control revs - ie, as the revs rise, so do the hertz and the controller uses this info to talk to the little ram that's attached to the throttle arm
If you had a google, there might be info about a simple version of this? If you have or wanted to fit a simple automotive alternator - taking a signal off that might be easy and I guess you could set limits with a simple controller
Folks here who know more about this stuff may chime in?
Cheers
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