Hey All -
Well, I'm toying with starting yet *another* project ... We have a 12kW diesel generator here, connected to a Trace/Xantrex inverter with several large batteries. Kind of a partial house UPS.
It works great. Power goes out, and the inverter kicks in for the protected circuits cleanly - not even the computers notice it. The inverter has a 2-line LCD that I can scroll through to see the current voltages, current usage, etc, but it's not particularly friendly, not can I log stuff.
The generator has rudimentary meters - voltage, current, frequency. Analog, and jumpy as anything with the engine running. Useless really.
I want to build an information box, two actually, one for the generator and one inside with the inverter and batteries. Something with a bunch of 3 1/2 digit LCDs that will show the current status of everything. Also with an rs232 port so I can log things on a PC. Also with another port (rs485 ?) so I can pass the data between inside and the generator shed.
So, things to monitor at the gen are :
Generator volts - should be 120 or so
Generator current - should max out at around 90amps full load
Generator frequency - should be 60Hz
Coolant temp - use a sensor taped to the radiator hose or similar
Inside would be :
Generator volts - either directly or via commo from shed
Generator current - ditto
Generator freq - ditto
Battery current - both into and out of the batteries
Inverter output current
I suppose I could just buy a few voltage and current panel meters off ebay, with appropriate shunts. But those would just be static displays with no logging capabilities. Besides, I would still need something for the generator ...
This should not be rocket science. Basic signal conditioning circuitry up front (isolation, opamps, etc) feeding ADC in the AVR. Multiplexed 3 1/2 digit LCD panels, maybe latches to hold their data. Will also have some outputs - engine shutdown driver for solenoid to stop engine in case of overtemp, overpressure, etc.
So, before I really start digging into this, I'm looking for opinions. On all aspects. There are things here I no idea about, for example, getting the oil pressure/temp, measuring AC amps/voltage safely.