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| Pete.:
You're doing better than we did at work today. We're running a quite new towable 70kva genny (hired in) on a job and today I asked one of the lads to go up and find out why we suddenly had no power (genny is on the next level up). He leaned over the wall and shouted "IT'S ON FIRE!". I ran up there thinking it's maybe a burnt out plug but no, it was fully on fire and of course they had opened the enclosure door so what was a cloud of smoke turned into an inferno as soon as it got some proper oxygen to breathe. We put it out with a powder fire extinguisher. On inspection it looks like the 12v battery leads had rubbed together before finally shorting and setting the insulation alight. |
| awemawson:
Bad luck, a lot of energy in Lead Acid batteries waiting to leap out. Your fire reminds me of when my ‘road compressor’ burst into flames when I was grit blasting. Luckily just a diesel pipe leaking and soon put out with a CO2 extinguisher but quite dramatic. |
| PekkaNF:
Very good work and write up. I learned lot of new stuff again. Did I understand it right that this has three completely isolated power distribution systems: 1: "Domestic" plugged into mains power normally on 1 phase 240 VAC: * Startter battery charger * Diesel engine heater? 2: Low voltage circuit diesel engine control system: * starter/alternator/battery * Engine health transducers * Deepsea genset controller + generator output monitoring 3: Generator line (out) * This has no connection to other systems (other than current transformers and voltage measurement) * Are all line output terminals wired? How is ground and neutral wired? I have a small diesel generator, output is galvanically totally isolated from the genset I.E. totally floating - there is separate terminal to ground the unit. |
| awemawson:
Pekka, yes essentially that's it. a/ The 'domestic' 240 / single phase input keeps the starting battery topped up, keeps the control cabinet dry with a 60 watt tubular 'greenhouse' heater, and warms the engine water jacket with a 200 watt immersion heater, and all three items are independently switched on the front panel. b/ When the generator is in use the 24 volt starter battery is charged by the AC5-24 vehicle alternator running off the fan belt and this 24 volts is used as you say for engine function monitoring as well as running the Deep Sea 3110 controller. I'm not sure how advisable it would be to leave the trickle charger on when the engine is running, but that seems to be the way it was previously used. c/ The main generator alternator is wired through a 225 amp breaker / isolator that is labelled as having been modified to trip at 150 amps, and is wired from there directly to the huge 125 amp five pin (L1, L2, L3, N, E) 'Commando Socket' that includes an isolator switch that is interlinked, so the plug cannot be withdrawn unless it is in the 'off' position. From the generator output and before the breaker / isolator are three thin voltage sensing wires for the phases that previously went directly to the voltmeter switching on the front panel with no fuse or earth leakage protection. I have run them via a modified 'consumer unit' incorporating a 30 mA RCD earth leakage trip and a 6 amp MCB (as that's the lowest value that seems to be available - one amp would be more than enough) The only points of contact between the systems are: a/ The Trickle charger and the vehicle alternator could both charge the batteries if left switched on b/ The Deep Sea 3110 takes in L1 and Neutral to monitor voltage / frequency etc and this I derive from the 30 mA RCD protected and 6 amp MCB protected source, but it also goes through a 2 amp wire fuse 'just in case' At the moment chassis earth and Neutral are not connected - they probably will be and they were originally, but it's handy to have them isolated for leakage testing. It all sounds more complicated than it really is when you work with it day in day out as I have for the last five weeks! |
| John Rudd:
Andrew, Are you going to earth the Neutral of the generator? If so you ought to consider connecting it via an NER with fault current monitoring in case of Phase to earth faults.... :zap: But I guess if the sole use of the genset is for the furnace and there's phase breakers for protection it may not be needed.... Perhaps an un-necessary complication.... |
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