With the purchase of land on the island of Kefalonia, and the start of plans to build and emigrate, I suddenly had the excuse I had been looking for, for many years, to build an automatic stand by generator set. The electrical supply on the Greek island has proved to be less than fully reliable on several of our holidays over there. And come to that there are scare stories about our electrical supply becoming less reliable.
The design brief I set myself was to build a fully automatic stand by plant which would take the majority of the domestic supply in the event of mains failure.
Money was a large consideration in the project, in as much as I did not have an endless supply to throw at the project, so I would have to be careful. This would also preclude simply buying a small commercially available package set.
I set about finding
a reasonably priced generator set capable of delivering enough power to supply
a domestic property. The fuel was important, as the set may stand idle for quite
some time, and petrol may evaporate, or worse, go stale. To this end I decided
I would find either a diesel or an LPG generator. I do not expect the generator
to run for long periods, or to be running that often, so I decided to look for
a "portable" frame generator. However, as this was going to need to be a fully
automatic set, electric start would be necessary.
Ebay was the first port of call, (and as my story rolls on, was the first port of call on many many occasions, coming up trumps more times than it didn't) and after a few weeks of searching I selected an electric start single cylinder 6KVA diesel generator in its own sound proof enclosure.
On first appearances this was a lovely set, just right for my application. I had an eye (or ear) to the quiet nature of the location on Kefalonia, and the quiet nature was very appealing. I bid for, and won the auction for the set, and went to collect it. The generator set ran up without any problems, and took a 3KW load, without missing a beat. I paid my money, and loaded the set into the back of my car, a very happy bunny.
It was only at home, when I started to inspect the generator I started to see the possible problems with my purchase. I began to realise that I would need spare parts for the engine, it would need regular servicing at least, and what would happen if it suffered a mechanical breakdown? This might be a problem in this country, but how would I source this kit in Greece. Then I stripped off the casing, and another nightmare ensued. The bolts were made of monkey metal, and stripped at the slightest provocation. No this set would not do. At this stage I decided to sell it on, and try again, this time I decided I would invest in a named generator, from a company with a world-wide presence. I knew I might well pay a premium for the name, but getting hold of spares was something I had to consider.
So the diesel set was consigned to Ebay, and eventually sold. The quest for a replacement began. This time I found a 7KVA petrol Honda with an LPG conversion.
That would do a treat! Another trip out in the car, to collect, and I came home again, with a smile on my face, and a portable generator in the back of the car.
The project then began in earnest. To begin with I needed to make the engine run on LPG. Part of the conversion was in place, but I had been handed the "Atmospheric" valve as an after thought before I left. I had seen the set running, but only on petrol. The seller told me about running the set on LPG, and advised me that the governor he had given me needed to be fed direct from a cylinder, without a primary regulator.
A quick trip to the local Calor gas centre confirmed the details I had been given, and I bought a cylinder connector and some pipe to be able to connect the atmospheric governor direct to the gas cylinder.
All connected up I turned on the gas at the cylinder. LPG poured out of everywhere, including the output to the engine. Now I'm not an expert on these matters, but this did not seem right. Time to seek further information.
The internet is a wonderful place, full of information, both from manufacturers and individuals alike. I typed the make and model of the Garretson valve I had into Google hoping for a wealth of information to spring forward. I only ever found one page with any help on it whatsoever. The page told me that the valve should not need adjustment, but should it become necessary I should wind it off until no gas passed through the valve when the engine was stationary. The page stated quite clearly that the Atmospheric valve I had needed to be fed with a nice friendly GOVERNED 39mb. I did need a *!"%$£& governor after all! I set about finding one.
A suitable governor was located, and removed from the plumbing torch it had been originally used for. This was connected to the atmospheric valve, and with some adjustment, we got to the point where gas was no longer pouring out through the atmospheric governor. With some trepidation I set about starting the engine. After some considerable coughing and spluttering the engine started, and ran! I felt things were getting somewhere. I needed to learn what would be required to make the engine start and run successfully. When you are stood over an engine, turning the key, you can hear when it fires and starts ( or doesn't as the case may be) and take the appropriate action ( even if it is letting go of the key to dis-engage the starter when it fires up) However, I need to ensure the engine would start reliably so that I could fully automate the system.
Safety is always at the top of my mind when building a project like this, and to this end I decided I would like to have a high pressure solenoid connected to the cylinder, so that gas would only be allowed to leave the cylinder when the engine was required to run. The idea of gas leaking by, and then exploding as the engine turned over in the event of a mains failure held a very limited appeal to me!
I set about trying to find a suitable solenoid valve. I looked everywhere, but to no avail. The valve had to routinely deal with pressures of 25Bar and operate at 12VDC. Nowhere seems to sell such an animal. I contacted a couple of suppliers outlining my requirements, and one even sent back information on a valve he said would do the trick. I checked out the information and noticed that the valve would only cope with up to 500mb. Don't these people read emails!!
At this stage I have to say a little about the shopping methods I was using. The majority of kit was sourced not only via the internet, but via Ebay. Some of the kit was on a "Buy it Now" basis, but some of it was not. I would have to bid for an item, if necessary wait for it to end, and then for await the black magic know as the Royal Mail to deliver the item into my waiting hands. Quite often I would go out to "tinker" on the project (as it was always so condescendingly described by my girlfriend) and return within only a few minutes with yet another new item for the shopping list. Then sometimes as much as a week or ten days would pass before I could proceed. And very often the process would start all over again!
After a month or so I gave up on the quest, and started to see if I could come with another idea. I had a look at a solenoid valve from an air conditioning manufacturer. The pressure would be OK, the coil voltage would be great, but the seat material might be a problem. After all this was a device used to control refrigerant, not LPG. I didn't know if it would safely do the trick. The manufacturers ran a mile when I asked their opinion. I was on my own again.
I discovered that ball type gas valves would cope with the pressure, and that they would turn through 360 degrees. I thought I might be onto something here. If I set up a motor, with a disc, and four slots cut in the edge, I might well be able to set up a quarter turn on - quarter turn off arrangement. This seemed to be the only way I would get a high pressure valve working on the un-governed cylinder feed.
Another conundrum was working its way through my mind. I needed to find some way of "priming" or "purging" the gas train prior to starting the engine. This seemed to be the only way getting the engine to start reliably. To this end there was a purge button on the back of the atmospheric governor. I was trying to arrange a solenoid to operate this button, so that the automation process could continue.
It was then that the internet struck again. I had decided for one reason or another that the Garretson valve I was using was, well to be blunt, knackered. I sought a replacement. I found a company in the States, who would not only sell me a brand new Garretson valve (with a priming solenoid) but could also supply a high pressure solenoid valve.
I wrote the to company, ordering the parts, which I paid for. Well they did say they would supply world wide, and the price was far better than any I was being offered in this country ( less than half the cost, even including the postage)
I waited and waited, but no one contacted me! Eventually I gave in, and rang them. They said they were on the point of refunding my money, as they were unsure about a postage option. When I said that I really needed to go ahead, they reluctantly agreed to take my money, and send me the bits out!
The gas bits arrived, and I was now in a position to fit them to the generator. However yet another problem reared it's head.
The high pressure valve ( as seen connected to the cylinder in the picture above) had a threaded output, and the regulator I had all had cylinder type connections. I tried to remove the brass nipple from a regulator, and discovered int he process that it was a "crimp fit" unfortunatley the process involved destroying the body of the regulator.
I was back on Ebay again. Eventually I found a gas regulator that appeared to have a threaded adapter on the supply side. the only problem was it was on the American Ebay site, and in Hawai! The supllier was happy to take my money, and send out a valve! but there was another ten day wait for the postman.
It was at this point that a certain amount of luck came into play. The threads on the valve were the same as the threads on the regulator, the advert on ebay had been correct! The assembly was built and tested. It held gas! Another little success to chalk up in the long chapter of the project.
At last, I had the mechanics all in place, and could then set about building the control cabinets for the fully automating the process.
So it was back to Ebay. Well to be honest I had never left Ebay! Bang on cue, I noticed that someone was selling an engine control unit. The module promised to be able to start the engine, and transfer the load automatically. I was very pleased in fact I was like a dog with two di…. Er tails!
The auction ran it's course, and for very little money I became the proud owner of a "Deep-sea 520" engine control module. The seller had agreed to program it up to my requirements, but to be honest, at this stage, I had no idea what they were! So I paid some extra money, and had him send a connection cable, and a copy of the software so I could make any alterations myself. ( theres another story here about the software not loading, and having to go back to my sellor, who eventually was able to get me a copy of the software that would load and run, but that's a story for another day)
Connecting the control unit and the generator together was actually pretty easy. I used two multicore cables to provide a removable umbilical connection cord for the control lines. These included such things as power, solenoid valves, ignition coil, oil pressure, starter supply and the like. A further mains cable connected to the alternator output so the control module could sense the engine state and speed.
I used relays to interface between the control module and the engine controls ( starter, ignition switch etc) as I did not want to overload any particular aspects of the control module.
I also had a minor problem to sort out with the oil switch.
The control module expected a normal pressure fed engine oil supply. This would start with an earth signal, and when pressure had built up (as the engine cranked and started), would then go diss (open circuit). Any further problems with the oil supply would re-trigger the oil switch which would again give out an earth.
The Honda engine I had only had an oil level switch. This shows a diss, until such time as there is a low oil problem, and then it shows an earth.
A simple timer triggered on start up masked the problem, fooling the control panel into thinking it had an earth before starting, and a diss shortly afterwards. The engine oil level switch remained connected to the sensing port to give an oil alarm, and shut down the engine if necessary, but the control unit was fooled by the timer, and worked a charm.
The automation was in place, and the engine could be relied upon to start reliably. Now I had to build the mains changeover and sensing panel.
Building the Mains voltage panel was a reasonably easy task. I elected to use motor driven circuit breakers, rather than two contactors for the changeover. I have dealt with many large contactors in the past, and they almost always end up going noisy. However, the motor drive units for the changeover were the most new expensive items I bought for the project. Ebay did not work its magic on this occasion, and I had to buy this very specialist bit of kit from the wholesalers.
Voltage sensing of the incoming supply was achieved by a simple relay for single phase operation, and a phase failure relay for three phase. The outputs are selectable. A multitude of gauges were installed so as to be able to monitor all aspects of voltage and supply usage, both on the mains and the generator.
The Project was almost at an end. The kit had been built, tested, and proved to be working. I was all set to begin the process of installing the set up. I might as well have some use out of it in the intervening years, prior to taking it out, and installing it in our house in Kefalonia!
However one aspect worried me. I knew it to be a function of the 13Hp engine that the speed was dragged down, when confronted by a load. This gave a reasonably unstable output voltage (and frequency!) I had been casually looking on Ebay for a more suitable generator, along with a spare engine control unit, just in case this one went toes up!
Then it happened. The guy I had bought the generator from suddenly popped up with another generator! In fact he was selling the one, he had replaced the one I bought with. I had seen it running. It had a twin cylinder 18 HP engine, and the same sized alternator. That's 5 extra HP not to be dragged down with.
I thought long and hard, and bid for the generator. Actually I put a bid in via Auction stealer, and won the engine with a bid at about 20 seconds before close of auction, even though I was sat in a meeting away from a computer at the time!
I collected the engine the following day, and set about un-converting the Honda engine I had spent so many hours lovingly converting. That too went the way of Ebay for a very disappointing price (but that's another story!!) I took comfort that I had not paid a lot more for the replacement (I think my seller had been disappointed too!)
Converting the new engine (A Kholer) was a reasonably quick and easy task. By this time I knew what I was about! One of the flies in the ointment, as it were was the oil warning. We were back to a pressure fed system (far better than the Honda) so I had to remove my pressure masking timer from the control panel!
The other aforementioned fly was the fact that the previous owner had cut away the frame from the generator, and I wanted to reinstate it. A couple of hours with an arc welder sorted that out. ( I must take an angle grinder to my welding, and then some paint some time!)
At last I had a generator all set and ready to go. I set about installing it at home. I already had a small lean to shed at the end of the garage, and I found I could just about fit the generator in there. The control panels are fitted in the main body of the garage.
I installed some fibreglass inside the walls of the shed to cut down the noise from the generator, and this seems to have been very successful. However, I need to see if I can locate a small silencer or two, as the noise from the exhaust port is the noisiest part! I really don't want to annoy the neighbours. And that could be even worse if we suffer a power cut, and I'm the only one with electricity ( and a noisy generator as well!)
I had yet to install an external maintenance switch so I can test run the set without switching off the house. Yet another Ebay purchase has netted me a suitable switch panel, and yet more purchases have got me some suitable MCBs to put in the panel. However, I had some work to do to make it all work as I want to. A couple of weekends later, and finally I have the house working on a stand by engine set!
The bypass cabinet works on the principle of only being able to couple the suplies together when the engine is at rest. hence there are three key switches and only two keys. The first keyswitch is on the LV cabinet of the engine set, and disables the engine set.
The process would go like this. the engine set key is removed, and put into the spare slot in the bypass cabinet. this ensures the engine is at rest, and the load will be on the mains. the key is operated, which will now allow the maintenace circuit breaker to close. The cabinet is now bypassed. The second key can now be removed, this will automatically open the output breaker, thus disconnecting the output from the engine control cabinet. the key can be removed, and placed in the engine set control cabinet. This allows the engine to be started, and test run, without breaking the station load, and without the engine supplying the station load. To bring the engine back on line, the process is reveresed. The pictures show the keys in the "normal" position.
Not too many people will know this fact, or understand the significance, but in this country the Neutral of the public supply is connected to earth. The more astute readers of this little section will also know that where they are connected to a "PME" supply the Earth and the Neutral are combined on the supply authorities cable.
This is important for many reasons, amongst them being that the voltage on the circuit you are dealing with will be limited to the output voltage of the supply transformer, when measure in respect of the general mass of earth..
The above reason is of no concern when taking a supply from a generator. However, a lot of generators I have had dealings with seem to have an earth connection. Quite often this simply connects to the case of the generator, and is not connected to the Neutral. Under these circumstances the nice shiny RCD ( Residual Current Device) you have connected between the generator, and whatever it is you are supplying is a complete white elephant.
If you have tested the output of a generator using a three pin plug tester, you may have noticed some funny readings, including no earth. Now you know why. The neutral is not referenced to earth, as the tester is expecting to see!
If the Neutral is not earthed ( or "referenced") then there is no earth (alternative) return path to operate the RCD. If the generator is going to be used to supply any fixed wiring ( IE connected to your house wiring) then it really should be referenced.
I feel the need to add a little note here. Any connection to a fixed wiring installation MUST be done in such a way that the generator IS NOT connected across the incoming mains. AT NO TIME should the incoming mains, and the generator supply be coupled. I would suggest the use of a suitable (interlocked) changeover switch.
Method of testing and referencing the earth.
Important safety note. This is a potentially dangerous process, involving testing on a live running generator. If you are not suitably qualified, or experienced leave this work to a professional
1) Run up the generator, and test for voltage between the presented earth and both the "phase" and the "neutral ". Connections. (You may note that I have put the phase and neutral in quotes, as until the neutral is referenced to earth, the terms do not apply.) There should be no appreciable voltage at any point. If you read zero volts at the Neutral, and 240v at the phase ( assuming this to be a 240v generator) then the Neutral has already been referenced. If the is 120V either side then the generator may be referenced in the middle of the coil. You should only proceed onto stage 2 if no voltage has been detected on either terminal when read with reference to earth.
2) With the generator running connect a 240v bulb between the earth and both the phase and neutral terminals. The bulb should not light. If it does, Stop. Do not proceed.
3) With the generator running use a 6A MCB to connect between earth and Neutral ( if this involves making connections to the generator then turn off the generator, and run it up each time you have made the connections and need to test!) When the MCB is closed the generator should not "struggle" or change the tone it's making. If it does, STOP, open the MCB immediately and seek assistance.
4) If all the above tests indicate no connection between the earth terminal of the generator and the neutral then insert a strap or cable of no lesser size than the rest of the generator connections, between the earth connection, and the neutral. run up the generator and test again.
5) Assuming all has gone well, and you have not fried yourself in the process, you have just successfully referenced your neutral. The generator is now safe to use.