Hi Rolf, welcome to Outdoorking.
The Scorpion HM63 is a small 640 Watt camping generator. It seems to be the same item which is called Telimax or Sun New Haomai TS950 by its manufacturer. I haven't found any detailed information, but the manufacturer says it runs at 3,600 rpm, which if true is unfortunate. To suit Australian conditions it has to produce AC output at 50 Hertz, and it has a high-speed engine and therefore will have a 2 pole alternator, direct-driven by the engine. (Belt drive generators do exist, but only in slightly larger sizes, and even then they seem to me to be uncommon unless rather crudely engineered by small firms. It is a dumb way to make a generator.) This means the engine has to run at exactly 3,000 rpm. It is common for a lot of the medium-sized and larger diesel engines to have 4 pole alternators and therefore run at exactly 1,500 rpm, because the engine lasts a great deal longer that way, but your Scorpion must run at 3,000. If it does not run at 3,000 rpm, its output will not be 50 Hertz, and appliances you connect to it may not operate correctly. Because the manufacturer says it runs at 3,600 rpm, we have to hope that the Scorpion-branded version has its governor set for 3,000 rpm not 3,600 rpm, or it will produce 60 Hertz electricity, which will not make 50 Hertz appliances happy.
I'm not accustomed to tiny generators that change speed when they run at no load. The ones I've seen maintain the 3,000 rpm at all times. The major reason for that is to achieve a rapid uptake of load when you switch on a 240 volt appliance. For a rather bigger generator of several kVA that is powering a household it is practicable to drop the engine speed to idle when no appliances are running, then use electronic load sensing to delay switching on the generator output until it comes up to speed, but I haven't seen anyone do that on a tiny camping generator like yours.
Just in case you enjoy your generator so much that you want to buy a lot more of them, bear in mind that the manufacturer says he would like to sell them at $50 to $70 per unit, Free On Board at Fuzhou, depending on how many you order. That often means that whoever Scorpion is, he bought them for considerably less than that, since the "quoted" price tends to be the opening ask rather than the final agreement.
http://telimax.en.alibaba.com/product/249216113-210363370/Generator.html
