Some interesting information about electricity supply in Indonesia.
To cope with the economics of peak hour demands, the local solution is to ration. In dire circumstances the power may be off between 5 pm and 9 pm every second night. More usually it is off every fourth or fifth night, but with no discernable program, meaning that you cant organise life around the jadwal, or schedule.
If you run a fridge and freezer, and have people needing good lighting, for example to study, a genset is a must.
This is not a backup system made ready for emergencies. It is a necessary part of almost continuous electricity supply. If you want uninterrupted power supply, that will involve a battery system and UPS device in addition to a genset.
In Indonesia, the low-start current fridge is much advertised. When an electric motor switches on, the initial current draw can be very high and enough to kill a small genset or trip a fuse. The low start current model is supposed to alleviate this problem.
I began by hastily buying a small 2-stroke generator at around 1 million rupiah (about 100 dollars). It bore the hopeful code of 1300, but the small print said a rated 700 watts with a higher short term capacity of 750 watts. Honest enough, thought I. With lighting using less than 100 watts there was enough, I thought, to start up the fridge, rated at 75 watts.
Indeed there was, but when the fridge came on it seemed as if the genset had been kicked in the guts, rpm dropping dramatically before recovering. But when the fridge, ostensibly drawing 75 watts, switched itself off, the genset would race, blowing the occasional bulb before the governor got things under control. The addition of a freezer to the household at around 100 watts brought things to a head. I began alternately plugging in the two refrigerator systems. It was impossible to leave the house during the power cut. Gensets in Indonesia are highly over-rated .
A popular device in Indonesia is the STAVOL, a unit which is supposed to regulate AC voltage and protect appliances. I bought a 1500 watt unit. It clearly couldnt cope with voltage surges, and the time delays in corrections were of the order of governor response in the genset.
I reasoned that the flywheel effect of a heavier genset might get us over the sudden load changes, and bought a single-cylinder 8 HP diesel to couple with a 3 KW generator. Such couplings in Indonesia can be dreadful, and I paid attention to belt tightness and alignment. The flywheel and crank is deliciously heavy, but engine experts know that the power delivered by an engine with one cylinder, and its rotational speed, fluctuates wildly. Even a four cylinder diesel has this problem, and a coil-spring infested coupling (incorporated in every cars clutch plate) is used to connect the engine less wearingly to a constant load. Obviously, a v-belt coupling can absorb the fluctuations of a single-cylinder engine and the fluctuating load of a single-phase dynamo.
Out of the box, the engine gets rid of its heat by boiling water in a small tank enough to last about a half hour. An operator must top up this water very regularly if the unit is to run the four jadwal hours. I soon bought a bolt-on plate with two pipes welded in to do the water circulation thing. Locals hook it up to a 200 litre drum of water, using what should be a thermo-siphon. There was a question of whether to drain the engines tank after every use. Hooking up a 20 litre bucket above the engine, discarding the hot water, gave me about 30 minutes respite. I needed a larger reservoir. Meanwhile, a great idea arose. We had been heating bath water on a not inexpensive wood fire. The first ten litres of water from the engine were a bit rusty, but after that there was a good supply of hot water which was clean enough for everyone to luxuriate in a free hot bath! Tending the water supply became a family bath routine. Great!
I also bought a DC HF welder, knowing that it would not operate on the 1300 watt limit of the power supply in our town, which lies at 1200 above sea level in Indonesia. Yes! This means it gets cold here! Love that hot bath at night!
With a 3000 watt generator I felt that I could do light stick welding to my hearts content. I just had to weld the frame for the genset first . A trial run using 2.6 mm electrodes on the house supply (1300 watts, remember) with fridges, iron, rice cooker and kettle turned off proved successful, and the genset was completed. With relish I fired it up to do some serious welding.
I was shocked. The genset response to the wildly fluctuating load of a welder was hopeless. I could not successfully burn the small rods. It was much better to use the house supply, drawing perhaps 1000 watts that the genset could not deliver.
Chastened, I next discovered that when the genset was running both fridges ran with a worrying low-frequency vibration superimposed over the normal slight vibration. Was I heading for fridge failure? The lights also flicker.
My first checks were frequency and voltage. Here there is a problem Indonesians do not measure the frequency of their genset output. The small commercial genset units are factory preset to 50 herz, but what about the popular diesel thumpers? This was resolved by borrowing a Herz meter from the power company none could be bought in town. I found that when the output voltage was around 220-230 volts the frequency was close enough to 50 Herz. The vibration remained. It also showed, slightly less, when using the small genset.
Searching the net, I found a few reports of flickering lights and one or two technical treatises on interharmonics. My lay mind sees this as the potential problem: fluctuations in engine-dynamo speed set up a beat effect, the combination of cycles of different frequency resulting in something like spring tide in-phase voltages interspersed with neap tide wave interference, explaining the flickering lights, the vibrating fridges, and the high-tech high frequency welder tormented beyond all reason.
One website suggested that there is a commercial unit which overcomes this problem. Little else.
Is there a neat explanation of this phenomenon, and a simple and cheap solution?
To cope with the economics of peak hour demands, the local solution is to ration. In dire circumstances the power may be off between 5 pm and 9 pm every second night. More usually it is off every fourth or fifth night, but with no discernable program, meaning that you cant organise life around the jadwal, or schedule.
If you run a fridge and freezer, and have people needing good lighting, for example to study, a genset is a must.
This is not a backup system made ready for emergencies. It is a necessary part of almost continuous electricity supply. If you want uninterrupted power supply, that will involve a battery system and UPS device in addition to a genset.
In Indonesia, the low-start current fridge is much advertised. When an electric motor switches on, the initial current draw can be very high and enough to kill a small genset or trip a fuse. The low start current model is supposed to alleviate this problem.
I began by hastily buying a small 2-stroke generator at around 1 million rupiah (about 100 dollars). It bore the hopeful code of 1300, but the small print said a rated 700 watts with a higher short term capacity of 750 watts. Honest enough, thought I. With lighting using less than 100 watts there was enough, I thought, to start up the fridge, rated at 75 watts.
Indeed there was, but when the fridge came on it seemed as if the genset had been kicked in the guts, rpm dropping dramatically before recovering. But when the fridge, ostensibly drawing 75 watts, switched itself off, the genset would race, blowing the occasional bulb before the governor got things under control. The addition of a freezer to the household at around 100 watts brought things to a head. I began alternately plugging in the two refrigerator systems. It was impossible to leave the house during the power cut. Gensets in Indonesia are highly over-rated .
A popular device in Indonesia is the STAVOL, a unit which is supposed to regulate AC voltage and protect appliances. I bought a 1500 watt unit. It clearly couldnt cope with voltage surges, and the time delays in corrections were of the order of governor response in the genset.
I reasoned that the flywheel effect of a heavier genset might get us over the sudden load changes, and bought a single-cylinder 8 HP diesel to couple with a 3 KW generator. Such couplings in Indonesia can be dreadful, and I paid attention to belt tightness and alignment. The flywheel and crank is deliciously heavy, but engine experts know that the power delivered by an engine with one cylinder, and its rotational speed, fluctuates wildly. Even a four cylinder diesel has this problem, and a coil-spring infested coupling (incorporated in every cars clutch plate) is used to connect the engine less wearingly to a constant load. Obviously, a v-belt coupling can absorb the fluctuations of a single-cylinder engine and the fluctuating load of a single-phase dynamo.
Out of the box, the engine gets rid of its heat by boiling water in a small tank enough to last about a half hour. An operator must top up this water very regularly if the unit is to run the four jadwal hours. I soon bought a bolt-on plate with two pipes welded in to do the water circulation thing. Locals hook it up to a 200 litre drum of water, using what should be a thermo-siphon. There was a question of whether to drain the engines tank after every use. Hooking up a 20 litre bucket above the engine, discarding the hot water, gave me about 30 minutes respite. I needed a larger reservoir. Meanwhile, a great idea arose. We had been heating bath water on a not inexpensive wood fire. The first ten litres of water from the engine were a bit rusty, but after that there was a good supply of hot water which was clean enough for everyone to luxuriate in a free hot bath! Tending the water supply became a family bath routine. Great!
I also bought a DC HF welder, knowing that it would not operate on the 1300 watt limit of the power supply in our town, which lies at 1200 above sea level in Indonesia. Yes! This means it gets cold here! Love that hot bath at night!
With a 3000 watt generator I felt that I could do light stick welding to my hearts content. I just had to weld the frame for the genset first . A trial run using 2.6 mm electrodes on the house supply (1300 watts, remember) with fridges, iron, rice cooker and kettle turned off proved successful, and the genset was completed. With relish I fired it up to do some serious welding.
I was shocked. The genset response to the wildly fluctuating load of a welder was hopeless. I could not successfully burn the small rods. It was much better to use the house supply, drawing perhaps 1000 watts that the genset could not deliver.
Chastened, I next discovered that when the genset was running both fridges ran with a worrying low-frequency vibration superimposed over the normal slight vibration. Was I heading for fridge failure? The lights also flicker.
My first checks were frequency and voltage. Here there is a problem Indonesians do not measure the frequency of their genset output. The small commercial genset units are factory preset to 50 herz, but what about the popular diesel thumpers? This was resolved by borrowing a Herz meter from the power company none could be bought in town. I found that when the output voltage was around 220-230 volts the frequency was close enough to 50 Herz. The vibration remained. It also showed, slightly less, when using the small genset.
Searching the net, I found a few reports of flickering lights and one or two technical treatises on interharmonics. My lay mind sees this as the potential problem: fluctuations in engine-dynamo speed set up a beat effect, the combination of cycles of different frequency resulting in something like spring tide in-phase voltages interspersed with neap tide wave interference, explaining the flickering lights, the vibrating fridges, and the high-tech high frequency welder tormented beyond all reason.
One website suggested that there is a commercial unit which overcomes this problem. Little else.
Is there a neat explanation of this phenomenon, and a simple and cheap solution?