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Thread ID: 87744	2008-03-02 12:38:00	3 phase power	motorbyclist (188)	PC World Chat

Post ID	Timestamp	Content	User
645659	2008-03-02 12:38:00	what should the line to line voltage be? the plug at work is reading 390V, whereas i was expecting 400V... line neutral of course was roughly 230V so, is 390V normal or what? i would do the maths, or simply look it up, but i want to know what we should expect in practice rather than what we get in theory. would go into more detail, but long story short - machine at work horribly crippled, crashing ridiculously often, engineers puzzled, i'm out of work till it's running again:(	motorbyclist (188)
645660	2008-03-02 21:33:00	Ring your Power Board & get them to check. Do any other of the business' near you have the same problem? is it all the time or only at certain times of the day, Like peak periods? Does the machine have an input transformer? Some Japanese M/cs DO. Standard M/c with an Input transformer to suit the country it is going to. Some Transformerst have "Tappings" that can be adjusted. Finally. Has this just started? PJ	Poppa John (284)
645661	2008-03-02 23:01:00	Ring your Power Board & get them to check. Do any other of the business' near you have the same problem? is it all the time or only at certain times of the day, Like peak periods? Does the machine have an input transformer? Some Japanese M/cs DO. Standard M/c with an Input transformer to suit the country it is going to. Some Transformerst have "Tappings" that can be adjusted. Finally. Has this just started? PJ we don't know if any nearby businesses have the same problem, but doubt it as not many of them have the sort of machinery we use. the machine is question is an older italian cnc cutting laser. we have a newer german one in the next building but that doesn't seem to have any problems, but it has alot of gear between it and the mains to make sure of that. the failing laser doesn't.... it has been worst between 8am and 4:30pm, which is why i have been suspecting the power supply i don't know about input transformer, but looking inside the most prominent parts are the HUGE capacitors and step-up transformers (up to 36KV i am led to believe) it had been giving occasional trouble in the past, but since last monday it's been un-usable. apparently a truck downed some nearby power lines during the previous weekend - so another reason to suspect the power late last year when it gave trouble we had a monitor put on, and nothing was found to be wrong with the supply, and then it went ok. the engineers looking at it now are still unsure of the root of our problem. they were looking at feedback through the earth (probably part of our problem), possibly damaged capacitors, wiring, corrupted software data.... asfaik still no joy most common failures relate to the table motor/controllers failing for whatever reasons, but it seems to only happen while the laser beam is on - ie, drawing a serious amount of power. poking around with a multimeter and looking at the wiring diagrams, a voltage output sent to the table determines the engine speed, but the motors seem to be getting out of step with the computers and causing it all to emergency shut off. occasionally the whole system will just drop it's program and sit there waiting for intructions, but that's pretty rare. unfortunately the error codes our diagnostic cards give us mean nothing as we don't have any manuals for them :( all we can do is reset the table axis (plural) that fail and start again	motorbyclist (188)
645662	2008-03-03 00:11:00	we don't know if any nearby businesses have the same problem, but doubt it as not many of them have the sort of machinery we use. the machine is question is an older italian cnc cutting laser. we have a newer german one in the next building but that doesn't seem to have any problems, but it has alot of gear between it and the mains to make sure of that. the failing laser doesn't.... it has been worst between 8am and 4:30pm, which is why i have been suspecting the power supply i don't know about input transformer, but looking inside the most prominent parts are the HUGE capacitors and step-up transformers (up to 36KV i am led to believe) it had been giving occasional trouble in the past, but since last monday it's been un-usable. apparently a truck downed some nearby power lines during the previous weekend - so another reason to suspect the power late last year when it gave trouble we had a monitor put on, and nothing was found to be wrong with the supply, and then it went ok. the engineers looking at it now are still unsure of the root of our problem. they were looking at feedback through the earth (probably part of our problem), possibly damaged capacitors, wiring, corrupted software data.... asfaik still no joy most common failures relate to the table motor/controllers failing for whatever reasons, but it seems to only happen while the laser beam is on - ie, drawing a serious amount of power. poking around with a multimeter and looking at the wiring diagrams, a voltage output sent to the table determines the engine speed, but the motors seem to be getting out of step with the computers and causing it all to emergency shut off. occasionally the whole system will just drop it's program and sit there waiting for intructions, but that's pretty rare. unfortunately the error codes our diagnostic cards give us mean nothing as we don't have any manuals for them :( all we can do is reset the table axis (plural) that fail and start again Where are you? As an old factory electrician, these are my thoughts. 1...You recently had some disturbance with the power board supply. The problem is worst 8.00/4.30. This does suggest to me that the power supply is not as it was before. 2..What is the voltage to the m/c before you run it & whilst you run it. 3...The stepup trans. Does it have step up connections on the primary side. or the secondary side, or both. 4...An old Italian m/c. What is the supply voltage on the m/c nameplate?. The voltage in the UK used to be 440 volt & some of the continental m/cs, being 380volt, didnt like this. Some electrical parts got hot. 5...Earth, capacitors, wiring, software. Cannot think how/why feedback thro the earth is a problem. Except perhaps for screened cables not being earthed. Being earthed at both ends of the screen instead of one end only. 6...The table motors. Is there more friction there than there used to be. 7...getting out of step with the computer sounds familiar. But I cannot bring it to the light. It goes something like this. A packaging /bagging m/c. makes 60 bags per minute..Each operation takes one second. That second in the computer is broken down into milleseconds. Something has to happen in each of those set mille seconds. An input from a micro switch or an output to a solenoid, for instance. When this brand new Packing m/c first ran, everthing was fine. After about a month we had problems like those you describe. We eventually found that the m/c had. Frred Up, Run In" so to speake. Because of this some of the inpu/outputs were outside the prescribed window & the m/c threw a wobbly. Does that make sense. How did we fix it? WE didnt. An engineer for the American company who supplied these m/cs was in Australia & fling homw via Auckland. He stopped off at our factory & connected his laptop up to the m/c computer & reset all the time gates. After that there was no problems for quite a while. So I guess I am saying, "How are your timings"? 8... The manuals. Nothing on the Internet. Is the Italion company still "Alive"? if so can you contact them? Cannot think of anything else, but I sympathise with you. I always found this kind of problem the worst to diagnose & fix. PJ	Poppa John (284)
645663	2008-03-03 02:38:00	what should the line to line voltage be? the plug at work is reading 390V, whereas i was expecting 400V... line neutral of course was roughly 230V Yes, the phase to phase voltage should be 400volts and the phase to neutral should be 400/sq.root3 - approx 230.94 volts.	decibel (11645)
645664	2008-03-03 06:38:00	so, is 390v a problematic difference? what i need to know is what is "normal"	motorbyclist (188)
645665	2008-03-03 06:50:00	5...Earth, capacitors, wiring, software. Cannot think how/why feedback thro the earth is a problem. Except perhaps for screened cables not being earthed. Being earthed at both ends of the screen instead of one end only. 8... The manuals. Nothing on the Internet. Is the Italion company still "Alive"? if so can you contact them? manuals for the software in english and german (bosch controller), wiring diagrams etc are all in italian. internet searches have found very little due to the age and nature of this machine, and of course the company who made the machine died a few years ago the maintenance manuals are all exactly that - maintenance, lens changing/cleaning, gas charging, nozzle alignment etc etc i occasionally find a floppy disk lying around, the contents of which is invariably in itialian an engineer who came by saw the earth outside had been covered in tar, then noticed that the table failed only when the laser beam was on. the soil around our factory is basically scoria, so of course if it was bone dry it would be a poor earth with some resistance, so he reckoned there might be some feedback through the earth, ie it wasn't actually 0V. got his apprentice to hack the tar off and put some water down the hole... took about 6 litres before it stopped simply disappearing down there. it did alleviate the problem a bit, but not much	motorbyclist (188)
645666	2008-03-03 09:46:00	so, is 390v a problematic difference? what i need to know is what is "normal" If the m/c nameplate says 400v then 390 is not a problem. PJ	Poppa John (284)
645667	2008-03-03 09:51:00	If the m/c nameplate says 400v then 390 is not a problem. PJ right.... should start looking for a nameplate...... anyone speak italian?	motorbyclist (188)
645668	2008-03-03 09:53:00	manuals for the software in english and german (bosch controller), wiring diagrams etc are all in italian. internet searches have found very little due to the age and nature of this machine, and of course the company who made the machine died a few years ago the maintenance manuals are all exactly that - maintenance, lens changing/cleaning, gas charging, nozzle alignment etc etc i occasionally find a floppy disk lying around, the contents of which is invariably in itialian an engineer who came by saw the earth outside had been covered in tar, then noticed that the table failed only when the laser beam was on. the soil around our factory is basically scoria, so of course if it was bone dry it would be a poor earth with some resistance, so he reckoned there might be some feedback through the earth, ie it wasn't actually 0V. got his apprentice to hack the tar off and put some water down the hole... took about 6 litres before it stopped simply disappearing down there. it did alleviate the problem a bit, but not much I dont think it is an earth spike problem. In your fuse board the Neutral & Earth bars will be hard linked with a brass strip. The main neutral & the main earth (down to the earth spike) would be on the same neutral stud. So there should be NO potential difference between the earth & the neutral. The neutral is the earth & the earth is the neutral. The neutral will be bigger than the earth wire anyway & so will carry any fault current better than the earth. They go to the same point on the supply transformer anyway. PJ	Poppa John (284)
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