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Hi all. Has anyone had any (bad) experiences with an irregular exciter air gap of a synchronous generator? Generator in question: 31.2MVA/25MW, 13.8kV, 60Hz; Brushless Exciter 76V, 9.8Amps. The exciter air gap was measured by the original manufacturer and was 4.3mm, 2.7mm, 0.95mm, 3.0mm at...

Dear all, has anyone a manual for the Fuji Electric Hirex 80 AVR, (DC135V, 15A)? I have searched online to no avail so far. Thanks

Hi all. A Dynamic Postioning drilling rig I'm on has 5 x 5.1 MVA generators per 11kV bus (2) and bus-tie open. Mostly, only two generators run in parallel at a time per bus. This is minumum requirement. The generators have the Symap BCG Protection relays and 95 i Inrush Blocking Relay function...

Hello to all. Can anyone point me in the direction of where I can get hold of the Unitrol M AVR pcb extender-card - site, part-number, other suggestion? I would make an extender-card so that I can hang a scope or multimeter lead off a component or test point and test some of the pcbs poking...

Hi all. We have a customer with an overhead travelling crane with a conical rotor motor on the main hoist. This was a recente upgrade. The motor is DOL and when energised, the rotor aligns and opens the integral brake but the inrush current is causing voltage dips in his factory. Especially...

Hi all. I have a load of UPS and battery charger system batteries to test at a customer's site (44 systems) and was sent a Megger BITE 3. But it seems to have a fault - the display reads "out of Range" when I perform the cell and strap tests. The only reading is the cell voltage. The manual has...

Hi all. I'm on a job replacing PWM filter capacitors - 20uF, 690V - for active front end drives. Recently, one of the filters was not working and the cause were the capacitors that although measured out within tolerance, were making the filter draw too low current and the protection detected...

Hi all. In my company's shop we have an ABB two speed motor for repair, two seperate windings in the same stator - 6 pole and 8 pole, both Delta connected. It was badly burnt so re-wound but now we have the following problem: The 8 pole machine runs fine no load - expected no-load current of...

Hi all. I have a colleague at a remote site calibrating some Siemens Siprotec relays - 7UM62114 EB92-3AAO/FF and 7SJ6225-4ED903FGO/FF but he needs to change some settings to inhibit other functions to be able to test Overcurrent (50/51) and Imbalance (46). Trouble is, customer cannot find (or...

Hi all. When to replace Voltage Source Inverter drives DC link capacitors? I have some customers asking me about this (in large power drives) and how do we measure them to know if they need replacing? A capacitor has a design lifetime in number of hours at a certain ambient temperature. I have...

Hi all. Mechanical question. I know that low loads on large diesel generators is not good for the diesels, apart from not being very efficient. I understand that there is coking-up of the exhaust, increased maintenance and I was told that an engine can seize. What's going on? - ie what are...

Is this allowed? Happy 2012 to everyone. ‘Tis the moment for good cheer, As we start a new year. So let us all in 2012, Technical questions delve. With answers galore, I’m sure there will be more. Simple and complicated Intelligent and educated. So thanks one and all, For the cry and the...

Hi all. I've Googled and and found plenty of manuals etc but I need to upgrade 2 x GE239 relays to include the MOD505 function. These are a recent new fitted and a spare. (There are another 9 with the function). I've been told that we may have to return the relays to Canada for re-programming...

Hi all. Anyone got any experience with a motor causing the IGBTs of a drive to go short-circuit? I have a 690V, 3000Amp drive and approx 1800Amp motor on a propulsion application. Drive to Motor is within 5metres of each other. I can't tell if it's the IGBT or it's internal anti-parallel diode...

Hi all. I have a customer that wants to upgrade his old dc drives. A new drive solution I have. The application is a downhill conveyor where the motors constantly regenerate and the existing drives have high speed dc circuit breakers with trip circuits connected to shunts in the dc circuits...

Hi all. I followed with great interest the previous threads with experiences on selective brush wear on offshore drilling installations - now I’ve been called to something similar! But in this case, all the brushes wear out very quickly. Last incident; in a space of 5 hours the brushes went...

Hi All! Anyone any experience with applying a dc drive to a series dc motor that didn't have one before? Added complication is that there is an electrical brake also in series. I can think of possible problems with discontinuous current and maybe should include a dc choke for current...

Hi all! I probably know the answer but have been unable to convince my customer as to why it is necessary to clamp a disc type thyristor when wanting to test it's properties with a multimeter. Without contacting a thyristor manufacturer can you guys tell me me the reasons? Any suggestions as to...

Hi all! What would be the advantages of using a Dd0Dy5 double secondary transformer for a large 12 pulse ac drive instead of Dd0Dy1? Both configurations shift the Y secondary voltage waveforms 30degrees for low order harmonic elimination/reduction which is what I am looking for. I understand...

Hi all! Does anyone recognise this encoder and manufacturer? AEBRIELTD (or perhaps AEBRIE Ltd??) model 9DITCW/33/24-P/6 24Vdc Optical My customer has one that has gone wrong and asked to find a replacement. The best info would be the number of pulses as 24Vdc encoders are easy to source. I...