The corona will cause the oil to decompose, expand the case, and lower the oil surface to cause breakdown. In addition, when sealing, if the welding time at the corner is too long, the internal insulation will be burned and oil and gas will be generated, which will greatly reduce the voltage and damage it.
Charged closing causes capacitor explosion Any capacitor bank of rated voltage is forbidden to be live closed. Each time the capacitor bank is re-closed, the capacitor must be discharged for 3 minutes with the switch off, otherwise the voltage polarity at the moment of closing may be opposite to the polarity of the residual charge on the capacitor and cause an explosion.
For this reason, it is generally stipulated that the capacitor bank with a capacity of kvar or more should be equipped with an automatic trip device when there is no voltage, and the switch of the capacitor bank is not allowed to be equipped with automatic reclosing. There were also a few ancillary components like fuses, fixed and variable resistors, and a voltmeter.
Explosive times When the power supply was completed, it was installed in its position among the others on the rack. The complete computer occupied four 6-foot racks linked together with the memory stacks cantilevered out.
All went well for a few days and the power supply did its job perfectly…. The senior engineer on the project rushed from his office, peered through the smoke and settling dust at the smoking ruins of his prototype FCC, and demanded an explanation, not of TYM fortunately , but of the senior team leader — the strict hierarchy of command and responsibility protected TYM.
The team leader explained that he thought a large defective electrolytic capacitor in a power supply had exploded. It would appear that the explosion had somehow provided a volt surge to the 5-volt devices on the arithmetic unit board. The machine gun fire sound was caused by the chain reaction of exploding diodes and other components as the volt power surge progressed through the various circuits.
The team was instructed to not let this happen again. A few weeks or a month or so later, all the damaged boards had been rebuilt and replaced, and the power supply had been rebuilt exactly as before. This time the electrolytic capacitor was formed and double checked. The development and the collection of performance data continued until, once again on an otherwise quiet afternoon, the computer room was rocked with a repeat explosion of the same capacitor.
This time some precautions had been taken to prevent much of the earlier chain reaction damage. Even so, some damage to other boards and power supplies occurred. After much by way of raised voices and robust discussion in the chief engineers office expletives deleted , careful analysis showed the explosion had forced the cantilevered circuit board of TYM's power supply down onto a power supply below it and there was evidence of a massive arc.
Things were now getting serious. Jobs were at risk. Eventually, careful analysis by the full engineering team of the offending power supply and its design tracked-down the culprit.
Neon gas tubes used as voltage reference sources for power supplies get very hot, so placing one on a circuit board next to an electrolytic capacitor is not the best design move. Lesson learned. A few months later, the FCC was back on course. By that time, the machine was at least six months late and not the most competitive of machines.
TYM suspects that by that time the computer may have had a different power supply design, but he could not be sure as he had moved on to the physics lab in the same company and was now pursuing the development of ferroelectric memory based on triglycene sulphate and barium titanate and multi-aperture ferrite memory — MAD devices. TYM pursued his career in electronics in various parts of the world peppered with other explosions, some more serious including — along the way — some very large ones underground in Nevada.
Sometimes, TYM could be found bathed in the blue light of Cherenkov radiation while crawling around atop of the nuclear reactor at the Wright Patterson USAF base pursuing dreams of radiation-hard memory components.
Now slowly raise the voltage output of the source. Be careful while dealing with polarized capacitors. Feel free to comment to improve this instructable. Participated in the Circuits Contest View Contest. Did you make this project?
Share it with us! I Made It! NeilRG 1 year ago. Reply Upvote. Loved it :- But I did explode some amount of capacitors in my life What were we doing wrong? Our setup was simply a few wires and our capacitor.
So while we were in school, our physics laboratory assistant called up an electrician from downstairs to show how to do stuff. The electrician brought a ceiling fan capacitor and showed us how to connect it to the socket. Maybe he thought we were dealing with such capacitors too. So he charged the capacitor and took it out and touched its two ends in such a way that there was sparking proof of charging.
Why didn't this capacitor blow up? Current must have surged in this one too right? Thank God it didn't blow up! The guy was holding it in his palms. There wasn't any considerable difference in capacitance it was microfarad against the microfarad we used so why didn't it?
Your uF V capacitors were undoubtedly low cost aluminum electrolytic capacitors rated only for use on a DC circuit.
When you connect such capacitor to the AC mains you are alternately subjecting the component to a positive peak of the V and then V at a rate of some 50 or 60 times per second.
The polarized plates in the electrolytic capacitor very quickly break down under these conditions and can lead to an internal short. Even if the capacitor plates were able to survive the negative voltage for a short time the effective AC impedance of a uF capacitor connected to the AC mains without many other series components to limit the current would result in a goodly amount of power being dissipated in the component resulting in the sealed can expanding and exploding.
If it was a polarized capacitor, remember AC will be the wrong polarity half the time, so it will go boom. Someone stated that putting an AC-rated capacitor across a V line would be like putting a 30Ohm resistor across it. That is very much incorrect with regard to the dissipated power but correct with regard to the peak currents.
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