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| Subject - hy-pot procedure and definition | |
| gymnut14 | what is it and is there a method of procedure |
| lctrc789 | gymnut14, I will try to explain to you what it is and why they do it etc..... HI-POT is a contraction for high potential HIGH VOLTAGE TESTING. It is basically sending high voltage through a wire to test the strength of the insulation, similar to megging..... It is a basic form of VOLTAGE WITHSTAND TESTING, DIE ELECTRIC TESTING as well as INSULATION.. Hi pot can be done in A/C or D/C either. It is usually a test of the line voltage twice as much plus 1000 volts, and checked for one minute or a few seconds depends on the safety standards they are set for. Basically this test checks the conductors for any breakdown of insulation that they could have, (i.e) knicks frays, bad etc. It will tell you if you have a problem before you really have a problem, such as power up a high voltage line with a break and this could be serious trouble. I hope this helps you some, any one else care to add anything I may have missed here. |
| gymnut14 | quote: |
| JimmyDee | Hi-potting is the testing of cables and other high voltage equipment used for transmission of power. A voltage that is equal to the cable rating is applied to the main conductor and the copper ribbon on the bled off area of the conductor. The one procedure I would like to caution you about is that after a high voltage cable has been high-potted, you have a very large capacitor that is charged and very lethal. High voltage cable usually has a copper ribbon wrapped on the outer part of the main insulation before the final covering. You have, because of this ribbon and the main conductor, 2 conductors with an insulation between them. (a capacitor) We high-potted 4 150kv submersible cables and after shorting them out between the ribbon and conductor, (with a hot stick) we had to leave them shorted for 24 hrs before handling them. (It made a noise similar to an M-80 going off) For other procedures, for this process, hire someone with the equipment to do it and knows what they are doing. Can be very dangerous and no second chances. Jim |
| gymnut14 | quote: Thankl you for your explanation - being new to this world can further clarify line and load |
| JimmyDee | Line = incoming side of a device, Load = outgoing side of a device. Jim |
| lctrc789 | Good point Jimmy, I always, always, have to make sure conductor is discharged. Many times we run a ground, bond test as well when we hi pot. A quick release from a charged conductor can get your attention. |
| lctrc789 | This reminds me of a job a few years back. We had a FOX studios re-hab, job. Actaully this job was taking out a generator and installing new 13,200 transformer from new primary , this job had two 13.2 primaries form 2 different sub stations, rather then a generator. We also had the job of installing 800 amp transfer switch, maintenance bypass switch etc. Any way part of the job was to hook up new transformers for FOX they where 13,700 volts d/c form 480 volts a/c. We had a young guy working for FOX and told him we have checked all the d/c transformers earlier that moring and he opened one up and did not discharge capacitor, WOW what a bang. It didn't hurt him from the shock it hurt him when he turned and tried to run, He ran right in to a corner of a transformer, BANG 14 stitches in his head. Always have to have communication and he was told he just didn't listen I guess LOL |