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| arc flash study https://brainfiller.com/arcflashforum/viewtopic.php?f=12&t=2582 |
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| Author: | bure961 [ Tue Jan 01, 2013 5:22 pm ] |
| Post subject: | arc flash study |
Can the firm doing the arc flash study for a company calculate the ie for the switchgear mains and feeding brakers use just the clearing times and anyother information taken from the manufacture of the cb's or do they have to do some type of testing and get real numbers for cb's? to list on labels. This equipment has not had any pm done in atleast 6-10 years ago. I am concerned the labels would not be listing the true information. |
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| Author: | Zog [ Wed Jan 02, 2013 7:12 am ] |
| Post subject: | |
You can use the OEM trip curves however that is a big assumption. 70E recently added some maintenence requirements. 130.5 Arc Flash Hazard Analysis [SIZE=1][font=ArialNarrow](partial quote)[/font][/size] The arc flash hazard analysis shall take into consideration the design of the overcurrent protective device and its opening time, including its condition of maintenance... IN No. 1: Improper or inadequate maintenance can result in increased opening time of the overcurrent protective device, thus increasing the incident energy. 205.4 General Maintenance Requirements. Overcurrent protective devices shall be maintained in accordance with the manufacturers’ instructions or industry consensus standards. Maintenance, tests, and inspections shall be documented. 210.5 Protective Devices. Protective devices shall be maintained to adequately withstand or interrupt available fault current. [SIZE=3] IN: Failure to properly maintain protective devices can have an adverse effect on the arc flash hazard analysis incident energy values.[/size] |
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| Author: | PaulEngr [ Sun Jan 06, 2013 6:15 pm ] |
| Post subject: | |
If you buy into the 2 second rule in 1584 you can still do the calculation assuming the protective device fails. With fuses of course you don't do this since fuses fail or take an exceptionally long opening time only very rarely. |
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| Author: | wbd [ Wed Jan 16, 2013 5:55 pm ] |
| Post subject: | |
I would use the 2 second rule, if appropriate. Also one should add to the report that it is based on the equipment being maintained according to manufacturer's recommendations. Strongly emphasize that, especially for LV swgr bkrs where grease hardening is a known issue |
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