5/15/2024 0 Comments Arc flash boundary distanceSince the incident energy of arc faults is more sensitive to arcing time than it is to arc currents, it is necessary to obtain a more accurate arcing time. For inverse-time over-current characteristics of protective devices, the arcing time is greater for smaller currents than it is for larger currents. This is due to the fact that arc currents may be random and usually vary by some proportion about the estimated value. Use the worst case arcing currents: IEEE 1584 recommends using two scenarios – one with 100% of estimated arc current and the other with 85% of estimated arc current. Detailed: This option evaluates the results for the bus bar as well as the load side terminals of all protective devices attached to and downstream from the bus. Both (Incl & Excl Main): This option yields the results for fault on the bus bar as well as on the line side of the main breaker/fuse, provided the bus has a main breaker/fuse attached on the upstream side.To simulate this hazard, select the Excluding Main option, since the device to interrupt faults would have to be an upstream device. Opening the front cover would expose a worker to arc on the line side of the main breaker. Note: Panels typically have the main breaker, bus bar and feeder breakers housed inside the same enclosure. The remote upstream trip device is used to calculate the arcing time. This option of output is applicable to energized work on the line side of the main breaker of the bus. Excluding Main: This option yields the results for fault on the bus bar excluding the tripping effect of the main breaker.However, this option of output should not be used if energized work is required on the line side of the main breaker/fuse. If a worker is working on the bus or on the load side of the main breaker/fuse, then this option of output applies. If a main breaker or fuse protects the bus and this breaker or fuse is connected to the bus, then the arcing time would be equal to the trip time for this main device. Including Main: This option yields the results for fault on the bus bar itself.Output: Select one of the options in the drop down box to evaluate the arc flash hazard results for any bus in the following ways: This option works only if you have the PowerProtector™ feature included in your EasyPower. The program uses the coordination feature PowerProtector™ to calculate the trip time for the estimated fault current passing through the protective device. Worst-Case Arc Flash Hazards: EasyPower obtains the arcing time from the upstream protective device of the faulted bus. This method has the distance exponent of 2. Above 15kV, the program uses the Ralph Lee method, and the distance “X’ factor and the gap from the library do not apply. The IEEE 1584 equations are applicable up to 15kV. Standard: You can select any of the following standards for calculation method. To select arc flash hazard options, click SC Options from the ribbon and select the Arc Flash Hazard tab.įigure 1: Short Circuit Options – Arc Flash Hazard tab You are here: Arc Flash Hazard Analysis > Arc Flash Hazard Options Arc Flash Hazard Options
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