Etap arc flash study presentation for project deliverables and engineering work
- 13. Steps for arc flash performance : Step 1: Collect the system and installation data
- 21. Step 2: Determine the system modes of operation In a site with a simple radial distribution system there is only one mode of operation—normal—but a more complex system can have many modes. Examples of modes include: — One or more utility feeders in service. — Utility interface substation secondary bus tie breaker open or closed. — Unit substation with one or two primary feeders. — Unit substation with two transformers with secondary tie opened or closed. — MCC with one or two feeders, one or both energized. — Generators running in parallel with the utility supply or in standby
- 22. Step 3: Determine the bolted fault currents Input all data from the single-line diagrams and the data collection effort into a short-circuit program. Commercially available programs can run short circuit calculation to thousands of buses and allow easy switching between modes. Find the symmetrical root-mean-square (RMS) bolted fault current and X/R ratio at each point of concern—all locations where people could be working—by making each of these points a bus. Not every bus needs to be run for every mode because some modes will not significantly impact bolted fault current at some buses.
- 23. Step 4: Determine the arc fault currents The arc fault current depends primarily on the bolted fault current. The bolted fault current in the protective device can be found from the short- circuit study by looking at a one-bus-away run. This will separate fault contributions from feeder and downstream motors . The calculated arc fault current will be lower than the bolted fault current due to arc impedance, especially for applications under 1000 V. For medium voltage applications the arc current is still a bit lower than the bolted fault current, and it must be calculated.
- 24. Step 5: Find the protective device characteristics and the duration of the arcs it is possible to use protective device characteristics, which can be found in manufacturer’s data. For fuses the manufacturer’s time-current curves may include both melting and clearing time. For circuit breakers circuit breakers with integral trip units, the manufacturer’s time-current curves include both tripping time and clearing time For relay operated circuit breakers the relay curves show only the relay operating time in the time-delay region. The circuit breaker opening time must be added. Table shows recommended circuit breaker operating times..
- 25. Step 6: Document the system voltages and classes of equipment
- 26. Step 7: Select the working distances Arc-flash protection is always based on the incident energy level on the person’s head and body at the working distance, not the incident energy on the hands or arms. The degree of injury in a burn depends on the percentage of a person’s skin that is burned. The head and body are a large percentage of total skin surface area and injury to these areas is much more life threatening than burns on the extremities. Typical working distances are shown in Table 3. Typical working distance is the sum of the distance between the worker standing in front of the equipment, and from the front of the equipment to the potential arc source inside the equipment.
- 27. Step 8: Determine the incident energy for all equipment A software program for calculating incident energy must be selected Step 9: Determine the flash-protection boundary for all equipment
- 28. Arcing current For applications with a system voltage under 1000 V use this the equation
- 29. For applications with a system voltage of 1KV to 15 KV use this equation For buses with nominal kV rating greater than 15 kV, the arcing current can be considered to be the same as the bolted fault current Ia= I bf
- 30. Incident energy Empirical method (1.0 to 15.0 kV) Lee method (higher than 15.0 kV)
- 32. Flash-protection boundary Empirical method (1.0 to 15.0 kV) Lee method (higher than 15.0 kV)
- 41. arc thermal performance value
- 42. The Stoll Curve is the predictive model used to measure the probability of burn injury. It quantifies the heat levels and exposure times that result in a second-degree burn, including high temperature exposure for a short time and low temperature exposure for a much longer duration.
- 62. ARC FLASH INPUT DATA
- 63. BUS EDITOR / RATING PAGE
- 64. Standard IEC TYPE Enclosure isolation if this option is checked etap assume that there is enough isolation and main PD can de-energized the bus arc fault if this option is unchecked etap assumes that no adequate isolation exist and main PD are ignored adequate isolation means (sheet metal or sufficient barriers preventing bus side arc fault from damaging the protective device)
- 65. Continuous is the bus bar rated current Bracing is the current peak value of bus bar ARC flash parameters Gap between conductors / buses Is the distance between conductors or buses for the equipment on fault location If the voltage (0.6kv<kv<15 kv) the Gap is 254 mm If the voltage (kv>15kv) use that table
- 66. Gap between conductors and ground Is the distance between phase conductors and ground conductive
- 67. Electrode configuration This field represents orientation of conductors This field is used to select multiplying factors for arc current and incident energy Conductors type CU OR AL
- 68. HEIGHT , WIDTH , DEPTH a and K
- 69. HOW TO DO ARC FLASH STUDY ON ETAP
- 70. For low voltage circuit breakers Step one Enter star view study and do coordination study between main protective circuit breaker (that feed the main bus of equipment) and other circuit breaker on down stream . Step two Go to arc flash study edit and go to parameters then select type of NFPA70E to show PPE LEVEL TYPE(level 0,1,2 or level A,B,C) Step three Go to project ---setting-----arc flash-----incident energy then PPE Step four Run arc flash study Step five Print report and label for arc flash Step sex If you want see arc fault current on TCC you can create TCC from arc flash study FCT IS SUM OF OPERATING TIME OF SHORT CIRCUIT PROTECTION OF LOW VOLTAGE CIRCUIT BREAKER AND THE BREAK TIME OF CIRCUIT BREAKER)
- 71. For medium voltage Step one Go to relay page for main circuit breaker and check INPUT & OUTPUT page Step two Go to star view then do coordination study between this relay and other relays Step three Go to project ---setting-----arc flash-----incident energy then PPE Step four Run arc flash study Step five Print report and label for arc flash Step sex If you want see arc fault current on TCC you can create TCC from arc flash study FCT IS SUM OF OPERATING TIME OF SHORT CIRCUIT PROTECTION OF RELAY AND THE BREAK TIME OF CIRCUIT BREAKER)