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The fault currents correspond to a worst-case transformer impedance of 90% of nominal impedance, as transformer standards allow for a 10% tolerance on nominal impedance. The first step of calculation procedure is to convert classic single-line diagram of the power network to an equivalent MVA diagram. Voltage (kV) Impulse Voltage (kV Peak) Power Frequency Voltage (kV) 1 0.433 - 3 2 11 75 28 3 33 170 70 11 LOSSES: 11.1 The transformer of HV voltage up to 11kV,the total losses(no-load + load losses at 75 0C) at 50% of rated load and total losses at 100% of rated load shall not exceed the maximum total loss and hence 2, 2014, pp. The FCL enables the substation to run with all three 33/11-kV transformers connected to the 11-kV bus bars with a fault level of 11.3 kA. PDF Load Flow & Short Circuit Analysis of 132/33/11KV Substation using ETAP Copyright All rights reserved. A low-energy, slow, apathetic interviewing style will communicate low-energy, Why Ask This Question? Many thanks. Site growth took our fault level beyond the existing equipment's 250MVA rating with a predicted level of 350MVA. Your IP: Hence there is need of load flow management. : Electrical Fault Level Calculations Using the MVA Method. SNTL Prague, Czech Republic, 1970. each. Home for the terminally bewildered, one step ahead, New Solar PV design - split system (u/floor heating + domestic supply), Using a Clamp-on Ground Tester for normal & isolated grounds measurements, Do-It-Yourself (DIY) Question & Answer Forum, Options to protect cables entering consumer unit. Street lighting, as well as the switching control for street lighting, can be installed in a substation. Fault Level Calculation Using The MVA Method - PAC Basics single line to ground fault and determine the GCS/4/01 and 02 THerefore the maximum fault level at 11kV will be 2.5 divided by 0,0675 (pu) = 37.037MVA. I need to know the fault current at one of the sites to enable a design of the earthing grid to proceed. and is generating 1.15 pu voltage. A case study of fault level calculations for a MV/LV network using /Contents 4 0 R design of electrical equipment (from the point of view of thermal and dynamic effects of short-circuit currents). Fault levels are most commonly modelled using power . Joined: 12 January 2012. A transformer is rated at 11 kV/0.4 kV, 500 KVA, 5% reactance. Copyright 1998-2023 engineering.com, Inc. All rights reserved.Unauthorized reproduction or linking forbidden without expressed written permission. A 3-phase short circuit occurs at its terminals. This means, the fault level on the primary side of the transformer is considered to be infinite. Electric power is an essential facilitator for sustainable development of the modern nation state. Switchgear should be tested for Breaker, Cable and Busbar Distribution system voltage (kV) Single phase fault level withstand. Finally, the initial symmetrical short-circuit current at the fault point can be calculated from the equivalent network MVA. Please include what you were doing when this page came up and the Cloudflare Ray ID found at the bottom of this page. Effective impedance on 11X1 = 0.258pu (this needs delta to star conversion and series parallel combination of impedance, in the single line diagram) Fault level on 11X1 = 387.44MVA, 20335 Amps. Having experienced in fault analysis, trouble shooting and rectification of electrical system. /ProcSet [/PDF /Text ] The 132 kV busbar three-phase fault level is equal to 100 MVA/0.0188 pu = 5319 MVA and this corresponds to a three-phase fault current of 5319 MVA/ which exceeds the 21.9 kA rating.