Electrical Design Analysis

Below is a modified version of Example D14 (Simplified Fault Current Calculation) in Appendix D of the 2017 Philippine Electrical Code (PEC). This post presents a single-phase system, without any motors present in the adjacent circuits, tapping into the three-phase source. This serves as a comparison to the previous scenario where a three-phase system taps into the three-phase source. The goal here is to examine what magnitudes are to be expected in single-phase circuits compared to three-phase circuits, and how these magnitudes factor into the selection of protective device ratings. SITUATION An industrial complex receives 230 V, 60 Hz from a single-phase distribution transformer rated 300 kVA and an impedance of 5%. The transformer taps into a three-phase 34.5 kV supply with a 1,000 MVA short-circuit capacity. Using the per-unit method, what maximum symmetrical fault currents may occur in each of the fault points "a", "b", and "c"? From the...

Below is a modified version of Example D14 (Simplified Fault Current Calculation) in Appendix D of the 2017 Philippine Electrical Code (PEC). This post is a single-phase version of the three-phase example in the previous scenario  without any motors present in the adjacent circuits. The goal here is to examine what magnitudes are to be expected in single-phase circuits compared to three-phase circuits, and how these magnitudes factor into the selection of protective device ratings. SITUATION An industrial complex receives 230 V, 60 Hz from a single-phase distribution transformer rated 300 kVA and an impedance of 5%. The transformer taps into a single-phase 34.5 kV supply with a 1,000 MVA short-circuit capacity. Using the per-unit method, what maximum symmetrical fault currents may occur in each of the fault points "a", "b", and "c"? From these fault currents, what are the minimum symmetrical kiloAmpere Interrupting Capacity (kAIC) ratings needed fo...

Below is a modified version of Example D14 (Simplified Fault Current Calculation) in Appendix D of the 2017 Philippine Electrical Code (PEC). This post is almost identical to the previous scenario , except that there are no motors present in the adjacent circuits. SITUATION An industrial complex receives 230 V, 60 Hz from a bank of three single-phase distribution transformers interconnected into a three-phase configuration. Each distribution transformer is rated 100 kVA, and the entire bank has an impedance of 5%. The transformer bank taps into a 34.5 kV supply with a 1,000 MVA short-circuit capacity. Using the per-unit method, what maximum symmetrical fault currents may occur in each of the fault points "a", "b", and "c"? From these fault currents, what are the minimum symmetrical kiloAmpere Interrupting Capacity (kAIC) ratings needed for each molded case circuit breaker (MCCB) A, B, and C? ANALYSIS 1.) ESTABLISH COMMON BASE VALUES. ...

Get it on  Huawei AppGallery now! (Keyword: "ElectricalDEAN") ========== Electrical DEAN for Mobile Devices is an electrical design analysis app based on the Philippine Electrical Code, the SI Modernized Metric System, and equivalent provisions from the National Electrical Code (NFPA 70). Electrical design analysis is primarily about detailed calculations of wire gauges, conduit sizes, protective device ratings, fault currents, voltage drops and other technical matters necessary for the safe and proper operation of electrical systems. The Electrical DEAN mobile app is intended as an educational tool for those who are new in the electrical trade, and as a research tool for veterans who need quick calculations to compare with their own electrical designs. Currently, it covers the fundamentals of electrical design analysis: conductor and conduit data, fault currents and voltage drops (1-phase and 3-phase), and general-purpose circuit sizing (circui...