Showing posts from July, 2019

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Loads - Scenario 4

This post is inspired by Problem 31, Chapter 14 (Synchronous Motor) of "Textbook-Reviewer in Electrical Engineering, 1st Edition" by Professional Electrical Engr. (PEE) Marcialito M. Valenzona. SITUATION A Y-configured, three-phase synchronous motor draws its rated current of 70 Amperes at a leading power factor of 0.8, with 6.6 kiloVolts at its terminals. If each phase has 2 ohms armature resistance and 20 ohms synchronous reactance, what is the induced electromotive force between the lines? ANALYSIS 1.) One-line diagram: o|---V,load,LN---R,ar,1ph---X,sy,1ph---EMF,load,LN---|> -V,load,LN-> + i,load-> (R,ar,1ph +j X,sy,1ph) + EMF,load,LN-> = 0 EMF,load,LN-> = V,load,LN-> - [ i,load-> (R,ar,1ph +j X,sy,1ph) ] EMF,load,LN-> = V,load,LN-> - [ i,load-> (Z,load,1ph) ] 2.) Armature resistance, 1-phase: R,ar,1ph = 2 ohms 3.) Synchronous reactance, 1-phase: X,sy,1ph = 20 ohms 4.) Load impedance, 1-phase: Z,load,1ph-> = R,ar,1p

Standards - Note 2

The following items are examples listed in 2017 PEC Appendix D (Wiring Design Examples). Example D1: "Single Family Dwelling Unit, up to 50 square meters Floor Area with Load not exceeding 3,680 Volt-Amperes" Example D2: "Single Family Dwelling Unit, up to 150 square meters Floor Area (Not more than six circuits)" Example D3: "Single Family Dwelling Unit, up to 150 square meters Floor Area (More than six circuits)" Example D4: "Single Family Dwelling Unit, up to 150 square meters Floor Area, Optional Calculation" Example D5: "Single Family Dwelling Unit, more than 150 square meters Floor Area, 230 Volts, Single-Phase Service" Example D6: "Single Family Dwelling Unit, more than 150 square meters Floor Area, 400/230 Volts, Three-Phase, 4-Wire Service" Example D7: "Multi Family Dwelling Unit, 230 Volts, Single-Phase Service" Example D8: "Multi Family Dwelling Unit, 400/230 Volts, Three-Phase,

Standards - Note 1

TREATING DESIGN ANALYSIS AS MANDATORY It is important to keep in mind that, before any actual electrical work is done, everything starts at the design stage. Considerations on SAFETY and QUALITY need to be included (and examined) on paper in order to avoid any mistakes that may result in costly back jobs, or worse, loss of life and property due to electrical fire. Therefore, electrical practitioners in the Philippines need to be aware of the following provisions in the Philippine Electrical Code (PEC) concerning design analysis. ===== 2017 PEC (A) Mandatory Rules. [ 2017 NEC 90.5 (A) ] "Mandatory rules of this Code are those that identify actions that are specifically required or prohibited and are characterized by the use of the terms SHALL or SHALL NOT." ===== 2017 PEC (F) Plan Requirements - Design Analysis . [ This PEC provision does not exist in NEC. ] "Design analysis SHALL be included on the drawings or SHALL be submitted on se