A three-phase, 230 V, 72 kVA, 0.9 pf (lagging) load is suppliedby three 29 kVA, 1330/230 V, 60 Hz transformers connected inYd5 by means of a common three-phase feeder with an impedanceof 0.003+j0.015 ohms per phase. The transformers are suppliedfrom a three-phase source (substation) through a three-phase linewith an impedance of 0.55+j4.6 ohms per phase. The equivalentimpedance (Rsc+jJXsc) of one or the single-phase transformersreferred to the low-voltage side is 0.16+j0.32 ohms. (a) Deter-mine the required supply voltage if the load voltage is 230 V. (b)Determine the voltage regulation.Single-line diagram showing the substation, line, transformer,feeder and load.lineⒸ | +substationYd5feeder(a) Required substation supply voltage :(b) Voltage regulation: %.loadvolts.

Given, The single line diagram is shown below, Where,Feeder impedance, ZF=0.003+j0.015 Ω/phaseLine…

A three-phase, 230 V, 72 kVA, 0.9 pf (lagging) load is supplied by three 29 kVA, 1330/230 V, 60 Hz transformers connected in Yd5 by means of a common three-phase feeder with an impedance of 0.003+j0.015 ohms per phase. The transformers are supplied from a three-phase source (substation) through a three-phase line with an impedance of 0.55+j4.6 ohms per phase. The equivalent impedance (Rse + jXsc) of one or the single-phase transformers referred to the low-voltage side is 0.16+j0.32 ohms. (a) Deter- mine the required supply voltage if the load voltage is 230 V. (b) Determine the voltage regulation. Single-line diagram showing the substation, line, transformer, feeder and load. line substation ###### feeder Yd5 (b) Voltage regulation: (a) Required substation supply voltage : load volts.

A three-phase, 230 V, 72 kVA, 0.9 pf (lagging) load is supplied by three 29 kVA, 1330/230 V, 60 Hz transformers connected in Yd5 by means of a common three-phase feeder with an impedance of 0.003+j0.015 ohms per phase. The transformers are supplied from a three-phase source (substation) through a three-phase line with an impedance of 0.55+j4.6 ohms per phase. The equivalent impedance (Rse + jXsc) of one or the single-phase transformers referred to the low-voltage side is 0.16+j0.32 ohms. (a) Deter- mine the required supply voltage if the load voltage is 230 V. (b) Determine the voltage regulation. Single-line diagram showing the substation, line, transformer, feeder and load. line substation ###### feeder Yd5 (b) Voltage regulation: (a) Required substation supply voltage : load volts.

Introductory Circuit Analysis (13th Edition)

13th Edition

ISBN:9780133923605

Author:Robert L. Boylestad

Publisher:Robert L. Boylestad

Chapter1: Introduction

Section: Chapter Questions

Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...

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Three single-phase distribution transformers, each rated for 18 kVA, 20000/220 volts, are connected in a Dy three-phase bank. For convenience, at the factory, the OCT and the SCT were per- formed as per standards with the whole three-phase bank already connected and the measured values were as follows: Vline 381.051V, line 1.78436A, P30 = 372.414 W. Vline = 5656.85 V, Iline = 1.55885 A, P30 = 2160 W. Three phase bank of single phase transformer on a utility pole. 37.5 K (a) Find the single phase equivalent circuit referred to the low volt- age side. (b) Find the transformer regulation at the rated load and voltage and a power factor of 0.45 lagging (Neglect the excitation current). (c) Using the "load" model, what is the approximate transformer- bank's efficiency, n, under these conditions of load? (a) R2 X=2 Rsc=mXsc = mS (b) Vreg= (c) n = %
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8) A 500 kVA single-phase transformer A with percentage impedance of 0.010 + j0.05 is connected in parallel with a 250 kVA transformer B with a percentage impedance of 0.015 + j0.04. If the transformers are serving a single-phase load rated 800 kVA, 80% lagging pf, determine the (a) kVA delivered and (b) operating pf of each transformer. Assume that the transformers have the same turns ratio. Subject Electrical Apparatus and Divices
Two single phase transformers A and B with equal turns ratio have reactance of j3.2 and j19.2 referred to secondary. When operated in parallel, the load sharing of 100 kW at 0.8 pf lag between A and B transformers would respectively be a) 75 kw and 25kw b) 60 kw and 40 kw c) 20 kw and 80 kw d) 25 kw and 75 kw
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