Aim To carry out the Polarity Test on a single-phase transformer Equipment: 3.3kVA 220/110V single-phase transformer ● Variac ● Multi-meters ● Clamp meter ● Lab leads Circuit Diagram 1.1 Vsupply Procedure S wwwwwww RANSFORMER V 3 ΑΛΛΛΛΛΛΑ MACHINE ctical V₂ One of the pre-requisites of parallel operation of transformers is that it must have the same polarity. This test is done to determine the similar polarity ends of a transformer LV and HV terminals. The ends that simultaneously acquire positive or negative polarity because of the emf's induced in them are said to be similar polarity ends. During this test two windings of a transformer are connected in series and one of the windings is excited from a suitable voltage source. If the voltage V3 is greater than V₁ the polarity is additive (i.e. the terminals which are connected together has different polarities). It V3 is less than Vi the polarity is subtractive meaning that the terminals connected together has the same polarity.

Aim To carry out the Polarity Test on a single-phase transformer Equipment: 3.3kVA 220/110V single-phase transformer ● Variac ● Multi-meters ● Clamp meter ● Lab leads Circuit Diagram 1.1 Vsupply Procedure S wwwwwww RANSFORMER V 3 ΑΛΛΛΛΛΛΑ MACHINE ctical V₂ One of the pre-requisites of parallel operation of transformers is that it must have the same polarity. This test is done to determine the similar polarity ends of a transformer LV and HV terminals. The ends that simultaneously acquire positive or negative polarity because of the emf's induced in them are said to be similar polarity ends. During this test two windings of a transformer are connected in series and one of the windings is excited from a suitable voltage source. If the voltage V3 is greater than V₁ the polarity is additive (i.e. the terminals which are connected together has different polarities). It V3 is less than Vi the polarity is subtractive meaning that the terminals connected together has the same polarity.

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter3: Power Transformers

Section: Chapter Questions

Problem 3.9P

See similar textbooks

Similar questions

A bank of three single-phase transformers, each rated 30MVA,38.1/3.81kV, are connected in Y- with a balanced load of three 1, Y-connected resistors. Choosing a base of 90MVA,66kV for the high-voltage side of the three-phase transformer. spify the base for the low-voltage side. Compute the per-unit resistance of the load on the base for the low-voltage side. Also, determine the load resistance in ohms referred to the high-voltage side and the per-unit value on the chosen base.
In per-unit equivalent circuits of practical three-phase transformers, under balanced thr-phase operation, in which of the following connect ions would a phase-shifting transformer come up? (a) Y-Y (b) Y- (c) -
An ideal transformer has no real or reactive power loss. (a) True (b) False
The direct electrical connection of the windings allows transient over voltages to pass through the auto transfonner more easily, and that is an important disadvantage of the autotransformer. (a) True (b) False
For a short-circuit test on a 2-winding transformer, with one winding shorted, can you apply the rated voltage on the other winding? (a) Yes (b) No
In developing per-unit circuits of systems such as the one shown in Figure 3.10. when moving across a transformer, the voltage base is changed in proportion to the transformer voltage ratings. (a) True (b) False
Three single-phase, two-winding transformers, each rated 450MVA,20kV/288.7kV, with leakage reactance Xeq=0.10perunit, are connected to form a three-phase bank. The high-voltage windings are connected in Y with a solidly grounded neutral. Draw the per-unit equivalent circuit if the low-voltage windings are connected (a) in with American standard phase shift or (b) in Y with an open neutral. Use the transformer ratings as base quantities. Winding resistances and exciting current are neglected.
The ratings of a three-phase three-winding transformer are Primary(1): Y connected 66kV,15MVA Secondary (2): Y connected, 13.2kV,10MVA Tertiary (3): A connected, 2.3kV,5MVA Neglecting winding resistances and exciting current, the per-unit leakage reactances are X12=0.08 on a 15-MVA,66-kV base X13=0.10 on a 15-MVA,66-kV base X23=0.09 on a 10-MVA,13.2-kV base (a) Determine the per-unit reactances X1,X2,X3 of the equivalent circuit on a 15-MVA,66-kV base at the primary terminals. (b) Purely resistive loads of 7.5 MW at 13.2 kV and 5 MW at 2.3kV are connected to the secondary and tertiary sides of the transformer, respectively. Draw the per- unit impedance diagram, showing the per-unit impedances on a 15-MVA,66-kV base at the primary terminals.
The ideal transformer windings are eliminated from the per-unit equivalent circuit of a transformer. (a) True (b) False
In developing per-unit equivalent circuits for three-phase transformers. under balanced three-phase operation. (i) A common Sbase is selected for both the H and X terminals. (ii) The ratio of the voltage bases Vbase/VbaseX is selected to be equal to the ratio of the rated line-to-line voltages VratedHLL/VratedXLL. (a) Only one of the above is true. (b) Neither is true. (C) Both statements are true.
Consider an ideal transformer with N1=3000andN2=1000 turns. Let winding 1 be connected to a source whose voltage is e1(t)=100(1| t |)volts for 1t1ande1(t)=0 for | t |1 second. A2- farad capacitor is connected across winding 2. Sketch e1(t),e2(t),i1(t),andi2(t) versus time t.
Consider a bank of this single-phase two-winding transformers whose high-voltage terminals are connected to a three-phase, 13.8-kV feeder. The low-voltage terminals are connected to a three-phase substation load rated 2.0 MVA and 2.5 kV. Determine the required voltage, current, and MVA ratings of both windings of each transformer, when the high-voltage/low- voltage windings are connected (a) Y-, (b) -Y, (c) Y-Y, and (d) -.