The secondary winding of a real transformer has a terminal voltage of v,() = 282.8 sin 3771 V. The turns ratio of the transformer is 100-200 (a=0.50) If the secondary current of the transformer is i,(t) = 7.07 sin (3771-36.87") A, what is the primary current of this transformer? What are its voltage regulation and efficiency? The im- pedances of this transformer referred to the primary side are 36.87 19 R = 0.202 Xeq = 0.80 Re=300 X = 1002

An ideal transformer has no real or reactive power loss. (a) True (b) False

For an ideal 2-winding transformer, an impedance Z2 connected across winding 2 (secondary) is referred to winding 1 (primary) by multiplying Z2 by (a) The turns ratio (N1/N2) (b) The square of the turns ratio (N1/N2)2 (c) The cubed turns ratio (N1/N2)3

What is the purpose of a transformer? Draw the symbols for a transformer.

All values of a transformer are proportional to its __________________ ___________________.

A single-phase, 50-kVA,2400/240-V,60-Hz distribution transformer has the following parameters: Resistance of the 2400-V winding: R1=0.75 Resistance of the 240-V winding: R2=0.0075 Leakage reactance of the 2400-V winding: X1=1.0 Leakage reactance of the 240-V winding: X2=0.01 Exciting admittance on the 240-V side =0.003j0.02S (a) Draw the equivalent circuit referred to the high-voltage side of the transformer. (b) Draw the equivalent circuit referred to the low-voltage side of the transformer. Show the numerical values of impedances on the equivalent circuits.

An ideal transformer with N1=1000andN2=250 is connected with an impedance Z22 across winding 2. If V1=10000VandI1=530 A, determine V2,I2,Z2, and the impedance Z2, which is the value of Z2 referred to the primary side of the transformer.

A single-phase step-down transformer is rated 13MVA,66kV/11.5kV. With the 11.5 kV winding short-circuited, rated current flows when the voltage applied to the primary is 5.5 kV. The power input is read as 100 kW. Determine Req1andXeq1 in ohms referred to the high-voltage winding.

A 23/230-kV step-up transformer feeds a three-phase transmission line, which in turn supplies a 150-MVA,0.8 lagging power factor load through a step-down 230/23-kV transformer. The impedance of the line and transformers at 230kVis18+j60. Determine the tap setting for each transformer to maintain the voltage at the load at 23 kV.

Which of the following statements is true about an ideal transformer? O It changes the magnitude of DC signals. O It converts DC signals into AC signals. O It changes the magnitude of AC signals. O It converts AC signals into DC signals.