a. Given an ideal 3-winding single-phase transformer rated at 13.8 kV/230 kV/ 4.157 kV and 120

MVA/120 MVA/ 10 MVA

Terminations:

13.8 kV source

Primary:

Secondary:

Tertiary:

0+||

Draw the equivalent circuit and determine all phasor voltages and currents, placing them on your

diagram.

(primary/secondary/tertiary).

100 MVA Load @ pf = 0.8 lag

8 MVA Load @ pf = 0.8 lead

b. Consider the following transformer (Transformer X):

Single-phase Transformer

Ratings: 100 kVA 2400 V 240 V

Equivalent circuit Values...

Referred to HV side (n); LV side (2);

Series Resistance

Series Reactance

Shunt Mag Reactance

Shunt CL Resistance

0.8064;

5.000;

1097;

7314;

Source

4.157 KV

ABCN

0.008064;

0.05000;

10.97;

73.14;

per-unit

0.01400

0.08680

(1) Draw the equivalent circuit with the primary assigned as the HV side. Given a load of 100 kVA, pf =

0.8 lagging @ rated voltage, compute all primary and secondary quantities and the efficiency.

19.05

127.0

(2) Repeat (1) with the primary assigned as the LV side.

(3) Repeat (1) using the pu equivalent circuit.

c. Three transformer X's make up a three-phase bank, HV wye-connected 4157/2400 V primary, LV

delta-connected 240V secondary, serving a balanced 300 KVA 3-ph load. Make the Y- A connections,

and show current magnitudes in all branches of the circuit on the diagram. Model the Xfmr's as ideal.

a

TDCE

с

Load

240V

300

KVA

need to do handwritten