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(Solved): Power systems 3A (Electrical and Electronics Engineering) Question 1. A 10-kVA,(2400)/(240)V transf ...
Power systems 3A (Electrical and Electronics Engineering)
Question 1.
A 10-kVA,(2400)/(240)V transformer in a steel mill must be reconfigured as an autotransformer
to step-down 2640 V to 2400 V .
a. Draw the autotransformer connection diagram [8]
b. Calculate the new kVA rating of the autotransformer. [4]
c. Determine the maximum allowable load current in the autotransformer mode. [3]
Question2.
An industrial plant uses a 25-kVA,(2400)/(240)-V,60-Hz single-phase transformer for machine isolation. The following test results are obtained:
Open-Circuit Test (conducted on low-voltage side): Voltage =240V, Current =1.2A, Power =80W
Short-Circuit Test (conducted on high-voltage side): Voltage =95V, Current =10.4A, Power =320W
a. Calculate the equivalent circuit parameters referred to the low-voltage side. [12]
b. Draw the equivalent circuit with these parameters referred to the low-voltage side. [8]
Question 3.
A 20-kVA,(480)/(120)V,60-Hz, single-phase transformer has the following test data:
Open-Circuit Test (LV Side): 120V,1.2A,40W
Short-Circuit Test (HV Side): 30 V, 41.67 A, 500 W
The transformer supplies a lagging power factor load ( 0.8 PF ) at rated secondary current.
a. Calculate the efficiency of the transformer at this load.[6]
b. Determine the secondary terminal voltage under this load condition. [14]