Question 521Electricity/Electronics - QMED70% to pass
What is the maximum allowable primary current of a 2 kVA step-down transformer with a four to one turns ratio if the primary is connected across a 440 volt line?
AI Explanation
The correct answer is B) 4.5 amps.
To arrive at this answer, we can use the formula for power, voltage, and current in a transformer:
Power (P) = Voltage (V) x Current (I)
Since the transformer is step-down with a 4:1 turns ratio, the primary voltage is 440V and the secondary voltage is 440V / 4 = 110V.
The power rating of the transformer is 2 kVA, which is equivalent to 2000 watts.
Rearranging the power formula, we can solve for the primary current:
I = P / V
I = 2000 watts / 440 volts
I = 4.5 amps
The other answer choices are incorrect because:
A) 1.1 amps is too low for a 2 kVA transformer on a 440V line.
C) 18.1 amps is too high for a 2 kVA transformer on a 440V line.
D) 27.7 amps is also too high for a 2 kVA transformer on a 440V line.
Related Questions
#519 The turns ratio of the step-down transformer with dual voltage secondary as shown in figure "B" of the illustration is two to one (total). If 440 volts were applied to terminals 'H1' and 'H2', what would be measured across 'X1-X3' and 'X2-X4' assuming that the secondary windings are connected in parallel? Illustration EL-0082 #520 In figure "2" of the diagram shown in the illustration, the three phase power transformer has a step-down turns ratio of four to one. If a three-phase 440 volt supply is connected to terminals 'A1-B1-C1’, what voltage should develop across terminals 'A2-B2-C2'? Illustration EL-0084 #522 A load is connected across the secondary of the step-up transformer shown in figure "B" of the illustration and the current drawn by the load is 10 amps. If the turns ratio is 1 to 10 and the input voltage is 110 VAC, what will be the current drawn by the primary? Illustration EL-0055 #523 As load is added to a DC shunt motor, how will the motor respond? #524 In an ungrounded distribution system, as compared to a normal indication, what is the indication on a switchboard of a current carrying conductor making an accidental electrical contact with a wiring metal conduit?