First slide

Electrical machines and devices

Question

A transformer with efficiency 80% works at 4 kW and 100 V. If the secondary voltage is 200 V, then the primary and secondary currents are respectively

Moderate

A

40 A, 16 A
B

16 A, 40 A
C

20 A, 40 A
D

40 A, 20 A

Solution

$\begin{array}{l} η = \frac{output power}{input power} = \frac{E_{s} I_{s}}{E_{p} I_{p}} \Rightarrow \frac{80}{100} = \frac{200 \times I_{s}}{4 \times 10^{3}} \\ \Rightarrow I_{S} = \frac{80}{100} \times \frac{4 \times 1000}{200} = 16 A \end{array}$
$Also, E_{p} I_{p} = 4 KW \Rightarrow I_{p} = \frac{4 \times 10^{3}}{100} = 40 A$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App