Question

The maximum allowable potential difference across a 200 mH inductor is 400 V. You need to raise the current through the inductor from 1.0 A to 3.0 A. What is the minimum time you should allow for changing the current?

Short answer

The minimum time allowed for changing the current is 1 ms.

Step-by-step solution

Given information 

We have given that, the maximum allowable potential difference across a 200 mH inductor is 400 V, and current has to be raised through the inductor from 1.0 A to 3.0 A.

Step 1.

We will use induced emf formula to calculate time.

$\epsilon =L\frac{di}{dt}$

here $\epsilon$= Induced emf

$L$= Self inductance

$di$= Change in current

$dt$= time

Step 2.

Substituting the values in formula :

$$\begin{gathered} 400V=2\times {10}^{-3}H\frac{(3-1)A}{dt} \\ dt=1ms \end{gathered}$$