Question

A transformer connected to a 120-V (rms) ac line is to supply 13,000 V (rms) for a neon sign. To reduce shock hazard, a fuse is to be inserted in the primary circuit; the fuse is to blow when the rms current in the secondary circuit exceeds 8.50 mA. What current rating should the fuse in the primary circuit have?

Answer 1

Answer:

The current is 0.921 A.

Explanation:

Given that,

Voltage = 120 V

Current = 13000

Current exceeds = 8.50 mA

We need to calculate the current rating

Using relation of current and voltage

$\dfrac{I_{p}}{I_{s}}=\dfrac{V_{s}}{V_{p}}$

$I_{s}=\dfrac{I_{p}\timesV_{p}}{V_{s}}$.....(I)

Where, $I_{s}$ = current in primary circuit

$I_{s}$ = current in secondary circuit

$V_{s}$ = voltage in primary circuit

$V_{s}$ = voltage in primary circuit

Put the value into the formula

$I_{s}=\dfrac{13000\times8.50\times10^{-3}}{120}$

$I_{s}=0.921\ A$

Hence, The current is 0.921 A.