Question

A 125 kva transformer having primary voltage of 2000v at 50 hz has 182 primary and 40 secondary turns. Neglecting losses, calculate: i) the full load primary and secondary currents. Ii) the no-load secondary induced emf. Iii) maximum flux in the core.

Answer 1

Answer:

• Describe the process by which a bill becomes Law?

Answer 2

(i) Full load primary current = 62.5 A

Full load secondary current = 284.375 A

(ii) For an ideal transformer, E2 = V2 = 439.56 V

(iii) Maximum flux in core = 2.475 Wb

For full load primary current can be calculated from the rated power.

P (kva) = $\frac{V*I}{1000}$

∴ 125 × 1000 = V × Ip

∴ Ip = $\frac{12500}{2000}$

∴ Ip = 62.5 Ampere

As $\frac{Is}{Ip}$ = $\frac{Np}{Ns}$,

Is = $\frac{182*62.5}{40}$

∴ Is = 284.375 Ampere

For an ideal transformer, E2 = V2

∴ Vs = $\frac{Ns*Vp}{Np}$

∴ Vs = 439.56 V

∴ It is a step down transformer.

(iii) Equation for maximum flux:

V1 = 4.44 × N1 × Фm

∴ Фm = 2.475 Wb