Rating of machines

Rating of machines

Rating of a motor is the power output or the designated operating power limit based upon certain definite conditions assigned to it by the manufacturer.

The rating of machine refer to the whole of the numerical values of electrical and mechanical quantities with their duration and sequence assigned to the machines by the manufacturer and stated on the rating plate, the machine complying with the specified conditions.

Rating of a single phase & three phase transformer in KVA is given as

Q = 2.22 f B_m δ K_w A_w A_i * 10^-3

Q = 3.33 f B_m δ K_w A_w A_i * 10^-3

Where f = frequency, Hz

B_m = maximum flux density, Wb/m²

δ = current density, A/mm²

K_w = Window space factor A_w = Window area, m²

A_i = Net core area, m²