What is the relation between KW and HP?

Answer 1

When calculating kW, power factor is brought into the equation

Formula for single phase kVA = I x E/1000,

3 phase kVA = I x E x 1.73/1000

Formula for single phase KW = I x E x pf/1000,

3 phase kW = I x E x 1.73 x pf/1000

Alternative Answer

When an AC current flows through a purely resistive circuits, its temperature increases above the ambient temperature, and energy is lost to the surroundings through heat transfer. This energy transfer is irreversible. The rate at which this energy loss is taking place is called the true power of the circuit, and is expressed in watts (symbol: W).

When an AC current flows through a purely reactive (i.e. inductive or capacitive) circuit, during the first quarter-cycle, energy is stored in the magnetic or electric field, and returned to the circuit during the next quarter cycle. So, although energy transfer is taking place, there is no net loss of energy. The rate at which this energy transfer is taking place is called the reactive power of the circuit, and is expressed in reactive volt amperes(symbol: var).

However, most practical circuits are inductive-reactive circuits. So, when AC current flows through an inductive-reactive circuit, some energy is permanently lost while some energy is transferred from and back to the circuit. In other words, most circuits exhibit a combination of true power and reactive power. The vector sum of true power and reactive power is called apparent power, and is expressed in volt amperes (symbol: V.A).

To summarise:(Apparent Power)2 = (True Power)2 + (Reactive Power)2

From the above equation, in a purely resistive circuit, the apparent power will be equal to the true power. For resistive-reactive circuits, the apparent power will always be larger than the true power.

Read more: What_is_KW_and_KVA

Answer 2

1 HP = 746 watts = 0.746 KW Example of a 200 HP motor: KW = 200 x 0.746 = 149.2 KW