# Difference Between HP and BHP (With Table)

Power is defined as the capacity of doing work. Its value is found by dividing the energy of the system by the time. The SI unit of power is Watt. However, for large quantities of power, the unit horsepower is used. It is different from brake horsepower.

## HP vs BHP

The main difference between hp and bhp is that the hp is a unit of measurement of the power of the entire system and does not include frictional losses, whereas the bhp is the amount of the power output by the engine and includes frictional losses.

The horsepower or hp is a unit of measurement of the output power of a mechanical or electrical system. It has various types such as the metric hp and the mechanical hp.

The brake horsepower or bhp is the amount of engine power of a mechanical or electrical system. It also takes into account the various losses due to friction the engine.

## What is HP?

The horsepower is the unit of measurement of the output power of a system. It is represented by hp and is a supplementary unit. The inception of hp began in the 18th century with the development of the steam engine by James Watt. It is a practical approach for power measurement and gives only the useful output power.

The following formula is used for the measurement of horsepower :

P[hp] = ( τ[ft. lbf] × N[rpm] ) /5252

Here, τ is the torque, and N is the speed of revolution of the engine.

To measure the horsepower of an engine, a dynamometer and a torque-converter is connected to the engine.

1. The mechanical horsepower is represented by hp[l]. It is equal to 76.04 kgf. m/s or 550 ft-lbf/s.
2. The metric horsepower is represented by hp[M]. It is equal to 75 kgf. m/s or 542.47604 ft-lbf/s.
3. The Electrical horsepower is represented by hp[E]. It is equal to 746W.

## What is BHP?

The brake horsepower is the amount of power output by the engine. It is represented by bhp. It is a theoretical approach for power measurement. It also includes frictional losses of the engine.

The measurement of brake horsepower is carried out under controlled conditions in a laboratory. The measurement is done on either the crankshaft or the wheels of the system. A braking force is applied to balance the engine’s output force. Then, the output torque and rotational speed of the engine are measured.

The brake horsepower is always higher than the horsepower.1bph is equal to 1.013869 hp.

## Main Differences Between HP and BHP

The horsepower is a useful supplementary unit for the measurement of large amounts of power. It is different from brake horsepower.

The main differences between the two are :

1. The horsepower hp is the output power of a mechanical or electrical system, whereas the brake horsepower bhp is the output power of the engine.
2. The hp is measured for determining the efficiency of the entire system, whereas the bhp is measured for determining the efficiency of the engine only.
3. The hp doesn’t include the power losses in the form of friction. On the other hand, the bhp includes the frictional losses too.
4. The hp is measured using a simple dynamometer, whereas the bhp is measured using a brake type dynamometer.
5. The hp is usually less as the losses are subtracted from it, whereas the bhp is higher as it includes the losses also.

## Conclusion

Electrical engineering involves the efficiency analysis of engines and motors. New techniques are being adopted for achieving better power efficiency in engines.

A machine converting input power to output power with a higher efficiency is preferred. This leads to less wastage of energy.

Horsepower and brake horsepower measure the amount of output power of a system. The horsepower measures the power of the entire system, while the brake horsepower is limited to the output power of the engine only.

Nowadays, components such as controllers and compensators are used in motors. They form an inherent part of the Control Systems Engineering.

However, it should be kept in mind that need and greed for higher efficiency should not adversely affect the environment. The incidents such as the Oil Blowout in Assam could have been averted if the area had been properly evaluated for extraction operations. Today, the carcasses of endangered animals can be seen floating in the ponds, and the Maguri Wetland is under a great threat of destruction.

## References

1. https://www.sae.org/publications/technical-papers/content/770465/
2. https://journals.sagepub.com/doi/pdf/10.1243/PIME_PROC_1924_106_024_02