Before the detailed discussion, let fathom the definition of horsepower. Well, it is a unit of power measurement. In simple words, you can consider it to be the rate of work. Most of the time, it is used to signify the power of motors and various other machines. Here, we will try to understand the horsepower rating of the hoists. It will help you understand the working principle of the hoists. Besides, it will help you to conduct your lifting operations precisely. So, let us discuss the horsepower rating on the hoists and everything that comes with it.
Some important points to know about horsepower ratings on the hoist
One of the most momentous things you have to know about horsepower is its history. Horsepower units came into existence during the time of the steam engines. The engineers wanted to know the capability of these engines, and for that reason, they come up with the concept of horsepower. They compared it with the horse, and from there, the term ‘Horsepower’ originated. Since then, it is one of the important units that we are using.
We already mentioned that horsepower is nothing but the measurement of power. It will help you understand the rate of work. While measuring the power of a horse, we notice that a horse can do 4562 kg-m of work per minute. Based on this calculation, an expert measures the horsepower of a machine, hoist, or engine.
Now, let us talk about the hoists and their horsepower ratings. If you look at the hoists, you will notice that different hoists come with different horsepower ratings. It is because it depends on their speed as well as their capacity. Let us provide you with some examples, which will help you understand the ratings better.
- ½ ton unit that comes with a lifting speed of 2 m/min will have ¼ horsepower.
- Similarly, if there is a ½ ton unit and the 4 m/min, it will be ½ hp.
- The rating will be one horsepower if the same ½-ton unit is having a lifting speed of 8 m/min.
- You will get it for 2 HP if the speed is 16 m/min.
You have to understand the gear ratio and the size of the stator that you use in the motor to comprehend the weight. Besides, you also have to understand the speed of the hoist that you need to achieve for your application.
Should you consider a lower rating?
After reading the important points about HP ratings on the hoists, you must be wondering about the balance that the power and the motor need to maintain. It may not be a big deal for a 25 HP motor to get a 25 HP controller. But it can be considered a case of an open and shut code violation.
In that case, you should consider a larger AC motor that you require. Moreover, the HP rating of the AC motor and the KW rating of the DC motor with an adjustable voltage generator does not have any direct relationship. The reason behind this is the difference in time of the rating of the motors that are involved.
Based on the running condition of the full load, the hoist motor is rated as a 60-minute or 30 minutes rated motor. This type of rating is useful during intermittent duty that requires elevators. The normal duty cycle of the motor involves 120 to 80 starts per hour with 40% runtime. Due to the duty cycle, you can experience less amount of heating. But it removes the requirement of running overload protection.
How does the rating vary on a hoist?
The HP rating of any drive motor is a result of the time reaching. It varies significantly with the change of drive motor from AC drive motor to DC drive motor. It happens because the AC drive motor on the drive system needs to be continuously rated following the applicable standards of NEMA. Moreover, the DC generator can be nominally overloaded.
Altitude and its effect on the hoists
The lifespan of the hoists depends on the high temperature. When you operate a hoist at a high temperature, it shortens the lifespan of the hoists. It happens due to the high heat that impacts the motor cooling tendency. But in a cold environment, the cooling becomes faster than that in a hot environment. Thus, you need to check for the derating factor before you operate your motor. For instance, a 50 HP motor can operate at the height of 1800 meters where it should be directed at 47 HP with a 40 degree Celsius ambient rating. With such requirements, you can handle the highest optimally.
You should also look for the proper dissipation of the heat while you are operating the hoists at a higher altitude. Hence, variable frequency drive and the horsepower rating become important factors during the proper functioning of the hoists at an elevated level.
So, these are all the vital things that you have to understand the horsepower ratings of the hoists. Apart from that, the ambient temperature of the motor and the power supply also plays an important role during its operation.