High altitudes cause breathing issues in people. The shortness of breath arises above 3,000' sea level in people. High altitudes not only affect people but also hoists. As we are aware of hoist pulls or lower down the load through rope employing motor. The hoisting equipment gets impacted by the thin air at high altitude. In general, the hoist motor devices are designed to function below 3300 feet.
If we talk about the types of hoist motors, then majorly used are TENV, and some also make use of TEFC motors. The difference between the two lies in the ventilation. The TEFC motors are fan-cooled. In this one, a fan is used to push air over the motor, and housing. And so in turn, the heat generated by the motor operation is dissipated.
On the other hand, TENV is non-ventilated. This type comes with a heavier frame having fins or heat sinks that operates to cool the ambient air around the frame. Now, here comes the point, how thin air is affecting the performance of hoist at higher altitudes? When heat is dissipated by the motor frame, due to thin air at an altitude above 3300 feet, dissipation is difficult, and so it starts harming the hoist in return.
So, motors of hoist if needed to work on the high altitude, it must be derated for safe and proper functioning. In such a case of the hoist, what will derating result in? It directly results in derating the upper limit load capacity for a specific design duty for which the hoist is designed to operate, or it can also result in the number of minutes the hoist is operating vs rest that is supposed by the hoist to run, i.e. CDF.
The lifespan is also majorly affected by the high temperature. When a hoist is operating at high temperatures, it results in a shortened lifespan of hoists. It is because high heat impacts the cooling of the motor. In a cold environment, cooling will be faster than that in a hotter one. Thus, The derating factor needs to be checked specifically for each motor. However, the following chart mentioned below gives a fair idea of typical horsepower derating factors. If we take an example when a 50 HP motor is supposed to operate at 6000 feet, it needs to be derated to 47 HP, and a further 40°C ambient rating remains a requirement. And if we go for 50 Ton capacity of the hoist, the hoist needs to be derated by 6% capacity. A new maximum hoist capacity and the duty cycle are required to based-off on 47 Ton capacity.
Altitude Derating factor chart:
There is more than one factor that is up for attention while checking for heat dissipation by hoist motors. Variable frequency drives are one significant one that should be checked for proper dissipation of the heat when the hoist is operating at high altitudes. Also, another factor we discussed prior herein is motor. Load brakes too needed to function appropriately at such elevation. A buyer needs to ask for all the information and make a well-informed decision before purchasing.
General Applications of crane duty motors:
Manufacturing Range:
The power supply of crane duty motors: Crane duty motors are appropriate for 3 phases of supply. It can be wound for frequencies from 50 Hz or 60 Hz and any single voltage from 220 to 650 volts. The rotor voltage is dedicated to a stator supply of 415 V, 50 HZ.
The ambient temperature of motors: The hoist motors are rated at 45°C ambient temperature. For other than 45°C temperatures, a deration factor needs to be applied.
Altitude: The motors are designed in general for altitude up to 1000 m above mean sea level. For more than this altitude, the deration factor is required to apply.
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