Ms. Can and her childhood friend, Brother J, got together again for a special celebration. Brother J's conversation always revolved around his old profession, and he quickly steered the conversation to motors. He recounted a story he was quite proud of: a piece of equipment manufacturer visited their company, intending to order several IC616 motors. Their company happened to have a batch of high-voltage motors in stock, but with IC611 cooling systems; all other parameters, such as rated voltage and rated power, perfectly matched the customer's requirements. Brother J tried to persuade the customer to purchase the IC611 motors, but the customer refused to change their plans, citing the different cooling methods. In a moment of urgency, Brother J analyzed the characteristics of the IC616 and IC611 cooling systems, suggesting that IC611 motors were more suitable for fan and pump loads. The final result was satisfactory: the customer saved costs, the motor manufacturer cleared its inventory, and crucially, delivery was extremely timely.
Motor cooling methods are a very complex issue when ordering high-voltage motors, involving factors such as cost, installation space, and ventilation and heat dissipation effectiveness. Today, Ms. Can will discuss commonly used motor cooling methods with you.
Overview of common cooling methods
Cooling methods for rotating electric motors include three aspects: the properties of the cooling medium, the arrangement of various cooling circuits, and the method by which the cooling medium is driven. Commonly used cooling methods for electric motors include IC01, IC11, IC21, IC31, IC37, IC81W, IC611, and IC616.
● Typical Cooling Method
IC01: Self-cooling start-up type, fan mounted on the shaft.
IC11: Self-ventilated with an air intake duct.
IC21: Self-ventilated with exhaust duct.
IC31: Self-ventilated with inlet and outlet air ducts.
IC37: Equipped with inlet and outlet air ducts and an independent or separate blower or cooling medium pressure source.
IC611: Fully enclosed fan-cooled self-ventilated unit with a heat exchanger (air-to-air) mounted on the motor.
IC616: Fully enclosed internal air self-circulation, with an independent blower heat exchanger (air-to-air) mounted on the motor.
IC666: A motor with a fully enclosed cooling air recirculation system and an independent air/air cooler.
IC81W: Fully enclosed air-cooled and self-ventilated, with a heat exchanger (air to water) mounted on the motor, and water circulation powered by an independent water pump or water system.
The IC86W motor is a fully enclosed motor with an independent air/water cooler.
● Meaning of Cooling Medium Codes
The cooling medium code consists of "identifying letter" + "cooling circuit layout code" + "primary cooling medium code" + "primary cooling medium movement propulsion method" + "secondary cooling medium code" + "secondary cooling medium movement propulsion method".
Taking IC86W as an example, the complete marking is IC8A6W7, which means: "IC" is the marking letter (internationally recognized cooling symbol), "8" indicates an external cooler (using a remote medium), "A" indicates the primary cooling medium is air (can be omitted), "6" indicates that the primary cooling medium is driven by an independent component, "W" indicates that the secondary cooling medium is water, and "7" indicates that the secondary cooling medium is driven by a separate independent component or by the pressure of the cooling medium system (the cooling medium is water and the driving method is 7, the number 7 can be omitted).
How to select a cooling method for a variable frequency motor
Depending on the specific load characteristics, variable frequency speed control motors typically use several cooling methods such as IC411, IC416, IC611, IC616, IC666, and IC86W. A wise and reasonable approach is to select the appropriate cooling method based on the specific circumstances, which not only reduces the purchase cost but also significantly lowers operating expenses.
● Constant torque load
The load characteristics are constant torque below the base speed and constant power above the base speed. That is, during low-frequency start-up and low-frequency operation, the variable frequency speed control motor still outputs a large torque (rated torque). If a cooling method with its own fan (such as IC411 or IC611) is used at this time, the motor will overheat severely due to the low speed and deteriorating cooling conditions. It is necessary to add an independent forced cooling fan to the motor to ensure safe operation across the entire frequency band.
● Fan and pump loads
When a variable frequency speed control motor drives a fan or pump, the load torque changes with the square of the speed (TL∝n2). When running at low speed, the load torque is very small, the motor shaft output power is very low, and the heat generation is also very small. There is no need to worry about the heat dissipation of the variable frequency speed control motor when running at low speed. The IC411 and IC611 with built-in internal and external fan cooling can be selected. This is the theoretical basis for J-ge to recommend the IC611 motor to customers.
in conclusion
When selecting a variable frequency speed control motor, it is essential to choose the appropriate cooling method based on the characteristics of the driven load and the differences in the operating environment. Only in this way can the safe and economical operation of the variable frequency speed control motor be guaranteed.
