An IP rating is a standard means of measure how well the enclosure around an electric motors provides protection for the motor against dust and water. When you are selecting an electric motor for a process that utilize pumps or conveyors, for example, the IP rating of the motor will tell you how much protection that the motor provides against environmental factor. An IP rating isnt a marketing tool; instead, the IP rating is a formal specification that tells you how well the motor enclosure will protect the motor against dust and water.
Should you select an IP rating that is too low for the environment in which you plan to utilize your motor, the motor will fail due to water or dust entering the motor. However, if you select an IP rating that is appropriate for the environment in which you will utilize the motor, the motor will function as it is suppose to function and for a more longer period of time. The IP rating utilizes two digit to indicate the protection of the motor against solid objects and liquids.
IP Ratings for Electric Motors
The first digit of the IP rating indicates the protection of the motor against solid objects and dust, while the second digit of the IP rating indicates the protection of the motor against water. Because these ratings are based off a standard test procedure, you can compare the IP ratings of any two motors even if different manufacturer manufactured them. Thus, motor designer do not have to guess as to whether or not the motor will be weatherproof; the specifications provided for the motor will indicate whether the motor has protection against dust and water.
The type of environment in which you will utilize the motor will determine the IP rating of the motor. Motors that you will utilize in indoor environments that are known to be especially clean and air-conditioned will require fewer protections against solid objects and dust and water than motors that will be utilized in factories that produce products that contain grinding dust, or factories whose floors require frequent hose cleaning to remove any accumulated dust. Motors with higher IP ratings have been constructed with motor enclosures that are constructed to prevent water and dust from entering the motor enclosure.
Motors with higher ratings are protected against more types of liquids, with higher levels of protection against the liquids, and against higher temperatures of the liquids. Thus, motors with higher IP ratings will typically cost more then motors with lower IP ratings. The design of the motor will determine the possible IP rating that can be assigned to that motor.
Motors that are “open drip-proof” are constructed with vents of specific angles that allow the motor to cool while allowing dust and water to enter the motor enclosure. Motors that are “totally enclosed fan-cooled” motors are constructed in a way that prevent water and dust from entering the motor enclosure; they contain a fan that circulates air around the motor, but the motor itself is sealed. Motors that are constructed from stainless steel, such as stainless steel washdown motors, are constructed with motor enclosures made from stainless steel so that water and chemicals will not harm the motor.
Motors that are constructed of these types of metal and design will be utilized in environments in which the motor is subjected to daily high-pressure cleaning. Motors have the same specifications as each other, but you can place them into different types of motor enclosures; thus, a motor can have different IP ratings based upon the type of motor enclosure into which it is place. Another method of rating motors is the NEMA rating system.
Unlike the IP rating system, NEMA ratings include tests that measure the motor’s resistance to corrosion and icing, but the IP rating does not include tests for corrosion or icing resistance. For instance, an IP 66 motor may pass the tests for a NEMA 4 rating for protection against dust and water, but may not pass the tests for gaskets or icing for the same NEMA 4 rating. Thus, you cannot assume the rating of a motor based upon either the IP rating or the NEMA rating; each system has slightly different test.
The IP rating can have an impact upon the cost of the motor. Should you choose an IP rating that is too low for the environment in which you plan to utilize the motor, the motor will fail and lead to expensive downtime costs. However, should you choose an IP rating that is too high for the motor, the motor will cost you more money due to the higher price of motors with higher IP ratings, as well as the additional cost of the motors increased weight.
Therefore, you should determine the worst environmental condition in which you will utilize the motor, and ensure the motor has an IP rating that account for that environmental factor. Additionally, it is important to ensure that the motor can handle temperature changes. Motors that are exposed to high temperatures will experience the same condensation issue as motors that are exposed to high amounts of water; the motor enclosure may not prevent water from entering the motor, but if the motors temperature change, the moisture in the air may condense into the motor.
Motors with high IP ratings may contain heater inside the motor enclosure that prevent condensation from forming within the motor enclosure.