How do the NEMA and the IEC design of the electromechanical motor control devices differ? When it comes to business, flexibility is an important asset. If you manage to apply either NEMA or IEC design products, that means that you have the flexibility to adapt to the local traditions as well as the product supply no matter where you are in the world. This will enable you to have the best advantage of local accessibility as well as expertise which can be a very important competitive cutting edge when it comes to the global economy. Before you decide to opt and apply one among the two, let us analyze the differences that exist between them.
They have different philosophies
The NEMA normally emphasizes many robust designs that can be used in different applications. They are easy to select and can be applied in broader applications. There are two fundamental basics within the NEMA design philosophy.
The NEMA Industrial Control Standard (ICS-2) governs the designs of NEMA motor control products. This is a formal document that consists of all the essential information regarding the design of electromechanical NEMA design motor control.
On the other hand, IEC philosophy emphasizes application and performance. To select the IEC devices, you have to have a more understanding of the application as compared to when you are selecting the NEMA devices which are general-purpose devices. For example, when you are selecting the IEC contactor you need to know the motor load, the full load current, as well as the duty cycle.
This requirement is what might bring a setback in some of the situations when it comes to clients, but for the Original Equipment Manufacturers (OEM) is an advantage. For example, an equivalent HP-rated IEC device tends to be smaller as compared to the NEMA same rated device. This is what brings a significant advantage to the OEM manufacturers. Besides, the IEC devices are cheaper as compared to the NEMA.
The features and benefits of NEMA
The easy selection is the basic advantage when it comes to the NEMA design starter. To choose a NEMA design device you only need to know the horsepower as well as the voltage of your motor.
The NEMA products are easily serviceable as compared to the IEC products. Besides they provide front access to the internal components easily. Unless there is a need for replacing the entire device, contacts, and coils of different sizes can be repaired easily without having to remove the device from the panel.
Besides the reserve capacity is among the things that make the NEMA products to be among the most considered. They are normally designed to work widely across different applications. That is why they are normally referred to as the general-purpose devices as opposed to the IEC devices which are designed for specific applications.
The NEMA design devices consist of interchangeable heater elements. In fact, different ranges of thermal units are available for different overloads. This is what makes the NEMA product so attractive on most of the construction applications where there is ultimate motor use or when the actual motor nameplate cannot be identified.
The motor control center (MCC) or the enclosed package solution is the tradition of NEMA. Normally most of the NEMA devices are sold in the form of starters in either open design or in different enclosed designs.
The features and benefits of IEC
The wide number of IEC contactor sizes enables the user to be able to closely match the contactor to the application or load. Different from the NEMA where the available sizes are standardized throughout the industry, the number of different contactor size ratings varies with the OEM.
Normally the IEC starter is half the size of the same ratings of its counterpart (NEMA). This means the physical differences between the IEC and the NEMA are significant.
The IEC devices are so modular as they can snap within a 35-mm or within larger sizes, such as a 75-mm DIN rail. This removes the need of drilling holes and mounting each component independently. That is why installing them into the panel is quite simple.
As compared to the NEMA starters which are normally sold as fully assembled, the IEC starters are normally sold as components allowing you to assemble them yourself. You have a chance of selecting only the parts that you need and connect them together without a need for using tools.
Besides, as compared to the NEMA starters, the IEC thermal overload relays normally consist of fixed thermal elements which have an adjustment range that might need replacing the entire overload relay in case of a significant motor FLC changes due to application needs.
Most of the IEC contactors are used in group installations, as well as NEC 430-53 handles this application facet. But this is not identical to IEC contactors as you can install any starter via using this method.
The IEC products are normally sold to OEMs, and then they are installed within the application where many devices are needed to handle different operations of the machine.
The type 2 coordination refers to the IEC standard that can be used to a NEMA design product as well.
The type 2 protection makes sure that there is a use of the correctly rated and a class of fuse with the contactor or starter. This protection type needs that, after the occurrence of a short-circuit condition testing, the starter or contactor must be capable of being reused without having to replace any component or part. Besides, no significant alteration is allowed within the operating time-current features of the overload relay. This is known as a coordinated protection standard when it comes to short-circuit protective components, contactor, or the overload relay.
The rules are entirely the same for both the NEMA and the IEC design devices. For the type 2 coordination, the traditional higher withstanding rating of the NEMA design starter offers a wide selection of short circuit protection appliances. The type 2 coordination having the IEC style devices will offer identical coordination as well as the degree of protection, but the selection of the fuse classes might be more limited. For the short circuit currents of u to 5000 A. The Type 2 protection when it comes to the IEC rated motor starter would need Class RK5, J, CC, or RK1 fuses. For the short circuit currents that can go to up to 100Ka, CLASS RK1, as well as the CC fuses, are needed.
In comparison to the NEMA design devices, the IEC style devices are more disposable as compared to NEMA devices which are more serviceable. The fact is the IEC devices that are below 100A are normally considered as being disposable as they can be isolated from the DIN rail and thrown away while being replaced with a new product in a matter of few minutes.
The self-protected starters are the new category that involves starters as defined in a UL 508-E. normally that kind of a starter has a contactor, a short-circuit, and an overload relay protection. The device also undergoes a unique procedure, one that moves beyond that of a conventional combination of the motor controllers. This procedure is responsible for testing the starters at different fault levels, hence verifying that coordinated protection that is identical to Type 2 is offered.
Training is the basic difference that exists between the NEMA and the IEC design products. This is due to their application-specific styles. The IEC devices need a more understanding of the application performance when it comes to the device selection process. But when it comes to NEMA you do not need many of the variables that are needed when selecting the IECs devices.
This does not mean that you will need to have extensive training before you can select an IEC product. It only means that your training should be specific in nature. To select an IEC products needs more time as well as knowledge to make sure that the selection complies with the application.
Once you have selected the exact device, then everything will go as intended. Remember that both the IEC and NEMA design devices will produce identical outcomes.