The most critical element that shapes a panel design project must be addressed at the very beginning of a project: where is the completed unit going to be installed? This very basic question dictates the type of protection the enclosure must provide to the equipment. The electrical switchgear inside the enclosure must be protected from the environment, and the plant and people around it must be protected from electrical dangers.
There are three types of external threats capable of causing equipment problems:
- Solid objects, which can range from large pieces to dust
- Water, which can come with varying levels of force and multiple directions, and
- Mechanical impact.
These threats have been quantified and are described in detail in two standards: IEC 60529 (IP) covering solids and water, and IEC 62262 (IK) covering mechanical shock. Temperature is also a consideration and covered later in this series.
As Table 1 shows, the IP rating uses a two-digit number. The first numeral describes the degree of protection from solids and the second from water. The higher the number, the higher the level of protection.
The IK rating is similar but has only one number between 0 and 10. Again, the higher the number, the greater the level of protection. Most industrial-grade enclosures are IK08 or better.
What level of protection is necessary?
One approach is to build every enclosure for the highest protection ratings; however, this adds a high level of complexity and cost. Customers not needing high levels of protection will not want to pay for such an enclosure. It is important to offer enough protection without going too far.
In most cases, customers are very specific about their final use environment, in which case the panel builder should choose the most optimized protection level to meet the requirement. Schneider Electric offers helpful information on its Partner Portal, including a detailed instruction set which will guide you through the evaluation, step by step. It considers basic questions such as the environment in which the enclosure will be placed and the nature of the company. It also begins the process of making other choices, such as enclosure size and other appointments.
Where situations are not clearly defined, discussions with the customer will be important to answer the full range of questions. The next post in this designing and building and electrical panel will discuss enclosure location, fixing and cable entry.