Motor Load Calculations, Part 2

You should have a record of the nameplate data for every motor in your facility. For over two decades, itís been the rare facility that doesnít manage the maintenance of its physical assets via a Computerized Maintenance Management System (CMMS). So, weíll assume youíre using a CMMS.

The typical CMMS allows you to record relevant data values of an asset, such as a motor, via a text field interface. With todayís inexpensive digital cameras, you also want to store an image of each motorís nameplate. If your CMMS canít store jpgs or other image formats in its database, use an external system but record the filenames in your CMMS.

So now that youíve made sure to go through all this effort to have the nameplate data duly recorded two different ways, guess what? Youíre not going to use them to perform the motor load calculations, unless the application meets the exceptions of 430.6(A)(1). Instead, you will use Tables 430.247, 430.248, 430.249, and 430.250 as appropriate. All of these are at the end of Article 430.

You can easily pick the wrong value from a table, and not know it until fixing the mistake is costly. While you wonít use the nameplate data to actually perform the calculations (unless an exception applies), always compare the table values to the nameplate values and look for any sizeable difference.

You will also need the nameplate data for other purposes (e.g., replacement), and you may need it per one of those exceptions.

ę Part 1 |†Part 3 Ľ |†Source: Mark Lamendola |†Mindconnection

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