Motor Load Calculations, Part 2

You should have a record of the nameplate data for every motor in your facility. For over two decades, it’s been the rare facility that doesn’t manage the maintenance of its physical assets via a Computerized Maintenance Management System (CMMS). So, we’ll assume you’re 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 today’s inexpensive digital cameras, you also want to store an image of each motor’s nameplate. If your CMMS can’t store jpgs or other image formats in its database, use an external system but record the filenames in your CMMS.

So now that you’ve made sure to go through all this effort to have the nameplate data duly recorded two different ways, guess what? You’re 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 won’t 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.

« Part 1Part 3 » | Source: Mark Lamendola | Mindconnection

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