Power Up: When your generator doesn't carry a 30% load
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February 7, 2019
Particularly for smaller facilities (or, I suppose, big places with multiple generators), consistently meeting the requirement for a 30% load during monthly generator testing activities can be a bit of a chore. And it can result in having to consider performing an annual load test at increasing loads, which usually means that you have to contract out that extra load test (and they ain’t cheap, all things being equal).
But if you look at NFPA 110-2010, it does provide another means of complying with the monthly requirements. Section 8.4.2 indicates that “(d)iesel generator sets in service shall be exercised at least once monthly, for a minimum of 30 minutes, using one of the following methods:
- Loading that maintains the minimum exhaust gas temperatures as recommended by the manufacturer
- Under operating temperature conditions and at not less than 30 percent of the EPS standby nameplate KW rating
Note: The 2019 edition of NFPA 110 removes the word “diesel” for the text, which opens things up a bit for folks who don’t have diesel generators.
So, the trick becomes how best to capture the exhaust gas temperatures, so you are assured of a compliant test and not being at risk for wet-stacking during the generator test. Fortunately, when it comes to emergency power system information, there is no better source than the good folks at Motor & Generator Institute (MGI). Dan Chisholm and the folks at MGI have just the thing to get you started and even if you’re an experienced generator owner/operator, I would encourage you to check out the information here.
It might just give you a leg up on the survey process!