Data Center Generator Maintenance & Sizing Key To Preventing Expensive Repairs, Increasing Lifetime Of Unit

Wet Stacking Leads To Costly Repairs & Downtime For Data Centers

Routine maintenance is key to smooth engine operation, and it’s no truer than when it comes to standby generators. Like many engines you count on day-in-day-out, an industrial generator that you rely on for standby power, should also be maintained, well-serviced and exercised regularly to ensure it’s in peak condition no matter your industry.

Data centers seem to be the top segment in our industry where generator maintenance is overlooked but actually needed more often. The reasons, data centers do not pull a large amount of load or the center invested in too many or too big of a unit for what they do.

The following is an article from our friends at Kohler and some of the issues found with diesel generators when they are not properly maintained, run or load tested on a regular basis. The main problem seems to occur at data centers when a generator isn’t run near maximum load or maintained regularly. One problem seen often is diesel generator wet stacking.

“Wet stacking or engine slobber is a costly and time-consuming issue that data center operators must deal with,” said Brad Meissner, Kohler product manager. “Most commonly found in generators run at 30% of capacity for extended periods of time, wet stacking is a buildup of unburned fuel in the exhaust system. The result is reduced engine performance and potentially a shorter lifespan. The most common solution to wet stacking is to connect an external load bank, though that comes with added fuel costs and emissions.”

Meissner explains the benefits of no-load exercising of diesel generators with data center operations at the forefront of this problem in a recent white paper, highlighted below.?

Wet stacking typically occurs when generators frequently run with little or no load because the generator is improperly sized for the power required or because adequate load is not available during the exercising period, according to Meissner.

Data center providers frequently have insufficient load and incur the added costs and time to connect an external load bank with resultant higher emissions and extra fuel costs, added Brad. But you must ask yourself, is burning extra fuel and spending a small amount of money for a load bank/regular maintenance going to cost as much as replacing the generator prematurely? Definitely not! And of course, Generator Source can handle service and the required load bank service.

“When generators run at less than 30% of capacity for extended periods of time, their engines are unable to sustain the optimal operating temperatures needed to burn fuel completely,” says Meissner. “Pressure inside the combustion chamber falls below crankcase pressure, and piston rings can’t expand enough to seal the space between the pistons and cylinder walls.

“So wet stacking occurs,” continues Brad. “Fuel injectors get fouled up, it causes excessive valve guide wear, and can lead to damaged pistons, piston liners, and rings-- among other problems with emissions. In addition to shortened engine life and higher maintenance costs, operators may also run afoul of emissions regulations, which have grown tighter in recent years.”

But what about new emissions technology?

“Wet stacking has become a more critical issue in recent years as diesel generator makers have incorporated new emissions control technologies into their products,” adds Meissner. “These include diesel oxidation catalysts (DOC), selective catalytic reduction (SCR) components, and diesel particulate filters (DPF).

“Such aftertreatment technologies are all negatively affected by low-load operation, which can cause emissions targets to be missed,” wrote Meissner. “SCR and DPF components, in particular, must operate within a specific exhaust temperature range.”

How Can Data Centers Prevent Wet Stacking?

The obvious solution for wet stacking has been to exercise a generator at 30% of the rated capacity once a month to burn off unused fuel and prevent buildup, according to Meissner. “The simplest way to avoid wet stacking during monthly exercise is to run the generator at the manufacturer’s recommended minimum loading.

“Because data center operators do not wish to transition to building load, the monthly exercise requires use of a load bank, which can be used to supplement or perform loaded maintenance activities,” added Brad. “This load-bank testing artificially boosts the load placed on the generator to burn the accumulated buildup.

“Most generator operators recommend that load-bank testing be done monthly for a minimum of 30 minutes runtime,” wrote Meissner “In addition to runtime, data centers also need to consider the time it takes to set up the load bank. For a typical data center facility using between five and ten generators, that can add up to a significant time commitment by operations personnel, not to mention fuel consumption.”

It's time consuming to load test generators each month to ensure they are maintained and not falling victim to wet stacking. That’s where Generator Source comes in. Let our field services team deal with monthly to-dos allowing you and your team to focus on the bottom line.

The other big problem at data centers is they often invest in too large of generators for their needs. Working closely with industry experts and electricians will give a company a more concrete idea of just how much power they need. Click here to see how sizing is calculated or call us at (877) 866-6895.

Don’t Let Your Generator Fail

So, there you have advice from an industry product manager about wet stacking and how to avoid driving your generator into the ground. Our field services team can ensure your generators never miss a beat and can take the monthly, yearly generator exercising and maintenance off your plate. Our teams operate in Colorado, Southern Wyoming, Florida, Georgia and Austin, TX. Click here for more information.