What maintenance to do is a challenging question for redundant equipment maintenance of any sort, not only for power generation plants.
Like all maintenance, redundant equipment maintenance is done because the business risk justifies it.
Below is a question sent to us about choosing and justifying redundant equipment maintenance when the entire operation is a redundancy in their business.
How would I carry out a maintenance program in a power plant which hardly operates because we are getting our source from a sister country?
Thanks in advance, Salifu
You do not have a maintenance problem. You have a business risk management problem. Maintenance is done to manage and reduce business risk. You need to know the complete range and consequences of the risks to your company from the unavailability of the power plant. Until risks are priced, you are not able to make sensible decisions on what maintenance to do and what not to do.
Someone who knows how to properly determine and measure individual and total risk needs to quantify in money value the range of business risks if your power plant is not available when it needs to be used. Once you know the financial value of the risks, you can work out how much maintenance cost to spend each year and each month to (hopefully) prevent the risk events occurring that stop the plant operating when needed.
The power plant that your question applies to is fundamentally a stand-by that starts when the “duty” power station is unavailable. The common practice for maintaining stand-by equipment is to run-it-up on a regular schedule and ensure it starts and behaves correctly. During operation, observe the state of critical components and assemblies to gather information on their condition and capability to be serviceable in future when the plant is needed to run in earnest.
The point of running stand-by plant and equipment is to prove it has not yet failed. A stand-by that is failed, but the failure is unknown, has suffered a “hidden failure.” You never know you have a hidden failure until you need to use the equipment. If it’s an item of last resort that must function when called-on, then it’s got to work properly with total certainty. Hidden failures can produce massive risks. Think Chernobyl size risks. To protect against hidden failures you do functional failure tests on a regular cycle. At each successful test you have evidence that at that point in time the item worked properly. Starting-up a stand-by power station is a functional failure test to check for hidden failures in any of its equipment.
Firing up an entire redundant power station to test its availability is probably unnecessary. It’s more practical to check items of plant are operational, which when all equipment is tested confirms the power station’s availability and readiness to operate. It’s likely that you can develop a schedule of equipment that are separately operated, and when the testing schedule is finished you are confident the whole power station, as a single power generator, works properly.
All the very best to you,
LRS Consultants Global