We’ve discussed a few different aspects of Emergency Power Supply Systems in these past weeks (here and here), and hopefully I’ve managed to either refresh some important concepts for you or even given you some direction for further research. What we haven’t covered yet, is what happens in the event of negligence. The primary enemy of an efficient and reliable system is an inadequate maintenance program.
For every “what if?” that arises, rest assured that there is an answer. And more often than not, the answer usually begins with, “well that shouldn’t happen if…” And that “if” can be a lot of things, but the vast majority of variables relate back to maintenance. When you’re dealing with a system comprised of several different integrated pieces of equipment, a lot can happen in the chain of command. When certain aspects of maintenance are neglected, those areas become likely candidates for failure.
It is important to keep in mind that while there are many different configurations for an EPSS, they all still require a team of skilled and qualified professionals to maintain them so that they operate as intended. For now, we’re going to focus on your Automatic Transfer Switch. The long and short of it is that when you do not maintain your ATS, it can fail. And in all honesty, even when you do maintain your equipment, there is a chance of failure. But your goal as a maintenance professional or facilities manager is to limit that chance of failure to the lowest possible percentage. And the more you know about your equipment, the easier this task will be.
Let’s consider all the areas and steps where your ATS can encounter problems or fail.
When your equipment senses the interruption of utility power
Sending a signal to your generator to start
Sensing that your EPS is available to supply power
The actual transfer of load to the generator
Sensing when utility power is restored
Making the transfer back to utility power
Sending a stop signal to the EPS
If this process sounds familiar, it should. A lot can happen during normal operation to moving components, relays, contacts, connections, and controls. You wouldn’t care as much if you discovered that your ATS needed new components during a routine inspection. But during a real loss of power scenario, the integrity of your equipment matters a great deal more.
Now let’s get into some more specific examples. The following are common issues that we encounter when performing tests and inspections on different ATS brands. If you have any of these brands at your facility, these would be great places to start looking for problems.
Asco: Timing cards can go bad and lose their ability to transfer within the programmed timeframe.
Kohler: Parts of the motherboard can short out and older style relays can wear down or acquire a build-up of dirt and cease functioning.
Onan: The operator motor can become stuck if it's not cleaned properly, causing it to burn up.
Russelectric: Operator motor can eventually fail and older relays tend to fail over time and lose their ability to reliably initiate transfer.
Westinghouse: On this double breaker switch, the gears responsible for operation can become stripped and the transfer linkage can break. The timing cards can also fail.
While it’s nice to be aware of what your ATS is likely to do when routine maintenance is neglected, it’s also important to understand the distinction between poor ownership and aging equipment. We’ll cover aging systems in our next article, but I hope that I was able to offer you some clarity when it comes to why every last step of maintenance is critical to the success of your EPSS. As always, feel free to contact me with any questions or to find out more about our recommended maintenance practices.