There is a sweet spot between underdesign and overdesign for redundant controls. If you underdesign the backup, there could be a risk of failure or spill. For example, many controllers, including the MPE controllers, can perform various types of backup control as well as serving as your main controls. It wouldn't get more simple than that - no extra equipment in the control panel. But what happens if your controller gets hit by lightning, taking the whole unit out? Then both your main and backup controls are toasted. So good engineering design practices dictates that the backup control be a separate function from the main controls.
On the flip side you can overdesign by putting in redundant controls that are costly and too complex – not easy to troubleshoot. In other words, you can have redundancy have still have a bad panel design. The key is keeping the redundant controls simple, effective, and trustworthy. Back-up control is ultimately the key to the reliability of any pumping application.
Now I know there's a lot of stations out there that don't have any redundant controls. Perhaps the backup controls failed over time, or they were "robbed" from the station to get another one in town going and then never replaced. Perhaps they were never in the original design. For whatever reason they don't have backup controls, those are the stations that I worry about the most.
Sure, it’s just a lift station – until fines are incurred and/or you’re running the lift station in hand all night/in sub-zero temperatures and/or you have to call for emergency service. All of those aren't really fun times to have, especially when they can easily be prevented. Fines, the cost of running in hand, or one time of emergency service far outweigh the cost of redundant design and implementation.
Do you have stations where you're not sure what your backup system is? This is what we can do for you:
- Determine the type of backup
- Ensure backup control is included where needed
- Specify a difference in technology between main and backup control
- Call for separate power sources when justified
- Analyze for Single Point failures
- Installation of redundant controls
- Is it simple?
- Does it have backup control?
- Have you minimized the number of items that could realistically bring the lift station down?