That issue wouldn't be controller related. If in fact brownouts are occurring the system (and many other control systems) would most likely be getting an under voltage fault. Typically the frequency drive (Magnitech) will pick up that power loss and record it as an under voltage fault. However, those same under voltage issues could be simply an individual building issue and not necessarily a grid problem. Loosing 10% of your power, or more, for more than a minute is technically a brownout. Though these issues can be directly related to the building and or installation. Things to look for would be the mainline wire's capacity and the length of that run, other equipment sharing the same power, and believe it or not loose connections. What's more if the building has poor power and everyone turns their AC on during a hot day, the voltage can drop and cause a bottle neck at the transformer restricting the elevators needed power.

Moving forward, I realize i'm rambling here although, I do want to share another possibility that could be causing your control issues. Due to the fact SmartRise controllers are entirely serial link, they are also very sensitive to harmonics or electrical noise. Check all connection, add/replace shielding or shielded wires and be sure every piece of equipment is grounded.

I've installed many of these controllers and have found verifying all of the above typically results in the problems being found.

Good luck hope you find the issue.