'Surge arrester' is to blame this time

A citywide MAX disruption was caused by the failure of a replacement part that was, ironically, designed to prevent a massive chain-reaction power outage like the one that threatened Monday night's big Portland sports commute, TriMet says.
The fried "surge arrestor" near the Steel Bridge was replaced just a couple hours before tens of thousands of Portland Trail Blazer and Winterhawks fans needed to use the light-rail system to get to playoff games in the Rose Quarter.
The system of transformers and lines that carries electricity to the MAX system is extraordinarily complex, Altstadt said. "There are dozens of possible points of failure, and many potential
errors that can cause an uneven power flow," she said. "In today's system of electricity distribution, power surges are an unavoidable occurrence. The surge arrestor is the mechanism that is designed to control these occurrences and we have numerous arrestors throughout the system."(as we can see Ms Altstadt obviously has an advanced degree in electrical engineering)

If the collapse of MAX from Northwest Portland to Gateway Transit Center seems familiar, it should. On May 6, 2013, one of the old surge protectors on the bridge failed, causing one of MAX's worst non-weather-related meltdowns in recent memory.
In case you're wondering, TriMet maintenance records show that MAX failures and delays have been on the decline.Portland MAX meltdown: TriMet says small replacement part caused Monday's massive power outage | OregonLive.com