Hey Folks,

Just a some info sharing if you're experiencing a similar issue at some point in the future-

Background: Our frame 7AE DLN unit was tripping off on flame out whenever we attempted to transition out of premix and back to primary firing mode. It was a tricky problem to troubleshoot as out unit spends 99% of its time running in premix.

The initial conclusion what that the ignitor transformer was weak and wasn't producing enough spark.

The actual issue ended up being ignitor misalignment, the ignitors in cans 1 and 10 were not protruding past the combustion liners. I'll see if I can attach some photos below.

Cheers,
Jeff

 

jeff3300, nice find on this. Concrete boroscope pictures like this are few and far between. It is kind of surprising that whoever put this machine back together after a CI? or hot gas? did not check this prior to putting the primary fuel nozzle back on. I am guessing both plugs and possibly the spark plug ball joints were replaced during this maintenance activity?
Glad you were able to find the issue, hopefully without replacing too many parts. Unison is definitely proud of the pricing for the ignitor and the plugs themselves for sure.

 

Hi Mike,
You are correct, the ignitor assembly was initially replaced and misaligned on a hot gas outage- the annoying thing was the machine was able to crank and fire just fine when coming up from a stop so we never realized there was a problem until much later when coming down for some unrelated maintenance.

The misalignment was discovered and corrected at the following outage.

Cheers!

 

Jeff, thanks for the feedback!!!