RDS successfully troubleshoots legacy Load Commutated Inverter (LCI) startup issue
A customer turbine with a difficult-to-diagnose problem brought GE Vernova’s RDS team to the rescue.
Overview
Our customer attempted to start their 7FA unit several times, but it would not get up to purge speed.
The challenge
Despite having all the startup permissives met, the turbine would trip within seconds of attempting to start. The only alarm was a generic Static Starter fault indication. The customer was unsure how to troubleshoot and decided to contact the GE Vernova Controls Remote Diagnostic Services (RDS) team.
The solution
GE Vernova's RDS team was able to solve a difficult-to-diagnose legacy Load Commutated Inverter (LCI) startup issue for a 7FA gas turbine within 4 hours—saving this customer potentially hundreds of thousands of dollars in potential downtime and repair costs.
Outcomes
Solving issues in both new and legacy systems
GE Vernova’s RDS team set up a trend to record data at the customer’s site using the remote services gateway (RSG) workstation while the customer attempted another start. During the start, the RDS team noticed that a particular fault signal picked up and locked in – something that is not always easy to find even in newer systems, let alone older systems like this one.
These systems can be highly difficult to troubleshoot. The documentation is not always clear or easy to follow and may not even exist. Additionally, alarms on older systems can be generic as was the case here.
The team knew that this particular fault only occurs when the system does not detect a close feedback within a certain period of issuing a close command to the LCI source breaker. From that point, the team went through the software and drawings at the site to trace the signal path back to either the wiring or auxiliary contacts associated with the 52SS breaker. Upon inspection, an issue was found with one of the auxiliary contacts and, once fixed, the unit started up normally.
The RDS team diagnosed and recommended a successful resolution to this customer’s legacy system within four hours. Without this support, it likely would have taken several days or more to send a field engineer to site to troubleshoot the issue in person, resulting in additional downtime and loss of availability.
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