Lakeland Electric officials in Florida are investigating potentially significant problems that were recently discovered at McIntosh Unit 3 regarding how switchgears and other equipment might respond under “emergency’ events.
The Florida municipal utility acknowledged the problem in a March 22 news release posted to the Lakeland website.
“Engineers have determined the McIntosh Unit 3 Power Plant 480 Volt (480V) and 4160 Volt (4160V) switchgears, circuit breakers, and motor control centers* perform exactly as they should in a normal operating condition, but some do not meet the rating requirements for the most extreme emergency electric events, such as power cable failure or severe motor failure,” Lakeland said in the news release.
There are 360 total switchgears, circuit breakers, and motor control centers rated for 480 Volts (480V) and 4160 Volts (4160V) at McIntosh Unit 3 Power Plant. One hundred sixty four (164) of these are considered “underrated” for the most extreme events.
In researching the issue, it was discovered that there was an error within the original design plans for the McIntosh Unit 3 facility, created over 34 years ago.
Engineers became aware of the issue when an “Arc Flash Study” was completed in May, 2012. The study was done to identify the correct type of safety clothing and equipment required for workers in different parts of the power plant. The identification of the underrated circuit breakers was a part of this study.
The study recommended the installation of Current Limiting Reactors (CLR) at a cost of roughly $2mon the 4160 Volt switchgears to mitigate the issue. It was believed at that time by our engineers the CLR would compensate for the underrated breakers and there was no immediate safety concern.
Therefore, in July, 2013 Lakeland Electric began the process to design and purchase the CLR. The engineering contract was awarded to a consultant in January, 2014.
In October, 2015, the consultant released a re-evaluation report and determined Lakeland Electric could forego installing the CLR with some minor changes implemented on the 4160V system, but would now need to address the issue with 480V system.
After evaluating the consultant’s report, utility engineers advised Lakeland Electric leadership of the issue last week and this week the engineers have recommended a three stage mitigation plan:
- Immediate Solution: Ensure the safety of the workers at the power plant by having them wear higher rated protective clothing and equipment and cordoning off the areas around the underrated equipment.
- Intermediate Solution: Engineers will identify and implement viable quick-fix improvements as they work in parallel on the permanent solution.
- Permanent Solution: Lakeland Electric is forming an internal team of engineers, along with engineers from the consultant firm, to create a new and permanent solution to the issue, identify a project timeline, and quantify a budget. The team will work to have a solution as soon as possible, but no later than this fall.
“This issue does not impact our customers’ safety and it is anticipated that the expenses will be covered by our projected revenues without a base rate increase,” Lakeland said in the recent news release.
An online news report from a Florida television station indicated that the McIntosh plant is currently out of service, although it is currently expected to resume commercial operations later this spring.
The entire McIntosh power plant is a 990-MW facility with various generating units that can burn coal along with natural gas, oil, and fuel oil. Unit 3 is listed in GenerationHub data as a 364-MW coal unit.
An attempt to contact a Lakeland spokesperson was unsuccessful on March 24.