A cross the country, linemen work year-round on live lines and energized systems. Electric utilities, however, face one key challenge when implementing energized work method: training their linemen to work live in a safe, controlled environment before they begin jobs in the field.
For example, at Delmarva Power, an Exelon company, line crews work on energized lines daily to provide safe, reliable service for the company’s 520,000 electric customers in Delaware and Maryland. Every day, the line crews make enhancements to the local energy grid, and when outages do occur, they work as safely and efficiently as possible to restore service to customers. As a result, this daily work does not leave a lot of room for on-the-job training.
To prepare its apprentices for a career working on live lines, Delmarva Power knows it must provide a comprehensive training program that includes creating a safe, energized experience, before putting linemen in the field. In the past, Delmarva Power tried several different training systems, including a neon voltage system and simply pretending its training yard was energized. However, neither setup provided the complete experience or training environment needed to efficiently and effectively get its apprentices ready for working in the field and serving its customers.
Keeping Apprentices Safe
To provide real-world experience on live lines for its apprentices, Delmarva Power invested in the Timpson Training Unit to energize the aerial lines in its training yard. The system, which was invented by two lead journeymen linemen/trainers and other developers, can expose the trainee to non-lethal currents, and, similar to a GFI, it trips out when a mistake is made.
The Timpson Training Unit also can track who made an error, which is nearly impossible when training on de-energized lines. In addition, the system allows utilities to energize multiple transformers and other yard equipment, allowing several trainees to work on different tasks at the same time.
Once the yard is energized, the unit can measure current changes down to 60 mA and automatically de-energize the yard in less than 60 ms with a current threshold of 1.5 mA. To keep the apprentices safe while they are working in the energized training yard, the unit includes several layers of redundant safety features. Once the system completes self checks of the safety systems to ensure they are functioning properly, then the transformers in the system backfeed the training yard to 7,200 V.
The system trips at 1.5 mA to protect the apprentices. To know precisely when to trip, the system measures the excitation current of the transformers and lines in the training yard to establish a baseline and then adds 1.5 mA on top of this current. For example, if an apprentice makes a mistake by coming into contact with a wire, the unit detects 1.5 mA above the established baseline excitation current, and the entire circuit trips out. In addition, visual and audible alarms go off, alerting the apprentice and the instructors when the mistake was made.
A restriction bypass key allows trainees to complete tasks such as energizing the second half of the training yard. This feature allows the apprentices to throw in cutouts without the system tripping out when it senses additional current. When the task is complete and the bypass is switched off, the system re-establishes a new baseline and the apprentice can continue working.
Offering Training Benefits
In Delmarva Power’s training yard, as well as across the company, safety is a top priority. The new equipment allows the employees to practice working on high-voltage power lines in a safe, controlled environment, while still experiencing the pressures and consequences needed for a successful training experience.
By training with real-life scenarios, the utility can productively engage and train its apprentices faster than in the past, when they could only work on de-energized lines and equipment in the training yard. Trainers in the company’s yard know they can talk about the consequences of not following procedures, work practices or safety rules all day, but, ultimately, it is a much more impactful and effective lesson for apprentices to experience the consequences first-hand in a safe, controlled environment.
In Delmarva Power’s experience, the energized system has changed the way the apprentices approach training. The system helped create a training environment with greater focus and dedication, ultimately creating a better learning environment for all apprentices.
Everyone can learn from their mistakes and the mistakes of others. To that end, the system helps identify those small mistakes, so the trainers can use them as teaching opportunities. The Timpson Training Unit catches the small mistakes that instructors might not see, which creates more opportunities for teachable moments. The apprentices receive immediate feedback and know exactly when the mistake was made and why.
As an added benefit, the system also has created an element of friendly competition among the apprentices. In this new environment, all the apprentices want to better themselves, and they all are constantly working to improve their performance and knowledge. Also, none of the apprentices want to be the one who triggers the alarm, indicating that they blew a short.
Investing in Another System
After investing in one system to energize its overhead lines, Delmarva Power recently purchased a second unit to energize its underground portion. By obtaining another unit, it expands the utility’s ability to train apprentices on an energized system.
For example, the overhead linemen perform URD switching as well as terminate URD. The second unit, however, will allow Delmarva Power to train employees in energized padmounts, energize an overhead single-phase section of the training yard and energize a transformer to energize a secondary bus on the service wall.
So far, the utility has received nothing but positive feedback from its employees. Supervisors and seasoned workers appreciate that the new apprentices can practice working on energized conductors in the training yard so they are better prepared for the jobs in the field on day one. The utility can then develop a professional workforce who is ready to work safely and efficiently from the first time they step foot in the field. ♦