Upgrading Legacy Power Systems
EP Editorial Staff | June 13, 2016
A Q & A with Danita Knox, GE Energy Connections.
When’s the best time to upgrade a power system? According to Danita Knox of GE Energy Connections, Atlanta, it can vary. Consider the following situations as ideal opportunities:
- if a facility had or is planning a significant expansion that might affect overall power-system loading
- if a recent arc-flash study revealed significant incident levels or danger of exposure for electrical workers or operators
- if personnel are having difficulty locating replacement and spare parts for the site’s electrical system
- if plant personnel desire better monitoring of the overall power system.
Once the decision has been made to move forward on an upgrade, what’s next? We asked Knox for some insight into what facilities can do to make these projects go smoothly.
MT: What trends in power-system upgrades are you seeing among older installations?
Knox: One trend involves customers replacing older electromechanical relays, meters, and trip units with newer digital “smart” equivalents. This provides a single, multi-function device that incorporates communications (local and network), event logging, and monitoring (graphical screens and remotely using web tools). Critical applications include upgrading to smart switchgear offerings that feature built-in monitoring, diagnostics, redundancy, and remote-control capabilities.
Facilities are also adding devices to their power systems that help locate workers further away from the equipment they operate. This is done, in some cases, by adding remote racking devices to existing breakers or using robot-type devices to operate equipment from a safe distance. We’re seeing more sites updating old fused devices, such as a load interrupter switch, with faster-operating vacuum breakers and relay equivalents that reduce arc-flash incident levels.
Finally, with limited budgets for large capital projects in many plants, it’s essential for them to find ways to extend the life of their existing equipment. To that end, facilities are often looking at retrofit options.
MT: What tips do you have for sites that are embarking on a power system upgrade?
Knox: Ideally, it helps to start with a comprehensive arc-flash study. This can provide remediation suggestions on how to reduce arc-flash exposure levels and improve personnel and equipment safety. To begin an arc flash study, an operation needs an accurate schematic or diagram of the facility. Plant personnel familiar with the electrical system can usually collect the information needed to build this diagram. An accurate schematic also provides critical information that can be a great tool to develop safe and proper LOTO (lock-out/tag-out) practices.
With a thorough arc-flash study, plant operators can then evaluate multiple options that help define steps to start upgrading a power system. Upgrade projects can be prioritized into smaller projects, depending on employee exposure, process needs, available outage periods and budget constraints.
MT: To get management buy-in, what’s the best way to estimate the return on investment (ROI) and benefits of an upgrade?
Knox: Often the need to upgrade is based on some failure or electrical incident that has caused downtime, equipment damage, or, worst-case scenario, employee injury.
When you look at the cost associated with downtime and/or injury, it’s fairly easy to calculate ROI if the project is done in a phased approach. Some trip unit, relay, and breaker upgrades can be done under the threshold of a maintenance budget.
MT: Are there any budget-friendly ways to upgrade a legacy system?
Knox: Yes, there are. It’s important to look at upgrade options that solve the most problems with minimal disruption to plant operations and equipment.
Consider, for example, if a single upstream breaker/relay combination in the facility can reduce arc-flash exposure for downstream feeder breakers without upgrading each breaker. Does the site have unused spare breakers that can be rotated out with a local service shop for upgrades that can later be installed during a short outage?
If a plant is updating old relays and meters, it should get new doors with new components prewired. This allows a shorter outage while equipment is being replaced. Also, “replacing the guts” in the existing compartment in a field outage can help reduce upgrade costs, assuming the new equipment has been pre-determined to fit the compartment and it can be easily wired. MT
Danita Knox is senior product manager for Power Delivery Services within GE Energy Connections, headquartered in Atlanta.
Steps to a Successful Power-System Upgrade
According to GE’s Danita Knox, as a site prepares for a power-system upgrade, it’s important to identify and select a reputable vendor that’s experienced, trained, and knowledgeable in designing this type of complex project. A power-system upgrade includes these steps:
- Budgeting for hardware, software, and labor.
- Development of a project schedule and careful outage planning for the upgrade.
- Design of the system and procurement of all components prior to the outage.
- Labor and logistics planning for the outage to ensure that work is completed on time.
- Testing of all critical components prior to the outage.
- Failure mode and effects analysis to plan for challenges during the outage and prepare solutions or workarounds.
- Site safety and work policy that includes LOTO (lock-out/tag-out) training and documentation.
“During the upgrade,” Knox said, “an experienced project manager with a background in power systems is indispensable. Many facilities operate continuously with infrequent planned outages. Careful planning and execution is required to maximize work and re-energize systems in a timely manner.”
Knox advises creating a detailed schedule and work procedures early on, including planning types of labor and required skill-sets and procuring all materials well in advance. “Regarding procurement,” she cautioned, “be careful to consider smaller items, such as personal protective equipment and installation components. If these small details are missed in outage planning, they can create schedule slippage, safety risks, or technical errors while limiting the amount of work accomplished.”