Coal, Nuclear

Ergonomic Control Room Design Improves Operator Comfort and Safety

Issue 7 and Volume 114.

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Control room at Southern Company’s Plant McDonough

By Vanessa Graves, Industrial Designer, Winsted Technical Interiors

As the power industry makes the shift from analog to digital control systems, power utilities are redesigning their control rooms to accommodate the digital control upgrades.

The new technology has made it possible for operators to access most of their controls through the monitor and keyboard, rather than standing at the control boards. This represents not only a shift in technology but also a change in the way operators work.

Safety is a chief concern for these power plants and a primary focus of control room design. An ergonomic approach to the design of control workstations and the layout of the control room contributes to achieving safety and performance objectives set for power plant control rooms.

Effective control room design considers both form and function to create workspaces that facilitate the complex interaction between operators, technology and the environment. Raised flooring, acoustic concerns, indirect lighting and the wellbeing, health and safety of each operator all need to be addressed.

Operators in the power plant control room work 24 hours a day, 7 days a week. Unlike a desk for a typical 9-to-5 office worker, which would be used 40 hours a week, these consoles are used 168 hours a week.

Operators don’t get to just walk away if they need a break. So they need to be comfortable while they are at the console. Some things that are considered are knee space, countertop height, monitor height, viewing angles, reach and the amount of space the operator has behind the desk.

That being said, an example of something that’s important to operators in terms of comfort is where the cup holders are located. It may seem trivial, but details like this really are critical to operator comfort and plant safety. From the layout of the room to determining the precise placement of every keyboard, mouse and telephone, not a single detail is left to chance.

 

General Design Considerations

 

When designing a control room for any type of process control operation, designers must take into consideration room size, number of operators, viewing requirements, equipment and budget.

One of the biggest challenges to control room design in the power industry is the number of control rooms that are very small, yet still need to retain clearance between the consoles and the control boards as well as fit a lot of equipment.

The number of operators in a control room setting contributes to not just the number of workstations required, but also the room layout. When designing a console it is necessary to determine if the workstation will be used as an isolated unit or in conjunction with overview displays or other workstations. Operators need to be able to communicate with each other as well as have easy access to essential equipment.

Viewing requirements are affected by such details as the number, size and placement of monitors, as well as if the operators need to view a window or control panel in addition to the monitors.

The height of the console should be calculated so the shortest operator can see over the top of any workstation mounted electronics to remote monitor walls, control panels or displays. And the clearance underneath the work surface should allow for the tallest operator to sit comfortably.

In the power industry, placement of control boards is a significant aspect of control room design. The main control board may need to be very easily accessible to operators, while other less frequently used control boards may only need to be visible.

Nearly every project is unique, with few control rooms or consoles sharing the same form or function. However, regardless of whether the control room is for a coal-fired, gas-fired or nuclear plant, common overarching goals for the design include ergonomics and functionality.

 

Gas-fired Plant

 

As part of a project to retire two, smaller coal-fueled generating units at Plant McDonough near Smyrna, Georgia, and replace them with three 840 MW combined cycle natural gas units, Georgia Power enlisted the help of WTI to design a control room in a brand new building to oversee the system when it comes online.

The control room layout features three consoles arranged in a U-shape. Each console utilizes a monitor mounting system which allows operators to easily modify sightlines and viewing angles based on personal needs.

In addition to the Southern Company McDonough Control Room, WTI designed the distributed control system (DCS) and simulator for the plant.

 

Coal-fired Plant

 

Construction of the TVA Kingston Fossil Plant in Tennessee was completed in 1951 and today generates about 10 billion kilowatthours of electricity per year. The coal-fired plant’s control room was in dire need of an upgrade.

To accomplish ergonomic goals and improve functionality, designers were challenged with incorporating a lot of monitors on the console at a fairly low height in order for the operators to be able to view control panels. Additionally, the consoles needed space internally to accommodate a lot of equipment.

By designing a console with a low profile, WTI incorporated the necessary number of monitors, maintain crucial sightlines and still accommodate space for crucial equipment within the console. The resulting design improved operator comfort and productivity.

 

Nuclear Plant

 

Control rooms for nuclear plants are without a doubt the most complex. These control rooms require consoles that can withstand seismic events. This means that their consoles have a completely different construction: designers must consider how everything that goes into that console will move if there is an earthquake.

Additionally, these designs must adhere to the strict ergonomic and control room requirements specific to nuclear power set by the Nuclear Regulatory Commission.

WTI has experience working within NUREG guidelines over the years. Most recently designing new consoles for an upgrade to the control rooms and simulator at Palo Verde Nuclear Generating Station in Arizona.

In order to meet seismic requirements for nuclear control rooms such as this, WTI typically uses a console system with a tube steel base in which each wall section has an inside and outside sheet metal panel to satisfy seismic requirements.

These consoles also use the monitor mounting system so if customers decide to upgrade from a 19-inch flat panel display to 22-inch wide screens, the mounting poles can be adjusted horizontally and the monitor amounts can be adjusted vertically.

Designers specify Corian work surfaces on consoles for nuclear environments, as well as most other 24/7 control rooms, because the material doesn’t show wear and tear over time and scratches can be buffed out when necessary.

As is often the case when upgrading an existing control room, design challenges for the Palo Verde control room included having to fit seven operators in a small room and having to work within the constraints of existing cable penetrations.

The control room designers were able to overcome these challenges to create a more efficient and comfortable control room and have since gone on to design three more control rooms and two simulator consoles for Palo Verde.

No matter the type of power plant, the ideal control room will have a great looking, durable, highly functional console. The operators will do their job without eyestrain, feeling cramped, or reaching too far for any control and never thinking to consider the effort that was put into making that possible.

 

Ergonomic Solutions for Operator Fatigue

 

There are several causes of fatigue and inefficiency in the control room, which are all easily addressed by well-designed ergonomic consoles.

First and foremost are improper sightlines, which cause operators to strain their eyes to see information on displays and/or to shift and adjust their bodies into improper positions causing discomfort and fatigue. Ergonomic consoles eliminate this issue by ensuring the ideal placement of monitors.

When designing display layouts questions to consider are:

  • How many monitors can surround the operator without overwhelming them with information?
  • What size is each of the monitors? This helps determine the minimum and maximum viewing distance from the operator to the monitor.
  • Does the operator need to be able to view a monitor wall in addition to monitors at the workstation?

 

The ideal monitor height and placement may vary depending on the operator. In control rooms where more than one operator may work at each workstation it is a good idea to choose a console design that allows monitors to be easily adjusted.

Additional causes of fatigue in the control room include poor lighting resulting in eyestrain; poor acoustics resulting in tension; incorrect traffic patterns resulting in noise and distraction; and inadequate operator proximity resulting in inefficient communication.

When designing a control room to address these and other concerns, the following steps should be taken to ensure operator comfort and minimize fatigue:

  • Test console layout with operators for “human tasks” including sequential task simulations.
  • Develop workstation layouts designed around acceptable reach zones and visual limitations.
  • Take into account maintenance requirements and removal of equipment from both the rear and front of the workstation.
  • Provide ergonomic footrests where appropriate.
  • Provide 24/7 chairs with full adjustment capabilities.
  • Reduce excess heat and noise by locating electronics in an equipment room.
  • In workstation dimensions, consider the full height and size range of the operators, utilizing height adjustable work surfaces where appropriate.

 

 

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