Intelligent ZigBee-enabled tablet design for use in smart grids

3Until recently, ZigBee readers were mostly independent devices dedicated to their singular ZigBee function. With the Smart Energy ZigBee standard, however, commercially available enterprise tablets can integrate this technology long with other utility-specific functionality to become more useful in the smart grid. This discussion explores the key design considerations for tablet computers used to install and maintain smart grids.

With worldwide power consumption on the rise, utilities are faced with the challenge of providing more power while reducing environmental impact. Smart grids have emerged as a solution for managing output by providing electricity exactly where and when it is needed, thereby improving energy availability and reliability while improving regulatory compliance. ZigBee technology is at the core of smart grid functionality, as its low-cost sensors can be used to manage demand response and load control, automate meter reading, and provide real-time data, along with the additional capability of individually or simultaneously targeting specific groups of devices, including HVACs, water heaters, lighting, electric vehicles, and generation systems.

Until recently, ZigBee-style communicators have been dedicated devices with the sole function of reading sensors. With the standardization of the ZigBee Smart Energy profile by the ZigBee Alliance, however, there is an opportunity for tablet computers to incorporate ZigBee and become more relevant tools in the installation and maintenance of smart grids (Figure 1).

The challenge in designing a tablet computer for use within the smart grid is finding a way to bridge emerging technologies with the traditional functions of the utilities market, all while packaging it in a rugged device that can stand up to the elements and inevitable drops and spills in the field. There are several key design considerations for tablet computers used for smart grid applications, including the ability for the device to manage multiple functions, modularity, connection with the cloud, and ruggedness.

ZigBee explained

ZigBee specifies a suite of high-level communications protocols with small, low-power digital radios based on the IEEE 802.15.4-2003 standard for Low-Rate Wireless Personal Area Networks (LR-WPANS). It takes the IEEE 802.15.4 standard a few steps further with additional network and security layers, as well as an application framework. From this framework, the ZigBee Alliance also developed standards – technically referred to as public application profiles – that can be used to create multi-vendor interoperable solutions, which allow for customization and favor total integration. ZigBee advantages include:

  • ZigBee uses the 2.4 GHz radio frequency to deliver a variety of reliable and easy-to-use standards anywhere in the world
  • ZigBee sensors can run on harvested power or batteries. Users can expect an extended battery life that could exceed 10 years for very low-duty applications, such as automatic meter reading, when using common alkaline batteries in a typical ZigBee product. For higher duty applications, battery life can range from 100 days to three years
  • Transmission distances are remarkable for a low-power solution, ranging from 1 to 1,000 meters (about 3 to 3,280 feet), depending on power output and environmental conditions such as other buildings, interior wall types, and geographic topology
  • Multiple ZigBee sensors can be configured into self-healing mesh networks that extend the range of multiple sensors by miles

A more secure network

ZigBee offers Machine-to-Machine (M2M) communication, offering an advantage over Wi-Fi and WiMAX solutions that are costly and potentially less secure. Recently, some utilities have explored automatic meter-reading systems that rely on home Wi-Fi networks to push usage data and provide customers with Web-based control of thermostats. Customers, however, have balked over the companies’ perceived access to other personal information flowing through Wi-Fi access points.

In contrast, ZigBee is a more secure proposition, offering end users the same remote control of their thermostats by smartphone or computer, but ensuring the utility company is receiving only the information they are intended to get. Since data for entire neighborhoods is conveyed though a mesh network and individual addresses are assigned numerical codes no identifying customer information that could breech privacy – like addresses – is transmitted over the network.

Colonizing the smart energy space

ZigBee wireless networks have been in use for more than a decade, establishing it as a proven technology for a range of applications, including home and building automation, remote controls, healthcare, and retail services. Until the recent adoption of a standard ZigBee Energy profile, however, solutions in the smart grid/energy space had been mostly custom developments, relying on proprietary radios and communicators dedicated solely to the function of communicating with the ZigBee radios, which, for example, read meters.

In the last decade, the ZigBee Alliance began an incremental release of the ZigBee Smart Energy standard in order to create a global ecosystem of interoperable products – including meters, thermostats, outlets, load-control devices, and transformers – that monitor, control, inform, and automate the delivery and use of energy and water. The Smart Energy profile calls for the certification of products in order to provide assurance they will perform and can communicate with one another, regardless of manufacturer.

One tablet, many functions

ZigBee-enabled smart grids have added a layer of sophistication to utility operations, allowing for management of demand response and load control, automated meter reading, and identification and repair of outages. The ability to natively communicate with the devices that manage these functions is imperative, but to focus purely on incorporating ZigBee into a tablet is shortsighted. It is important to also consider how technicians use their equipment in the field, and then build on strategies for managing those technicians, maintaining fleets and inventory, and serving customers.

During smart grid installation, for example, some technicians carry a ZigBee communicator, laptop computer, GPS, measurement instruments, and a camera. Incorporating all of these on a tablet computer simplifies their jobs and cuts costs. As each data point is gathered, the tablet can be used to test and validate the new meter or transformer, document and pinpoint its exact location using location-based services and GPS, acquire the work order and communicate with the central office, scan equipment barcodes, access mapping data and manuals, and more in a single lightweight portable computer. Ultimately, combining these tools into a single device lowers purchase and maintenance costs for the end user by as much as 50 percent. Alternatively, a technician might carry a rugged laptop worth $3,000 (sometimes also with a data plan for $50/month), GPS worth $300, a handheld worth $1,000 (with a data plan for $50/month), measurement devices (such as an ohmmeter) worth $500 to $1,000, and a ZigBee programming device worth $500. The cost of a similarly equipped mobile tablet could be about half.

After installation, the same tablet can be used for reading meters, assessing outages, maintaining the network, and restoring power – all while providing the company a powerful tool for routing assignments to the closest technician, maintaining inventory, and geofencing.

There isn’t an app for that: The importance of modularity

Industry-specific tools such as measurement equipment often inhibit using a computer as the primary tool for field service. In many cases an installer or field technician will carry a computer as well as separate equipment to fulfill their job function; smart grid installers need an ohmmeter to test voltage, transformer technicians need equipment to test for vibration, and solar installers need a compass.

Modular design that affords the integration of key equipment into a tablet is the antidote to static designs that disallow change and custom designs that require expensive R&D. DAP Technologies’ M9010 tablet, for example, features a backpack design that allows end users to add their own circuitry to accommodate a range of tools and data inputs for custom solutions, or specify packaged solutions such as RFID (Figure 2).

Figure 2: DAP Technologies’ M9010 tablet is ruggedized for portable use and includes a variety of communications options to keep technicians connected.
(Click graphic to zoom by 1.9x)

The future is in the cloud(s)

With ZigBee radios along the smart grid continually pinging data, cloud computing will play an ever greater role in managing the billions of bytes of data that are produced daily, providing real-time usage information to customers and technicians analyzing data in the field.

When designing a tablet for the smart grid, wireless broadband communication is imperative for accessing the vast quantities of data and providing field analysis. Field technicians might be sent to investigate repeat outages in a particular network. Using tablets to access the cloud, they could look for trends in peak consumption and use that data in conjunction with information from the ZigBee modules to correct the issue.

It is also important for the tablet to be compatible with the utilities’ existing systems. For most utilities, that means a Windows-based operating system.

Built to last

Any computer that is to be used in field applications must be built to withstand the elements and abuses that come with heavy outdoor use. In addition to remaining operational in weather conditions that range from driving rain, snow, and ice to humidity, blazing hot temperatures, and dust storms, tablets for utility applications should be safe for use around chemicals including acetone, crude oil, ISO-propane, diesel, oil, acetaldehyde, benzene, chloride, and more. Minimum requirements for rugged tablets in these applications should be IP67 – completely sealed against dust and water – and the ability to survive multiple 6-foot (1.8-meter) drops to concrete.

A multi-use, connected tool

Rugged tablets offer a lightweight, mobile, durable, and user-friendly platform for incorporating ZigBee into a solution that performs most of the required tasks for smart grid installation and maintenance. As ZigBee continues to gain prominence in smart grid applications and beyond, it is important to remember that incorporating this essential technology into a complete package will reap the most benefits for the user, both in terms of cost savings and field efficiency.

Khalid Kidari is Director of Product Management and Marketing at DAP Technologies. He oversees the company’s entire line of rugged tablet, handheld, and fixed-mount computers. DAP serves customers in industries that include field service, utilities, warehouse, supply chain, transportation, and logistics.

DAP Technologies