The "Gratto Shut" System, Built with ZigBee Modules, Provides Safety and Reassurance for Electricity Users by Preventing Secondary Damage after Earthquakes

In response, Ad-Sol Nissin is currently developing, in conjunction with the Tokyo Electric Power Company, a power supply control system called "Gratto Shut," which, roughly translated, means to shutdown on detecting the vibration of an earthquake. The system uses ZigBee wireless communication to turn off the electricity supply in the event of an earthquake of magnitude 5 or higher, and it can leave the power turned off even after the power supply is restored. The intention of this development concept is to help make society safer and give people more assurance that they have some protection against preventable accidents. The project is just one of the actions being taken by the Tokyo Electric Power Company to investigate future interaction between electricity and lifestyle. (Additional details are contained in the article, "Electricity, Lifestyles, and Networks ― Tokyo Electric Power's "Visualization" Concept and the Potential for Building Information Networks."

A development prototype of the Gratto Shut system has been built (see Photographs, below). It consists of a master unit equipped with an internal sensor that detects the vibration of an earthquake and slave units that perform the electricity disconnection. The master unit (photograph on left) is fitted over an AC power socket somewhere high in the room in a location that isn't usually touched, such as socket for an air conditioner. Slave units (photograph on right) are fitted to the AC sockets of all devices that should have their power disconnected when the shaking starts.

The slave units normally supply power to the electrical device just as a standard power socket does. However, when an earthquake occurs, the slave units receive a signal from the master unit that causes them to turn off the AC power supplied to the device. When electricity is restored, the slave units do not turn on the power until they are manually reset by someone who has checked that it is safe to do so. This manual operation prevents a fire or other damage that might otherwise occur if the supplied device were automatically powered up when nobody was present to check its condition.

When the master unit detects a magnitude-5 or higher earthquake, it uses ZigBee wireless communications to signal the slave units to turn off the electricity supply. The wireless transceiver in both types of units is a Renesas model YCSCZB2 ZigBee module that includes a M16C/28-group microcomputer. Mr. Yamauchi of Ad-Sol Nissin Corp. said, "Using ZigBee wireless communications eliminates the need for special installation work. Another big advantage is that the control area can easily be enlarged just by adding more slave units, because the wireless signal hops from slave unit to slave unit. Renesas ZigBee modules met our requirements that the completed units be small and have a form that wouldn't look out of place in a home. Our previous successes with Renesas M16C microcomputers was another reason for selecting these modules."

Now that the development prototype of the Gratto Shut system has been produced, the project team has started to investigate ways to commercialize it.

In addition to the Gratto Shut project, Ad-Sol Nissin is actively involved in developing other systems that use ZigBee wireless networking technology. One of these, called "Touch Tag," is an RFID tag that uses a communication technique that operates via the human body. In this unique system, the data reader/writer detects a tag carried by a person simply by having them step on a mat. The person's body acts as the communication medium between the tag and mat, and the mat connects to the reader/writer by a short cable. A Renesas ZigBee module implements communications between the reader/writer and a host machine. An advantage of the system is its flexible layout, made possible because the reader/writer connects to the host machine wirelessly.

Other applications for Renesas ZigBee modules at Ad-Sol Nissin Corporation are the "ES806R077" and "ES804R077". These and similar ES806R077 are used to test and check the ZigBee/802.15.4 communication environments. The ES806R077 allows a test unit to be temporarily installed in buildings or other locations where people are considering installing a ZigBee systems so that actual system communications are simulated for a long period of time for evaluation.

The ES804R077 for example, is a practical tool for site evaluations that helps identify the best place to install ZigBee transceivers. In operation, the handheld terminal is carried around the site. Lamps on the unit indicate the communication status in a four-step ranking display.

Ad-Sol Nissin sees great potential for more applications and new markets for ZigBee technology. The company intends to continue proposing and developing various ZigBee wireless networks in partnership with Renesas.