Signalling an end to wireless worries

Steven Hill, general manager of .steute UK & Ireland, examines control devices for use in safe and hazardous areas and considers whether engineers still have concerns specifying wireless in industrial applications

For engineers working in any sector of industry, and especially in potentially explosive/hazardous environments, .steute believes wireless control should be the default option. Ironically, the benefits that have led wireless to be widely adopted in Europe (safety, security, reliability) are often quoted as reasons not to adopt it in the UK.

So, are these concerns reasonable? History has played its part, as many first experiences of wireless devices were the early Broadband routers, which performed well but were sometimes unreliable due to infra-structure. As is often the case with human nature, we transpose our consumer experiences from the early days of wireless to industrial applications, creating or reinforcing the concern that wireless is not reliable enough for industrial environments.

So let's consider the historic concerns against the latest technical advances.

Is wireless stable? Today's wireless protocols are certainly stable and reliable; and there are more to choose from. Selection should take account of the environment and application. For example, the 868MHz licence-free wireless protocol can be used in safe areas and ATEX-certified zones; and due to a growing range of wireless explosion-proof control devices, it is no longer necessary to use the special tools, cables or glands associated with hardwired versions.

Is wireless reliable? For some, the ongoing issue of batteries being required to power the transmission data protocol is a barrier when considering wireless products for industrial applications, especially when switchgear is installed in difficult and/or remote locations.

The problem has been solved by companies such as .steute, which has developed battery-less control devices that generate their own power on demand, enabling them to transmit signals back to the receiver over distances of 300m when outside and 30m inside; and between five walls. Reliability is enhanced because the signal is transmitted quickly (<80ms), so there are no underlying issues with interference from external sources.

Benefits such as faster installation, easier engineering and, consequently, reduced capital spending, should encourage engineers to adopt wireless to solve challenging control problems, particularly where traditional wired-technology is both difficult and expensive. For example, to send a signal to a control room 80m away you need to employ a team of civil engineers to survey and prepare the ground for cable to be laid (expensive even without the cost of cable). Second, a team of electrical engineers is needed to lay and terminate the cable at either end. All this before your signal can even be transmitted. This demonstrates where wireless excels compared to hardwired systems. Not only would wireless save the cost of cable, it avoids the civil engineering.

Signal strength? A question often asked of wireless transmission is: "How do I know the strength of a signal after it's been transmitted from a device?"Apparently, some responses have been worryingly vague, such as: "If it's over a short distance, it should work." Fortunately most engineers know that this response is unacceptable as there is no proven test to show that the signal generated is just on the minimum receiver signal strength level required. To reassure engineers, .steute has introduced a meter to measure the signal strength transmitted from the switching device.Metering is offered as part of the standard service during installation and, if required, signal strength meters can also be purchased. In addition, if you believe wireless control will benefit your application it is possible to arrange a site survey to determine whether your installation requires a high-gain antenna or repeaters to re-direct the signal to the receiver.

Hazardous areas You may be convinced that wireless systems are capable of performing in industrial environments, but what about hazardous areas? The answer is that - for most applications - the combination of Ex and wireless shouldn't pose a problem to those wanting to use both technologies.

A few years ago, embracing wireless technology in industrial environments required an act of faith. Today wireless devices have advanced to a level where they are more than just a replacement for traditional technology. Engineers who have installed wireless control devices are now reaping the rewards.