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.