Transmitters with ATEX approval can be put directly into a potentially explosive atmosphere. The receiver is mounted outside the actual EX zone. This means that cost-intensive installations with protective barriers and supply isolators are unnecessary.
JUMO’s wireless technology shows a totally new approach here, and
allows the customer to transmit temperature measurements across
boundaries, out of the EX zone. The Wtrans transmitter can be located in
Zone 0, right up to the process connection. In this example, the probe
handle is in Zone 1. Of course, it is also possible to operate the
entire instrument in Zone 1. Then, for the first time, it is possible to
regard a hazardous EX area as being completely disconnected from the
“outside world”.
The transmitter is still located in the probe handle and is protected by
a waterproof and dustproof housing. A blue plastic handle was chosen as
an outward distinguishing feature.
Instruments with a temperature resistance up to 125°C are used in
applications where it is mandatory for the transmission electronics to
be installed in the actual process. This is the case in continuous
furnaces, for example, where the transmitters have to be in the product
to measure, and they transmit their temperature data out of the hot
zone. A gray plastic handle is the outward distinguishing feature here.
There are versions that can be used to measure from
–30 to +260°C with a fixed protection tube, as well as versions for a
temperature range of –200 to +600°C with M12 connectors and a remote
temperature sensor. It is the responsibility of the user to scale the
particular output value and this can be individually adapted to the
measurement task.
The rail-mounted receivers still make the measurement values available
over four analog outputs (0[4] - 20 mA, 0 - 10 V) or two analog outputs
and two floating relays, as well as over an RS-485 interface with a
Modbus protocol. As many as 16 Wtrans transmitters can be managed over
this interface for each receiver.
Because JUMO’s forward-looking wireless transmission technology is used,
there is a vast reduction in installation expenditure in all industrial
applications. There are also other perfectly obvious advantages. In
hard-wired systems, long connecting cables almost always hinder the
user. Wireless-based temperature sensors provide effective and
convenient alternatives compared to hard-wired systems, particularly at
higher process temperatures.
There are no vulnerable, costly, cable connections and the
wireless-based temperature sensor technology also works in a harsh,
industrial environment, as well as in potentially explosive atmospheres.
The costs for maintenance, repair and re-installation are also reduced,
compared to hard-wired measurement data transmission. These
developments open up totally new areas of application for user-friendly
measurement value recording and transmission of temperature data.