cpp – Process technology for the chemical industry 02.2020

Picture: E-T-A
Picture: E-T-A
Picture: E-T-A
The Module 18plus power distribution system
holds a compact wiring solution for all
load and signal lines of the 24 V(DC) control
voltage
E-T-A designed the ESX10 electronic circuit
protectors specifically for potentially explosive
atmospheres
The plug-in type modules make the Module
18plus power distribution system highly
flexible
accommodate cable cross sections of up to
16 mm 2 . This allows the distribution of up
to 80 A across the entire system. The connection
modules are added side-by-side to
this supply module by the plant operator.
The maximum solution consists of 30 modules
mounted side-by-side. Each connection
module can be operated with a max. load
current of 20 A. The wide range allows the
best possible distribution of the used loads.
Each connection module has two each protected
terminals for the loads as well as two
terminals for zero volt and functional earth.
This ensures a clear correlation between the
different loads and the corresponding circuit
protector.
The signalling module completes the system.
Each circuit protector has an auxiliary
contact transmitting the status. All circuit
protectors used are connected in series. If a
circuit protector trips, this is detected and
indicated by means of the signalling module.
A process control system monitors and
visualises this signal contact. The plant operator
can quickly gain an overview of the
status of the 24 V(DC) power distribution.
Plug-in type circuit protectors
The plug-in design of the power distribution
system allows the design engineer to meet
the requirements of his plant very individually.
A range of electronic circuit protectors
is available for the different applications.
E-T-A designed the ESX10 electronic circuit
protectors for the specific requirements of
potentially explosive atmospheres. They
have various approvals valid for the Atex
zone 2. This allows the use of decentralised
solutions and ideally protects the 24 V(DC)
power distribution. Current ratings are
available in a range of 0.5 to 16 A and are
internationally usable with approvals to
Atex, IECEx and ISA. To meet the rising demand
for electronic circuit protectors with
higher current ratings, E-T-A extended its
portfolio to include a 16 A version. This circuit
protector meets the requirements of
protecting the input and output sub-assemblies
of process control systems.
The plug-in design supports the system’s
flexibility. For applications in a standard industrial
environment, the above described
approvals are not required. In this case, an
electronic circuit breaker providing physical
isolation can alternatively be used. In the
event of a short circuit or overload, these
breakers do not only electronically disconnect
the circuit, but they also ensure physical
isolation through a mechanical contact.
In standard electronic circuit protectors, a
power mosfet disconnects the load circuit.
In normal duty, it is low-resistance and becomes
high-resistance when tripped. This
additional functionality offers extended
protection to the user. In the event of a
short circuit, the circuit protector first electronically
disconnects the load circuit. After
another five seconds, it will additionally
physically separate the load circuit. For this
purpose, a bimetal, which is connected in
series with the mosfet, is supplied with current.
When heating up, the bimetal deforms
and physically isolates the load circuit by a
clearance gap. This prevents hazardous return
supply on the 24 V(DC) level and increases
plant safety.
Conclusion
The change from centralised to decentralised
design in plants of the process industry
offers many advantages. However, we
also need to mention that design engineers
are faced with new challenges. The proximity
to the plant and the process affects the
available size of the control cabinets and
possibly also the safety requirements. A
possible temperature rise of the devices and
the compact design become more and more
important. This must be taken into account
when selecting the components to be used
in a 24 V(DC) power distribution. Due to its
compact and modular design, the Module
18plus is ideally suited to the task. In addition,
the plug-in design offers unrivalled
flexibility regarding suitable circuit protectors
or breakers.
www.cpp-net.com
Online search: E-T-A
AUTHOR:
Thomas Kramer
Business Development
Manager,
E-T-A
cpp 02-2020 37