The benefits of Remote I/O are generally well known in the industrial automation world. In more recent times these benefits have been made available for Ex areas, albeit with some special challenges to solve. Large, expensive, cumbersome power supplies, poor maintenance options and lack of redundancy for PSU and communications.
In order to overcome these issues Turck Banner have had to ignore convention and develop new solutions.
Traditionally, power supplies mounted in the hazardous area would have been EXD type. These power supplies cannot be disconnected during normal operation without obtaining a “Hot Work Permit” due to the risk of sparking when they are unplugged.
Hot swapping makes the Excom system particularly user-friendly. The system can be serviced and changed at any time. The I/O modules, and the power supply modules, can be plugged and unplugged during ongoing operation, even in zone 1, without interrupting the field communication.
The Excom power supplies from Turck can be freely removed and replaced without any special precautions. The infallible action of removing any one of the retaining screws interrupts an intrinsically safe monitoring circuit, which internally de-energises the output supply relays and removes the current, before the power supply can be unplugged. This is achieved, not with a complex monitoring circuit, but by the sheer simplicity of the retaining screws bridging two semi-circular pads on the circuit board. This facilitates the use of much smaller and less expensive power supplies rather than the costly, cumbersome approach of EXD technology.
The whole of the Excom backplane is essentially one galvanically isolated barrier, or more accurately, a series of galvanically isolated barriers. Each slot on the backplane has its own barrier built onto the circuit board. This allows the cards to be removed at any time without any safety issues. The whole of the Excom backplane is a certified component in its own right. These unique features increase plant availability and save time during commissioning and extension of the system.
In utilising this system in the hazardous area the traditional barrier interface panel in the control room can be dispensed with altogether.
The Excom remote I/O system has been extensively tried and tested in the process industry and meets the high demands of equipment safety in that sector. The system allows a fully redundant set-up of the power supply, as well as communication interfacing. A choice of 24VDC or 230VAC is available and as a standard feature Excom also provides a system-redundancy solution for the bus structure. This allows the redundant Excom system to be connected via redundant busses to dual PROFIBUS masters.
Thanks to the open standard, the redundancy system can be operated with any master available on the market. Excom takes advantage of the world-wide applied HART communication and allows field devices to be parameterized via the bus. This gives the control system additional information on process values, diagnostics and asset management directly in digital form.
The Excom I/O system has also been certified for maritime applications and can now be used in applications requiring certification from authorising bodies, including Lloyd’s Register. This includes, for example, mounting in control consoles, housings or cabinets on board seagoing vessels, tankers or oil platforms.
Excom remote I/O from Turck is a truly innovative design, allowing hot-swapping of power supplies, I/O modules and communications, thus simplifying all maintenance procedures.
