Turck says that, traditionally, power supplies mounted in hazardous areas would have been EXD type and could not 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 a user-friendly option. The system can be serviced and changed at any time. The I/O modules, and power supply modules, can be plugged and unplugged during ongoing operation, even in zone 1, without interrupting the field communication.

The Excom power supplies 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. Turck says this facilitates the use of smaller and less expensive power supplies.

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 safety issues. The entire Excom backplane is a certified component in its own right. These features increase plant availability and save time during commissioning and extension of the system.

In utilising this system in a 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.

Due to the open standard, the redundancy system can be operated with any master available on the market. Excom takes advantage of HART communication and allows field devices to be parameterised 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 onboard seagoing vessels, tankers or oil platforms.