Failsafe power helping to eliminate hospital blackouts

Pilkz

Whether in operating theatres or looking after patients in intensive care wards, a reliable power supply is essential for a modern hospital. If the power and therefore the medical life support equipment should fail during a surgical procedure, the consequences would be unimaginable.

That’s why energy supply systems in hospitals are doubly or even triply protected via emergency generators and battery buffers. Ultimately you want to leave nothing to chance in this situation.

Whether willingly or out of necessity, situations do arise where users need to switch back and forth between individual power supplies. For technical reasons, it’s not simply a case of flicking a switch and then all systems continuing to work as before.

The contactors and shunt releases installed in the network must be in a defined state when the switch is made. If not the system may break down, with resulting consequences for the expensive switchgear.

Depending on the situation, people in the immediate vicinity may also be put at risk.

A couple of years ago, White Technics was awarded a challenging contract by a hospital operator in a northern suburb of Melbourne. White Technics had a wide range of experience in the planning and implementation of complex supply and energy technology installations.

“The task we were set was to develop a simple, reliable solution, which would bring the alternative power generator online quickly and safely, whenever a changeover was required,” recalled Moffat.

Two independent substations supply power to this particular hospital. If these are unavailable, a diesel generator steps in.

If the power supply is shut down by the hospital during maintenance work or by the electricity supplier (a so-called brownout) the necessary switching arrangements can be made without any time pressure. In contrast, in the event of an unforeseeable power outage (also known as a blackout), the second substation or generator must come online immediately and seamlessly, without even a momentary failure of the hospital’s critical systems.

For a redundant energy supply system to come online safely, a reliable entity must poll the status of the installed contactors and shunt releases within the shortest time possible.

The same applies if the reason for the shutdown (brownout or blackout) has been found and rectified: before being reset to the original power source, safe signals must be polled again and the current flow aligned synchronously to each power source.

“As we were already familiar with Pilz and its competence in integrated solutions for control and safety tasks, we decided to turn to the safe automation experts from Pilz Australia with this challenge,” said Moffat.

Both companies developed an efficient safety concept based on the automation system PSS 4000. From a central control room, the system was intended to be able to communicate with the substation of the respective power grid, as well as with the generator.

As part of the automation system PSS 4000, the control system PSSuniversal monitors status inputs from each shunt release and contactor on the substations of the individual power grids.

Safety relays PNOZsigma from Pilz control the circuit breakers via contactors. The automation system PSS 4000 also sends this information to the engineering office for diagnostic purposes.

As the substations and the control room are around 800 metres apart, the connection between the control level and the remote I/Os in the field was implemented via fibre-optic cable and the real-time Ethernet SafetyNET p from Pilz.

“The ability to use the safe Ethernet protocol SafetyNET p via fibre-optic cable was an important prerequisite for our project,” Frank White is keen to stress. SafetyNET p networks all the control components and transfers data for safety-related and non safety-related control tasks in one system.

With the software platform PAS4000, the Program Editor PASmulti and EN/IEC 61131-3 Editors, the automation system is easy and flexible to manage. The hospital’s maintenance team receives detailed diagnostics in the control room, without having to enter any high voltage areas. As a result, technical problems can be resolved quickly and safely.

In this case, the integrated solution for control and safety tasks is suitable for both simple and complex applications. As it has a modular structure, it can be expanded any time to suit your requirement. Integration does not require any complex installation or handling processes.

Today the hospital engineers are happy with the performance of the automation system PSS 4000 controlling the switching of HV power supplies and overall smooth trouble-free operation over the past four years of the initial Installation.

For that reason, they have now commissioned White Electrics to expand the automation system to include “Safe Control” of the “Low-Voltage Circuit Breakers”.

“The ability to expand PSS 4000 is so easy to undertake that even further expansion is planned to be installed over the next two years,” concludes Frank White and adds, that it is a very successful project and a “win-win” for all those concerned.

“In the end, the key factor in selecting the automation system PSS 4000 from Pilz was that the complete solution for control and safety tasks, with its smart diagnostic functions, was simpler and more economical than comparable solutions from other suppliers,” said Moffat.

What’s more, with its decentralised IO modules it is small, compact and requires little space in the control cabinet.

So the Industry 4.0-compatible automation system PSS 4000, already established in industry has now arrived in building electrics and automation.

As in automated production plants, it provides protection for people operating in the area and saves expensive equipment from damage.