Reliability in automated power control

Reliability is a vital factor in the specification of control systems for automated power management systems in built applications like hospitals, banks and call centres, claims ComAp's Martin Malek.

Today, modern electronic control systems provide a seamless interface between mains power, building load and stand by provision utilising highly tailored system design, programming and installation to meet the specific requirements of the building. Typically, UPS systems provide a short-term solution to power loss, taking load between the mains going off and the generating starting, synchronising and coming onto the grid. However, complete reliability is delivered through the selection of a suitable control system that uses the latest electronic communication technology to manage this critical event effectively by monitoring multiple power supplies simultaneously and synchronising different sets to the mains without the need for human intervention.

From the moment the power's lost, these systems immediately attempt to start the generator - trying at least three times if required before deciding how much load to give each generator, dependent on the building load at the time. The system is then capable of monitoring the load and changing the configuration to ensure full load is delivered reliably and consistently.

A good example of a highly reliable control system can be found at the King Fahad Hospital in Al Baha City, Saudi Arabia where a recent upgrade saw the replacement of the old distribution panel with a new control solution installed by ComAp Systems Saudi Arabia. The complete system was tailored to the needs of the hospital and programmed to deliver continuous power in the event of failure. The two systems operated in the following way:

The first system is programmed so that when one, two or all of the ATS(s) experience AMF, a command from the synch system is sent to start over, synchronise and get ready to supply the failed ATS(s). The mains breaker is tripped and the ATS bus breaker will close to the load providing the power supply from the standby synch switchgear. This will start a load sharing process and start or stop the number of working gen-sets upon load demand. When the failed ATS(s) are restored, the ATS will change over from standby synch power supply back to mains supply. The gen-sets will be commanded by the ATS controllers to cool and shut down when required.

The second system is set up so one mains is feeding the load and the second mains acts as standby. If the prior mains gets the fail command, standby will feed the load and if the second also experiences failure, then the standby power generation will start running and synch on dead bus after what the BTB will close feeding the load from standby power. If one of the mains is restored, the BTB will open and the restored mains will feed the load and the standby power will cool down and stop.

Reliability of operation is an inherent and essential part of modern electronic control systems ensuring that business critical applications like hospitals and banks benefit from an embedded 'guarantee' built into the design of each standby control system.

Martin Malek is the Managing Director of ComAp Systems Group. He's worked in the company since its inception in 1991, and now looks after one of the ComAp divisions - ComAp Systems Group. The company designs, produces, supplies and commissions, control systems, complete switchboard and switchgear solutions and related systems for the power generation market.