Anyone concerned with the planning and design of nodal points for energy-supply networks (i.e. the management of networks, safety systems or metering) need to have access to technology that is both thoroughly tried-and-tested and suitable for meeting future requirements.
Varying load distribution and decentralisation are particularly likely to have an important influence over the service life of components in backup systems, such as those based on DC UPS devices. The robustness of components has usually been defined, up to now at least, in terms of the ability of the items selected to withstand general environmental factors, and thus ensure a long service life. Where performance was concerned, it was normally enough to know a system’s MTBF (Mean Time between Failure).
The questions to ask when it comes to today’s decentralised networks, which often have to handle load factors that are totally different to anything encountered so far, should in fact be: What effect do fluctuations in the network have on the UPS system? How many load variations is the system being subjected to? The task of monitoring has merely consisted, up to now, of determining whether the connected components are working, and that no error messages are being generated.
Zentro-Elektrik is now breaking new ground in this respect, with its innovative GWHD 500
Zentro’s team of development engineers set itself the task of creating an intelligent system capable of providing detailed status information on converters and the items supplied by them, going way beyond the system of error messages used previously.
The use of two mutually-interlinked DSP systems (one each for the primary and secondary circuits respectively) permits not only the digital regulation of output voltage and current, but also the digital control of reverse-feedback signals, by means of digital magnetic couplers instead of conventional optoelectronic couplers. This delivers a maximum degree of digitalisation, by making analogue switching components superfluous. The likelihood of system faults occurring is consequently reduced, thereby considerably increasing the reliability of the devices concerned. Output voltage and current are detected by a high-performance electronic metering system, which can be calibrated for each individual item of equipment. Digital readouts can also be obtained of the input voltage and of the temperature at various points on the device.
This all helps ensure a fast and measured reaction to events and incidents, while guaranteeing maximum safety protection. The user interface offers readouts for, and permits the entry of, a wide range of operating parameters, limit settings and status/operating-mode information, in addition to just voltage and current.
The default configuration of the devices in the GWHD500 range can also be altered by the user with, for example, an adjustment range of 50% to 120% for output voltage and maximum current. The reaction of the system in the event of an incident (voltage surge, excess temperature, insufficient input voltage, etc.) can also be configured.
Communication with the device is via a galvanically isolated, digital serial interface conforming to EIA485 (RS485), using a proprietary operating protocol. This permits connection to standard types of fieldbus. The interface can also be used for current-sharing during the parallel operation of various devices.
Communication with the battery is, in addition to the converter, an important feature of battery-buffered DC UPS systems. In a DC UPS system, the close interaction between its power-supply, battery and monitoring-and-alarm functions is closely related to load factors. The correct management and efficient interaction of all components are the key factors when it comes to system performance, which is why all elements should be sourced from a single supplier. Reliable systems operate these batteries in accordance with their specifications, i.e. they take into account the temperature properties and charging / discharge cycles of each battery in order to ensure a maximum useful service life for each unit. Only then can we speak of an assured, uninterrupted power supply.