The consequences of machinery coming to a sudden stop due to mains failure can be both expensive and time consuming. So, when developing new machines and systems, engineers and designers often choose power supply units with a standard mains bridging time of more than 20ms. During this time, the power supply delivers the output current from the power contained in the internal storage, which is enough to bridge short mains fluctuations and power failures.
Failures, however, are often longer, sometimes up to 180ms. A system may come to a sudden stop if there is no 24V DC control voltage which can, for example, result from a drill or cutter head becoming wedged in a workpiece. Following this, a complex restart process will often have to be initialized.
Designing a system which enables targeted shut down, even after a long mains failures, is therefore often necessary. Servo drive brakes need the time to open safely; and the control components should have enough time to finish current processes and to save data.
Buffer modules based on ultra capacitors can help. Energy is stored in high performance capacitors and can be delivered when required.
Lead-acid batteries are often used in conventional uninterrupted power supply (UPS) systems, but these have to be exchanged regularly. Buffer modules, however, can last up to 15 years if there is an ambient temperature of 40°C. Under lower temperatures, the lifespan can increase up to 60 years.
A solution is provided by Murrelektronik’s buffer module Emparro Cap 20/24 1s, which is designed for a load current of 20A. This completely buffers the current for a period of over one second – the capacity loss caused by the capacitors’ ageing is already included in the calculation. Not only does this long bridging time cover all short and middle mains failures, but it makes it possible to systematically shut down the peripheral devices that need to be buffered in the event of longer mains failures.
As a result of using this technology, productivity of machines and systems is increased, with the money spent on the installation paid off after the first mains failure that was successfully bridged, claims the company.
Measuring just 65mm wide, Emparro Cap has an operating temperature range of 100 Kelvin (from -40 up to +60°C), making it suitable for a wide range of applications – from extremely cold environments like wind turbines to hot environments such as control cabinets and terminal boxes.
Murrelektronik
