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What are ATSs and why are they used?
ATS units are installed in critical power applications to ensure a smooth transfer of power from mains to secondary supplies in the case of an outage. They switch loads and power up backup generators before switching back again when it is safe to do so.
Even the most reliable power supplies with five nine-level reliability (99.999 percent) will experience an outage at some point. As a result, mission-critical installations such as hospitals, data centres, telecoms sites and commercial and industrial sites all rely on ATSs to maintain constant, uninterrupted power to maintain supplies to fire critical equipment.
The same is true for high-rise and commercial buildings as well as sports arenas, where an ATS can power safety equipment such as sprinkler pumps, smoke extractor fans, emergency lighting and fire lifts. Towers and tall buildings are a particular area of scrutiny since the Grenfell Tower tragedy. ATSs are required on virtually every building more than three stories high and must meet the requirements of the BS 8519 fire safety standard, which was revised in 2010.
What features are important in an ATS?
Being a mission-critical piece of equipment, high reliability is essential. It’s therefore worth investing in an ATS with as few electronic connection points as possible between the switch and its controller. This is because electronic connections can be a potential source of failure. Some ATS units feature as many as 30 connection points, whereas the latest ATSs have a single wire connector, giving them higher inherent reliability.
Straightforward installation and maintenance is another important feature, especially in facilities with multiple units. With this in mind, it’s worth adopting an ATS with a self-contained design and minimal external components, accessories, wires and cables.
In general, the more straightforward the ATS, the less labour and wiring. This saves time for contractors and panel builders. Some units have the option to integrate modular accessories that plug into slots inside the unit, rather than needing space elsewhere in the panel. This is useful for panel builders as it enables the use of standard cabinets, even when the customer has specific requirements. It is also helpful to operators as it reduces downtime and service costs.
Another important feature is the ability to withstand environment extremes. These can be experienced due to unexpected situations in industrial environments and other sites. Therefore an ATS should be able to operate reliably in spite of extremes of temperature, voltage and vibration. The latest generation of ATSs have in-built condition and temperature monitoring to ensure they are always ready when an operator needs to switch to backup. They should also be able to remain fully operational even after exposure to a short circuit.
Communication interface for ATSs
Cloud-based monitoring and control is becoming more important. Facility managers now want remote and cloud-based control, monitoring and diagnostics. This will help them make the most of their operational budgets by keeping tabs on performance and status remotely, and performing maintenance only when it is needed.
The latest generation of ATSs supports these goals with built-in metering, diagnostics and the ability to interface with external control systems.
During the installation and commissioning phase, the communication interface also enables remote programming, configuration and testing. This is a major advantage for panel builders or installers who want to save time on a project for a facility with tens of ATS units on different circuits.
Once in operation, in-built intelligent software, metering and communication will enable the ATS to carry out automatic load shedding. This can help to improve a facility’s overall energy efficiency or keep energy consumption below a defined peak load.
It can also be vital for sites equipped with backup generators that are sized to power only essential equipment. An ATS that is capable of load-shedding can automatically disconnect low priority and non-critical loads as part of the process of powering up and switching on the generator. It will then re-connect these loads when mains power returns.
However, it’s also important that the communication interface is compatible with a facility’s existing technology. It’s therefore worth checking whether the ATS uses the relevant communication protocol, with the seven most common being Modbus, Profibus, DeviceNet, Modbus TCP, Profinet, EtherNet/IP and Open ADR, as well as the IEC 61850 smart grid communication protocol. Any two of the above can be used at one time.
Why has ABB launched the TruONE ATS?
ABB was aware that existing ATS technology was based on combining switches and controllers and installing them along with a variety of sensors and interfaces. Feedback from industry was that these ATSs are too time consuming to install.
ABB therefore developed the TruONE ATS as the first device to incorporate the switch and the controller in a single package. It enables straightforward operation, installation in standard enclosures and is compatible with standards in Europe, North America and Asia. Its digital technology also lends future-proofing as facility managers move towards remote diagnostics and cloud-based monitoring, such as the ABB Ability digital platform.
By using only a single digital connector between the switch and the Human Machine Interface (HMI), ABB’s ergonomic studies indicate that the TruONE will speed up installation by 80 percent and will cut cabling and commissioning time by up to 90 percent.
Being a digital connection, the HMI can be mounted on the exterior of a panel door and be completely isolated from line voltage, representing enhanced safety for operators.
Another notable difference with typical ATS solutions is that the switch allows emergency manual operation under load. This means that an operator can restore power immediately in the case of an equipment malfunction – avoiding having to evacuate the building to manually change over the supply. Mechanically, the switch uses new materials and construction to make load transfer more reliable.
About the author:
Len McGanity is Product Manager for low voltage breakers and switches for ABB’s Electrification Products division in the UK, and he has many years of experience in supporting customers with products and solutions for electrical power distribution systems in commercial and industrial facilities. He cut his teeth as an apprentice in his native Liverpool.
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