Rethinking UPS technology for water and wastewater infrastructure
For water and wastewater applications, UPS systems are often specified with good reason as industrial equipment.
The operating environment can be demanding. Systems may be installed at remote pumping stations, treatment works or control sites, where reliability, environmental protection and long service life matter far more than they would in a typical commercial installation.
But there is an important distinction between making a UPS suitable for an industrial environment and assuming that it must use conventional UPS technology.
Modern power conversion has moved on. Today, it is possible to combine the ruggedness required by water infrastructure with high efficiency, low input current distortion, high input power factor and a considerably more flexible system architecture.
So perhaps the question should not be whether a UPS is labelled industrial, but whether it is properly engineered for the application.
Start with the application
A UPS in a water or wastewater installation may be supporting PLCs, SCADA, instrumentation, communications, chemical dosing controls and other equipment that needs to remain available through a mains disturbance.
The UPS itself may also have to operate in an environment where dust, moisture, temperature variation and limited access for maintenance have to be considered.
These requirements are real, and they should influence the design of the complete system — from enclosure protection and cooling to batteries, communications, redundancy and maintainability.
In the UK water sector, WIMES 3.07 is a useful example of this application-led approach. It provides specific requirements for UPS systems used within the industry rather than relying simply on a broad equipment classification.
The important point is that meeting demanding environmental and operational requirements does not necessarily mean accepting conventional electrical performance.
The UPS is also a load
We normally think about a UPS in terms of what it provides to the equipment downstream: clean, continuous power when the incoming supply cannot.
It is equally worth considering what the UPS presents to the supply upstream.
Water and wastewater sites often contain variable-speed drives and other non-linear loads. Depending on the installation, these can already contribute significant harmonic current to the electrical system.
A low-harmonic UPS does not correct distortion created elsewhere on the site. It simply avoids adding unnecessary harmonic current of its own.
The significance will naturally vary from one installation to another. On a strong electrical network, a relatively small UPS may make little difference to overall site distortion. On weaker supplies, generator-backed systems or installations with a high proportion of non-linear loads, its input characteristics can become considerably more relevant.
It is therefore sensible to consider the electrical behaviour of the UPS on both sides of the system.
Rugged by design. Modern by technology.
This is the approach behind the DEWEN BlueShield™ Series.
BlueShield uses true online double-conversion UPS technology within an IP54 system designed around the requirements of water and wastewater infrastructure.
Depending on rating and configuration, input THDi does not exceed 4%, while input power factor is ≥0.99. Online efficiency reaches up to 96%.
But electrical performance is only part of the design.
BlueShield systems can be configured with VRLA, NiCd or lithium-ion batteries, parallel redundancy, remote communications and integrated air conditioning where required. The range covers 5 kVA to 100 kVA, with configurations engineered around the environmental and operational requirements of the installation.
For UK water-sector applications, BlueShield is designed to meet WIMES 3.07 requirements.
A different way to specify
There will always be applications where a conventional industrial UPS architecture is the right engineering choice.
The point is not to replace one general rule with another.
Instead, UPS selection should begin with the requirements of the installation: environment, autonomy, redundancy, maintainability, communications, power quality and expected operating conditions.
Once those requirements have been established, the technology can be selected around them.
Ruggedness should be an application requirement — not a reason to compromise on modern UPS performance.