While an integral part of many electrical and IT installations, uninterruptible power supplies remain something of an underappreciated mystery to many in the channel. Here are 4 of the biggest myths you’ll hear about UPS:
Myth #1 – All UPS systems are the same
While the ultimate task of any UPS is the same i.e. to protect any connected electronic equipment against power cuts and other mains supply failures, its far too simplistic to suggest they all carry out the same function.
So before you even think about all the various manufacturers and models, you should know there are 3 distinct types or topologies of UPS, each offering varying levels of protection.
- Offline or Standby UPS (also referred to as VFD – Voltage and Frequency Dependent)
- These are the cheapest option as they only offer the most basic protection. As the name suggests, the load is always supplied by the mains, with an internal battery charged on standby and ready for use.
- When there’s a mains failure, there’s a tiny break in supply, typically less than 25 milliseconds, when the inverter switches on and powers the load from the charged batteries. That might seem a very short period of time, but it is enough of a break for a sensitive electrical device to notice!
- That’s why VFD UPS are only used with non-critical equipment.
- Line Interactive UPS (also referred to as VI – Voltage Independent)
- This topology offers the next level of protection. In essence, it works in a similar way to an Offline UPS but it also incorporates automatic voltage stabilisation (AVS) technology that protects against sags, brownouts, surges, spikes, and electrical noise.
- Line interactive UPS protect against such voltage instabilities by increasing (or decreasing) the voltage if the mains supply falls out of tolerance. In the event of a mains failure, there is still a slight switchover period until the batteries take over, but typically this is around 5 milliseconds.
- With their additional protection and larger power capacities, VI UPS are well-suited for larger non-critical loads such as telephone switches, servers, and smaller motor applications.
- Online UPS (also referred to as VFI – Voltage and Frequency Independent)
- The ultimate in power protection and availability. This type of UPS offers maximum protection against all electrical issues because the load isn’t directly connected to the mains.
- Instead, electricity goes through what’s known as a double conversion process. The mains power enters the UPS and travels through a rectifier, which converts it from AC to DC. Then it flows through an inverter that converts it back from DC to AC, before powering the load. This dual conversion ‘cleans’ any abnormalities from the mains supply.
- The batteries in a VFI UPS are always connected to the inverter ready and waiting, so if there’s a mains power failure or disturbance there is no break in power while the system switches over. The rectifier just switches off and allows the inverter to automatically take power from the battery set.
- Online UPS typically range from 700 VA to multi megawatt systems. Thanks to their total power protection, they are the go-to choice for critical loads found in facilities such as data centres.
Myth #2 – UPS are too complicated to choose the correct one for my customers
Yes, there are various topologies as we’ve just explored. And yes, there are so many different manufacturers and models on the market that at first glance the choice might appear rather confusing or even daunting.
However, selecting the best right UPS basically boils down to 2 fundamental questions: 1 how big is the load? And 2 what runtime does the customer need (i.e. how long they need the batteries to last if a power cut happens)?
Of course, there are other factors to consider. For example, whether a load is critical or not. Say you’re a call centre. You always need your servers, computers and telephone systems to be online. So there’s your critical loads. But your office printers or desk fans probably aren’t so business critical…
You’ll also need to take your installation environment into account, as that will determine whether your UPS is freestanding or mounted in server racks.
But once you’ve established the initial load and runtime requirements, it’s pretty straightforward to tackle all the other criteria and identify the most suitable solutions.
Myth #3 – A UPS doesn’t need any maintenance
You probably don’t think this is the case with electronic devices such as computers, so why should an uninterruptible power supply be any different? A UPS is a sophisticated, hard working device and wear and tear is inevitable – parts like fans or capacitors will need replacing, while batteries have a service life too.
As the saying goes ‘prevention is better than cure’ and it’s certainly true that how well you look after and maintain your UPS will have a direct impact on how well it performs.
Regular UPS maintenance means your customers are less likely to experience a critical failure, while it ensures systems operate at peak efficiency, cutting the energy it takes to run them.
Myth #4 – UPS systems are big, bulky and inefficient
The stereotype of the big black power-hungry box sat buzzing away in the corner of a server or plant room might have been true 20 or even 10 years ago. But technology has come on in leaps and bounds since.
We’ve seen transformer-free models, which are smaller, lighter, and more efficient, become the mainstream option for pretty much all power ratings up to 10 kVA, while they’re also available up to around 300 kVA for larger-scale installations.
The past decade has also seen the evolution of modular UPS, which give customers risk-free scalability to ‘pay as you grow’ simply by adding power modules when their load requirements increase. Modular UPS offer high power density in a compact footprint, optimising floorspace. And as each power module is hot-swappable (i.e. can be replaced without having to power down the whole UPS), you are guaranteed downtime-free maintenance too.
The latest emerging trend is the move from traditional IGBTs used in UPS manufacturing in favour of silicon carbide (SiC) semiconductors. These components are much more efficient, produce less heat, deliver higher power density, can operate at higher temperatures, have faster switching capabilities, and are more durable too.
This has opened up a whole new world of opportunities for UPS manufacturing, for example, our modular Multi Power2 range can achieve market-leading 98.1 per cent efficiency in online double conversion mode.