Choosing the right critical power supply

Today, more than 3 billion people live in cities and the urban population of the planet increasing constantly. This means a growing demand for electrical power and more complex requirements for buildings and manufacturing facilities. Add strict energy standards to the equation and the process of identifying the right critical power supply for individual applications becomes exceedingly tricky. Here, Pat McLaughlin, Boulting Technology’s Operations Director, discusses what companies should keep in mind when choosing a switchboard.

Fault capacity and ruggedness
Before commissioning a low voltage switchboard, consider what kind of external fault you can expect to have in the application. Usually this means choosing a fault rating higher than the maximum supply capacity. The rule of thumb is: fault rating = (transformer VA /700) * 20. This way, your system should be safe even in the event of an external fault.

Boulting Power Centre

Another thing to consider is the product’s lifespan. Switchboards generally have relatively long lives and can last anywhere between 25 and 40 years, perhaps even more if you treat them right and ensure the regular maintenance they deserve. However, this also means they need to be rugged and durable, so they can withstand the occasional knock and abuse life throws their way.

Location and security
Industry has a tendency to leave the electrical room layout to the very end of the building design and adapt it to suit whatever space is left over. Try to avoid this approach if you can.

Ideally, you want your electrical room to be spacious and well ventilated. If possible, there should be enough space to allow repair and replacement work to take place as smoothly as possible. Switchboards are only installed once, but there’s a good chance you will need to add cables or modules as time goes by. Devices may have shrunk, but the laws of physics and the size of cables haven’t changed.

Access to your building’s power centre boards should only be granted to authorised personnel, rather than allowing just anyone to walk in and out. Ideally, the switchboard should be located in a secured room, out of the way, so visitors don’t just stumble in while looking for the rest rooms. In addition, electrical gear is a tempting target for thieves, so it’s important to protect it accordingly from malicious attacks or vandalism.

Futureproofing
Because of their long lifespan, switchboards should be designed to last a few decades. One way of future proofing a low voltage assembly is by using a modular design. There’s a chance that as you grow, you will require more capacity. You can easily achieve this by putting a bus coupler on the end, so you can extend and modify the switchboard without shutdown. Modularity also means that if a section of the power centre breaks down it can be easily replaced without having to turn off the whole thing.

Speaking of growth, another thing you might need if you want your switchboard to be future proof is a few spare distribution and motor control feeders. They might add to the final cost, but they might also be a lifesaver a few years down the line. You can’t predict the future, but you can make it easier for those who follow you.

Keeping it simple
To make sure sources can’t be cross-connected, even if the electrical control fails, all the switches should be mechanically interlocked. Interlocking switchgear ensures personnel are safe and equipment is operated according to the correct procedures.

Labelling in large switchboards can be very confusing, so colour coding is a good way of keeping track of supplies. Sometimes special symbols can also be used for multiple sources of supply, but colour coding is the simplest and best method. It offers an ‘at a glance’ view of the system and minimises the risks of mistakes.

Very few switchboards these days will operate critical processes manually, so remote signalling and switching is something you should consider when choosing a switchboard. It’s important to make sure that if the main power goes down in the middle of the night, or over the weekend, the generator needs to be on and fully functional.

Testing
Speaking of generators, you need to ensure that you test them regularly using a load bank. You should design the switchboard in such a way that testing is easy; otherwise excuses will appear and testing will be delayed. Make sure this doesn’t happen and you won’t be left in the dark when the power goes out. Switchboards need constant attention to always be at the top of their game.

These are just some of the main things to consider when deciding the requirements for low voltage switchboards. It can be a difficult process, but luckily help is never too far away. To find out more about what options are available for your low voltage assembly, get in touch with Boulting Technology on +44 1925 720 090.

Changing industry standards: one year on

Pat McLaughlin

In 1998, Google was founded, the first Apple iMac was introduced and the legendary Windows ’98 was released by Microsoft. In a less glamorous but equally important corner of industry, a new commission was being formed to revise the complex IEC 60439 industry standard, which governed the safety and performance of electrical switchgear assemblies. Although Windows ‘98 has long been consigned to history, the new industry standard – BS EN 61439 – only became mandatory on November 1, 2014. 

One year on, Pat McLaughlin, Boulting Technology’s Operations Director, evaluates how original equipment manufacturers, panel builders, electrical engineers, consulting engineers and contractors have been affected by the new BS EN 61439 standard.

Why a new standard?
In a market where the demand to optimise and reduce costs blends heavily with higher needs for assembly flexibility, the introduction of a new set of standards was needed to  guarantee the performance of Low Voltage Switchgear Assemblies.

Switchgear and Control Gear assemblies are multifaceted and have an endless number of component combinations. Before the introduction of the new standard, testing every conceivable variant was not only time consuming and costly, but impractical.

The intricate character of assemblies also meant that many did not fit into the previous two testing categories: Type Tested Assembly (TTA) and Partially Tested Assembly (PTTA). For example, panels which were too small to be covered by TTA and PTTA fell outside the standard. Finally, in the case of a PTTA, ensuring the safety and suitability of a design was often dependent strictly on the expertise and integrity of the manufacturer.

Design verification

The Boulting Power Centre

The major change introduced by the new BS EN 61439 standard refers to testing. It states that the capabilities of each assembly will be verified in two stages: design verification and routine verification. This means the new standard completely discards the type-tested (TTA) and partially type-tested assemblies (PTTA) categories in favour of design verification.

Although BS EN 61439 still regards type testing as the preferred option for verifying designs, it also introduces a series of alternative routes to design verification.

The options include using an already verified design for reference, calculation and interpolation. The BS EN 61439 standard specifies that specific margins must be added to the design, when using anything other than type testing.

One of the main benefits of the new design verification procedure is its flexibility. Under the old BS EN 60439 specification customers would demand a Type Test certificate for each assembly particularly Incoming Air Circuit Breakers, which was very expensive and time consuming.

The new standard allows users and specifiers to pertinently define the requirements of each application. Annex D of the BS EN 61439 standard provides a list of 13 categories or verifications required, what testing method can be used and what comparisons can be made. In order to optimise testing time, the standard allows derivation of the rating of similar variants without testing, assuming the ratings of critical variants have been established by test.

Dividing responsibility
The second major change implemented by the new industry standard refers to the responsibilities of each party involved in the design, test and implementation of low voltage switchboard assemblies. Unlike BS EN 60439, which stated the OEM or the system manufacturer was solely responsible throughout the testing programme, the new standard divides the responsibilities between the OEM and the assembly manufacturer, or panel builder.

The new standard recognises that several parties may be involved between concept and delivery of a switchboard assembly. The OEM is responsible for the basic design verification. In addition, the assembly manufacturer is meant to oversee the completion of the assembly and routine testing.

For innovators like Boulting Technology, the new BS EN 61439 has brought more freedom and flexibility when designing switchboard assemblies. For example, Boulting Technology has designed and launched the Boulting Power Centre, a range of low voltage switchboards, which are available in 25kA, 50kA, 80kA and 100kA, fault ratings, and up to 6300Amp current ratings.

Although change is never much fun, it’s what technology and industry are all about. If this wasn’t the case, we would all still be using Windows 98 or the indestructible Nokia 5110.