Article for EBM - Power Systems Technology



Article for EBM

Revolutionize your distribution system

Use Half the Space with the amazing new

MiniSub

Over the last 100 years or since the beginning of designing power systems, engineers have had limited options in bringing in power and distributing it throughout the building. As the years have passed and specifically as the electronic age has come upon us, the demanded for more power has greatly increased, putting greater demands on the electrical system design.

Engineers have had no alternative but to provide larger and larger services to meet the power demands, which have created three major problems. Greater space requirements ( not well accepted by the architects) higher costs ( definitely not well accepted by the owner) and significantly higher fault levels which have caused problems for everyone.

Up to know there has been little improvement in the basic design of power distribution equipment. Most of the improvements have come in better breakers and relays to deal with the higher fault levels, Series rated breakers to cut the cost but with serious draw backs for the owner. Major manufactures tried to make the distribution centres smaller and smaller until CSA stepped in and regulated sizes to allow for proper cable bending radius. Now there is another choice, Power Systems Technology developed a new ultra compact distribution system, which will change the way we power buildings. This system solves all three problems brought on by the increased power demands, smaller size, lower cost and reduced fault levels. This new product is called MiniSub.

What’s a MiniSub?

A MiniSub is a extremely compact unitized substation or service entrance module which incorporates the medium voltage switchgear, protection, transformation, metering, and secondary distribution all in a space about 2 meters wide, by 2 meters high, by 2.5 metes deep. This is the same for primary voltages from 5KV to 27.6 kV.

There are several key components in the MiniSub. The primary switching can include loop switches, dual radial or single switching. Primary auto transfer switching. Ground positions completely separate form the main contacts, all in a maintenance free totally sealed environment. MiniSub’s have no live primary live parts including the terminations. This means no maintenance, so no down time. Far greater safety is achieved over conventional switchgear. This is also the main reason for the small size.

Another key component in the MiniSub design is the use of transformers based on the CSA C227.4 spec. Designed for the Utility market, to give them the security to overload up to 200% for specified periods of time with out loss of life. We use the same basic transformer design but incorporate the CSA certified sealed switching up front to allow it to be operated by standard electrical personnel.

Of course in a CSA world these same transformers are fused to maximum 150%. This is like having a car designed to run at 200 MPH but operating at 100MPH in its fully loaded condition. A nice feeling to have if you system gets fully loaded.

Now we have this side of the Unit-Sub covered we have to deal with low voltage. These compact boxes can be supplied with a compliment of secondary distribution and metering to complete the package, and give the customer a totally assembled CSA approved compact unit substation ready to connect and energize.

Now you have a general idea of how the MiniSub is put together, how can we use this new technology to its best advantage to solve the three main problems, Space, price and fault levels.

Space:

Replacing a standard substation say 1000kVA with loop switches for a down town vault will take half the space or less. By ordering the fire rated fluid the whole substation can be installed in a parking space. All the main secondary distribution can come all installed ready to feed the power panels throughout the building. In larger projects say 4000kVA we use the MiniSub in Smaller components of 1000 to 2000 KVA and bring the kVA to the load as is done with the small 600-120/208 voltage distribution transformers. By using the internal medium voltage switching and using the primary cable to bring the power to the load , we can reduce the space required even more. Also by splitting up the kVA we have solved the second problem “ fault levels”.

Fault Levels:

Increasing the fault levels past 25kA increases the down stream cost exponentially. It also causes coordination problems and increases the potential for accidents. We do away with this problem by using multiple MiniSubs and maintaining a low fault level through out the system. The use of several transformers serves more that one purpose. It lowers the fault levels and increases the flexibility of the system. Eliminating a 4000 amp switchboard increases the flexibility, you don’t have to shut down all the building to service a main breaker. You can isolate one sub with out affecting others. Another sub can be added without shutting down the others. This is a whole new way of designing and requires a forward thinking person to embrace the new technology. It ‘s not for the

( that’s not the way my father did it) group.

You also need to keep in mind that this will eliminate up to 100% of the traditional high service switchgear required in the traditional design.

Cost

No mater what you come up with it all comes down to cost. Even the NASA shuttle is built by the lowest bidder. Speaking of NASA if you could go look at the power switching in the basement you would find our switching units. When looking at cost it requires looking at the whole system and what is the end result is. The basic cost of a simple MiniSub will normally be less costly than a similarly equipped unit substation. When you apply the total concept of the MiniSub in larger services the cast can be 50% less cost To our knowledge nothing has been developed which can lower the cost this dramatically and add this many benefits.

When looking at cost you need to compare all the savings. Square footage cost, maintenance, installation and assembly costs, design costs, safety costs, life cycle costs. Quality of the power it supplies, how can it be upgraded. All these factors contribute to the final price of the project, and what the owner ends up with.

Who can use this:

The MiniSub works for any project. Apartments can incorporate most of the distribution in one neat box, which can be placed anywhere. Large commercial buildings can split up the distribution and eliminate the big switchboards, bus ducts and maintenance shutdowns required every few years. Industrial projects can install the MiniSubs on the shop floor, they can even incorporate the MCC. Large industrial users can install multiple MiniSub on the roof and feed down to the loads below, while using one loop feed cable to give reliable redundancy.

Industrial parks where the utility places a sectionalizer and a pad mount on the lawn to feed the building can have only one box at less cost. If you are familiar with the term N+1 in the UPS world the MiniSub with the built in automatic transfer switch in the low voltage section can be set up to allow one spare sub to automatically take over from any failed unit. Each unit can be part of a SCADA system at low cost adders.

If the first units is ordered early in the project and used for construction power than move it to its final position when the construction is done. They come all assembled and ready to connect.

Utilities can build a substation in that looks like a doll house rather then a huge jungle jim.

Our latest invention is the Mini Mall Metering MiniSub. A MiniSub with up to 8 places for meter sockets 200 amp protected by a breaker. One of the meters can be up to 600 amps for the main store. Don’t need to take any rental space for the meter centre.

Who Can’t use this:

The MiniSub limit in size today is 3000kVA for units with low voltage secondary. There seems no reason to go higher, if you need more kVA add another unit. For projects which need larger kVA for one load and this would be few instances you may need to consider the old way. anyone else will definitely benefit.

For more information see the web site powersystems.ca, or call 613-692 0647

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