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Back in Black without AC/DC

 
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Mark



Joined: 13 Dec 2007
Posts: 883
Location: NW England

PostPosted: Thu Sep 14, 2017 12:14 pm    Post subject: Back in Black without AC/DC Reply with quote

Back in Black without AC/DC - university pilots low energy computing:
http://www.greenintelligence.org.uk/article/back-black-without-acdc-university-pilots-low-energy-computing
http://www.greenintelligence.org.uk/article/low-carbon-ict-firm-britain-s-most-innovative-small-business

Lancaster University’s Environment Centre was able to work through a blackout after installing an innovative DC-only computer system which is achieving at least 70 per cent energy savings. The solution was delivered by Lancashire-headquartered Extreme Low Energy, which provides IT infrastructure powered directly by DC current without the need for converting power from AC. Usually, low voltage DC generated by power plants is converted to AC current so it can be transported across the grid efficiently, and then converted back into DC by individual electrical appliances. To avoid the energy lost at each conversion, Extreme Low Energy has developed DC-only independent micro-grids that use electricity generated onsite through solar PV. Computers run on a single ethernet cable that delivers both power and data - meaning that there is no need for an AC/DC inverter on each appliance or a fan to take away excess heat. The breakthrough led to Extreme Low Energy being named Britain’s most innovative small business by the government’s Business is GREAT campaign in 2015.

Industry-first
Dr Andy Pickard, manager of Lancaster University’s Centre for Global Eco-Innovation, which is based in the university’s Environment Centre, said: “We had to buy new computers so I thought why don’t we live our ideals and buy low energy ones. “We decided to go with [Extreme Low Energy] to reduce our carbon footprint, to collect data and help the company gain the experience it needs to develop and market the product.” The technology has already been trialled in schools and colleges in the UK and South Africa, but this was its first use in a university setting and the first using dual screen technology - which is becoming standard in many workplaces. “It is the first time anywhere in the world that computers and dual screens have been powered off one ethernet cable,” said Caroline Clayton, operations director at Extreme Low Energy. “It is technically quite a feat to achieve this under a low voltage threshold.”

Energy savings
“We estimate the system can deliver at least 70 per cent energy savings. There are many other advantages too. There are no moving parts in our computers, so no fans to draw in dust and move it around the computers. This decreases the maintenance costs and increases longevity. “As there are no plugs, there is no PAT safety testing needed which saves money. The system can also continue operating in a power cut, so there is no interruption of business.” Early indications show the system installed at the university is actually delivering 75-80 per cent energy savings.
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adam2
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Joined: 02 Jul 2007
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PostPosted: Thu Sep 14, 2017 1:02 pm    Post subject: Reply with quote

Interesting, but I was somewhat put off by a glaring inaccuracy.
"power plants generate low voltage DC" Oh no they don't, with the exception of PV modules.
Virtually all modern power plants generate AC, often at 11,000 volts, historically somewhat lower AC voltage were used such as 3,300 or 6,600 volts.

DC generation for general use "went out with the war" and even then it was usually at about 500 volts.

Power over Ethernet (POE) is not that new, and is not in itself particularly efficient. The use of thin cables primarily designed for data and not for power, and the use of a relatively low voltage, 50 volts DC, leads to significant losses of up to 10% in the system.
By contrast use of 240 volts AC over the same distance would have losses of less than 1%
Most POE installations derive the 50 volts DC from the mains via a switched mode power supply, this entails small but real losses.

In the installation being discussed the power is derived from renewables, but losses would still occur in the charge controller, and presumably also in a voltage regulator.

A great merit of POE is that the limited available power forces efficient equipment design, however the same efficient design could be used for other supply voltages.

Another merit of POE is simplicity at the point of use, one cable instead of two, no risk of unplugging a PC to use another appliance, and no requirement for PAT testing.

50 volts DC has negligible electric shock risk, but is arguably as dangerous as the mains with regards to fire risk.
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fuzzy



Joined: 29 Nov 2013
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Location: The Marches, UK

PostPosted: Fri Sep 15, 2017 5:19 am    Post subject: Reply with quote

I find it depressing. It's not really a 'breakthrough' or an 'innovation'. It doesn't require a University to do it. It's just that universities have PR, marketing, business depts and lawyers. No one has to PAT test anything - it has no relevance except to damaged mains cables and metal kettles. Computers are all plastic and double insulated design with no earth connection, so it tells you nothing.

Eventually, DC systems will become widespread eg for lighting from solar. Most appliances run on low volts DC internally and should be mandatory fitted with DC input options [as every laptop has]
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clv101
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PostPosted: Fri Sep 15, 2017 8:27 am    Post subject: Reply with quote

fuzzy wrote:
Eventually, DC systems will become widespread eg for lighting from solar. Most appliances run on low volts DC internally and should be mandatory fitted with DC input options [as every laptop has]


The mobile phone industry (except Apple!) has standardised on a 5V DC power supply.

We are well overdue a similar standardisation for higher power systems, mainly laptops but also suitable for televisions, hi-fi etc. At 24V DC standard offering around 5A with a standard plug would seem like a good idea.
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fuzzy



Joined: 29 Nov 2013
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Location: The Marches, UK

PostPosted: Fri Sep 15, 2017 9:56 am    Post subject: Reply with quote

The gravy trainers in the IEE, bulding regs, etc won't like that. Seperated extra low voltage means they can't stop you doing it yourself.

Of course high power low voltages are a greater fire risk than mains and need sensible installation/terminations. No doubt the high priests will want medical level regulations to knobble it.
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fuzzy



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PostPosted: Fri Sep 15, 2017 10:07 am    Post subject: Reply with quote

I suggest the way forward is distributed, user replaceable lithium batteries at every device or wallport. Perhaps a dial or dip switches on every appliance dc input to set priority for charging - say 10 levels. When power struggles [assuming a lot of renewable sources] then battery chargers etc can cut out. This allows variation to be coped with. We can't assume constant power like the old days.
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adam2
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PostPosted: Fri Sep 15, 2017 10:09 am    Post subject: Reply with quote

fuzzy wrote:
The gravy trainers in the IEE, bulding regs, etc won't like that. Seperated extra low voltage means they can't stop you doing it yourself.

Of course high power low voltages are a greater fire risk than mains and need sensible installation/terminations. No doubt the high priests will want medical level regulations to knobble it.


I fear that you are correct. And do not forget the wretched part pee of the building regulations, that if pedantically interpreted ALREADY covers extra low voltage equipment. Even a battery door bell would seem to be included, though I have not heard of this bit being enforced yet.
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