Smart circuit-breakers for energy-efficient homes
The old fuse box gets **a new lease of life**
IN THE future, homes will use electricity much more sensibly than they
do now: turning the lights off automatically when no one is around;
adjusting the heating regularly to suit a householder’s daily routine;
making sure the electric car is charged up using off-peak rates;
even drawing power from the car’s battery in the event of a grid outage.
A variety of plug-in devices can already do some of these things. Yet
lurking in every home, usually in a dark cupboard or down in the
basement, is a humble piece of equipment that, with a bit of
tweaking, could replace them all with a single command centre.
The equipment concerned is often referred to as a fuse box, although
nowadays it is unlikely to use actual fuses—strands of wire that cut off
the current by melting in the event of a power surge. Instead, such
boxes contain a panel of electromechanical switches called circuit
breakers. Typically, a breaker contains an electromagnet through which
the current flows. If that flow exceeds a set level, the electromagnet
becomes sufficiently energised to throw a mechanical switch, which
breaks the circuit. A circuit breaker responds faster than a fuse, and
can also be reset manually instead of having to be replaced.
Circuit breakers are thus essential to help prevent electrical fires and
stop people from being electrocuted. But they also serve as a
distribution point for all the wires in a house, with breakers
monitoring the lights and power sockets in different rooms, and separate
breakers regulating some individual appliances, such as cookers and
water heaters. This makes the breaker box an ideal place from which
to manage energy use.
To make such management work, though, the breakers need to become
“smart”. One way to do that is to add electronics to them. This is what
Eaton, a multinational, is attempting in a trial taking place in America
with a dozen utilities and the Electric Power Research Institute, an
industry body. Eaton’s modified breakers have been installed in about 80
buildings, where they are monitoring and controlling power supplies
remotely. The breakers, which use encrypted internet connections, can
also meter each circuit separately. That permits a much broader analysis
to be made of a building’s power consumption and might in the future
allow utilities to offer different tariffs for circuits powering
different things, says Ron Thompson, one of the project’s leaders. A
second phase of the trial will begin next year, to develop more
applications. So far, the most popular ones control heating,air
conditioning, water heaters and recharging electric cars.
Manetos Labs, a Swedish firm, is going even further than this, by
developing a digital circuit-breaker. That has been made possible by
advances in high-power semiconductors, which allow “solid-state” circuit
breakers, with no moving parts, to be built. These would act as direct
replacements for electromechanical ones.
A digital breaker has several advantages. Its lack of mechanical parts
should make it both safer and more reliable. It can cut a circuit in
just 250 nanoseconds, which is substantially faster than a mechanical
version, says Trued Holmquist, a Swedish information-technology
entrepreneur who helped found Manetos. The programs it uses to control,
measure and communicate with appliances could be updated over the
internet, letting new features be added as they are developed. And, as
with most smart-energy services, these could be controlled by a
The level of detail smart breakers look at is impressive. Mr Holmquist
says that his can, for example, measure the revolutions-per-minute of
the compressor in a refrigerator. Not only would this let an app monitor
how hard the appliance is working, it could also give warning if that
appliance was about to break down.
A useful innovation, then, but one only likely to be taken up if the
price is right. To this end Manetos has teamed up with Flex, an
American firm that is one of the world’s largest contract manufacturers,
to work out how to make solid-state breakers as cheaply as possible. The
plan is to consolidate the electronic circuits into a single chip that
can be mass-produced for a few dollars. Breakers using such chips
should, Mr Holmquist reckons, be competitive with mechanical ones.
Other firms are taking a different approach to the question of price, by
seeking customers willing to pay a premium for a solid-state
breaker’s virtues. Atom Power, in North Carolina, is aiming the digital
breakers it is developing at commercial and industrial buildings, where
it thinks their benefits will be higher than in homes.
One of the advantages of a solid-state breaker is that it removes the
risk of arc flashes—electrical discharges that can run through the air
when a switch is thrown. Such sparks are particularly hazardous if there
are combustible materials around, which is more likely in an industrial
than a domestic setting.
Siemens, a German electricals giant, reckons digital breakers show
“great promise” and has taken a stake in the company. Atom’s
engineers have not given up on the domestic market, though. They hope
residential versions will be practical once production volumes grow.
Eaton also thinks that,at some point, the time for digital breakers
There is, however, one other obstacle besides price to the uptake of
domestic digital breakers: the regulators. These people, naturally and
sensibly conservative, tend to be more in tune with mechanical than
digital breaker systems. Their certification is necessary before
products can go on sale. To deal with that problem, Manetoshas a trick
up its sleeve. Its first digital breakers will also incorporate an
old-fashioned fuse. With this as a backup, the system should pass
existing tests with flying colours. Mr Holmquist is confident,
though, that the fuse will never be needed. Manetos will offer a
lifetime guarantee it will not blow.
a new lease of life 重获新生
Charge up = charge: to put electricity into a piece of electrical
equipment such as a battery. (on charge ) 充电
off-peak: less busy or active than other times.非高峰（时间）
humble: simple and with only basic equipment or features
be often referred to as 通常被称为
water heater 热水器
air conditioning 空调
team up with 联手…..
consolidate…..into…..: to join or combine together into one
mass-produced: the process of producing large quantites of goods by
using machines; 大量炮制。mass production
pay a premium for 支付…..的佣金
take a stake 参股
at some point: at some moment in time that is not made specific
go on sale 上市销售
have a trick up your sleeve: to have a plan that you can use if you
need to 有妙计
pass existing tests with flying colors 顺利通过现有的测试
with flying colors: if you do something such as pass an examination
with flying colors, you do it very successfully.
in tune: in a state in which people agree with or understand one
another –usually +with
as a backup 作为备份
blow: if something electrical blows, it stops working, usually
because too much electricity has passed through it.