SAFE, DURABLE, ACCURATE-The POWER METER was
designed to be safe to use. The circuitry utilizes listed components for
all high voltage componentsand physical design completely separates
high voltage from the user. The internal circuitry is protected
against voltage spike, surges, etc, and the self calibrating circuitry
compensates for temperature and other factors. The instrument is designed
to sustain rough handling, such as tossing the instrument in a tool box,
or dropping it. The POWER METER has been tested with a laboratory
grade Yokogawa Power Meter (Model 2533) to ensure accurate power
measurements regardless of load or power supply.
WHY DO I NEED THE DIGITAL POWER METER? WHAT CAN'T I
USE MY AMMETER?
A common misconception is that power is simply the
product of voltage times current, implying that any ammeter can be used to
determine power usage. This is only true in a few special cases.
Voltage and current work together to produce power.The DIGITAL POWER
METER utilizes a combination of analog and digital signal processing to
calculate power. It is designed to measure power in AC (alternating
current) systems. (DC applications are also available, please
In AC systems, voltage and current go from positive to
zero to negative generally 60 times a second (60 cycles or 60 Hz). If
voltage and current are "high" or "low" at the same time, then they are
said to be "in phase." A common term to describe the time relationship
between voltage and current is called "power factor." When voltage and
current are "in phase," the power factor is generally 1 (surprising, this
is not always the case ). When the current peak follows the voltage peak,
this is called " lagging power factor," when current leads voltage, this
is called "leading power factor." When voltage and current are exactly
opposite ( when voltage is at a peak and current is zero,or vice versa),
the power factor is 0.
Utilities charge us for "real power" i.e. how much
work must actually be done by a generator (no matter how it is driven, by
a steam turbine, internal combustion engine, dam, wind, etc). To find
"real power," you multiply volts time amps times power factor. The power
factor is determined by the load, that is, the device using the power. A
light bulb produces light by simply heating up a thin metal filament and
is called a resistive load (other examples are heaters, toasters, etc).
Resistive loads have a power factor of 1, and are the only loads where you
can find real power by simply multiplying voltage times
A common induction motor, such as those found in
washers, freezers, refrigerators and air conditioners, work by
storing some of the electricity it uses in a magnetic field. This storage
causes the voltage and current to be high at different times, and the
resulting real power usage can be a small fraction of voltage times
current; this fraction increases as the motor is loaded. For example, an
air compressor at start up with an empty tank may consume only 1000 watts,
but would over 2000 watts when near shut off pressure. If you measured the
current going to the compressor motor as it is loading, it only goes up a
little bit, not by a factor of 2! The reason is that the power factor of
the motor is changing as the motor is loaded.
Measuring power can be very complex, however,
measuring real power used by light bulbs and induction motors can be very
simple compared to many modern loads. Computers, energy efficient lights
and energy efficient freezers, have circuitry which draws power in
The BRAND ELECTRONICS DIGITAL POWER METER accurately
measures the power used by these complex devices. It does this by
measuring current and voltage approximately 4000 times per second.
These values are processed and the power used is updated 3 times
every second. The POWER METER accurately compensates for changes in
frequency (a gas generator might be running at 40 Hz or 80 Hz), voltage
(85-150 volts) and supply "wave form." Power supplied by utilities
comes as a nice "sine wave," that is the voltage and current change
with a very smooth curve. Many generators and inverters supply power with
jagged or square transitions. This makes power measurement even more
difficult. All of this is made irrelevant by the way the DIGITAL POWER
METER calculates power.
WHY WOULD I WANT TO SPEND $150 TO MEASURE
Most people spend at least $500 EVERY year on their
electric bills. Where does it go? How much does your freezer, computer,
air conditioner, TV really cost to run? You can use the POWER METER to
accurately find how much it costs to run these devices. Armed with this
information you can more easily find ways to cut down costs. Turn the
thermostat down a little on the freezer, turn the computer off at night,
etc. You could easily save enough money to pay for the POWER METER in a
year or less.
SAVE NATURAL RESOURCES
Producing electricity consumes resources, dams rivers,
uses open space. No matter how the electricity is produced, some resource
is consumed, oil, coal, water resources, prime space, wood, etc. Using
your POWER METER you can accurately find where you can use electricity and
make informed decisions about your usage. Maybe that basement dehumidifier
isn't worth running, or that extra refridgerator isn't worth the cost.
With the POWER METER you are able to make more responsible decisions about
how you use your electricity.
Professionals who make their living working with
electricity, whether an electrician, a repair technician, a consultant or
an engineer often spend valuable time on problems related to electrical
power consumption. Up to this time, purchasing an instrument that
accurately measures power was a major investment. With the POWER METER the
electrician can more easily diagnose the circuit that keeps tripping, or
more precisely size a circuit line. The repair technician can use the
POWER METER to determine if a device is drawing too much or too little
power to help diagnose a problem. An engineer could use the POWER METER to
measure system efficiency. The consultant can use the POWER METER to help
clients with energy management decisions.
BEST BRAND FOR THE MONEY
Brand Electronics was able to develop an affordable POWER METER for
several reasons. The two principal partners have extensive experience in
real-time software development and innovative design. In addition, recent
developments in "computer in a chip" technology have brought the necessary
high-speed complex capabilities needed for real time power measurement at
an affordable price. The combination of these two factors has made the
POWER METER possible. The BRAND ELECTRONICS DIGITAL POWER METER finally
brings affordable power measurement to the market.
Ethan holds a Masters Degree in Engineering, and has been a licensed
and practicing engineer for over 20 years. Ethan holds a Patent on an
early version of the DIGITAL POWER METER (US Patent 5,869,960).
The POWER METER uses a single chip microcomputer, programmed by
Richard McGrath. Rick holds a degree in Engineering, and his backround
includes over 15 years in software development and maintenance for a
real-time training simulator.