Switches
There are only two switches to operate:
•
Battery – OFF - Computer
•
Select
Set it to Battery when you want to make your
measurements outside or without using a
computer
, or set it to Computer when it’s
plugged into your computer using the supplied
USB cable. And set it to
OFF
when it’s not in
use.
Push the
Select
button to cycle through the
four main LCD screens. You can even hold
the
Select
button to “freeze” the display if the
numbers are changing too fast.
USB Connection
A USB “type B” connector on the back of the unit
allows connection to a Windows PC computer
.
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Power for the
Renewable Energy Monitor
is
supplied by the PC via the USB cable.
Battery Requirements
The
Renewable Energy Monitor
uses a
standard 9 volt radio battery that is easily
replaced when necessary. The LCD screen will
indicate when
Units of Measurements
The
Renewable Energy Monitor
measures
standard electrical units like voltage, current,
power, energy and resistance. It also
measures the RPM speed of the WindPitch
wind turbine.
Voltage
is measured in volts or millivolts
(mV). A millivolts is 1/1000 of a volt but when
seen on the LCD screen it can provide a
more accurate measure of the voltage. For
example…
1.23 volts = 1230 mV
10.456 volts = 10456 mV
Current
is measured in amps or milliamps
(mA). A milliamp is 1/1000 of an amp. For
example…
0.003 amps = 3 mA
1.256 amps = 1256 mA
Power
is measured in watts or milliwatts
(mW). A milliwatt is 1/1000 of a watt. For
example…
0.034 watts = 34 mW
2.987 watts = 2987 mW
Energy
is measured in Joules. Energy is
basically power x time and one Joule is equal
to one watt-second. For example.
21 Joules = 21 watt-seconds or the amount of
power used in 21 seconds.
RPM
is a measure of the rotational speed
of the wind turbines blades. RPM is used
in experiments to show how the above
parameters are affected by higher or lower
RPM rates.
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b a t t e r y i s l o w a n d
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B e s u r e t o s e t t h e
s w i t c h t o
O F F
t o
extend the battery life
when not in use.
Input and Output Terminals
There are two sets of
Input
and
Output
terminals. The
Input
terminals are on the
left side and the
Output
terminals are on the
right side of the unit. The Red terminal is +
or positive while the Black terminal is – or
negative. You must observe the correct polarity
when hooking up batteries, solar panels, wind
turbines or fuel cells to the terminals.
S
pecifica
tions
The
Renewable Energy Monitor
will measure
electrical parameters up to the following limits:
Voltage:
0 - 28 VDC
Current:
0 - 1 amp DC
Power:
0 - 28 watts
Resistance: 0 - 999 ohms
Energy:
0 - 65535 Joules
RPM:
200 - 2500
Note: very low and very high RPM speeds
cannot be accurately measured. Even though
the wind turbine may be spinning the electronic
circuitry is only capable of measuring a certain
range of RPM speeds. Low voltage outputs
from the WindPitch wind turbine may also affect
RPM accuracy.
Common Equations
The Renewable Energy Monitor uses the
following common equations internally to
measure and compute voltage, current,
resistance and power.
V = I * R
where V = voltage
I = current
R = Resistance
P = V * I
where P = power
V = voltage
I = current
J = P * T
where J = Joules
T = time in sec
Operating Tips
Electrical Fundamentals
– Refer to the
REES
Experiment Manual
for an explanation of the
fundamental electrical parameters such as
voltage, current, power, resistance and more.
Measuring Resistance
– A voltage must be
applied across the Input terminals in order to
measure the resistance attached to the Output
terminals.
Also, the resistance will vary depending on the
voltage and current produced in the circuit. The
Renewable Energy Monitor
uses Ohm’s Law
to compute resistance, so any small variations
in voltage and current will affect the resistance
reading.
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