Wattmeter and Watt-Hours
Wattmeter



Wattmeter measures the instantaneous
power.
Watt-hour meter measures the amount of
power used in a given time.
Kilowatt-hours (kWh) – because watt-hour is
very small, utility meters read in kilowatts


Number of
VxI
kW 
1000
Electric power consumed is purchased at
current rates per kWh.
Efficiency

Efficiency is a ratio of electrical power.

powerout
x100
% efficiency =
powerin
EER


Federal government tests products to
ensure that the energy efficiency rating,
EER, is correct.
Higher percentage, more efficient the
unit, the cheaper to operate.
Gears, Pulleys, and Power

By using gears and pulleys in an electromechanical
system, we can manipulate such facts as torque,
work and rpm while maintaining the same
horsepower.
Conservation of Energy

The law of conservation of energy
states that energy can neither be
created nor destroyed. Energy can
only be converted from one form to
another.
Gear Reducers

To avoid the safety
problems associated with
pulleys and chains, many
applications use gear
reducers to obtain great
twisting forces. The gear
reducers lower the rpm
of the motor which in
turn increases the
twisting forces of the
gear reducer shaft.