Power and Energy, Two Concepts
NB Power invoices most General Service and Industrial customers for power
(demand) and energy (consumption) as two separate components. Demand charges
are intended to recover the cost of facilities (such as transformation, wires
and generators) available to provide the maximum amount of electricity which
customers may require at any time.
This is why "Customer A" pays a higher demand charge than "Customer B."
To illustrate this, lets look at two customers whose load profiles are shown
below.
To serve Customer A, NB Power needs to install facilities 10 times the
capacity of those required to serve Customer B. Customer A,
however, uses the facilities only 1/10 as long as Customer B. These
two customers consume the same amount of energy, but the cost of providing
service is different.
WHAT IS POWER?
Power is the rate at which the electricity is consumed. It is expressed in watts
(W) or kilowatts (1 kW = 1000 W).
The maximum power recorded during a certain period of time is called demand.
It’s measured in “kW” (Real Power) and/or “kVA” (Apparent Power). NB
Power uses 15-minute intervals for billing demand.
WHAT IS ENERGY?
Energy is the product of power supplied, multiplied by the length of time it is
used. It is measured in kilowatt-hours (kWh).
WHAT IS VOLTAGE?
Voltage is the difference in electrical potential between two points. It is
expressed in volts (V) and is a function of power in watts (W) and current in
amperes (A).
(note: The term potential also means voltage)
WHAT IS CURRENT?
Current is the quantity of electrons flowing through a conducting material in
one second. It is expressed in amperes (A) and is a function of voltage in
volts (V) and resistance in ohms .
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