ATEM MODULE 4: ELECTRICAL
The Goal…
Electricity is a Form of Energy
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Three Basic Components of Electricity
-
Voltage
-
Current
Let’s look at the physical definition of work
Work = Force X Distance
To Simplify…
Current is flow of electric charge
through a medium
Units: Amps
What is Current?
Resistance is the opposition to flow of
electric current
Units: Ohms
What is Resistance?
What Increases Resistance?
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Type of materials used for wire
-
Aluminum is more resistive to current
flow, than copper
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The length of the wire
-
The longer the wire, the more
resistance to current flow will be
present
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The cross-sectional area of the wire
-
The smaller the wire diameter, the
more resistance to current flow will
be present
Three Basic Components of Electricity
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How are the three basic components related?
Ohm’s Law
Voltage = Current x Resistance
The amount of work that can be done
by moving an electric charge a distance
The amount of work that can be done
by moving an electric charge a distance
Units: Watts
What is Power?
Dis
tance
Pipe=Wire
Electrical Power
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We learned:
-
Ohm’s Law -
V = I x R
Power = Voltage x Time
Wh = V x Hours
Where:
Wh = Watt hours
Not All Power Is Useful
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Total
-
Apparent Power
-
Units: Volt-Ampere
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Not Useful
-
Reactive Power
-
Units: Volt-Ampere Reactive
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Useful
-
Real Power
-
Units: Watts
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Not ALL of the energy made was
transferred to the right place
Non-Useable Power
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Inductive loads have high reactive power
-
T12 Ballasts
-
Large Motors
-
Arc Welders
How Are the Powers Related?
(Apparent Power)
2
= (Real Power)
2
+ (Reactive Power)
2
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Apparent Power
-
Total Power delivered to the building from the electricity utility company
-
Units: Volt-Ampere or VA
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Real Power
-
Power that you were able to use
-
Units: Watts or W
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Reactive Power
-
Power that you wasted
How is Power Related to Voltage and Current?
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Apparent Power (𝑃)
-
Total Power delivered to the building from the electricity utility company
-
Units: Volt-Ampere or VA
Single Phase
Three Phase
What is kWh?
Understanding kWh
What is Power Factor?
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Power Factor is the ratio of the real power to the total power (apparent
power)
Power Factor =
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Power factor will range from 0 to 1 or 0% to 100%
Real Power (Watts)
Power Factor Example
Power Factor =
Real Power (Watts)
Apparent Power (Volt-Amps)
0.97 =
Real Power (Watts)
Power Factor Correction
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Power factor correction will only decrease your electric bill, if the utility
imposes a penalty on power factor
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Why?
-
Because most utility companies charge customers on an hourly average of
What is Load Factor?
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Load factor is how much energy is used in comparison to the total peak
energy available
Load Factor =
Load Factor =
Load Factor =
=
=
50%
Total kWh consumed per billing period
Total potential energy available
Total kWh consumer per billing period
Peak Demand in kW x billing period x 24 hrs/day
36,000 kWh
100 kW x 30 days x 24 hrs/day
Understanding Load Factor
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Both low and high load factors can represent energy cost saving
opportunities
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High LF may mean that you shaved the Peak Demand or reduced your
monthly consumption
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Low LF may mean that you reduced you operating hours, to save kWh
but didn’t improve the Peak Demand
General Rule
Peak Demand (KW)
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Electric meters count the amount of KW used
in a time period
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Typical time period is 15 minutes or 30
minutes
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The largest consumption per time period is
the Peak Demand
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There can be a “ratcheted” annual peak
Demand Limiting
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The practice of limiting or reducing the peak demand each day
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Typically performed with a BAS system turning off extraneous
Demand Limiting Ideas
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Don’t run heavy loads from 1 pm – 7 pm
-
Instead use them at night
›
Kilns, computer on wheels, dishwashers, dryers
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Cycle needed equipment so the entire group does not run in the same
time period
What can I do to lower my peak
kW demand, lower total
Add VFD’s
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Variable Frequency Drive
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Varies the incoming frequency, in order
to change the motor speed and torque
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Typically install 1 VFD per motor
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A VFD can run a motor efficiently
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It can also soft start motors and lower
Savings Example
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A 15 Horsepower motor can be reduced
from 60 Hz to 45 Hz
Fan Affinity Law:
Where:
Adding VFD’s
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Real World Example
-
Added VFD’s to two 50 HP motors and
evaluated the cost savings
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Saved in a year
-
190,126 kWh from total consumption
-
47 kW from the Peak Demand
Change Indoor Lighting
4 Foot Lamp
T12 = 40W
T8 = 32W
T5 = 28W
Comparable light
output for less
wattage of electricity
Example
Small Building
200 2’ x 4’ Fixtures
4 Lamps each
T12 vs T5?
32,000W vs 22,400 W
9,600W
Change Indoor Lighting
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Fluorescent – Change T12 fluorescent lamps to T8 or T5 lamps, and its
9,600W x 270 occupied days/year x 9.5 hours/day = 24,624 kWh
24,624 kWh x 0.085540/kWh =
$2,106.33 savings a year
Change Indoor Lighting
Add Lighting Controls
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Occupancy Sensors
Ashley Williams, MCRP & ATEM
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Texas Energy Managers Association
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