Power Factor: what it is, how to measure it and how to improve it to reduce utility fees.
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Transcript of Power Factor: what it is, how to measure it and how to improve it to reduce utility fees.
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Power Factor:Causes, Costs, Case Study
Michael Wrinch, P.Eng.(Canada)
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Power Factor Agenda
• Background on Electricity
• What is Power Factor?
• What it can cost you
• How it effects your buildings
• How to fix it
• Case Study
• Software Demo
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Electricity It’s Like Traffic on a long road
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Electricity BasicsRoad
Wire
Speed
Volts
V
Cars
Amps
A
Traffic
Watts
W
* on =
Traffic per hour
Watt-hour, Wh
An amp is a measurement of many electrons
per second!)
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Traffic and Toasters
V*A=W
• Drive too fast: Car Crash (sparks)
• Too many cars = A crash. We prevent it by: __________
EXAMPLE: Take a Toaster – 1000 W, Plug Voltage is 100 V, running for 1 hour.
How many Watt-hours (Wh) of Energy ? ______________
How many Amperes (A) of current ? ______________
Bigger Roads/
(Wires)
1000 Wh or 1 kWh
1000/100 = 10 A
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Unfortunately,
this is not completely true….
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Electricity Is MORE like traffic in a City !
Flow (Amps) is delayed from speed (Volts) by city traffic lights etc.(motors) the delay is a utilization of energy with no work – it is called “imaginary”, Reactive Power or VARs.
The total of Watts and VARS is called APPARENT POWER or VA. They are related by: 22 VARWVA
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Apparent PowerRoad
Wire
Speed
Volts
V
Cars
Amps
A
City Traffic
Apparent Power
VA
Traffic per hour
is still: Watt-hours (Wh)(We use expensive energy meters to figure this out)
* on =
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Traffic and Fans/Motors make VARs
• Most Common Sources of VARs: Motors (ie:Fans/HVAC), and Computer power supplies.
• VARs are BAD because they increase the amps but they produce no real work ! (i.e. cars are now stuck in traffic revving engines but not moving, (Do we need to make the road bigger? OR Fix the traffic lights?)
• So: V*A=W is now: V*A=VA –> Apparent Power
• EXAMPLE: Take a Fan – 1000 VA, 900 W, Plug Voltage is 100V, running for 1 hour.
• How many Watt-hours (Wh) of Energy ? ________ ??900 Wh
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Power Factor – making power Super easy!
• POWER FACTOR (PF) was created
so power engineers do not have to think much!
• Power factor is the ratio of Watts to Apparent Power or: PF=W/VA.
• EXAMPLE: If a Fan delivers 100 W
and uses 120 VA,
the Power Factor is: 100/120 = 0.833.
• SIMPLIFYING: Turn VA, VAR and
W into one number ! PF
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Why a Low Power Factor is a BAD Thing
Low Power Factor (PF) will force you and the Utility to upgrade power lines to bigger wires. The Utility charges their customers for low power factor. EXAMPLE:
W VAR VA pf V A% Inc.
of A
100 0 100 1 1 100 100%
60 117 0.86 1 116.6 117%
120 156 0.64 1 156.2 156%
180 206 0.49 1 205.9 206%
Wow!
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Why Would You Have a PF Issue?
• Competitive bidding: will commonly leave out power factor correction kits as it adds to the cost of construction (and your monthly power bill).
• Building Improvements: may not take into consideration the additional VARs. Examples include heat pumps and geothermal upgrades
• Old buildings: with malfunctioning, inappropriate or non existent power factor correction systems.
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How Do You Know if You Have a Problem?
• It will show up on your electricity bill as “Power Factor Charges”.
• Charge Examples:
– BC Hydro: penalty charge on monthly PF average. Penalty ranges from 2% to 80% of your kWh charge. Starting at PF less than 0.9.
– California PG&E: charges on monthly PF average. Ranging from +1% credit to a -2.1% penalty of your kWh charge. Penalty starts at PF less than 0.85.
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Case Study: Community Center
• New community center on British Columbia coast
• Yearly energy bill: $100,000
• Power Factor averaged: 0.70 resulting in 24% penalty charge (approximately $20,000/yr)
• Using Pulse Energy Management System to view the real time demands, a $10,000 power factor correction kit was specified and installed.
• Payback period of 6 months.
• NPR over 25 yrs of $390,000 !
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How You Can Identify and Correct for PF
1. Identify if you have a power factor issue by looking at your energy bills.
2. Power Factor charges greater than $100/month are worth addressing
3. In Pulse Software, Create a power factor and a kVAR chart.
4. Show this to an Electrical Contractor who will then work with you to select the right size of power factor correction kit.
– The kit size is typically 75% the maximum kVARs and ordered as a static or variable size. A static power factor correcting kit poses a risk of over correcting which can damage a building – use variable.
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Example - Software
MAX Power = 130 kW
MIN Power = 50 kW
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Example - Software
MAX Power = 130 kW
MIN Power = 50 kW
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Example - Software
MAX PF = 0.81
MIN PF = 0.6
Average PF = 0.71
Penalty Range:
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Example - Software
MAX kVAR = 90
MIN kVAR = 50
Solution: Variable PF correction
kit: 80,60,40,20 kVAR steps.
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Summary • Watt-hrs are the amount of watts used for one hour
and we pay for kWatt-hours (kWh = 1000 watt-hrs)
• VARs are caused by motors, HVAC, and computers and cause excessive current in power lines.
• Low PF: can result in costly penalties seen on your electricity bill. Caused by excessive VARs.
• PF: can be corrected with the right tools and can reduce energy bills typically around 24% !
• Pulse Energy Management Software is an effective tool for identifying VARs and managing your day to day energy.
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Thank you! Additional questions?
Contact Pulse Energy at: 1-877-331-0500 or at [email protected]
Look for future and archived webinars on our website: www.pulseenergy.com/resources/webinars
Look for the webinar summary and further discussion on our blog: http://blog.pulseenergy.com/
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