Power Factor: what it is, how to measure it and how to improve it to reduce utility fees.
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Slide: 1 of 20 Power Factor: Causes, Costs, Case Study Michael Wrinch, P.Eng.(Canada)
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Low power factor is expensive and inefficient. Energy utility companies often charge additional fees to large commercial, institutional, and industrial clients when their power factor drops below 0.95. Understanding power factor and knowing how to measure it and improve it generates significant energy savings for very little cost. Mike Wrinch, P. Eng. presented an informative 45 minute webinar on understanding, measuring, and improving power factor to reduce energy bills in buildings and facilities. Mike’s presentation included: * An explanation of power factor and how it affects energy bills and electric systems' distribution capacity * An overview of the hardware and software needed to measure the power factor in buildings * Solutions to improve a building’s power factor
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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Go To Webinar Control Panel
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questions!
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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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