McGill Power Sales & Engineering, INC.

1

2007 Eaton Corporation. All rights reserved.

Power Factor Correction

Terry McGill President McGill Power Sales & Engineering Inc.

3

Agenda

What is power factor? What are the costs of low power factor? What are the solutions to low power factor? Power factor correction selection considerations Design considerations and pitfalls

4

Power factor definition

Real power = working power = kW Apparent power = Volts x Amps = kVA Reactive power = magnetizing power = kVAR

kVA kVAr

kW

Power factor is the ratio between the real power and the apparent power of an electrical system

5

Is the Glass Half Empty or Half Full?

Full Capacity

(KVA)

Foam/Fizz Capacity (KVAR)

Liquid (KW)

6

Utility must generate, transmit, and distribute active AND reactive power

7

If reactive power could come from another source utility can reduce

2007 Eaton Corporation. All rights reserved.

Demonstration

Power Factor Demonstration Unit

9

Why Consider PFC? PF correction provides many benefits: Primary Benefit:

Reduced electric utility bill if there is a penalty (a typical payback period is less than two years)

Other Benefits: Increased system capacity Improved voltage regulation Reduced losses in transformers and cables May reduce harmonics on the power system (with

harmonic filters)

10

Where has all the money gone?

+

Energy (kWh)

Demand (kW)

PF Charges

Taxes

11

Typical Uncorrected Power Factor

Low PF typically results from unloaded or lightly loaded motors Unloaded motor PF = .20 Loaded motor rated PF = .85

Industry Percent Uncorrected PF

Brewery 76-80

Cement 80-85

Chemical 65-75

Coal Mine 65-80

Clothing 35-60

Electroplating 65-70

Foundry 75-80

Forge 70-80

Hospital 75-80

Machine manufacturing 60-65

Metal working 65-70

Office building 80-90

Oil-field pumping 40-60

Paint manufacturing 55-65

Plastic 75-80

Stamping 60-70

Steelworks 65-80

Textile 65-75

PresenterPresentation NotesSpeaker A

12

Typical Sources of Low Power Factor

Reactive power is required by many loads to provide magnetizing current for: Motors Power transformers Welding machines Electric arc furnaces Inductors Lighting ballasts

13

Cost to end user or consumer- Utility fees and surcharges

There is no free lunch!! Many utilities pass on

the extra costs they incur through penalties, surcharges or other methods

Methods of recovering these costs vary with each utility and can be confusing to customers

14

Where do PF charges appear on a bill?

Explicit Power Factor Penalty Power Factor Adjustment Power Factor Multiplier Reactive Demand Charge Calculated Demand Billed Demand

15

Where do PF charges appear on a bill?

Shift to Temp 624 Model

16

Escalation in Electrical Energy Cost

Electrical Energy cost has increased nearly 50% over the last 10 years.

The rate of increase has accelerated in the past few years.

Currently the PF adjustment is being increased.

Industrial Electrical Energy Cost by Year

4

4.5

5

5.5

6

6.5

1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Pric

e/KW

H (c

ents

)

Source Energy Information Administration

17

Cost savings due to increased capacity

Correcting poor power factor can significantly reduce the load on transformers and conductors and allow for facility expansion Transformers are rated

by kVA and must be sized accordingly

18

Example increase capacity with new transformer Existing plant has a

power factor of 0.80 or 80% PF

Existing transformer is 500kVA

Plant needs to add new production line of 75kW

kVA = 500

kVAr

=30

0

kW = 400

19

Example increase capacity with new transformer

Cost to increase capacity to accommodate new production New transformer

next standard size 750kVA Long lead-time

Plant shut down to add new transformer days? Labor and materials to install new transformer

Upsize conductors for 750kVA transformer

Disposal of old transformer

20

Example increase capacity by adding PFCC Correct power factor

from 80% PF to 97% PF by adding 200kVAR power factor correction capacitor

Keep existing 500kVA Add 75kW of new load Existing 500kVA

transformer actually runs cooler than before!!!!

kVA = 412

kVAr

= 1

00

kW =400

kVA = 485

kVAr

= 1

00

kW =475

Power Factor Correction

Power Factor Correction and addition of 75kW

21

Example increase capacity by adding PFCC

Cost to increase capacity to accommodate new production New power factor correction capacitor Minimal interruption to energize and start up new

capacitor system

2007 Eaton Corporation. All rights reserved.

How to correct poor power factor

23

Capacitor Selection Capacitor selection issues (besides size) Utility penalties Installed cost, payback of equipment, and NPV Load variability Voltage regulation Load requirements (Speed of changing PF) Harmonic resonance

PresenterPresentation NotesThis section of the paper is devoted to discussing factors in selecting a capacitor, other than the initial kvar sizing calculation, which was already discussed early in the paper. Some of the items in this list will be discussed further later in this paper (some in this section, some, i.e. harmonics, will be discussed in later sections), some wont. The utility penalties were touched on briefly earlier in the paper.

24

Effect of Location

R2 R1 Motor Load

Resistive Load

Place here for utility PF penalty

Place here for utility PF penalty (utility owned transformer)

or

Place here to reduce losses in transformer or free capacity

Place here for line loss reduction and voltage

improvement

25

LV Fixed Capacitor Banks Designed for industrial and

commercial power systems Lowest installed cost var Range: 1 kvar to 400 kvar 208 Volts through 600 Volts AC Must be harmonic free

environment

26

LV Switched (Automatic) PFC Capacitors Banks Automatically sense changes in load

Automatic Controller Steps of 50 kvar standard

Smaller wall mounted units are available, and can be a real cost savings!

27

Provides similar PF correction (as caps)

Avoid harmonic capacitor interaction problems

Filter harmonics to reduce voltage and current distortion

LV Harmonic Filtering Equipment

28

MV Capacitors

Pole Mounted These banks have exposed live parts and

are typically supported on a wood power pole.

Rack Mounted These banks have exposed live parts and

are supported on a steel structure. These banks are usually located in fenced-in substations.

Metal Enclosed or Pad Mounted These banks are typically enclosed in a

steel enclosure and are usually located within a fenced-in substation or switchgear room.

29

Cost of Power Factor Correction

TABLE 4 INSTALLED COST COMPARISON

OF POWER FACTOR CORRECTION EQUIPMENT

TYPE OF CORRECTION INSTALLED COST, $/KVAR

Fixed (LV motor applied) $15

Fixed (LV) $25

Fixed (MV) $30

Switched (LV) $50

Switched (MV) $50

Static Switched (LV) $75

Switched Harmonic Filter (LV) $75

Switched Harmonic Filter (MV) $60

Active Harmonic Filter (LV) $150

PresenterPresentation NotesSpeaker B

A zero sequence trap is a special third harmonic filter designed for application on 120/208V circuit neutrals. The rating is based upon the third harmonic duty in the neutral conductor, the size of the neutral conductor, and its distance from the transformer. The trap is typically installed at the transformer or at the panel.

30

Additional Application considerations

Switching transients Potential resonance

31

Capacitor switching transients

Capacitor energization (common event) Voltage difference between system and capacitor Capacitor voltage cannot change instantaneously System voltage pulled nearly to initial capacitor

voltage Inrush current as capacitor charges Voltage overshoots and oscillation occurs

32

Definition Steady state components of voltage and current at

higher frequencies than 60 Hz (or fundamental frequency)

Causes Nonlinear loads, normally electronic loads In industrial facility, predominately motor drives (AC

or DC), also large UPSs, computer loads, rectifiers These electronic loads draw non-sinusoidal current All load current (particularly transformers and motors)

has some amount of harmonic content

Harmonics

33

H = NP+/-1

i.e. 6 Pulse Drive - 5, 7, 11, 13, 17, 19,

Source Typical Harmonics* 6 Pulse Drive/Rectifier 5, 7, 11, 13, 17, 19 12 Pulse Drive /Rectifier 11, 13, 23, 25 18 Pulse Drive 17, 19, 35, 37 Switch-Mode Power Supply 3, 5, 7, 9, 11, 13 Fluorescent Lights 3, 5, 7, 9, 11, 13 Arcing Devices 2, 3, 4, 5, 7... Transformer Energization 2, 3, 4 * Generally, magnitude decreases as harmonic order increases

Expected Harmonics

PresenterPresentation NotesSpeaker BTransformer heating - Increased RMS current causes increased lossed: conductor losses, eddy current losses, core losses. For every 10 degrees Celcius rise in temperature, there is a corresponding reduction in the life of that transformer. Discuss K-factor here.Motor and generator - voltage distortion at the motor terminals cause harmonic flux within motors. Negative sequence harmonics rotate opposite the rotor synchronous frequency causing heating.NEMA - MG1 tells you how to derate the motor for harmonics or will estimate a decrease in life from harmonics.Neutral heating - Triplen harmonics act like zero sequence components and add arithmetically on the neutralNuisance fuse - increased current, especially at higher frequenciesInsulation deterioration - Continuous magnitude voltage peaks due to distortion deteriorating the dielectric strength of the insulationElectronic Control Malfunctioning - Higher magnitude voltage peaks and premature zero crossings.Inconsistent meter readings - Phase unbalance and high harmonic voltages and currents. Revenue energy meters may read incorrect due to harmonics I[ to +/- 20% off. Two court cases due to this in Ontario and CAVoltage regulator misoperation - voltage distortion affecting the rms magnitude of the voltage may cause regulators to misinterpret the 60 Hz voltage.

34

If a capacitor exists on the power system

AND

Harmonic producing loads are in use

You MUST check for harmonic resonance.

(Series and Parallel)

Harmonic Resonance

The Self Correcting Problem Blown Fuses Failed Capacitor

35

Harmonic Resonance - Solutions 1. Change the method of kvar compensation (harmonic

filter, active filter, etc.) 2. Change the size of the capacitor bank to over-

compensate or under-compensate for the required kvar and live with the ramifications (i.e. overvoltage or PF penalty).

Natural System frequency of oscillation typically at 5th to 13th harmonic

36

Several factors must converge simultaneously for resonance to be a potential problem

1) P.F. correction kVAr >25% of xfmr kVA 2) Nonlinear load > 25% of xfmr kVA 3) Larger, fixed capacitance Often, resonance effects exist to some degree, but is not

severe enough to cause problems

When is resonance a concern ?

37

Resonance not generally a concern when: Total kVAR

38

Resonance will happen when: Ht = (Sqrt ((xfmer kva / z)/kvar)) Ht = (Sqrt((1000/.058)/300) Ht = (Sqrt(17,241/300)) Ht = (Sqrt (57.47)) Ht = 7.58 Record harmonic data. Determine resonance points. Compare to required kVAr.

How to know for sure?

39

?

Questions

40

Power Quality Experience Center and Lab Overview of Lab and Capabilities

Purpose To demonstrate and Test PQ

Problems and Solutions Power Quality solutions, especially

harmonic solutions, are difficult to understand

Demystify solutions mis-information and confusion regarding PQ and energy savings

Equipment (Harmonic Related) 18 Pulse Drives

HMTs Active Filters Broadband Filters

Link:http://www.eaton.com/EatonCom/Markets/Electrical/ServicesSupport/Experience/index.htm Simply search on Google for Eaton Experience Center

Passive (Fixed) Filters Passive (Switched) Filters Active Rectifier (UPS) Reactors

41

Thank You.

McGill Power Sales & Engineering, INC.Power Factor CorrectionAgendaPower factor definitionIs the Glass Half Empty or Half Full?Utility must generate, transmit, and distribute active AND reactive powerIf reactive power could come from another source utility can reduce DemonstrationWhy Consider PFC?Where has all the money gone?Typical Uncorrected Power FactorTypical Sources of Low Power FactorCost to end user or consumer- Utility fees and surchargesWhere do PF charges appear on a bill?Where do PF charges appear on a bill?Escalation in Electrical Energy CostCost savings due to increased capacityExample increase capacity with new transformerExample increase capacity with new transformerExample increase capacity by adding PFCCExample increase capacity by adding PFCCHow to correct poor power factorCapacitor SelectionEffect of LocationLV Fixed Capacitor BanksLV Switched (Automatic) PFC Capacitors BanksLV Harmonic Filtering EquipmentMV CapacitorsCost of Power Factor CorrectionAdditional Application considerationsCapacitor switching transientsHarmonicsExpected HarmonicsHarmonic ResonanceHarmonic Resonance - SolutionsWhen is resonance a concern ?When is resonance not a concern ?How to know for sure?QuestionsSlide Number 40Slide Number 41