Power Factor Capacitors Tutorial

8/13/2019 Power Factor Capacitors Tutorial

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Transient Free

Power Factor CapacitorsLow Voltage

Improve Power Factor & Reduce Electric Energy Costs

Fixed Capacity

Automatic


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Determine Your Power Factor Objectives 2

Alternative Solutions from Arteche 3

Benefits of Improving Power Factor 4

Switching Capacitors with Motors 6

Power Factor Tutorial 7

Determining Your Capacitor KVAR Requirement 8

Product Specifications 9

Product Selection - 480V 10

Useful Capacitor Formulae 11

Table of Contents

Determine Your Power Factor Objectives

2. Improve Power Factor for Entire Facility

2

3. Improve Power Factor for Large Induct ion Equipment

1. Improve Power Factor for Individual Motors

Harmonics will reduce the life of power factorcapacitors. Whenever there are harmonic producingloads on the power system, the capacitor bankshould include a capacitor protection reactor, thatwill detune the capacitor bank to a frequencywhere no harmonic energy exists. Consult factoryfor detuned capacitor banks.

Use Fixed Power Factor CapacitorsPower factor capacitors may conveniently beswitched on and off with individual motors. Thisassures that the capacitor is energized only duringthe times when the motor is energized - when youneed power factor correction. For this type ofapplication, typically a Fixed Capacitor Bank is used.This is the simplest and most economical form ofpower factor correction. Depending on the manner inwhich you connect the capacitor, you may or maynot need to include fuses. See page 6 for more details.

Harmonics will reduce the life of power factorcapacitors, whenever there are harmonic producingloads on the power system, this type of capacitorbank should include a capacitor protection reactor,that will detune the capacitor bank to a frequencywhere no harmonic energy exists. Alternatively itcan be supplied as a harmonic filter that will removeunwanted harmonic frequencies from the powersystem. Consult factory for detuned capacitorbanks or harmonic filters.

Use smARTvar

TM

Dynamic Power Factor CapacitorsLarge inductive loads (large motors, oil drilling rigs,wind turbines, amusement rides, auto crushers, arcfurnaces, induction furnaces, etc.) typically havedynamic requirements for reactive energy (kVARs),these applications require more sophisticatedautomatic type capacitor systems with extremelyfast response capabilities. Use smARTvar forapplications with large dynamic loads.

Harmonics will reduce the life of power factorcapacitors. Whenever there are harmonic producing

loads on the power system, the automatic capacitorbank should include a capacitor protection reactor,that will detune the capacitor bank to a frequencywhere harmonic energy does not exist. Alternativelyit can be supplied as a harmonic filter thatwill remove unwanted harmonic frequencies fromthe power system. Consult factory for detunedcapacitors or harmonic filters.

Use Automatic Power Factor CapacitorsWhen the load conditions and power factor in afacility change frequently, the demand for power

factor improving capacitors also changes frequently.In order to assure that the proper amount of powerfactor capacitor kvars are always connected to thesystem (without over-correcting), an Automatic TypeCapacitor System should be used for applicationsinvolving multiple loads.


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Arteche Type CFB Power Factor Capacitor Systems offer a fixedamount of kVARs. They can be supplied with or without fuses or withcircuit breakers. The internal circuit breaker can provide over currentprotection as well as satisfy the NEC requirements for a disconnecting

means (when capacitor is not connected between motor and overloadrelay). For applications where there may be harmonic producingloads on the power system, detuned capacitor banks are availableto reduce the flow of harmonic currents into the capacitor. Artechealso offers harmonic filters that will remove harmonics from the powersystem.

Power Factor Solutions from Arteche

Fixed Capacitor Banks (non-automatic)

Arteche Type CAB Automatic Power Factor Capacitor Systemsautomatically adjust the connected capacitor kVAR to the system

needs based on commands from the internal electronic power factorcontroller. The total bank of capacitors is segmented into convenientincrements of kVAR which are switched on-line as needed. Automaticcapacitor systems can be supplied either with or without a main circuitbreaker or switch. For applications that have harmonic producingloads, automatic capacitor systems can be supplied with an optionaldetuning reactor to reduce the flow of harmonic currents in capacitors.

Arteche also offers harmonic filters that will remove harmonics from thepower system.

Automatic Capacitor Banks

smARTvarTMType SMVAutomatic Capacitor Systems utilize power electronictechnology to achieve extremely fast switching of power factor capacitors. Notonly is this an automatic power factor system, it can switch capacitors on-line inless than one cycle, to maintain designed power factor when large inductiveloads have very dynamic characteristics. It can respond to the most dynamic ofloads including arc furnaces, amusement rides, wind turbines, etc. The totalbank of capacitors is segmented into convenient increments of kVAR which areswitched as needed using zero-cross switching thyristors. Capacitor switching isaccomplished rapidly but without transients. These systems can be suppliedeither with or without a main circuit breaker or switch. For those applications thathave harmonic producing loads, these capacitor systems are available with anoptional detuning reactor to reduce harmonic currents in the capacitor. Artechealso offers harmonic filters to remove harmonics from the power system.

smARTvarTMTransient-Free Automatic Capacitor Banks

3

Preciseincrementsof kVAR areswitched on-line as needed.

Capacitor switching is accomplishedin less than one cycle without

transients.

FixedPower Factor Capacitorsmay conveniently beswitched on and offwith individual motors.


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Benefits are only realized upstream of the point of

capacitor connection.

Benefits of Improving Power Factor

Inductive loads can demand large amounts of reactive

power and reduce overall facility power factor. The powerfactor of individual motors can range from 0.60 to 0.93 anddrops steadily as the load is reduced. Since many motorsare de-rated or operate well below full load conditions,actual power factors are often lower than stated on themotor nameplate.

When capacitors are added to power systems supplyinginduction motors, the capacitor supplies the reactive powerneeded by the motor, thus reducing the reactive powerdemanded from the facility power source and improvingpower factor upstream of the capacitor connection point.

Arteche capacitors improve the power factor, reduce kVA

demand, save energy and can reduce electric bills. Byreducing the reactive power demand, they can alsorelease capacity available from existing transformers.

How much is kVA reduced?Raise PF from 0.80 to 0.95 => reduce kVA by 15.8%Raise PF from 0.70 to 0.95 => reduce kVA by 26.3%

How Much is current reduced?Raise PF from 0.80 to 0.95 => reduce Amps by 15.8%Raise PF from 0.70 to 0.95 => reduce Amps by 26.3%

Eliminate Power Factor penalties Reduce electricity costs Reduce current draw

Reduce kVA demand & demand charges Reduce system power losses Increase kVA available from transformers Improve facility voltage levels

Improve Power Factor and Increase Power System Capacity

OriginalPF

FinalPF

CurrentReduced

By

KVADemandReduced

by

0.93 1.0 7% 7%

0.90 1.0 10% 10%

0.88 1.0 12% 12%

0.85 1.0 15% 15%

0.80 1.0 20% 20%

0.75 1.0 25% 25%

0.70 1.0 30% 30%

0.65 1.0 35% 35%

0.60 1.0 40% 40%

ReduceCurrent & KVA

Arteche PF Capacitor Systems Offer Rapid ROI

Raise Power FactorArteche Power Factor Capacitors will raise the power factorof motors and other inductive loads. Type CFB capacitorsmay be used for individual inductive loads, or to improve

power factor for an entire facility or electrical service.Use Type CFB Capacitors for commercial, industrial ormunicipal applications.

Precise Control of Power FactorFor large facilities or electrical services, consider ArtecheType CAB Automatic Capacitor Systems. Automaticcapacitor systems are required for multiple loads so thatcapacitance can be adjusted based upon varying loadconditions and varying reactive power demand.

Ach ieve Maximum Reducti on of Power LossesCapacitors should be connected as close (electrically) aspossible to individual inductive loads in order to recover thehighest percentage of branch circuit conductor power

losses. Properly applied capacitors can lower the powersystem losses by reducing the circuit current and I2R powerlosses.

Reduce Electric Energy Cost sThe use of Power Factor Capacitors can eliminate the utilitycharges for low power factor.

4

Working Power (kW)

Reactive Power (kVAR)

Utility supplies Reactive kVARs you pay for

PFC

ReactivePower (kVAR)

Working Power (kW)

Capacitor supplies Reactive

Motors needboth

Reactive VARsand

working wattsLet a capacitor

provide thekVARs

instead ofpaying the

utility for thisreactive power.


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How much w ill kVA be reduced?

Adding up the Benefits

Capacitors improve the power factor of induction loads.Additionally, they reduce current and kVA demanded

from the power sources. The payback period will dependon your electricity rate structure and penalties associatedwith low power factor. We can help you determine theROI of a capacitor investment. Contact our offices for aROI analysis based on your electricity rates and usage.

In electrical equipment, such as transformers or cables,capacitors can release capacity and thus allow a greaterpayload. By furnishing the necessary magnetizing currentfor induction motors and transformers, capacitors reducethe current drawn from the power supply. Less currentmeans less loading on transformers and feeder circuits. Ifa system has an existing overload, the capacitor mayeliminate it. If the system is not overloaded, capacitorscan release capacity and postpone or avoid aninvestment in more expensive transformers, switchgearand cable, otherwise required to serve additional loads.

ROI for your Capacitor Investment

=

orig

neworiginalreleased

PF

PFkVAkVA 1

How much will voltage rise?

Excessive voltage sags can make your motors sluggish,and cause them to overheat. Low voltage also interfereswith lighting, the proper operation of motor controls andelectrical and electronics instruments. Capacitors willraise your plant voltage level, and can maintain it allalong your feeders, right out to the furthest motors.

How much energy will capacitors save?

By supplying kilovars at the point where they are needed,capacitors will relieve the system of delivering reactivecurrent. Since electrical current in the lines is reduced,the circuit I

2R losses also decrease. Therefore, fewer

kWh need to be purchased from the utility. ROI will varydepending on factors such as utility rate structure, loadconditions, old PF and new PF.

5

).(. rtransformeup

rtransforme

capacitor

Rise ZkVAR

kVARV = )r

Saving Energy and Energy Costs


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Switching Fixed Capacitors with Motors

Non-Fused Power Factor Capacitor

Fused Power Factor Capacitor

Power Factor Capacitor with Circuit Breaker

nameplate

new

oldnew FLA

PF

PFFLA *=

Between Motor Starter & Motor

No extra switch or fuses required.

Contactor serves as capacitor disconnect.

Change overload relays to compensate for

reduced motor current.

Too much kVAR can damage motors.Check motor manufacturer or Nema MG-1recommendations for maximum kVAR.

Calculate new (reduced) motor current. Setoverload relays for this new motor FLA.

Upstream of Motor Starter

Disconnect switch is required. (per NEC)

Must include fuses in series with capacitor(per NEC).

No changes to overload relays.

Fuses must have an interrupting currentrating that is greater than the availableshort circuit current. (per NEC)

Upstream of Motor Starter

Circuit Breaker serves as disconnect.

Circuit breaker is over current protection.

Fuses not required.

No changes to overload relays.

Circuit breaker must have an interruptingcurrent rating greater than the availableshort circuit current. (per NEC)

6


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Power Factor Tutorial

Induction motors, transformers and many other electricalloads require working power (kW) as well as magnetizingpower (kVAR). Considering kW and kVAR as thesides of a right triangle, we can determine theapparent power (kVA) based on the right triangle rule.

To reduce the kVA required for any given load, you mustreduce the line that represents the kVAR. This is preciselywhat capacitors do-.

By supplying kVAR directly at the load, the motor receivesthe reactive power that it needs and the capacitor relievesthe utility of the burden of carrying the extra kVAR.This reduces both current and kVA in the branch circuitconductors and in the upstream power system. This makesthe utility transmission and distribution systems moreefficient, reducing cost for the utility and their customers.The ratio of actual power and apparent power is usuallyexpressed in percentage and is called power factor.

In the illustration below, addition of capacitors improvedpower factor and subtracted the non-working current fromthe upstream conductors. This reactive current is nowsupplied by the capacitor rather than the utility.

222 kVARkWkVA +=

cos==

kVA

kWPF

Understand Power Factor & Determine Capacitor Requirements

Electrical systems perform with some degree of efficiencyranging from poor to excellent. One measure of efficiencycompares the work produced (kW) with the apparentpower (kVA) that is demanded from the power source,for the purpose of performing that work. The kW/kVA is

a measure of electrical efficiency and is known asPower Factor (PF).

Motors need kVARsCapacitors supp ly kVARsMotors and other inductive equipment in a plant requiretwo kinds of electric power. One type is working power,measured by the kilowatt (kW). This is what powers theequipment and performs useful work. Secondly, inductiveequipment needs magnetizing power to produce the fluxnecessary for the operation of inductive devices. The unitof measure of magnetizing or reactive power is the kilovar(kVAR). The working power (kW) and reactive power(kVAR) together make up the apparent power which ismeasured in kilovolt-amperes (kVA).

Capacitors most effective at the Load

Most AC power systems require both kW (kilowatts) andkVAR (kilovars). Capacitors installed near the inductiveloads in a facility are the most effective way of supplyingthese kilovars, and can provide the greatest reduction ofbranch circuit power losses. If not supplied by localcapacitors, then these kilovars will need to be provided bythe electric utility. Arteche low voltage capacitors are a lowcost, high reliability and maintenance free means ofproviding the needed kilovars.

Capacitors Relieve Power System of Reactive CurrentIf magnetizing current for inductive loads is provided bycapacitors, then those kilovars do not have to be sent allthe way from the utility to the inductive loads. This relievesboth your electrical system and your utility of the cost of

carrying these extra kilovars. The utility typically chargesfor this reactive power through either a direct or indirectpower factor penalty charge. Capacitors can reduce yourelectricity demand and can reduce your utility bill, gainsystem capacity, improve voltage and reduce powerlosses.

Induction

Motor

loads

Power

supply

Active

Current

80 A

Reactive

Current

60 A

Total line

current

100 A

Active

Current

80 A

Induction

Motor

loads

Reactive Current

60 A

Total line

current

80 A

Power

supply

Capacitor

kW

kVA

kV

A

R

By supplying this

kilovars with capcitors

Thus eliminating these kVA

from the kVA demand charge

1 2

Typical Power Factor by Industry

Industry Power Factor

Arc Furnaces 0.70 to 0.90

Arc Welding 0.35 to 0.60

Breweries 0.75 to 0.80

Cement Works 0.78 to 0.80

Chemical 0.65 to 0.75

Foundries 0.50 to 0.80

Induction Furnaces 0.15 to 0.40

Machine Shops 0.40 to 0.65

Printing 0.55 to 0.70

Quarries 0.50 to 0.70

7


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Determining your capacitor kVAR requirement

Select Proper Capacitor (kVAR) in 3 easy steps :1) Find your Desired Power Factor at top of chart.2) Slide down to the row corresponding to your

Original Power Factor3) Multiply your KW by this factor to determine the

required capacitor kVARs.

Example:If Load is 720kW, 0.75 PF and Desired PF = 0.95 (95%)

1) Find 95% in top row.2) Slide down that column to the row beginning with 75%.

Find factor = 0.553.

3) Multiply 720kW by 0.553.Capacitor needed is 398.16kVAR (use 400kVAR).

8

Find the kVARs you need in 3 easy steps.


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Type CFB Capacitor Banks utilize ArtecheCapacitors that are constructed using metallizedpolypropylene elements which are encasedin aluminum canisters and filled with highperformance, biodegradable dielectric fluid(free of PCBs) for superior heat transfer.

Arteche capacitors are harmonic rated and suitable for usein applications where harmonics are present.

Our capacitors are self-healing and self-protecting.Arteche capacitors have the ability to heal the internalwinding by removing small short circuits caused by voltagetransients. In the event of a capacitor cell failure, ourcapacitors also include an internal pressure switch. Theinternal pressure switch will disconnect the individual cellthat has failed, leaving the other cells intact to continueimproving power factor.

Voltage:Rated voltage + 10% maximumCurrent:Rated current + 35% maximumPower:..Rated kVAR + 35% maximum

Temperature:..80C maximum operating temperatureAlti tude:...2000 meters (6600 feet) without derating

Power Loss:Low ESR; 0.4 W per kVAR

Protection:..Self healing, self protecting capacitorsInternal pressure switch

Harmonic Distortion:.Suitable for < 10% THD-v @ 25CDischarge:...Discharges to


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Type CFB Fixed Capacitor Banks 480V, 60Hz, Nema 1

Basic Fixed PFC PFC w/ Fuse & Indicator s PFC w/ Circuit Breaker Rated Current Wire Size Fuse Rating Switch Rating

Catalog No. Catalog No. Catalog No. (Amperes) (AWG-90C) (Amperes) (Amperes)

1.5 CFB 001.5 480 N1 CFB 001.5 480 F N1 CFB 001.5 480 ITM N1 1.8 14 3 30

2 CFB 0002 480 N1 CFB 0002 480 F N1 CFB 0002 480 ITM N1 2.4 14 6 30

2.5 CFB 002.5 480 N1 CFB 002.5 480 F N1 CFB 002.5 480 ITM N1 3 14 6 303 CFB 0003 480 N1 CFB 0003 480 F N1 CFB 0003 480 ITM N1 3.6 14 6 30


5 CFB 0005 480 N1 CFB 0005 480 F N1 CFB 0005 480 ITM N1 6 14 10 30


7.5 CFB 007.5 480 N1 CFB 007.5 480 F N1 CFB 007.5 480 ITM N1 9 14 15 30




12.5 CFB 012.5 480 N1 CFB 0012 480 F N1 CFB 0012 480 ITM N1 15 14 25 30


17.5 CFB 017.5 480 N1 CFB 017.5 480 F N1 CFB 017.5 480 ITM N1 21 10 40 6020 CFB 0020 480 N1 CFB 0020 480 F N1 CFB 0020 480 ITM N1 24 10 40 60














65 CFB 0065 480 N1 CFB 0065 480 F N1 CFB 0065 480 ITM N1 78 1/0 150 200









kVAR

Selection Tables for 480 Volts, 60Hz [1.5 to 125 KVAR]

This short form catalog l ists only 480V capacitors.Contact factory for other vol tage and KVAR ratings.

Other Ratings Available:

200V, 208V, 240V, 380V, 415V, 480V, 600V & 690V.

1 kVAR thru 1000kVAR.


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Available Short Circu it Cur rent:

Voltage Sag due to Locked Rotor Amps:

Useful Formulae

3

1000

)(

=

LL

cV

kVAR

I

PF Capacitor Current:

%100%

%

=xfmr

xfmrcapacitor

risekVA

ZkVARV

100

%)(2

xfmr

xfmr

xfmrSEC

sc

Z

MVA

kVI =

Voltage Boost due to PF Capacitor:

Three Phase Capacitors

scLR

scLL

kVAkVA

kVAVV

+= )(min

2

%100

%1

1

+

=THDikVA

kWPFTotal

Harmonic Resonance:(four accepted industry methods)

Total Power Factor:

)( cap

rMVAr

MVAsch =

xfmrcap

xfmr

rZkVAR

kVAh

%

%100

)(

=

Xsc

Xch r =

Effective (p.u.) kVAR for Capacitor used on lower system vol tage

System Voltage

208/60 240/50 240/60 400/50 480/60

600/60 0.12 0.133 0.16 0.37 0.64

480/60 0.187 0.21 0.25 0.576 1.0

240/60 0.75 0.83 1.0 - -

Capacitor

Voltage

Capacitance per phase:(wye connected) )(

2

10002

FaradsfV

kVARC

=

Capacitance per phase:(delta connected) )(

32

10002

FaradsfV

kVARC

=

LCfr

2

1=

1

Other Related Formulae


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Contact ARTECHE PQ for solutions toHarmonic Distortion and Low Power Factor

Low Voltage, Medium Voltage and High Voltage Solutions

ARTECHE PQ, Inc.16964 West Victor Road New Berlin, WI 53151Phone: 1-262-754-3883 Fax: 1-262-754-3993

www.artechepq.comPOWER QUAL I TY

Fixed Capacitor Systems

De-Tuned Capacitor

Active PF Compensation

Automatic Capaci torsDynamic VAR Compensation

Transient Free Capacitor Systems

Power Factor Improvement

Low Pass Harmonic Filters (5%THD-i)

Tuned Harmonic Filters

Active Harmonic Fil ters (5% THD-i)

Automatic Harmonic Fil ters12 & 18 Pulse Rectif ier Upgrade Kits

Soft Switching Harmonic Filters

Harmonic Filters

Form No. C07-2009 / Feb 2010

Documents

Power Factor Capacitors Tutorial