Mikro PFCR Explanation

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Power Factor Regulator

Industri Teknologi Mikro Sdn. Bhd. Industri Teknologi Mikro Sdn. Bhd.

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Electric Loads

  



Resistive Load



 Power supplied is totally tPower supplied is totally transformed into usefulPower supplied is totally Power supplied is totally transformed into usefultransformed into usefulransformed into useful

work

work work

•••

• Current Current = Current Current = Active = = Active Current Active Active Current (ICurrent Current (I(I(I_A_A_A_A))))

  



Reactive Load



 Power supplied isPower supplied is NOTPower supplied isPower supplied is NOTNOT transformed into usefulNOT transformed into usefultransformed into usefultransformed into useful

work work work work   

 Inductive load and capacitive loadInductive load and capacitive loadInductive load and capacitive loadInductive load and capacitive load

•••

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V

(5)

Power

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Power

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Inductive + Resistive

Power

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Power

 Active Power (P)

Power actually consumed by the load P = V · I_A (kW)

 Reactive Power (Q)

Necessary power but not transformable in useful energy Q = V · IR (kVAR)

 Apparent Power (S)

Total power that flows toward the load S = V · I (kVA)

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Power Factor (PF)



PF is a measurement of how effectively a

system is converting electric power to

useful output power.



PF always less than or equal to one (1).



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Power Factor Readings

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Displacement Power Factor (DPF

Displacement Power Factor (

DPF))

Cos

Cos ϕϕ -- Cosine of the phase angle (Cosine of the phase angle (ϕ)ϕ) betweenbetween the fundamental frequency of voltage and

the fundamental frequency of voltage and current. Only phase shift between V & I. current. Only phase shift between V & I.



Total Power Factor (PF

Total Power Factor (

PF))

True ratio of active power to apparent power True ratio of active power to apparent power

Phase shift and harmonic distortion Phase shift and harmonic distortion

PF = Active Power (P)

Apparent Power (S) =

kW kVA

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Power Triangle



"Power triangle" without effect of

harmonics

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Harmonic Effect



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Causes of Low Power Factor



 Most electrical systems have lagging powerMost electrical systems have lagging power

factor due to inductive loads such as motor, factor due to inductive loads such as motor, air

air --conditioner, fluorescent lighting etc.conditioner, fluorescent lighting etc.

0.40

0.40 – – 0.900.90 Phase controlled rectifier

Phase controlled rectifier

0.50 0.50 Arc welding Arc welding 0.70 0.70 Fluorescent lighting Fluorescent lighting 0.70 0.70 – – 0.800.80 Induction motor Induction motor Power factor Power factor Load Load Typical PF of loads

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Benefits of PF Correction



Reduced electricity bills



Gained in system capacity



Reduced line losses



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PF Correction Methods



Connect capacitors in parallel to the

system.

Capacitor produces leading PF thus Capacitor produces leading PF thus

neutralize the lagging PF. neutralize the lagging PF.



If low PF due to harmonics is significant,

harmonic filter is required.

Capacitor will

Capacitor will NOTNOT help to improve low PFhelp to improve low PF caused by harmonics.

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PF Correction by Capacitor

Before

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Calculate Required kVAR

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Table of Output Factor k

0.48 0.48 0.26 0.26 0.16 0.16 --0.90 0.90 0.75 0.75 0.52 0.52 0.42 0.42 0.27 0.27 0.13 0.13 --0.80 0.80 1.02 1.02 0.79 0.79 0.69 0.69 0.54 0.54 0.40 0.40 0.27 0.27 0.14 0.14 --0.70 0.70 1.33 1.33 1.10 1.10 1.00 1.00 0.85 0.85 0.71 0.71 0.58 0.58 0.45 0.45 0.31 0.31 0.16 0.16 --0.60 0.60 1.73 1.73 1.50 1.50 1.40 1.40 1.25 1.25 1.11 1.11 0.98 0.98 0.85 0.85 0.71 0.71 0.56 0.56 0.40 0.40 0.50 0.50 1.00 1.00 0.98 0.98 0.95 0.95 0.90 0.90 0.85 0.85 0.80 0.80 0.75 0.75 0.70 0.70 0.65 0.65 0.60 0.60 (Cos (Cosϕϕϕϕϕϕϕϕ₁₁)) Desired

Desired PF(CosPF(Cos ϕϕϕϕϕϕϕϕ₂₂)) Original

Original PF PF

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Power Factor Regulator (PFR)



What is PFR?

A device to monitor and maintain the A device to monitor and maintain the required power factor of an electrical required power factor of an electrical network.

network.



Working principle of PFR

PFR continuously measures the network's PFR continuously measures the network's reactive power (

reactive power (kVARkVAR) and then correct it by) and then correct it by switching in/out of the capacitor banks to

switching in/out of the capacitor banks to achieve the targeted power factor.

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Mikro's Power Factor

Regulator

Model PFR60

Model PFR60 –

– 6 switching outputs

6 switching outputs

Model PFR80

Model PFR80 –

– 8 switching outputs

8 switching outputs

Model PFR120

Model PFR120 –

– 12 switching outputs

12 switching outputs

Model PFR140

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Power Factor Measurement:

DPF or PF?



Capacitor banks

Capacitor

banks are only designed to

are only designed to

compensate

compensate the

the reactive power

reactive power of the

of the

fundamental frequency component.



Capacitor banks are not designed to

Capacitor

banks are not designed to

correct total power factor where harmonic

currents are included.



DPF measurement method is

DPF

measurement method is more

more

suitable for power factor regulat

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How to measure DPF



Zero crossing method

Measure

Measures thes the phase anglephase angle differencedifference between

between the respectivethe respective zero crossing of thezero crossing of the voltage & current waveforms.

voltage & current waveforms.



Numerical m

Numerical

method

ethod

The phase angle is computed using The phase angle is computed using mathematical method

mathematical method through the regularlythrough the regularly sampled voltage and current waveforms. sampled voltage and current waveforms.

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DPF Measurement (1)

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DPF Measurement (2)

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Features of Mikro's PFR



DPF measurement by numerical method.

Accurate measurement even in the presence Accurate measurement even in the presence

of harmonics. of harmonics.

Capacitors improve DPF only. Capacitors improve DPF only.

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Cause & Effect of Harmonics



Causes

Non

Non--linear loads draw nonlinear loads draw non--sinusoidalsinusoidal currents.

currents.

e.g. Adjustable

e.g. Adjustable--speed motor drive &speed motor drive & energy saving lighting.

energy saving lighting.



Effects

Overheating and dielectric breakdown of Overheating and dielectric breakdown of

capacitors. capacitors.

Excessive current caused by resonance Excessive current caused by resonance

Increase losses. Increase losses.

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Features of Mikro's PFR (2)



Total harmonics distortion (THD)

measurement and alarm.



Able to measure current THD.



Disconnect all capacitor banks in the

event of THD alarm to prevent damage

of capacitors due to harmonics.

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Features of Mikro's PFR (3)



Intelligent automatic switching program.

Improve switching efficiency by reducing Improve switching efficiency by reducing

the number of switching operation the number of switching operationss..

Able to measure

Able to measure kvar kvar required and selectrequired and select thethe most appropriate

most appropriate switchingswitching stepsteps.s.

Evenly distribute usage of each capacitor Evenly distribute usage of each capacitor

bank. bank.

Switch in least used capacitor Switch in least used capacitor

Switch out longest used capacitor Switch out longest used capacitor

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Features of

Features of Mikro's

Mikro's PFR (4)

PFR (4)



Programmable switching sensitivity.

Optimized switching speed. Optimized switching speed.

Reaction time inversely proportional to the Reaction time inversely proportional to the reactive power

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Features of Mikro's PFR (5)



Alarm functions

Under/over voltage alarm. Under/over voltage alarm.

Under/over load current alarm. Under/over load current alarm. Under/over compensate alarm. Under/over compensate alarm.

THD alarm. THD alarm.

Light indicator for alarm. Light indicator for alarm.

Programmable last output

Programmable last output stepstep as alarmas alarm output contact.

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Features of Mikro's PFR (6)



Automatic current transformer (

Automatic

current transformer (CT

CT)) polarity

polarity

Automatic correction of CT polarity when Automatic correction of CT polarity when

reversed. reversed.



Programmable rated step

Enable flexible usage of capacitor with Enable flexible usage of capacitor with different sizes.