Product: Power Factor & Harmonics: StacoVAR: Lets Discuss Power Factor Correction
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StacoVAR: Power Factor Correction
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Transcript of Product: Power Factor & Harmonics: StacoVAR: Lets Discuss Power Factor Correction
StacoVAR: Power Factor Correction
POWER FACTOR CORRECTION (PFC)
Power Factor (PF):
Term used in regard to the efficiency of
an electrical power distribution system.
Power factor is a measurement
between the current and voltage phase
shift waveforms.
PF COMPONENTS
Power factor consist of 3 components:
• KW, which is the working, or real, power
(does the actual work)
• KVA, which is called the apparent power
(relationship between KW and KVAR)
• KVAR, or reactive power
(does not do any beneficial work)
DETERMINE YOUR PF
Divide the working power (KW) by the
apparent power (KVA)
PF of 1, or unity, being the highest (or best)
power factor possible.
When correcting PF, in general, a measurement of .9 or higher is considered good.
INDUSTRIES KNOWN TO HAVE POOR PF
Industries where power factor problems
are common:
o Steel/Foundries
o Chemicals
o Textiles
o Pulp and paper processing
o Automotive and other automated assembly
o Rubber and plastics processing
o Breweries
o Electroplating
CAUSES OF PF PROBLEMS
Loads that cause power factor problems:
o Induction motors
o Electric arc furnaces
o Machining
o Stamping
o Welding
o Variable Frequency Drives (VFDs)
o Fluorescent lights with magnetic ballasts
o Computers
o Computer controlled equipment
BENEFITS OF IMPROVING PF
Improving PF:
o Lowers your electrical cost
o Increases KVA capacity (increase the KW used for the same KVA)
o Improves voltage regulation
o Allows for the size reductions in cables, transformers and switchgear
o Allows for expansion without additional electrical improvements
UTILITY COMPANY’S POINT OF VIEW
Raising the average operating PF of the entire grid network from .70 to .90 means:
oReduced costs from inefficiencies
o Increased generation and distribution potential
oLower demand on the grid
BETTER PF MEANS
Utilities can save hundreds of thousands of tons of fuel (and produce fewer emissions), have more transformers available, and reduce building new power plants and their support systems.
This is why more utility companies are starting to charge a “Power Factor Penalty” so they can recover additional cost they incur from supporting an inefficient system.
PF IMPROVEMENT EXAMPLE
Assume you have a load of 100kVA with a PF
of .80, then you have enough power to light 800
100-wattlight bulbs. If you improve the PF to .95,
you now have enough power to light 950 100-watt
light bulbs.
PF IMPROVEMENTS CAN SAVE $
Because power factor correction capacitors:
o Use less energy
o Lengthen the life of equipment
o Reduce electrical requirements for any new or future equipment that is installed
UTILITY KVA BILLING
Most utilities use the kVA billing method therefore:
o You are charged for the current your system draws from the grid
o Many utilities add a surcharge or adjustment for PF.
o Special tariffs applied
o Interruptible rates applied
o Off-peak rates
Some utilities give credits or bonuses for higher than average
PF, or one that is above a predetermined level
EXAMPLE
Most utilities use the kVA billing method therefore:
o You are charged for the current your system draws from the grid
o Many utilities add a surcharge or adjustment for PF.
o Special tariffs applied
o Interruptible rates applied
o Off-peak rates
Some utilities give credits or bonuses for higher than average
PF, or one that is above a predetermined level
RETURN ON INVESTMENT (ROI)
Using the previous example, if you are billed at $11.22 per kVA:
o100kW @ .70 PF = 142 kVA, or $1,593
o100kW @ .95 PF = 105 kVA, or $1,178
This represents a monthly savings of $415, or
$4,980 annually. Assuming the equipment cost
was $5,600 the ROI would be about 14 months.
After this period there can be an ongoing 26%
savings.
PF CORRECTION CAPACITORS
A capacitor’s function is to:
oProvide kilovars to a system at the point of connection
o Improve PF
oReduce lagging components on the circuit
oReduce power losses
oReduce kVA load.
oProvide reactive power to replace the VARs wasted by an inefficient load
PF CORRECTION CAPACITORS
Are the most economical means of improving PF because of their:
oRelative Low Cost
oEasy Installation
oLow Installation Cost
oMinimal Maintenance
oHigh Efficiency and Low Losses
DETERMINING THE PF
Find poor PF problems by:
oMonitoring at the incoming service entrance or at specific loads can identify problems within a facility
oConduct a Facility Power Study and have reviewed by a power analyst / consultant
Some utilities offer analysis for businesses wanting to improve their efficiency.
TYPES OF CAPACITOR SYSTEMS
oSimple small fixed capacitors can be installed at a single motor to be switched on and off with the load, this is ideal.
• However, this can be expensive, and can create technical problems, since it may require a large number of low-power units at several points throughout the facility, making it difficult to monitor and maintain over time
TYPES OF CAPACITOR SYSTEMS
oAutomatic capacitor bank installed on the bus bars of the distribution panel. This method provides centralized PF correction for an entire facility.
• It also allows for fixed capacitors to be added to correct the power of any piece of equipment that causes a significant problem.
INSTALLATIONS LOCATIONS
NEXT STEP - DETERMINE THE KVAR
After you have determined what type capacitor
system you need, the next step is to determine
the size or amount of kVAR, you need to correct
the PF.
Staco Energy Products Co. has easy to use
tables that will assist you in determining the
required kVAR you need to add to your system
to improve the PF.
NEXT STEP
Example: If your existing PF is .71 and you want to bring it
up to .95, the number in the table is .663 (kW multiplier).
Multiply .663 by the number of kW your system uses (say
590). The total kVAR would require 390 kVAR, which would
be rounded up to 400 kVAR. Therefore a 400kVAr rated unit
would be used.
FINAL STEP
Purchase a Staco
Automatic Switched
400 kVAR StacoVAR
System,
OF COURSE!
FIXED CAPACITOR ASSEMBLIES
Fixed capacitor assemblies, also called motor load
capacitors, are ideal for improving PF where
induction motors are located. They are also used
anywhere there are small kVAR requirements.
You can achieve maximum benefits from capacitors
when located at the load. Because the capacitor is
Usually switched on and off with the load, over
correction is also avoided
SIZING FIXED CAPACITORS
Capacitors must be carefully sized when switched
with the motor as a unit, because:
o Dangerous over voltages and transient torques can occur if the kVAR exceeds the motor’s magnetizing current
WHAT YOU NEED TO KNOW!
When sizing fixed capacitors you need the following
Motor information:
oU-Frame (U, T etc.)
oNEMA Class (B, 2B, C, D etc.)
oA or B Normal Starting Torque – Normal Running Current
INSTALLATION LOCATIONS
1. Motor Side of Overload Relayo Use this for new motor installations where overloads
can be sized in reference to reduced current draw
o Existing motors where no overload change is needed
2. Motor Side of Startero Use this for existing motors when the overload rating
exceeds code
3. Line Side of Startero Use this for Multi-speed motors
o Motors that are jogged or reversed
o Motors that star frequently
o Starters that disconnect/reconnect capacitors during cycle and starters with open transitions
o High inertia loads, when disconnecting the motor with the capacitor turns the motor into a self-exciting generator
INSTALLATION LOCATIONS
MOTOR REFERENCE TABLES
Staco Energy Products Co. has all the reference tables available to make it easier to select and size the correct StacoVAR Motor Load Capacitor for your application.
STACOVAR SOLUTIONS
Staco Energy provides various solutions,
specific to correction of poor power
factor and/or harmonics. Equipment
available:
oFixed capacitors from 2 to 400kvar.
oAutomatically switched type from 75 to 600kvar (240vac) and 100 to 2400kvar (480 and 600vac).
STACOVAR FIXED MODELS
Fixed Power Factor Correction: PF Model
o Wall mounted/freestanding motor load “ML” products include liquid filled long life three phase power capacitors and freestanding (larger kvar) products with heavy duty, dry type three phase power capacitors, and both types include discharge resistors and over pressure protection.
o Fixed only, no switching, no control, located at individual motor loads.
STACOVAR STANDARD FEATURES
Automatic Power Factor Correction Standard Features:
o NEMA 1 enclosure, with bottom entry access and modular design allowing for easy future expansion.
o UL 508A listed, complete assembly.
o Heavy duty, dry type three phase power capacitors, with discharge resistors and over pressure protection.
o PA units accommodate up to 10% THD environment.
o (PH, PT, and PR units use 480 volt rated capacitors for 240 volt system and 690 volt rated capacitors for 480 volt system, for even higher harmonic level protection).
o 5-year warranty on the capacitors.
o Individual step fuse protection (200kaic) with blown fuse indication.
o Control power transformer with fused primary & secondary, and nickel-plated electrical grade cooper bus bar system.
STACOVAR AUTOMATIC PA MODELS
Automatic Power Factor Correction:
PA ModelAdditional features:
o Type of Switching: Electro-mechanical contactors with damping resistors to reduce switching inrush currents.
o Controller: adjustable (0.5 to 300) second response microprocessor based power factor controller (twelve-step regulation) with front panel LED display.
o Automatically switched (contactors), basic, economical. Product accommodates most requirements.
STACOVAR AUTOMATIC PH MODELS
Automatic Power Factor Correction:
PH Model
Additional features:
o Type of Switching: Electro-mechanical, heavy duty contactors.
o Controller: adjustable (0.5 to 300) second response microprocessor based power factor controller (twelve-step regulation) with front panel LED display.
o Reactor: Three phase 5TH order, iron-core reactors with a 227hz tuning frequency.
o Automatically switched (contactors), for a harmonic environment where capacitors may be damaged. Use of iron-core reactors necessary for a detuning - majority of requirements for the 5th order. Product accommodates many applications and is cost effective.
STACOVAR OPTIONS
Automatic Power Factor Correction
Options:
o Circuit Breakers: Circuit breakers are three-pole molded case type, with a thermal-magnetic trip. Amperes are based upon breaker frame size. Circuit Breaker option may increase standard cabinet dimensions, consult factory for sizing.
o TVSS – Surge Protection.
o CT – Current Transformer: multi-tap, (3000:5, 2500:5, 2200:5, 2000:5, 1500:5, 1200:5, 1000:5, 800:5, 500:5, 300:5), split core type for ease of installation. CT’s shipped loose. 1-5% accuracy depending on ratio.
