Medium Voltage Real Time

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Medium Voltage Real Time Transient Free
Capacitor Systems
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Outline

• Introduction
• Why RTRC or TFRC?
• Limitations of Conventional Solutions
• The RTRC and TFRC Solution
• Applications
• Benefits
• Product Characteristics

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Capacitor Offering

• Schneider Electric is the worlds largest LV
  capacitor manufacturer by market share
• Power Quality Correction Group (PQc) located in
  Toronto, Canada has marketing, sales, application
  engineering, design and technical support
  responsibility for North America
• Low Voltage Equipment is manufactured at the
  Waterman facility
• Medium Voltage Equipment is assembled at Square
  D facility outside of Cincinnati

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Capacitor Offering

• Fixed Capacitors
• Standard Automatic Capacitor Banks
• Anti-Resonant Automatic Capacitor Banks
• Filtered Automatic Capacitor Banks
• Real Time Reactive Compensation Systems
• Transient Free Reactive Compensation Systems
• MV Metal Enclosed Systems
• MV Real Time Transient Free Systems

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Service Offering

• On-site measurement
• Computer Network Simulations
• Analysis of Problem
• Report
• Specifications
• Custom Engineered Equipment
• Commissioning
• Verification of Performance
• Training
• After Sale Servicing

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Power Factor

• Ratio of Active (Real) Power to Total (Apparent)
  Power (kW/kVA)
• A measure of efficiency
• Depends on the phase angle between voltage and
  current waveforms

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Power Factor Defined

• Reactive Power develops the magnetic field
  required by machines to perform useful work

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Power Factor Fundamentals

• In this example, demand was reduced to 8 250 kVA
  from 10 000 kVA.
• The power factor was improved from 80 to 97

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Increased System Capacity

• Any capacitor based system reduces apparent power
  (KVA) and load current
• Potential savings in capital investment
• Alternately, additional load can be added to the
  network without the risk of overload

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Harmonics

• Current Limiting Reactors in multi-step MV
  standard systems limit capacitor inrush currents
• Air or Iron Core reactors in MV Anti-Resonant and
  Filtered systems detune the system to prevent
  resonance and remove up to 50 of the 5th harmonic

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Harmonic Current Waveform(Typical 6 Pulse Drive)
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Resonance

• The installation of standard capacitors can
  magnify harmonic currents on the network

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Resonance
Resonant Point likely to amplify dominant
harmonic (typically 5th)
Magnification of Harmonic Current when Standard
Capacitors are Added to the Network
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Detune to Avoid Resonance
Resonant Point where no Harmonic Content present
(3.7th typical)
5th Harmonic on Network is reduced
(4.4 Tuning)
Effect on Harmonic Current when Anti-Resonant
Capacitor Bank is Applied
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The Real Time Challenge

• To compensate reactive power required by rapid
  and frequent load variations
• motivation
• increased productivity
• elimination of voltage flicker and sags
• increased system capacity and energy efficiency

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Conventional Technology

• Compensates reactive energy of stable loads only
• Unable to cope with rapid and frequent load
  variations

• To reduce wear of vacuum switches
• To allow capacitors to discharge before
  reconnection
• Conventional Controller speed limitation

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Conventional Switch Structure
L1
L2
L3
Vacuum (or SF6)contactors or breakers are used to
connect a capacitor group.
HRC Fuses
Vacuum Contactors
Optional De-tuned Inductor
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Real TimeReactive Compensation

• One cycle (17 ms) or less response to load
  fluctuations
• Transient Free Connection of Capacitors
• Minimal wear of electronic switching elements

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Transient Free Reactive Compensation

• 3-4 second response to load fluctuations
• Transient Free Connection of Capacitors
• Minimal wear of electronic switching elements

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Electronic Switch Structure
L1
L2
L3
Fuses
SCR-Diode
De-tuned Inductor
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Transient Free Switching

• Current inrush with vacuum switching can be 15 -
  20 times steady state current
• Resultant voltage transient can effect sensitive
  electronics
• RTRC and TFRC systems generate no network voltage
  transient

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RT Acquisition Response
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End Result

• Any variation in reactive power is compensated
  within one cycle (16.7 ms) using transient free
  switching of capacitor stages resulting in
• increased productivity
• elimination of voltage flicker sags
• increased system capacity energy efficiency

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Real Time Applications

• Unstable Loads (rapid changes)
• Injection molding machines
• Elevators
• Presses
• Rock Crushers

• Wood Chippers
• Mining Conveyors
• Induction Heat Treating
• DC Hoisting

• Motor Starting
• compensation of inrush current for many motors
• allows normal starting torque
• Spot Welding (typically at low voltage)
• extremely fast changes - less than one second
  (typically at low voltage)
• Re-enforced Mesh for concrete
• Automotive industry

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Results of RTRC Installation

• Gas Pumping Station in Colorado
• 25 KV Line to 2.5 MVA Transformer step down to
  2.4 KV
• Three FVNR Motors (500 HP, 700 HP, 700 HP)
• Motor start causing unacceptable voltage drop on
  25 KV line (16-18)

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Results of RTRC Installation

• Solution was a 3.6 MVAR, 2.4 KV Real Time System
• Three equal steps of 1.2 MVAR each
• Utilized air cooled SCR/Diode modules
• Installed outdoors
• Goal to obtain less than 5 voltage drop on the
  25 KV line

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Results of RTRC Installation
500 HP 700 HP Running Starting 2nd 700 HP Motor
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Results of RTRC Installation

• Objective to limit voltage drop to less than 5
  on the 25 KV line has been met
• initial voltage drop is only 4.2 on the 2.4 KV
  line
• secondary voltage drop of 7.3 at 2.4 KV line (as
  stages turn off)
• modifications to the control will improve this
  further
• Motors previously took 4-6 seconds to come up to
  speed
• with RTRC, motors are up to speed in less than 2
  seconds

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Transient Free Applications

• Sensitive Networks
• Hospitals
• Data Processing Centers
• Microelectronics Fab Facilities
• Pharmaceutical Facilities
• Airports
• Research laboratories
• Other Industrial and commercial facilities with
  high concentrations of sensitive electronic loads

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Voltage Sag and Flicker Reduction
With

• Voltage sag is reduced as a result of reactive
  compensation during the load fluctuation.
• The voltage sag during is affected more by the
  power factor than by current amplitude reduction.

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Energy Savings

• Energy saving due to reduction of losses and
  harmonics
• Losses in cables
• Copper losses - I2R.
• Skin effect losses due to reduction of harmonics.
• Losses in transformers
• Copper losses - I2R.
• Skin effect losses due to reduction of harmonics.
• Iron losses due to reduction of harmonics.

Total estimated saving 3 - 5
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RTRC Advantages

• Flicker Reduction
• Compliance with flicker standards
• Network Stabilization and reduced equipment
  outages
• Voltage Regulation Improvement
• Reduced duty on tap changers
• Improved Network Utilization
• Reduced Transformer loading
• Current reduction on Bus Bars, Breakers and
  Cables
• Energy Saving, Power Factor Correction Harmonic
  Reduction

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Process Productivity Improvements

• The RTRC will eliminate
• failed motor starts due to voltage sags
• undervoltage tripping of sensitive loads
• lighting flicker and HID lighting shutdown
• overloaded distribution equipment
• capacitor switching transients

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RTRC Summary

• ADVANTAGES
• Increases network capacity
• Minimizes voltage sags
• Minimizes voltage flicker
• Reduces load current
• Avoids wear of vacuum contactors capacitors
• Transient free switching in sensitive networks
• Avoids use of reduced voltage starters
• Saves energy and improves Power Factor

• DISADVANTAGES
• Costly solution compared to standard capacitor
  systems (but often the only viable solution)
• Physical space requirements

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MV RT TF Product Overview

• Metal Enclosed Systems up to 15 kV
• Three-Bushing, delta capacitor units available up
  to 5 kV. Two-bushing capacitors connected in
  Delta for higher voltages
• Type 1 indoor or Type 3R outdoor enclosure types.

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Real Time Reactive Compensation Systems
Transient Free Reactive Compensation Systems

• MT6000 Series
• Power Factor Correction of networks with
  sensitive electronic loads

• MV9000 Series
• Power Factor Correction of highly cyclical loads

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Standard, Detuned or Filtered?

• MT6000 MV9000 are typically Anti-resonant or
  filtered but may also be standard with current
  limiting reactors only
• Filtered used for Power Factor Correction of
  networks with more than 50 Non-Linear Loads
• Anti-resonant and filtered systems are
  manufactured with higher than nominal voltage
  capacitor elements to ensure long term system
  stability.

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Controller
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Protection

• Unbalance and Overload protection via phase
  current sensing standard for either wye or delta
  capacitor steps
• Optional unbalance protection by neutral current
  sensing on wye connected capacitor steps
• Optional Neutral to Ground Potential transformer
  for unbalance protection for wye connected banks

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Capacitors

• Merlin Gerin PROPIVAR or Cooper (McGraw Edison)
• External Fusing Standard

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Merlin Gerin Capacitors

• Available as Three Phase, Three-Bushing Delta
  Connected, up to 5 kV or Single Phase,
  Two-Bushing for voltages higher than 5 kV

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Merlin Gerin Capacitors

• Environmentally safe biodegradable non PCB
  dielectric liquid
• Good Heat Dissipation and Low dielectric losses
  result in long element life

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Merlin Gerin Capacitors

• High Overvoltage and Overcurrent withstand
• 10 Overvoltage for 12 hours a day
• 30 Continuous Overcurrent
• Highly resistant to transient overvoltages and
  partial discharge levels

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Merlin Gerin Capacitors

• Suitable for harmonic filtering applications and
  networks with poor voltage regulation

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Cooper Capacitors

• Single Phase, Two-Bushing for Wye or Delta
  connection
• 125 Continuous rms Overvoltage withstand and
  135 peak overvoltage capability
• Wide operating temperature range
• -40 to 131ºF (-40 to 55ºC)
• Environmentally acceptable dielectric fluid

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Cooper Capacitors

• Standard unit power rating from 50 to 400 kVAR
  single phase from 2.4kV

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Current Limiting Fuses

• To protect capacitors, fuses are rated as
  closely as possible to the capacitor steady state
  current
• Blown fuse indication directly on the fuse
  (pop-up indicators)
• Visible via viewing windows in enclosure

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Conventional Switching Stage
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Electronic Switching Modules

• Switching two phases with Delta connected
  capacitors
• Air or Liquid Cooled Stick Stacks of anti-polar
  SCR/Diodes with failsafe cooling systems
• temperature, air flow, pressure monitoring
• Multiple modules connected in series for higher
  voltages

Liquid Cooled Stick Stack
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HVL Interrupter Switch

• Direct Drive Operator
• Fused for short circuit protection or Unfused
  available
• Load Break to max 2400 kVAR _at_ 5 kV or 15 kV

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Iron Core Reactors

• Necessary to Detune network to prevent resonance
  when large harmonic producing loads are present
• Reactors Filter dominant harmonic (usually the
  5th)

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Iron Core Reactors

• Single or Three phase laminated low hysteresis
  reactors with precision air gap
• All copper windings, mounted on insulated
  bushings up to 95 kV BIL
• Current Limiting Reactors in standard systems
  are Air or Iron Core

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Enclosure

• Modular Style Design either indoor NEMA 1 or
  outdoor NEMA 3R (others available)
• All Silver-Flashed Copper Bus
• Better fault withstand ratings (50kA IC standard)

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Enclosure

• Removable Panels over bolted steel frame
• Rigid construction while allowing ease of
  servicing
• Standard ASA49 Gray paint finish. Other finishes
  available upon request.

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Enclosure

• Key interlocks standard
• Electrical interlocks standard
• Tamper resistant interlocked ground switch for
  each capacitor stage
• Viewing windows to ensure ground switch and main
  switch operation

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Enclosure

• Control Cabinet mounted rear or side of main
  (remote mounting optional)
• Optional thermostatically controlled, ball
  bearing fans
• Welded lifting eyes
• Three point door latch

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