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Medium Voltage Real Time &
Transient Free Capacitor Systems
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 world’s 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
Measure
 Report
 Specifications
Solution
 Custom Engineered
Commission
Equipment
Cycle
 Commissioning
 Verification of
Performance
Specify & Propose
 Training
 After Sale Servicing
Simulate
Analyze & Report
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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
Before
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After
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
Apparent Power
2500 KVA
1700 KVA
1
2
Real Power
1500 KW
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Any capacitor based
system reduces apparent
power (KVA) and load
current
Reactive Power
800 kVAR
Potential savings in
Compensated
capital investment
cos  1 = .60 Alternately, additional
cos  2 = .882 load can be added to the
network without the risk
of overload
Reactive Power
2000 kVAR
Uncompensated
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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
Limited Speed - Why?
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
HRC Fuses
Vacuum
Contactors
Optional
De-tuned
Inductor
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L2
L3
Vacuum (or
SF6)contactors
or breakers are
used to connect
a capacitor
group.
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Real Time
Reactive 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
noitcennoC htoomS - CRTR
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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

Load Current
V
A
System Voltage
Acquisition Time 17 ms
B
RTRC Bank Current
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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 •Wood Chippers
•Elevators
•Mining Conveyors
•Presses
•Induction Heat Treating
•Rock Crushers
•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 (1618%)
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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
0
Zs = |Zs| +90
With
ITOTAL
V
VL
VL
VS
VS
V
V
VS ~
VL
IC
RTRC
CAP
ILOAD
LOAD
•Voltage sag is reduced as a
result of reactive compensation
during the load fluctuation.
With
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•The voltage sag during is
Without 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
DISADVANTAGES
• Increases network capacity
• Costly solution
• Minimizes voltage sags
compared to
• Minimizes voltage flicker
standard capacitor
• Reduces load current
systems (but often
• Avoids wear of vacuum
the only viable
contactors & capacitors
solution)
• Transient free switching in
• Physical space
sensitive networks
requirements
• Avoids use of reduced voltage
starters
• Saves energy and improves
Power Factor
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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. Twobushing capacitors connected in
Delta for higher voltages
Type 1 indoor or Type 3R
outdoor enclosure types.
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Transient Free Reactive Compensation
Systems
 MT6000 Series
 Power Factor Correction of
networks with sensitive
electronic loads
Real Time Reactive Compensation Systems
 MV9000 Series
 Power Factor Correction of
highly cyclical loads
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Standard, Detuned or Filtered?
 MT6000 & MV9000 are typically Antiresonant 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
Status Indicators
Readings Display
Function Keys Description
Function Keys
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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
Three
Phase
Reactor
Capacitors
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Current
Transformers
for unbalance
detection
Vacuum
Contactor
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Electronic Switching Modules
 Switching two phases with
Liquid Cooled Stick Stack
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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
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HVL Interrupter Switch
 Direct Drive Operator
 Fused for short circuit
protection or Unfused
available
 Load Break to max
2400 kVAR @ 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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Schneider Electric
Power Quality Correction Group
255 Orenda Road
Bramalea, Ontario, L6T 1E6
www.reactivar.com
Tel.: (905) 459-8805
Fax: (905) 454-3603
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Schneider Electric Can ada Inc.
19 Waterman Avenue
Toronto, Ontario, M4B 1Y2
www.schneider-electric.ca
Tel.: (416) 752-8020
Fax: (416) 752-6230
© 2001 Schneider Electric Can ada, All Rights Reserved
June, 2001 57