Northeast Power Systems, Inc. | 66 Carey Road Queensbury, NY 12804 |Phone: 518-792-4776 |Fax: 518-792-5767 | www.NEPSI.com | email: sales@nepsi.com
Medium-Voltage Metal-Enclosed Products
Power Capacitor Banks, Harmonic Filter Banks,
actiVAR™, & Surge Protection Products
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Presented by Paul Steciuk
Presentation On Harmonic Filter Design
Harmonic Filter Design - Summary of Presentation
Medium voltage harmonic filters are used on all power systems at all voltage levels, but they are primarily used on industrial power systems at
the medium-voltage level where large non-linear loads are in use, to improve power factor, prevent harmonic resonance, and mitigate harmonic
distortion. Their design is not widely known or understood, and because of this, the task of design and specification is often left in the hands of
the drive/rectifier supplier or electrification equipment packager. Because of this approach, due to margin stacking, the limited number of
drive/rectifier suppliers, and the captive nature of the procurement process, the customer/EPC pays more and gets less. There is a better
approach, and that is to break the filter package from the drive/rectifier supplier or electrification packager, create your own filter design and
specification, and bid it out to vendors who specialize in harmonic filter design and manufacturing.
In this presentation, NEPSI demystifies harmonic filter design, paving the way for the EPC to break the filter package from the electrification
packager and/or drive/rectifier supplier. NEPSI discusses the basics of filter design, filter topology, most prevalent filter types, their
advantages/disadvantages, component selection and rating, vendor review, typical protection and control schemes, and more. This is an
interactive and technical L&L where engineers can ask questions and receive answers from a NEPSI engineer who specializes in filter design,
specification, and manufacturing.
This presentation contains confidential and privileged information for the sole use of the intended
recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Harmonic Filter Design – Presentation Outline
Corporate Introduction (5 Minutes)
• NEPSI’s Key Product offering
• Breaking the package
Filter Design Presentation
• Basics of Harmonic Filters, what they are, what they do
• Configuration Options
• Metal-Enclosed
• Open Air
• E-House
• Key Filter Ratings (V, I, I
h
, Q
eff
, Tuning Point, etc.)
• How is harmonic current rating is determined
• Filter Types, Topology of each, advantages/disadvantages of each
• Notch
• HP (Damping factor)
• C-HP (Damping factor)
• Single/Multi-stage
• Tuning calculation (calculating X
eff
, L, C, R)
• NEPSI Spreadsheet tool (a must have tool)
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Harmonic Filter Design – Presentation Outline (Continued)
Filter Design Presentation (Continued)
• Component selection
• Capacitor Rating Procedure, applicable standards
• Heavy Duty Vs. Standard Duty (beware of claims), Specification, Vendor Review
• Tuning Reactor Rating Procedure, applicable standards
• Types: Air-Core | Iron-Core (Advantages/Disadvantages, Specification, Vendor Review)
• Damping Resistor Rating Procedure, applicable standards, types, # of series elements, specification, vendor review
• Switching Device (Breaker/Switches)
• Typical Protection
• Capacitor protection (internally fused vs. externally fused)
• Blown Fuse Detection
• Reactor Protection
• Overload protection / thermal protection
• Resistor Protection
• Short Circuit Protection (50/51 phase/ground), arc flash
• Over-voltage, V
thd
/I
thd,
Over-Temperature, Fan failure
• Typical Control
NEPSI Resources
Questions/Answers
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
• Established in 1995
• Based in Queensbury, NY
• Key products designed and manufactured by NEPSI
• Medium-voltage metal-enclosed products (2.4kV – 38kV) 200 kV BIL Max
• Shunt Power Capacitor Banks (capacitive vars)
• Harmonic Filter Banks
• Shunt Reactor Banks (inductive vars)
• Hybrid Shunt Capacitor & Shunt Reactor Banks
• actiVAR™ – Fast Switching Capacitor Banks/Harmonic Filter Banks (2.4kV – 13.8kV) for motor
start – an alternate to large VFD drives and RVSS
• Medium Voltage Surge Protection Products
• RC Snubbers
• Motor Surge Protection
• Medium-Voltage Transient Voltage Surge Protection
• Service
• Startup | Commissioning | Maintenance
• Power System Studies
• Harmonic Analysis, Power Factor, Motor Start
NEPSI - Background
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Background
Large Harmonic Filter System 1 of 2 (1-line to follow)
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Large Harmonic Filter Systems Designed & Manufactured by NEPSI
A
CUSTOMER
SOURCE
PT
(1)
GROUND
SWITCH
ISOLATION
SWITCH
CT
CT
ARRESTER
SURGE
ROLLOUT
BREAKER
CAPACITOR
CURRENT
LIMITING
FUSES
AMP
CURRENT
LIMITING
FUSES
AUX
CAPACITOR
CONNECTED
WYE-UNGROUNDED
PT
(3)
CT
ROLLOUT
BREAKER
CAPACITOR
CURRENT
LIMITING
FUSES
AMP
CURRENT
LIMITING
FUSES
HARMONIC
FILTER
REACTORS
CONNECTED
WYE-UNGROUNDED
CT
ROLLOUT
BREAKER
HIGH-PASS
RESISTOR
CT
CAPACITOR
CURRENT
LIMITING
FUSES
AMP
CURRENT
LIMITING
FUSES
HIGH-PASS
RESISTOR
CONNECTED
WYE-UNGROUNDED
CT
CT
ROLLOUT
BREAKER
CAPACITOR
CURRENT
LIMITING
FUSES
AMP
CURRENT
LIMITING
FUSES
HIGH-PASS
RESISTOR
CONNECTED
WYE-UNGROUNDED
CT
CT
ROLLOUT
BREAKER
CAPACITOR
CURRENT
LIMITING
FUSES
AMP
CURRENT
LIMITING
FUSES
HIGH-PASS
RESISTOR
CONNECTED
WYE-UNGROUNDED
CT
25kV, 60Hz
HARMONIC
FILTER
REACTORS
HARMONIC
FILTER
REACTORS
HARMONIC
FILTER
REACTORS
HARMONIC
FILTER
REACTORS
Large Harmonic Filter One-Line Diagram
Background
Large Harmonic Filter System 2 of 2
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Solar
Wind Petro
Mining
UtilityChemical
• Mining (copper, gold, diamond, oil sands, limestone, lithium, rare earth metals)
• Renewable energy (wind & solar power )
• Oil/Gas, Petro-Chemical
• Electric Utilities (large IOU’s, electric cooperatives, municipalities)
• Steel
• Pulp & Paper
• Institutions (hospitals, universities, military bases, data centers, financial institutions)
• Private Label – Supplier of product to nearly all of the “majors”
• Others
• semiconductor, scrap recycling, pharma, waste water
NEPSI Sells Into All Major Markets
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
With an installed base of over 2000 systems over the last 24 years (more than 140 in mining and 800 in Oil/Gas)
NEPSI is the leading world supplier of medium-voltage metal-enclosed capacitor banks and harmonic filter banks
NEPSI also brand labels for ABB, GE, Schneider, Eaton and other large electrical brands
Largest Installed Based On The Globe
North & Central America South America Africa, Asia, Europe, Australia
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Northeast Power Systems, Inc. | 66 Carey Road Queensbury, NY 12804 |Phone: 518-792-4776 |Fax: 518-792-5767 | www.NEPSI.com | email: sales@nepsi.com
Technical Presentation
Harmonic Filter Design
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Presented by Paul Steciuk
Paul.Steciuk@NEPSI.COM
Harmonic Filters – What Are They and What Do They Do?
• Correct Power Factor (Reactive Compensation)
• Usually to avoid power factor penalties or
comply with interconnect agreement
• Reduce Harmonic Current / Voltage Distortion
• By providing a low impedance path for
harmonic currents
• To Become compliant with harmonic
standards
• IEEE 519
• IEC 61000-3-2 (EN 61000-3-2)
• Many others
• Prevent Harmonic Resonance
• Harmonic filters installed for the
prevention of resonance are often
called “de-tuned” capacitor banks.
• Applied when high-pulse drives
are used.
What They Do -
• Most Simply Stated –
• A capacitor bank with a tuning reactor
• The inductive reactance is a fraction of the
capacitive reactance of the capacitor bank.
As a result, they are, in many ways, a
capacitor bank.
What They Are -
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
When all costs are considered, including engineering & procurement, integration, site
preparation, installation, commissioning, maintenance, and liability,
the Metal-Enclosed configuration
provides the lowest cost of ownership
Open-Air
Harmonic Filter Configuration Options
Metal-Enclosed
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
When all costs are considered, including engineering & procurement, integration, site
preparation, installation, commissioning, maintenance, and liability,
the Metal-Enclosed configuration
provides the lowest cost of ownership
Harmonic Filter Configuration Options
E-House
Metal-Enclosed
Not Widely Used In
South/North America
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Key Filter Ratings
• Reactive Power Rating (KVAR / MVAR, 3-Phase Value)
• Usually based on reactive power requirement of load
• May be determined by harmonic duty requirements
• Voltage, based on system voltage (KV
LL
)
• Insulation Level (KV)
• BIL / 1 Minute Withstand
• Based on standard rating for voltage class of equipment
+pollution level, + elevation, + consideration for increased
reliability and arc flash mitigation
• Tuning Point (Hertz or Harmonic Number, i.e. 282 Hertz or 4.7
th
Harmonic for 60 Hertz System
• Filter Type (Notch, C-HP, HP)
• For C-HP, HP
• Damping Factor (R/X
inductor
at tuning frequency)
• Resistor Rating (Ohms, KW)
• Fundamental Current Rating, I
1
, (Amps), at 10% Over-voltage
• Harmonic Current Ratings (Amps), Include all significant
harmonics Under worst case conditions
• I
5
, I
7
, I
11
, I
13
…. etc. (be very conservative)
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
How Are Harmonic Filter Ratings Determined?
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
• Power System Studies
• Load Flow Analysis
• Determines reactive power rating of filter (MVAR)
• Harmonic Analysis
• Determines filter tuning
• Determines expected harmonic current flow into filter branch(s)
• Filter type (Notch, C-HP, HP)
• Based on above studies, L, R, C Filter Parameters, and reactive power ratings are determined. The
equipment specification is not normally developed from the study.
Filter Ratings
Filter Component Ratings (Capacitors | Reactors | Resistors)
• Harmonic Analysis Programs
• Spreadsheet Tools (NEPSI offers such a tool at: http://nepsi.com/resources/spreadsheet-tools/)
Harmonic Filter – Basic Concepts
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
OPEN
OPEN
OPEN OPEN OPEN
SOURCEBUS
1
3
8
k
V
SECMAIN
1
3
.
8
k
V
M-1
1000 HP
Induction
16.7%
M-5
1000 HP
Induction
16.7%
SOURCEEQUIVALENT
8kA
10 (X/R)
8kA
10 (X/R)
HARMONIC
3 MW
3 MVAR
TX-1
10 / 16.67 MVA
138 - 13.8 kV
7.5%
PCC
PCC
13
.8
k
V
CAPBUS
1.491 MVAR
23.953 mH
1.491 MVAR
23.953 mH
1.491 MVAR
23.953 mH
1.491 MVAR
23.953 mH
Harmonic Current Injection
4 MVAR 4 Stage/4 Step Capacitor Bank
4 Stages of 1 MVAR
0
10
20
30
40
50
60
1 3 5 7 9 11 13 15 17 19 21
13.8kV Bus Impedance (Ohms)
Harmonic Number
Harmonic Impedance Scan
Filter Bus (No Source Impedance) / Main Bus (No Filter)
FILTER IMPEDANCE
SOURCE IMPEDANCE
I
filter
I
source
Harmonic Filter – Basic Concepts
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
I
filter
I
source
Total Impedance
Source Impedance
OPEN
OPEN
OPEN OPEN OPEN
SOURCEBUS
1
3
8
k
V
SECMAIN
1
3
.
8
k
V
M-1
1000 HP
Induction
16.7%
M-5
1000 HP
Induction
16.7%
SOURCEEQUIVALENT
8kA
10 (X/R)
8kA
10 (X/R)
HARMONIC
3 MW
3 MVAR
TX-1
10 / 16.67 MVA
138 - 13.8 kV
7.5%
PCC
PCC
13
.8
k
V
CAPBUS
1.491 MVAR
23.953 mH
1.491 MVAR
23.953 mH
1.491 MVAR
23.953 mH
1.491 MVAR
23.953 mH
Harmonic Current Injection
4 MVAR 4 Stage/4 Step Capacitor Bank
4 Stages of 1 MVAR
Most Common Filter Types Used at Medium Voltage Level
Notch
High-Pass
HP
C-High-Pass
C-HP
• Notch Filters are preferred due to low cost, low
losses, and simplicity
• Most common on industrial power systems
• HP and C-HP Filters are common in projects
where non-characteristic harmonics might be
present, on systems with large drives, and where
there is stray capacitance concerns
• Most common in mine applications and
where large drive applications (LCI /
Cycloconverter)
• Projects with significant amounts of cable
capacitance (wind farms)
• Filter types, tuning point, reactive power rating, and
quantity can be grouped together to create multi-
staged harmonic filter systems
Application Considerations
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
• Low impedance at tuning point
• Low fundamental losses
• Less filtering at side-band
harmonics
• More susceptible to inter-
harmonic resonance
• Lowest cost filter
0
10
20
30
40
50
60
70
80
90
0 5 10 15 20 25 30 35 40 45 50
Filter Impedance (ohms)
Harmonic #
Notch Filter
Filter Impedance Vs. Harmonic Number
Notch Tuned Filter
Key Characteristics
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
• Attenuates higher order
harmonics
• Dampens resonance
• Provides less filtering than notch
filters at tuning point (as Q or
Damping Factor (R/X) decreases)
• Has higher fundamental losses
than notch filters
• Has higher cost when compared
to Notch filters
• Commonly used in large drive
projects and where inter-
harmonic resonance is of
concern.
0
10
20
30
40
50
60
70
0 5 10 15 20 25 30 35 40 45 50
Filter Impedance (ohms)
Harmonic #
High-Pass Filter
Filter Impedance Vs. Harmonic Number
Q=0.5, 27KW/PHASE LOSSES
Q=1.0, 15 KW/PHASE LOSSES
Q=3, 5KW/PHASE LOSSES
Q=5, 3.2KW/PHASE LOSSES
Q=10, 1.6KW/PHASE LOSSES
High-Pass (HP) Tuned Filter (Damped Harmonic Filter)
Key Characteristics
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
• Same benefits as standard high-pass-filter
• Impedance profile is the same as standard high-
pass filter
• Resistor has near 0 losses at fundamental
frequency
• Higher dampening capability due to lower losses
• Harmonic losses are nearly the same as standard
high-pass filters
• Higher Cost than C-HP and Notch Filters
• Commonly used in large drive projects and where
inter-harmonic resonance is of concern.
• Most often applied only at tuned frequencies below
the 5
th
harmonic (i.e. 2
nd
, 3
rd
, 4
th
, harmonics)
}
{
Tuned to
Desired
Frequency
Tuned to
Fundamental
Frequency
C-High-Pass (C-HP) Tuned Filter (Damped Harmonic Filter)
Key Characteristics
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Notch Filter
Application
High-Pass Filter
Application
High-Pass Vs. Notch Filter Impedance Scan Comparison
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
• High-Pass filters dampen resonant
peaks between tuning points on
multi-tuned harmonic filters
• Important in cycloconverter
and large drive applications or
where interharmonics exist
• High-Pass filter tuning tolerance is
less critical
• High-Pass filters help dampen
unwanted resonance form remote
capacitor banks or stray capacitance
• High-pass filters are better for
attenuating higher frequencies
harmonics
High-Pass Vs. Notch Filter Impedance Scan Comparison
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
High-Pass filters also help to dampen
resonance from stray cable capacitance
and other remotely located power
capacitor banks
High-Pass Filters (C-HP & HP) Dampen Resonance Conditions
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
(ohms) =
(13.8kV, 1000 kvar, 4.7
th
Tuned Notch Filter Type)
(ohms) =
190.4 (ohms)=199.47 (ohms)
=
= 23.95 mH
V
LN
JX
L
-JX
C
k
tor (ohms)
of Reactor (ohms)
Current in Amps at Each Harmonic
(Hz)
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Tuning Calculation (X
L
, X
C
, L, C) – Notch Filter Design
(ohms) =
(13.8kV, 1000 kvar, 4.7
th
Tuned HP Filter Type)
(ohms) =
190.4 (ohms)=199.4 (ohms)
=
= 23.95 mH
k
tor (Ohms)
of Reactor (Ohms)
Current in Amps at Each Harmonic
(Ohms)
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Tuning Calculation (X
L
, X
C
, L, C, R) – HP Filter Design
(f)
DF
R
V
LN
JX
L
-JX
C
R
(ohms) =
(13.8kV, 1000 kvar, 4.7
th
Tuned C-HP Filter Type)
=
= 23.95 mH
k
Current in Amps at Each Harmonic
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
(f)
R
V
LN
JX
L
-JX
CA
R
-JX
CM
tor Group (Ohms)
of Reactor (Ohms)
(Ohms)
DF
tor Group (Ohms)
=
Tuning Calculation (X
L
, X
C
, L, C, R) – C-HP Filter Design
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Spreadsheet Tools Speed Up & Confirm Design
How filters are really designed:
• Spreadsheet tools are most often used to confirm ratings and
do design work.
• Required values: System voltage, reactive power
rating, tuning point, system frequency, expected
harmonic current duty (don’t forget to add margin)
• Harmonic analysis programs calculate expected performance
(IEEE 519 compliance, Vthd, Ithd, etc..).
• Expected harmonic current flow into filter is used as input to
spreadsheet tools for validating component duty rating
against standards.
• NEPSI Spreadsheet tool available at:
http://nepsi.com/resources/spreadsheet-tools/
• Spreadsheet tool provides calculation for all major
filter types: Notch, High Pass (HP), and C-High-Pass
(C-HP)
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Component Selection & Rating - Capacitors, Reactors, Resistors
Recommendations When Selecting and Rating
Components
• Be conservative
• Systems Change / Expand
• Calculations Don’t Always Match Reality
• Wrong Assumptions
• Wrong Input Data
• Cost Increase For A Conservative Design Is Minimal –
Pennies on the dollar
• Component Supplier Ratings Don’t Always Meet
Expectations
• Improved Reliability
• Use Only Reputable Manufacturers
• Consider Availability, Service, and How Supplier Behaves
When There Are Problems
The cost for higher-rated,
higher-quality components
are pennies on the dollar
Improve reliability, ensure success
over-specify
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Shunt Power Capacitors
Capacitor Standards
• IEEE Std. 18-2002, IEEE Standard for Shunt Power Capacitors
• C22.2 No. 190-M1985, Capacitors for Power Factor Correction
• IEC 60871-1, Shunt Capacitors for a.c. Power Systems Having a Rated Voltage Above 1000V
Application Standards –
• IEEE Std. 1036 – 1992, IEEE Guide for Application of Shunt Power Capacitors
• IEEE Std. C37.99-2000, IEEE Guide for Protection of Shunt Capacitor Banks
• IEEE Std. 1531 – IEEE Guide for Application and Specification of Harmonic Filters
Main Suppliers:
ABB, Cooper Power (Eaton), General
Electric (GE), Vishay
Type:
Internally Fuses | Externally Fused
Most Prevalent Connection:
Ungrounded-Wye or Split-Wye-
Ungrounded
2-Bushing, Single-Phase
Capacitors
Capacitor Duty Rating in Filter
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Shunt Power Capacitors – Selection of Ratings
I
filter (n)
X
c
• 110% of rated RMS voltage
• 120% of rated peak voltage, i.e. peak voltage not exceeding
1.2 x (square root of two or 1.414) x rated rms voltage,
including harmonics, but excluding transients
• 135% of nominal RMS current based on rated kvar and
rated voltage
• 135% of rated kvar
/1000
X
c
= Fundamental Capacitive Reactance of Capacitor
Choose a capacitor voltage rating, calculate its maximum RMS current and voltage ratings, kvar rating,
and peak voltage rating and compare it to the expected duty it will see when in operation as part of the
harmonic filer.
Capacitor Standard Maximum Ratings
The minimum capacitor voltage rating for ungrounded-wye connected capacitor
banks is the system’s line-to-neutral voltage. For lower tuned filters, the voltage
must be higher. The tuning reactor adds fundamental voltage to the capacitor
and this value must be accounted for. A typical starting point would be 1.25 x
V
LN
Application Note
• Capacitors may be purchased with
additional margin beyond their nameplate
rating.
• Cold temperature ratings should always be
used in Canada and must be CSA rated.
• Capacitors used in harmonic filters should
leave 10% RMS overvoltage and 20% peak
overvoltage capability for system
overvoltage
• Standard allows for 0 +10% on capacitance.
They are typically 0 to +3%.
Know what capacitor you are getting, consider standard
duty rating only as test per standards are based on
nameplate values and not extra-duty rating.
Capacitors May Be Advertised As Exceeding Industry Standards
Table from Cooper Power, ABB, GE, and others have a similar
table, but additional margins can vary
Standard Capacitor Ratings
Considerations…
• Shunt Power Capacitor suppliers build custom sizes with no
cost premium.
• NEPSI typically uses standard voltage ratings, but not always
and it is not necessary.
• Tables only go up to 22,800 volts, but suppliers will go as
high as 24,000 volts.
• Internally fuse capacitors stop at 12kV and as a result
require multiple series capacitors to obtain line-to-neutral
voltage on higher-voltage systems, 20kV and up.
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
• Standards require 5-minute
discharge device (resistor)
✓ Discharge from peak voltage
to 50 volts in 300 seconds or
less
• Faster discharge times can be
purchased ~ 180 seconds
• Transformers may be used to
discharge trapped charge to allow
for faster re-energization
Capacitor Voltage = 1.05e
-(0.05xTime)
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
Capacitor Voltage
(Per Unit)
Time (in seconds)
Discharge Time from Peak Voltage
(Per Unit Peak Capacitor Voltage)
1 Per Unit Voltage = 1.414 x Rated RMS Voltage of Capacitor
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Standard Capacitor Discharge Curve
Typical Construction
• Capacitors are built of series and parallel sections to obtain desired kvar
and voltage rating.
• Sections typically have a 2000 volt rating.
• 1-Bushing and 2-Bushing designs
• Are filled with a non-PCB dielectric fluid, about 5 Gallons (18.9 Liters)
per capacitor
• Typically weigh less than 120 Pounds (~54 Kilograms)
Application Note:
• Capacitor section failures account for nearly 95% of capacitor failures
• A capacitor section failure will result in an increase of capacitance and
additional stress on all remaining sections
• Discharge resistors seldom fail
Resistor
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Typical Capacitor Construction – Externally Fused
0 50 100 150
453 kvar, 14.4kV
500 kvar, 22.8kV
525kvar, 19.94kV
592 kvar, 21kV
600 kvar, 22.2kV
647 kvar, 24.94kV
667 kvar, 24.94kV
Weight (LBS)
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Typical Capacitor Weight
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Modern All-Film Power Capacitors Are Quite Reliable
• Covered extensively in IEEE C37.99-2000 –
IEEE Guide for the Protection of Shunt
Capacitor Banks
• Protects against over-voltages due to phase
unbalance caused by fuse operation
• For capacitor banks, relays are set to
trip at 10%.
• For harmonic filter banks, relays are set
to trip due to de-tuning of filter.
• Protects against filter de-tuning due to
capacitance change in filter bank caused by
fuse operation
Split-Wye (Double-Wye)
CT in Neutral
Single-Wye
Neutral Voltage Detection
(preferred)
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Blown Fuse Detection – Neutral Unbalance Protection
Split-Wye (Double-Wye)
CT in Neutral
(preferred)
Advantages
• Easy to have trip and alarm set points for
capacitor banks (not filter banks) with more
than 4 or more capacitors per phase
• Not susceptible to false tripping from
system voltage unbalances
• Less costly than PT in neutral
Disadvantage
• Requires factory/field setting/calibration
• Does not protect against fuse failure
(VOLTS)
(VOLTS)
(AMPS)
Formulas
• I
CURRENT THROUGH NEUTRAL CT
= Current in amps through
CT for one or more capacitor fuse operations
• I
NOMINAL
= Phase Current of Entire Capacitor Bank (Both
Wye-Connected Banks Combined in amps)
• V
Ø
= Nominal Phase-to-Neutral System Voltage (volts)
• F = Number of Failed Capacitors per Phase
• N = Number of Capacitors per Phase (this includes both
sides of wye for split wye banks)
• V
REMAINING CAPACITOR VOLTAGE
= Voltage remaining on
capacitor after fuse operation (volts)
• V
CAP BANK NEUTRAL-TO-GROUND
= Voltage from Capacitor
Bank neutral to ground after fuse(s) operation.
This presentation contains confidential and privileged information for the sole use of the intended
recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Blown Fuse Detection, Split-Wye (CT In Neutral)
Advantages
• Easy to have trip and alarm set points for
capacitor banks (not filter banks) with more
than 4 or more capacitors per phase
• Neutral becomes grounded through PT
winding when bank is de-energized
Disadvantage
• Susceptible to false tripping from system
voltage unbalances
• Normal line voltage unbalances
• Unbalances due to line-to-ground
faults
• Increases likelihood of switch re-strike due
to TRV issues
• Reduce probability by using L-L
rated PT
• Requires factory/field setting/calibration
• Does not protect against fuse failure
Single-Wye
Neutral Voltage Detection
(not recommended)
(VOLTS)
(VOLTS)
• F = Number of Failed Capacitors per Phase
• N = Number of Capacitors per Phase (included on both sides of
wye connected capacitor bank)
• V
Ø
= Nominal Phase-to-Neutral System Voltage (volts)
• V
REMAINING CAPACITOR VOLTAGE
= Voltage remaining on capacitor
after fuse operation (volts)
• V
CAP BANK NEUTRAL-TO-GROUND
= Voltage from Capacitor BAnk
neutral to ground after fuse(s) operation.
Formulas
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Blown Fuse Detection, Single-Wye (PT In Neutral)
Tuning Reactors
Tuning Reactor Standards
• IEEE C57.16-2011 - IEEE Standard for Requirements, Terminology, and Test Code for Dry-Type Air-Core Series-Connected Reactors
• IEEE C57.120-2017 - IEEE Guide for Loss Evaluation of Distribution and Power Transformers and Reactors
• IEEE C57.12.01-2015 - IEEE Standard for General Requirements for Dry-Type Distribution and Power Transformers
• IEEE C57.12.91 - IEEE Standard Test Code for Dry-Type Distribution and Power Transformers
• IEC 60076-6 – Part 6: Reactors
Application Standards –
• IEEE Std. 1531 – IEEE Guide for Application and Specification of Harmonic Filters
Main Suppliers:
Air-Core Reactor Suppliers (open-air filter designs)
Trench, Phoenix Electric
Iron-Core Reactor Suppliers (metal-enclosed filter
designs)
Power Magnetics, Control Power Transformer, Hans Van
Mangoldt
Tuning Reactors, Iron-Core Vs. Air-Core
Air-CoreIron-Core
Single-Phase, Floating Core Design Single-Phase, Floating “Spider” Design
Tuning Reactor Options, Iron-Core Vs. Air-Core
Air-CoreIron-Core
Advantages
• Not susceptible to saturation
• Familiarity with some engineers
Disadvantages
• Stray magnetic fields
• Increases footprint area ~ 1 Diameter
• Difficult & costly to enclose
• Low Q (typically near 60)
• Shipped separate
• Requires field assembly
• Requires its own foundation
• Requires its own elevating structure
• Higher cost
• Long lead-times, Up to 26 Weeks
• Higher losses
• More difficult and costly to apply in high wind and
high seismic areas
Advantages
• No stray magnetic fields
• Easy to enclose
• Shipped installed within filter bank
• Requires no field assembly
• Requires no foundation
• Short lead-times ~ 6 to 8 weeks
• Well suited for high wind/seismic areas
• Lower cost
• Lower losses
• High Q ratings (typically on the order of 100 to 150)
Disadvantages
• Susceptible to saturation
• Must account for all possible harmonics – should
always be specified and designed with significant
designs margins
• When specified correctly, the iron-core reactor
is equal to or better than air-core reactors.
Iron-Core Tuning Reactors
Metal-Enclosed Harmonic Filter Banks Utilize Iron-
Core Tuning Reactors
• Capacitor bank tuning / de-tuning
• by Power Magnetics, Mangoldt
• 3-phase & 1-phase designs
• Nomex 410 UL, 220°C insulation system and other
ratings.
• Copper/Aluminum designs based on cost and
technical advantages
• Rating: 115°C rise, 60°C ambient vacuum, and other
ratings.
• Limit of inductance linearity: ~220%
• Vacuum Pressure Impregnation (VPI)
• Reduces noise from magnetic action and
protects from the environment
• Conservatively rated
• Must account for the unknown
• Heating proportional to frequency
2
• Attenuates switching transient
Iron-core Tuning Reactors can be quite large. They can be
sized to tune capacitor banks from the 1.5th harmonic to the
50th harmonic and can tune bank ratings as low as 50 kvar
at 480 volts on up to over 20 MVAR at 38kV.
1-Phase Iron-Core Tuning Reactor Arrangement
Features
• Floating Core Design
• Low voltage stress (similar to air-core reactor
design)
• 2 – winding design with winding barrier
Advantages
• More available ratings:
• BIL: 60 to 200kV (max)
• Filter 3Ø MVAR rating: 0.5 to 18 MVAR (max)
• Low stress design
• 95% of voltage stress is across HV Insulator
• 5% voltage stress across winding and winding to
core
• Low Noise
• High Reliability
Disadvantages
• Larger footprint when compared to 3-phase core design
3-Phase Iron-Core Tuning Reactor Arrangement
Usage:
• Maximum System Voltage to 13.8kV (110kV BIL)
• Smaller filters branches (up to 2 MVAR at 13.8kV)
Features
• Grounded Core
• Phase Barriers
Advantages
• More compact (smaller footprint)
• Less costly than 3 single phase reactors
Disadvantages
• More difficult to design
• 100% of voltage stress between winding and core
• Ratings:
• BIL: 60 to 95kV (max)
• Filter 3Ø MVAR rating: 0.5 to 3 MVAR (max)
• Higher Noise Levels
Tuning Reactors 6 of 12
Voltage Stress On 13.8kV Iron-Core Filter Reactor
Voltage Stress on 34.5kV Iron-Core Reactor
Iron-Core Reactor – Gapped Core
Iron-Core Tuning Reactor Ratings
Key Ratings
• # of Phases
• Inductance/Reactance at nominal frequency
• Nominal frequency
• Nominal System Voltage
• determines voltage class of insulation (BIL, withstand),
& winding margins
• RMS Current
• For rating winding ampacity
• Winding cooling requirements
• Harmonic Current Spectrum
• Peak current rating (summation of harmonic currents to
determine flux density of core.
• Heating in Core to determine cooling requirements
• Taps
• To adjust tuning point for component tolerance.
• To adjust kvar
• To adjust tuning point for reliability (for example a 5,7
tuning point.
• Ambient Temperature (normally 60C for metal-enclosed filters)
• Q Rating (normally very high for iron-core (near 100).
I
filter (n)
X
L
Ratings Table
Air-Core Reactor Mounting Arrangements
Stacked Reactor
Arrangement
Unstacked Reactor
Arrangement
Air-Core Reactor – Radial Magnetic Clearance Requirements
Installation Diagram
(magnetic field clearance requirements)
Notes:
• Stray magnetic fields are significant and can induce
currents in metallic parts that may causes thermal and
electrodynamic effects. Nearby metal structures,
electronics equipment, rebar, etc. shall be located in areas
where the effect will not create excessive heating.
• De ≈ 2x coil diameter
• MC1 ≈ 1.1 x coil diameter (metallic parts not forming
closed loops – as measured from center of reactor)
• MC2 ≈ 1.5 x coil diameter (metallic parts forming closed
loops – as measured from center of reactor)
Air-core tuning reactors have
significant footprint requirements
(typical coil diameter: ≈ 5 feet - thus a 15’
diameter is required for MC2 clearances)
Tuning Reactors 12 of 12
Air-Core Reactor – Axial/Radial Magnetic Clearance Requirements
(magnetic field clearance requirements)
Side View
Notes:
• Sides – Radial Distance
• MC1 ≈ 1.1 x coil diameter (metallic parts not
forming closed loops – as measured from center of
reactor)
• MC2 ≈ 1.5 x coil diameter (metallic parts forming
closed loops – as measured from center of reactor)
• Top/Bottom – Axial Distance
• MC1 ≈ 0.5 x coil diameter (metallic parts not
forming closed loops – as measured from center of
reactor)
• MC2 ≈ 1.0 x coil diameter (metallic parts forming
closed loops – as measured from center of reactor)
High-Pass Filter Resistors
HP Resistor Standards
• No Standard directly applies
• IEEE C57.32-2015 - IEEE Standard for Requirements, Terminology, and Test Procedures for Neutral Grounding Devices
Application Standards –
• IEEE Std. 1531 – IEEE Guide for Application and Specification of Harmonic Filters
Main Suppliers:
Post Glover, Avtron Power Resistors
Preferred Type:
Low Inductance, Stainless Steel Stamped Grid Design
Typical Ratings:
Minimum: 20kW/Phase
Maximum: 150kW – 200kW / Phase
High-Pass (HP) Filter Resistor – Rating Calculation
This presentation contains confidential and privileged information for the sole use of the intended
recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
High-Pass Filter
HP
I
filter (n)
I
R(n)
V
R(n)
JX
L
• R = Resistance = Based on Damping Factor (DF) of filter (Ohms)
• V
R(n)
= Harmonic voltage across resistor is calculated based on parallel impedance of
JX
L(n)
and R multiplied by expected harmonic filter current I
filter(n)
(Volts)
R
-JX
C
(Volts)
• I
R(n)
is obtained by dividing V
R(n)
/R (Amps)
(Amps)
• I
Resistor RMS Current
is obtained by taking the square root of the sum of squares of all
harmonic currents flowing in resistor
• The single-phase power rating of the resistor is calculated by squaring the RMS
current rating of the resistor and multiplying by R.
C-High-Pass (C-HP) Filter Resistor – Rating Calculation
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
C-High-Pass
C-HP
I
filter (n)
I
R(n)
JX
L
-JX
CA
V
R(n)
R
-JX
CM
• R = Resistance = Based on Damping Factor (DF) of filter (Ohms)
• V
R(n)
= Harmonic voltage across resistor is calculated based on parallel impedance of
JX
L(n)
, R, and X
CA(n)
multiplied by expected harmonic filter current I
filter(n)
(Volts)
• I
R(n)
is obtained by dividing V
R(n)
/R (Amps)
(Amps)
• I
Resistor RMS Current
is obtained by taking the square root of the sum of squares of all
harmonic currents flowing in resistor
• The single-phase power rating of the resistor is calculated by squaring the RMS
current rating of the resistor and multiplying by R.
(Volts)
High-pass Filter Resistor
Specify
• System Voltage, BIL, Single-Phase Resistance, Elevation, RMS
Current Rating of Resistor
• Specify Stainless Steel Stamped Grid Type Resistor Elements
• Cooling: Natural Convection
• Roof-mounted / Rack-mounted in 409/304/316 stainless steel
enclosure depending on type of filter
• Enclosure not painted
• Power / current ratings should be doubled to account for
unforeseen harmonic conditions
• Ohms are based on Damping Factor (DF) requirement of filter
• Number of series elements should be equal to V
LN
/5kV to
compensate for transient voltage during energization.
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recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Edge wound and wire wound
resistors should be avoided if
possible
Typical Stamped Grid
Resistor Element
Stamped Grid Resistors
• Multiple taps on each grid
for resistance
flexibility
• Welded connections
between grid plates
• No maintenance
This presentation contains confidential and privileged information for the sole use of the intended
recipient. Distribution, disclosure to other third parties is prohibited without prior consent.
Cross Section View
Other Design Details
• Switching
• Protection
• Control
• Arc Flash Mitigation
Arc Resistant Enclosure Design
Arc Flash Hazard Mitigation – Design Strategies
Arc Hazard Mitigating Design Strategies 1 of 2
• Technology that Reduces Arcing Time and Incident Energy
o Current limiting fuses
o ABB UFES system
o Arc flash detection relays
o Bus differential relays
• Design Features that Reduce Exposure to Arc Flash Hazard
o Locate equipment outdoors
o Delayed switching
o Arc resistant enclosure designs built to IEEE C37.20.7 requirements
o Remote switching | remote racking
o Remote protection & control system
One-Line
Enclosure Features
Arc Flash Hazard Mitigation – Design Strategies (cont.)
Arc Hazard Mitigating Design Strategies 2 of 2
• Design Practices that Reduce Probability of Arc Flash Event
o Key interlocks
o Proper choice of capacitor switching device
o Fuse failure protection
o Windows
o Condensation control with heaters
o Rodent screens/floor
o Signage
o Insulated bus bars
o Increase BIL rating
o Smoke detectors
o Partial discharge monitoring
o Infrared inspection windows
One-Line
Enclosure Features
NEPSI Resources
• Contact NEPSI about your application
• Application Engineers
• Firm / Budgetary Quotes, Drawings, etc.
• Web – nepsi.com
• Product literature
• Component Literature
• Guide form specifications
• Case studies
• Calculators
• Request for Quote Forms
• Spread Sheet tools
• YouTube / How-to Videos
Power Factor 19 of 20
