Distribution Engineers Workshop - RMEL(SAIDI and SAIFI) and ef-ficiency, decrease outage times, and...

Denver Marriott South at Park MeadowsLone Tree, CO

October 11-12, 2017

Distribution Engineers Workshop

Instructed by:Daniel Koppes, Sr. Substation Engineer, PacifiCorp

Timothy Day, Sr. Application Engineer, Eaton Corp.

Aaron Magnuson, Engineer 1, Kansas City Power and Light

Jon Grooters, Western Regional Sales/Applications Manager, Beckwith Electric

Brent Gerling, Distribution Engineer, Independence Power & Light

Daniel Wycklendt, Business Development Manager, Distribution Automation , G&W Electric Company

Danny McReynolds, Power System Engineer Sr., Distribution Design, Austin Energy

Bryan Cooper, Operations Engineer, Colorado Springs Utilities

Ryan Lane, Project Analyst, Burns & McDonnell

WiFi InformationNetwork: Marriott_ConferencePassword: RMEL2017

RMEL ~ 6855 S. Havana, Ste 430 ~ Centennial, CO 80112 ~ (303) 865-5544 ~ FAX: (303) 865-5548 ~ www.RMEL.org

Wednesday, October 11,

20178:30 a.m. - 8:45 a.m.Welcome and Opening Remarks

8:45 a.m. - 9:00 a.m.Overview Demonstrating the Flow From the Substation Down to the CustomerDanny McReynolds, Austin Energy

9:00 a.m. - 10:00 a.m.Introduction to Substation Design and SafetyDaniel Koppes, Sr. Substation Engineer, Pacificorp This training will provide information on the different components installed in a substation, as well as the benefits and drawbacks to the different types of equip-ment. The basics of reading substation design drawings will be covered, how to read physical design drawings as well as one lines and how the interrelate. Lastly, substa-tion grounding, both design and safety basics, will be covered.

10:00 a.m. - 10:15 a.m.Networking Break

10:15 a.m. - 11:15 a.m.Introduction to Substation Design and Safety (continued)Daniel Koppes, Sr. Substation Engineer, Pacificorp

11:15 a.m. - 12:15 p.m.Distribution System Protection Overview Timothy Day, Sr. Application Engineer, Eaton Corp.Have you ever wanted to get a good foundation on system protection and full

understand how to apply different protective devices? This session is targeted to do just that. The industry is changing and if you don’t understand the basics, the new devices and setting philosophies are only get-ting more complicated. This overview will provide you with the a good foundation of each device and their in-terface with other protective devices.

12:15 p.m. - 1:15 p.m.Networking Lunch

1:15 p.m. - 2:30 p.m.Standards and Applications of Distribution System ProtectionAaron Magnuson, Engineer 1, Kansas City Power and LightTimothy Day, Sr. Application Engineer, Eaton Corp.This presentation will cover the System Protec-tion standards that KCP&L Follows. Specifically, the differences between the KCP&L protection standards, and the protection standards followed in the GMO region, which was acquired in 2008. This presentation will also focus on the benefits and drawbacks of each of the protection standards, and some examples of each of the standards. Additionally, this presentation will go into some real-world problems that can come up when designing the protection for a circuit. These problems, such as low fault current, contingency situation, and cold load pickup can change what needs to be placed on the circuit, as well as adding additional problems that must be taken into consid-eration.

2:30 p.m. - 2:45 p.m.Networking Break

2:45 p.m. - 3:45 p.m.Auto-Circuit Reclosers: Features, Application and CoordinationTimothy Day, Sr. Application Engineer, Eaton Corp.Reclosing devices have come a long ways from the traditional reclosers. The traditional devices had more of a set it and forget it approach. However, as this grid transforms you can no longer take that approach. The devices today can deal with reverse power flow, operate in a distribution au-tomation scheme and even operate only one phase of a three-phase unit. These ca-pabilities can unlock the true potential of your distribution network and help improve reliability.

3:45 p.m. - 4:30 p.m.Group Discussion

Thursday, October 12,

20178:00 a.m. - 8:15 a.m.Welcome Back and Opening Remarks

8:15 a.m. 9:15 a.m.Voltage Regulator Controls Jon Grooters, Western Regional Sales/Applications Manager, Beckwith ElectricThis training will start by providing a basic overview of voltage regulator control basics including defini-tions of band center, band width, time delays, line drop compensation, and voltage limits/runbacks. It will then tackle more complex ap-plications such as voltage coordination, reverse power operation, DER effect on voltage regulation, and volt-age reduction.

9:15 a.m. - 10:00 a.m.Distribution Capacitor Banks and a Process for Independence Power & LightBrent Gerling, Distribution Engineer, Independence Power & LightMy intention is to provide a brief overview of capacitor banks and their uses on the distribution system. Talk about a process for feeder analysis and determining best sizes and locations for capbanks; reasons for fixed banks & switched banks; communication & monitoring options for both; construc-tion standards & materials; safety practices; calculated returns; installation cost and a plan for implementation.

10:00 a.m. - 10:15 a.m.Networking Break

10:15 a.m. - 12:00 p.m.Automatic Throw Overs (ATO’s) – 2 Parts

10:15 a.m. - 11:00 a.m.Part 1

Distribution Automation Schemes – Proven Solutions to Reduce the Duration of Power Outages and Improve System Reliability Daniel Wycklendt, Business Development Manager, Distribution Automation, G&W In this session we will discuss popular distribu-tion automation schemes of various complexity and magnitude. The focus will be on schemes that utilize decentralized automation logic. Throughout this session we will cover over-head and underground Automatic Throw Over schemes, various loop schemes, communicating and non-communicating

Workshop Topics

*Visit www.RMEL.org for the latest topic and speaker information.

CHAIRBill Galloway

Colorado Springs UtilitiesStandards Managing Engi-

neer

VICE CHAIRJoshua Jones

PacifiCorpDirector, T&D Standards

Engineering

Andy AlexanderKansas City Power & Light

Manager T&D Central Design

Thank You RMEL Distribution Committee

The RMEL Distribution Committee plans all RMEL Distribution events. If you’d like to send information

to the committee, email James Sakamoto at [email protected].

DISTRIbUTIOn EnGInEERS WORKSHOPDistribution Engineering From the

Substation to the Customer

schemes, as well as three-phase and single-phase trip and lockout options.besides the functional details on automation schemes, this session will also cover the need for distribution automation in the market place, minimal requirements for the dif-ferent tiers of automation, and installation examples including results and ben-efits. Automation schemes like these can help to improve system reliability (SAIDI and SAIFI) and ef-ficiency, decrease outage times, and significantly reduce total life cycle costs.

Part 2

11:00 a.m. - 11:30 a.m.Austin Energy Retrofit PresentationDanny McReynolds, Power System Engineer Senior, Distribution Design, Austin Energy

11:30 a.m. - 12:00 p.m.Enhanced Power ServiceBryan Cooper, Operations Engineer, Colorado Springs Utilities Automatic throw overs provide select custom-ers within the Colorado Springs electric service territory with additional availability. This pre-sentation will provide a background of the Enhanced Power Service program at Colorado Springs Utilities, de-scribe the design and operational attributes, and highlight specific ex-amples of recent events.

12:00 p.m. - 1:00 p.m.Networking Lunch

Steve DuranSRP

Engineer

Brent GerlingIndependence Power & Light

Distribution Engineer

Mark LesiwXcel Energy

Electric Standards Manager

Danny McReynoldsAustin Energy

Power System Engineer Sr.

1:00 p.m. - 2:00 p.m.Group Discussion

2:00 p.m. - 2:15 p.m.Networking Break

2:15 p.m. - 2:30 p.m.Attendee AnnouncementsAny registered attendee is invited to make a short announcement on their com-pany, new products, tech-nologies or informational updates. Announcements may include showing a prod-uct sample but not videos and power point slides. Please limit announcement to 5 minutes.

2:30 p.m. - 4:00 p.m.Modeling Strategies for the Modern GridRyan Lane, Project Analyst, Burns & McDonnellToday’s utility customers rely more on the grid now than they ever have-- not only do they use energy from the grid, they also generate it. Utilities have shown an ability to respond quickly to this fast-changing model, and rigorous planning proce-dures designed at the outset to complement modeling software will help them stay ahead of that curve. by approaching grid moderniza-tion from a proactive and holistic perspective, we can build a distribution system with improved reliability and resiliency that will be able to meet the demands of our shifting energy landscape. Accurate modeling is paramount in the process, and some of the modeling techniques we use at burns & McDonnell to implement this method will be demon-strated.

4:00 p.m. - 4:15 p.m.Wrap Up/Close of Day

Overview Demonstrating the Flow From the Substation Down to the

Customer

Danny McReynolds Power System Engineer Sr., Distribution Design

Austin Energy

Distribution Automation

34

Distributed Generation

AMI Meter Voltage

AMI Meter Voltage

EV Charging

Relay or Line Monitor

Capacitor Bank

Substation

AMI Meter Voltage

(EOL)

Mid-Line Regulator

Recloser

Capacitor Bank

LTC

Energy Storage

General Equipment Types - Some Combined • Sensing• Operating• Resource (Generation / Demand Reduction)

Dispatchable Load Diversity

AC / Heat Pumps

Water Heater

Pool Pumps

Fault Indicators Switchgear XFMR

XFMR

mcreynoldsd

Line

mcreynoldsd

Line

Introduction to Substation Design and Safety

Daniel Koppes Sr. Substation Engineer

PacifiCorp

PACIFICORP

Substation Training

By Daniel Koppes

Agenda

Substation Components Understanding One Lines Substation Layouts Substation Grounding Substation Safety Questions

Substation ComponentsBreakers

Substation ComponentsCircuit Switchers/Transrupters

Substation ComponentsSwitch Accessories

Substation ComponentsInstrument Voltage Transformers (VT)

Substation ComponentsInstrument Current Transformers (CT)

Substation ComponentsPower Transformers/Regulators

Substation ComponentsSwitchgear

Substation ComponentsCapacitor Banks

Substation ComponentsReactor

Substation ComponentsLightning/Surge Arresters

Substation ComponentsSVC/Synchronous Condenser

Understanding One Lines

Understanding One LinesEquipment Symbols

Understanding One LinesPhysical Layout

Substation LayoutsBus Configurations – Main-Transfer Bus #1

• Less expensive• 1 line, 1 breaker• Smaller Footprint• Uses transformer protection to

bypass for maintenance• Single point of failure

Substation LayoutsBus Configurations – Main-Transfer Bus #2

• Less expensive• 1 line, 1 breaker, more

switches• Slightly larger footprint than

type 1• Uses bus tie breaker to

bypass for maintenance• Single point of failure, unless

2 bus tie devices are used

Substation LayoutsBus Configurations – Dual Operate Bus

• Transformers can feed either bus

• Common newer distribution bus configuration

• Uses bus tie breaker to bypass for maintenance

Substation LayoutsBus Configurations – Double Breaker Ring Bus

• Most Expensive• Most Reliable• Largest footprint• Both buses are energized• Either bus can fail without

effecting service• Any breaker can be taken out

without effecting service

Substation LayoutsBus Configurations – Breaker-and-a-half Ring Bus

• Balances cost and reliability• Most common configuration

Substation LayoutsBus Configurations

• Each breaker protects two lines/transformers• Single breaker failure results in two lines/transformers

being dropped• Non-standard, unusual design

What is Grounding?Definition

A connection between an electrical conductor and the Earth. Grounds are used to establish a common zero-voltage reference for electric devices in order to prevent potentially dangerous voltages from arising between them and other objects.

Why is Grounding Needed?IEEE 80

Primary Objectives To provide means to carry electric currents into the earth

under normal and fault conditions without exceeding any operating and equipment limits or adversely affecting continuity of service.

To assure that a person in the vicinity of grounded facilities is not exposed to the danger of critical electric shock

Why is Grounding Needed?Equipment Protection

• Discharge currents

• Fast relay pickup• Create Earth

Reference• Fault Conditions

Equipment

Why is Grounding Needed?Safety

Safety

Lower grounding resistance

Provide equipotential

surfaces

Safety Goals

Safety GoalsTouch Potential

Minimum 4’ from grounded structure

Only applies to grounded structures within outer-most loop


30KΩ

29µA.01Ω .01Ω .01Ω .00333Ω

3.052Ω

15.42V

14,131V 500KΩ


TABLE I-1-AC PROOF-TEST REQUIREMENTS

Class of EquipmentProof-testVoltagerms V

Maximum proof-test current, mA(gloves only)

280-mm(11-in)glove

360-mm(14-in)glove

410-mm(16-in)glove

460-mm(18-in)glove

00 ............................................0 ..............................................1 ..............................................2 ..............................................3 ..............................................4 ..............................................

2,5005,00010,00020,00030,00040,000

88................................................................................................................

1212141618............................

............................1416182022

............................1618202224

Safety GoalsStep Potential

Extends beyond substation ground grid

Analyzed without the added safety of yard rock

Safety GoalsRecommended Actions

Remain calm Shuffle feet Keep hands

down Exit the facility

as quickly as possible

Factors that Affect GroundingResistivity Study – Wenner Method

Uniform Pin Spacing Preferred for the use

of short electrodes Typically used in the

power industry Input data for soil

model

Factors that Affect GroundingSoil Resistivity

Factors that Affect GroundingGrounding Area and Geometry

Factors that Affect GroundingFault Current – Aspen Model

Factors that Affect GroundingClearing Time

Factors that Affect GroundingSurface Material

3,000 Ohm-m 10,000 Ohm-m

Design ProcessResistivity Study – Validation

Design ProcessSoil Model

10-1 100 101 102 103 104

Inter-Electrode Spacing (feet)

100

101

102

103

App

aren

t Res

istiv

ity (O

hm-m

eter

s)

LEGEND

Measured Data Computed Results Curve Soil Model

Measurement Method..: Wenner RMS error...........: 2.704%

Layer Resistivity Thickness Number (Ohm-m) (Feet ) ====== ============== ============== Air Infinite Infinite 2 290.9859 1.102360 3 14.93528 11.03615 4 38.59013 24.21364 5 6.382704 35.70055 6 20.85475 Infinite

British/Logarithmic X and Y

RESAP <Snow Goose Aver >

Design ProcessSplit Factor

Design ProcessCurrent Splits

IEEE 80 -> Reduction of grid current through shield wires and distribution neutrals

Anywhere Substation:Available fault current: 6645A# distribution lines: 3# transmission line shields: 0Split Factor per IEEE 80: 0.614Analyzed fault current: 4800A

Split Factor per IEEE 80: = += 2.19 + 0.39= 1.17

SF = 0.614

Design ProcessCompany Standards

Standard Grid 18” depth 50’ spacing

Peripheral Grounds Ground rod size and spacing 4” Yard Finish Rock

Design ProcessCustom Ground Grid Design

16’ ground rods Angled ground rods Grounding wells 24” grid depth Counter Poise Asphalt

Questions?

?

Distribution System Protection Overview

Timothy Day Sr. Application Engineer

Eaton Corp.

1© 2015 Eaton. All Rights Reserved..

RMEL 2017 Distribution Engineers WorkshopSystem Protection

Timothy Day, Sr. Applications Engineer OCT


Learning Objectives• Identify basic distribution overcurrent devices.• Appreciate overcurrent protection philosophies.• Estimate maximum and minimum fault current magnitude.• Differentiate between tolerable and intolerable overcurrent

levels.• Quantify the effects of transformer impedance upon maximum

fault current magnitude.• Determine the impact of device placement on

reliability indices.


Basic Objectives of Distribution System Overcurrent Protection

• Prevent / Minimize damage to equipment;

• Prevent hazards to the public;

• Maintain high level of service continuity.


Meet Basic Objectives by utilizing:

• Construction practices;

• Planning;

• Protective Devices.

Our Focus: Protective Devices.


Causes and Nature of Faults on Overhead Power Systems

Causes Nature


Basic Rules of Coordination based upon

• high percentage of temporary faults,

• the objective to maintain high service continuity.

For Permanent Faults: Isolate (sectionalize) only the smallestportion of the system containing the faulted segment.

For Temporary Faults: Give all faults a chance to be temporary by performing automatic reclosing (where momentary outages are tolerated).


Basic Equipment for Distribution Protection

Fuses (ANSI C37.40)

Typical Ratings:Applied Voltage: 15 - 38kVCont. current < 200AInterrupting current: 10kA

Typical Ratings:8.3 - 23kV< 100A50kA

Typical Ratings:8.3 - 23kV< 140A< 3.5kA

Expulsion Current Limiting



Reclosers (ANSI C37.60)

Typical Ratings:15 - 38kV400 - 630A8 – 12.5 kA



Breakers (ANSI C37.100) with relays

Typical Ratings:15 - 38kV1200A25 - 40kA



Sectionalizers (ANSI C37.63)

Typical Ratings:15 - 38kV100 - 200A0 kA


System Quantities

• Proper Over Current Protection depends upon proper understanding of the power system’s parameters.• Fault Currents: operate

• Load Currents: restrain


Portion of Example Radial Feeder

Fuse

Fuse

25A

37.5 kVA 3% Z

If,69kV = 11.9 kA sym 69 / 12.47 kV15 MVA; 6.5% Z

5270

6050220

6650 240

RE

Fuse

Electronically controlled

Recloser9640240

7250220

5880


Quantifying Current Magnitudes

• Protective devices will be exposed to various overcurrent conditions • High magnitude, short duration fault currents limited only

by the equivalent system impedance.

• Minimum magnitude, longer duration fault currents limited mostly by conductor-ground contact resistance at the end of the device’s intended zone of protection

• Moderate magnitude, indefinite-duration load currents.


Fault Current Calculations

• Protective devices interrupt high fault currents (significant electro-mechanical forces).

• Proper equipment application assumes a reliable estimation of the greatest fault current available.



• Many software tools available to assist in short-circuit analysis

• Symmetrical Components theory is often utilized• Permits analysis of severe unbalances on a

3-phase power system with “balanced” assumptions.


Transformers

• Inherent impedance (of the transformer) will limit available fault current levels.

• Overcurrent protection devices are often located close to transformers.

• Variations in primary versus secondary current• Turns ratio

• Delta – Gnd Wye Windings and Fault Types


Transformers: Maximum Fault Current

15 MVA, Z = 6.5%



15 MVA, Z = 6.5%

• Maximum Fault assumes the source is infinite.

• Only the transformer impedance limits fault current.



15 MVA, Z = 6.5%

= = = ∅ . = %%= ps ×



15 MVA, Z = 6.5%

= ∅ = = . = %% = %. % = . = ps ×



15 MVA, Z = 6.5%

= . = . = ps × . =

10,684 Amps



Fuse

Fuse

25A

37.5 kVA 3% Z

If,69kV = 11.9 kA sym 69 / 12.47 kV15 MVA; 6.5% Z

5270

6050220

6650 240

RE

Fuse

Electronically controlled

Recloser9640240

7250220

5880



• On radial distribution feeders, the magnitude of fault currents is a function of• Distance

• Conductor type

• Fault resistance

• Fault type

• System strength

0 1 2 3 4 5 6 7 8 9 100

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

Ava

ilabl

e Fa

ult C

urre

nt (A

mps

)

Distance from Substation (miles)



Equivalent voltage source and source impedance.

Reactance of power transformer.

Impedance of distribution line segments.

RE


Device Inverse Time – Current Characteristics

• Inverse current-distance relationship lead to applying protective devices that exhibit inverse time – current characteristics

• Optimal for device-device coordination.

• The time-current characteristic (TCC) plot displays a protective device’s relationship of response time to fault current.


Example Device Inverse Time – Current Characteristics

The current vs. time data always assume a constant current magnitude during the time needed to evoke a protective response.


R

R

R

1000A03-Phase Fault Solution

69 kV 12.47 kV

1000A120

1000A-120

104A120

104A0

3 104A = 181A

System Ratio (N) = 69 / 12.47 = 5.53

3 104A = 181A

3 104A = 181A

104A-120

Transformers

Windings Turn Ratio = 69 / 7.2 = 9.58


181 104 1.0

3 Phase Fault

181-150A

181-30A

18190A

1000-120A

10000A

1000120A

104120A

SystemVoltageRatio(N)= . = 5.53WindingTurnsRatio= . = 9.5869kV : 12.47 kV


Phase – Ground Fault

Faster ?? Slower104 104 1.73

104180A

1040A10000A

SystemVoltageRatio(N)= . = 5.53WindingTurnsRatio= . = 9.5869kV : 12.47 kV

0A

0A

181 104 1.0


Phase – Phase Fault

208 104 Faster ?? Slower 0.87

1040A1000A

1000180A

0A

104180A1040A

208180A

Faster ?? Slower104 104 1.73

181 104 1.0

SystemVoltageRatio(N)= . = 5.53WindingTurns Ratio = . = 9.5869kV : 12.47 kV


208 104 0.87

104 104 1.73

181 104 1.0

SystemVoltageRatio(N)= . = 5.53WindingTurns Ratio = . = 9.5869kV : 12.47 kV

Observations:

> 1 sec.< 1 sec.


Phase Current, Iphase

• All fault types result in current flow in the phase conductor(s).

• Typically referred to as phase current.

• Phase current can cause a fuse to melt, recloser to trip, etc.

IA

IB

IC LOA

D

SOU

RC

E


Signal Processing Basics: Example – raw samples

FaultPre-fault Fault clear

timeAm

ps

• Power System frequency (fundamental) = 60 cyc/sec.

• Current waveform sampled 16x per cycle

• Sampling Frequency = 60 cyc/sec x 16 smp/cy = 960 smp/sec

• Nyquist Frequency = folding frequency = ½ Sampling Freq = 480 Hz.


Signal Processing Basics: Example

Nyquist, folding

frequency

Freq.

Mag

nitu

de

• Folding Frequency = 480 Hz = ½ Sampling Frequency

• Any energy present at 900 Hz will fold into the 60 Hz bin. A front-end analog low-pass filter is necessary to remove.

• All other harmonic signals are removed by digital processing, i.e., they don’t appear in the 60 Hz bin.

60 120

180

240

300

360

420

480

540

600

660

720

780

840

900

960


Signal Processing Basics: Digital Filtering16-point, fundamental frequency, filter

scaleadd all points

Delay all points

Multiply coefficients from cosine




timeAm

ps

• Filtered waveform contains only fundamental energy

Filtered waveform samples

Filtered

Unfiltered


Signal Processing Basics: Digital FilteringOrthogonal points (1/4 cycle separation) to phasor data

scaleadd all points


Delay all points

Phasor data, Re + j Imag,from ¼ cycle separated samples. Include scale.

+ real

+ imaginary


Signal Processing Basics: Digital FilteringOrthogonal points (1/4 cycle separation) to phasor data

scale

Convert phasor to magnitude


Delay all points

Phasor data, Re + j Imag,from ¼ cycle separated samples. Include scale.

+ real

+ imaginary




timeAm

ps

Magnitude of fundamental current

Filtered

Unfiltered

Am

ps


Phase Current, Iphase

• Some devices monitor all three phase currents• e.g., 3-Phase Recloser

• For protection purposes

Phase Current = MAX(|IA|, |IB|, |IC|)

(current magnitudes are RMS values).magnitude


Ground Current, IG

• Ground fault result in current flow in the phase conductors and in the neutral/earth return path.

• Fault Resistance may yield low fault current levels.

• Fault detection using I-Phase is difficult since load and fault levels may be similar.


Phase Current versus Ground Current

• Protection is improved with Ground Fault Sensing.

• All three phase must be monitored.

• The unbalance must involve the ground path.

Ground Current = |IA + IB + IC|

(currents are complex-valued phasors) Ground Current = IGGround Current = 3 I0

• Ground fault sensing devices today almost universally use IG versus I0



Phasor Plot of Balanced Phase Currents and Ground Current Calculation

Example|IA| |IB| |IC| 300A



Phasor Plot of Unbalanced Phase Currents and Ground Current Calculation



• Short circuits (faults) result in excessive current flow.

• The fault type determines how this current flows into various conductors and possibly ground.


Minimum Ground Fault Sensitivity• Calculations with a fault resistance value, or utility experience,

determine required sensitivity for reliable ground fault protection.

IA

IB

IC LOA

D

SOU

RC

E

40 fault resistanceassumed

12.47 kV L-L

= 12470340 = 180


Maximum Ground Fault Sensitivity• Ground fault settings must be great enough to prevent false

trip on significant load imbalance.

IC

IB = 360-120 A

SOU

RC

E

12.47 kV L-LIA = 3400 A

200120 A

R100120 A

= |IA + IB + IC| = | 3400 + 360-120 + 200120 |= | 340 + j0 – 180 – j312 – 100 + j173 |= | (340 – 180 – 100) + j(0 – 312 + 173) |= | 60 – j139 | = 151A


Ground Fault Setting• Ground setting must detect ground fault and ignore load imbalance.

151 < < 180


Load Current

• Effects thermal capability of equipment.

• Determines lower limits of protective device sensitivity.

• Vary over daily, season cycles


0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 240

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

HOURS

LO

AD

, P

U P

ea

k

MAX 15 MIN. DEMAND

AVERAGE

Example Load Current Variation


Load Current

• Load-growth must also be considered and properly estimated.

• Maximum Load conditions present the worst case.


Inrush / Cold Load Current

• Occurs after energizing a circuit following a power outage

• Results in higher-than-anticipated load current levels.• Causes thermal stress on equipment

• May cause undesired operation of protection equipment


Energization Transients: Hot Load Inrush

• Short duration

• System reaches a new electrical equilibrium after switching

• Current magnitudes many times normal load

• Satisfies the inrush requirements of down line motors, transformers and capacitor banks


Extended outage inrush (cold load inrush)

• Extended-Outage / Cold Load Inrush• Longer duration / lower magnitude.

• Cause by loss of diversity of loads controlled by thermostats.


Inrush and Cold Load Currents

Generally-accepted Current / Time points

– 2 x IFL for 100 seconds



– 12 x IFL for 0.1 seconds

– 25 x IFL for 0.01 seconds

Cold Load Inrush (system)

Hot Load Inrush (transformers, motors, capacitors etc.)


Example Time vs. Inrush Current Plot

0.01

0.1

1

10

100

0 5 10 15 20 25 30

Multiples of Full Load Current

Tim

e (s

econ

ds)


Obtaining Current Magnitudes

• Assumes the practical availability of the needed values thus permitting effective protective device application.

• Current data may appear on one-line diagrams.


Introduction to Reliability

• Reliability is a measure of product quality, be it an automobile or electric service.

• Reliability may be defined as the probability that a product, piece of equipment, or a system performs at its intended level for a stated period of time under specified operating conditions.


Reliability Indices: SAIFI

• System Average Interruption Frequency Index (Sustained Interruptions).

• Ideal SAIFI = 0. Typical SAIFI goal ~1.5 outage events


Reliability Indices: SAIDI

• System Average Interruption Duration Index (Sustained Interruptions).

• Ideal SAIDI = 0. Typical SAIDI goal 1 – 2 outage hours.


Reliability Indices: CAIDI, ASAI

= # = = ( . . )

= # −#

: . ( . . )

: ( )


Reliability Indices: MAIFIE

• A permanent fault causing a recloser to blink the circuit a few times before lockout would not impact MAIFIE.


Reliability: Areas of Investment to Reach Goals

• System Planning – reduce outage duration

• Fault Prevention – reduce outage frequency

• Fault Response – apply overcurrent protective devices to limit the number of customers affected by an event • Permanent Fault. Limit the number of customers affected and

reduce the time necessary to locate a fault. Requires careful device coordination.

• Temporary Fault. Use automatic reclosing to reduce permanent outages. MAIFI (will become worse).


Theoretical Reliability: Ideal Radial Circuit

C customers / mileM miles

Fault Incident Rate = F faults / mile / year. . Avg. Restoration Time =H hours / fault

SOU

RC

E



C customers / mileM miles

Fault Incident Rate = F faults / mile / year. . Avg. Restoration Time =H hours / fault


? QUESTIONS ?

Standards and Applications of Distribution System Protection

Aaron Magnuson Engineer 1

Kansas City Power and Light


Examples and standard practices utilized by KCP&L

KCPL Breaker Settings

• TCC Curve Utilized for breaker settings • Fast Ground curve turned off during

storms to prevent nuisance tripping• TCC Curve turned off during

maintenance

GMO Breaker Settings

• TCC Curve utilized for breaker settings• Set to instantaneous trip during

maintenance.

KCPL Fuse Standards

• 102 Positrol Coordinating fuse are generally used on each lateral

• All other fuses are Positrol Standard speed

• Risers, laterals off of the backbone feeder, and long taps off of laterals

KCPL Recloser Standards

• No Metro Reclosers• Mid-span reclosers on Long Rural Lines

KCPL Underground• Enclosures every 500ft. • Switchgears are utilized when a

customer has two potential sources (Throw-over Scheme)

• Switchgears should be fused to coordinate with the upstream device

GMO Fuse Standards• K Speed, and Standard Speed Power

Fuses(SM and SMU)• Fuse all laterals that come off the

backbone• Risers, as well as long taps off a lateral

should be fused

GMO Backbone Reclosers

• Three Phase lines that continue past city limits for at least 2 miles

GMO Lateral Reclosers

• Applied on laterals longer than two miles with at least 5 customers per mile

• Applied on Laterals with critical loads

GMO Substation Recloser Curves

• Reclosers at substations with 5MVA or more should typically have 4 “B” curves (all delayed)

• Reclosers at Rural substations with less than 5MVA may utilize “A” or fast/fuse save curves

GMO Line Recloser Curves

• Reclosers in metro areas typically do not utilize “A” curves (fuse save)

• Reclosers in Rural areas typically have 2A-2B, or 1A-3B operating sequences

Trip Saver 2

• Phase overcurrent protection device• Utilized on worst performing laterals

Coordination Challenges

• Low Fault Current• High Fault Current• Cold Load Pickup

Metro KCPL Example

• High Fault Current

Slide 1

Rural GMO Example

• Long rural circuit with over 50 miles of exposed overhead

• Low fault current• Cold load pickup concern

Questions?


Timothy Day Sr. Application Engineer

Eaton Corp.

1© 2013 Eaton. All rights reserved.

RMEL 2017 Distribution Engineers WorkshopCoordinating Reclosers and Fuses

Timothy Day, Sr. Applications Engineer, EATONAaron Magnuson, Kansas City Power & Light OCT


Two Categories of Fuses

Expulsion fuses• Expel hot gasses and

particles• “Zero awaiting devices”• Await passing zero point to

clear fault

Current-limiting fuses• Self-contained operation within

housing• “Zero forcing devices”• Force zero point early and limit

current


All Fuses

• “Monitor” current and prevent excessive current • Have maximum continuous load current ratings• Have maximum fault current interrupting ratings• Have maximum operating voltage ratings• Have fusible element• Have factors important to proper operation

• melting time, arcing time, clearing time, time/current characteristics, and characteristics of other devices on line.


Expulsion Fuses

• Zero Awaiting Devices• Clear the fault at current zero only.

• Economical• High Volumes; most common are fuse links• Used in open cutouts or in transformers


Expulsion Fuse Links


EXP. FUSE TIME CURRENT CHARACTERISTIC (TCC) CURVE

• Fix test current.• Measure average melting

and arcing time.• Subtract from avg. melt

point 10% on the current axis = Minimum Melt.

• Add to avg. melt point 10% on the current axis, then add arcing time = Maximum Clear.

• Repeat at other test currents.


Universal Fuse Links with ‘K’ and ‘T’ ratings• Per ANSI C37.42• Defines 3 points on TCC

• 300/600 second• 10 second• 0.1 second

• Only K and T links are electrically interchangeable

Expulsion Fuse Rating System


• Different curve shapes for common expulsion fuse links:• N Link• K Link• T Link• S Link

Expulsion Fuse TCC Variations


Expulsion Fuse Operation• Excess current heats fusible

element to melting point.• Molten particles begin arcing. • 2000 °C arc causes fiber walls

(holder tube) to release deionizing gasses.

• Gassing creates supersonic flow stretching and cooling the arc.

• Arc extinguished at current zero.• Dielectric build-up prevents arc re-strike.


Expulsion Fuse Operation

Fusemelting

Fusearcing

Fuse clearing

NormalSystemVoltage

Pre-fault load

Fault starts

Fault clears at current zero

Cur

rent

Thr

ough

Fus

eV

olta

ge A

cros

s Fu

se

time (msec.)


Expulsion Fuses: Zero-Awaiting Devices

• Extinguish arc after zero point• Have limited maximum interrupting currents• DO NOT limit available fault energy• DO NOT reduce peak let-thru currents• If unable to clear, will arc until upstream

device opens


Expulsion Fuse Classification

• Two ANSI Classifications• Power Fuse; C37.46

• Applied in / close to substations• 2.8 to 169 kV• Tested at High X/R ratios (15 to 25)

• Distribution Fuse; C37.47• Applied on distribution feeders• 2.8 to 38 kV• Tested at lower X/R ratios (8 to 15)


The X/R Ratio

Equivalent Single-Phase Diagram of a Faulted Distribution Feeder.

The circuit equation resulting from the above diagram yields a differential equation.

X = 260 L


Fuse TCC Tolerance

The following factors will have an effect on proper fuse operation:

• Ambient Temperature• Pre-loading• Pre-damage


Fuse TCC ToleranceAmbient Temperature Effects

• Fuse TCCs are developed based on 25ºC ambient temperature

• Above ambient temperatures reduce fuse melting time

• Below ambient temperature increases the melting time


Fuse TCC Tolerance

Pre-loading• Fuse TCCs developed assuming no pre-fault load

current• Current flow through the fuse before fault initiation

• raises the fuse’s temperature • reduces the melting time


Fuse TCC Tolerance

Pre-damage Effect• Fuses may be damaged by currents approaching

the minimum melt TCC• May change the fuse characteristic significantly

• Can occur for currents at:• 90% of the minimum melt time of tin fuse

• 95% of the minimum melt time of silver fuse


Accounting for Fuse TCC Tolerance• Employ techniques to account for:

• Ambient temperature• Pre-loading• Pre-damage

• Ensures that the fuse will always coordinate with other overcurrent protective devices.

• 75% Rule: Expulsion Fuse – Expulsion Fuse• K-factor: Expulsion Fuse – Recloser


NXC: Direct connect; Capacitor

ELSP fuse; under-oil, clip mount

Companion X-Limiter; S&C SM-20 Cutout

X-Limiter; direct connect

ELF: cutout mount (HX or interchangeable)

Bayonet mount

Tandem

Introduction: Current-Limiting (CL) Fuses


• A "zero forcing" device• Large impedance limits current to lower value &

"forces" current zero.• Limits damaging energy associated with a fault.• Quiet operation.• High interrupting ratings: 50 kA.• Higher $

Current-Limiting Fuses


Expulsion vs. Current-Limiting

Test parameters: 6400 A RMS symmetrical.Test results: Expulsion Let-Through Energy 9 x more than ELF’s

Expulsion Fuse

ELF Fuse


Current-Limiting Fuse Construction

Conductive silver ribbon element Low current element (full-range model)

Sand

Conductive ribbon element surrounded by fine granular silica sand, housed in an insulating tube.


Current-Limiting Fuse Operation

• Under fault current conditions, ribbon element quickly melts and vaporizes along its entire length - molten matter is blown into the surrounding sand

• Sand melts around the arc forming a glass-like fulgurite. • Fulgurite quickly increases the resistance of the fuse.• High resistance changes the power factor to near unity

causes a premature current crossing.

Sand(before)

Fulgurite(after)


Current-Limiting Fuse Operation


Fusemelting

Fusetransition

Normal System Voltage

Pre-fault load

Fault startsEarly current zeroFault cleared

Cur

rent

Thr

ough

Fus

eV

olta

ge A

cros

s Fu

se

time (msec.)

Current-Limiting Fuse OperationAvailable Fault Current Peak

Peak Arc Voltage

Current limited Peak


CL Fuse Energy Let-Through, I2T

341,133 A2Seconds(20 A K-link expulsion)

11,770 A2Seconds(20 A ELF Current Limiting)

Max

imum

Let

-Thr

ough

Cur

rent

(Pea

k ki

loA

mpe

res)


CL Fuse Classification

• Back-upInterrupts currents from maximum rated down to minimum rated interrupting current

• Full rangeInterrupts all currents from maximum rated down to current that causes melting of fusible element


Backup CL

30A ELSP


Full-Range CL

30A ELSP

30A ELF


Expulsion

30A ELSP

30A ELF

30A T


Auto Circuit Reclosers

• Opens under fault conditions• Selectable response parameters• Fast and delayed response for fuse-saving• May include ground-fault response

• Automatically re-closes• Allows faults a chance to be temporary• Improves reliability• Selectable reclose operations• Lock-out to de-energize the circuit for permanent faults.

• Hydraulically or Electronically controlled


Recloser’s Basic Characteristics

1st Open Interval

2nd Open Interval

3rd Open Interval

Fast Curve Operation

Fast Curve Operation

Delayed Curve Operation

Delayed Curve Operation

Pre-fault Lockout

• Typical multi-shot trip/reclose sequence• Two fast trips: A-curve• Followed by two delayed trip: B, C or D• Example: 2A-2C sequence

50A Type L


Recloser Control: Hydraulic

• Published curves: CLEAR• Min. Trip current threshold fixed by

internal coil size• Open interval time fixed by hydraulics• Delayed curve fixed by hydraulics• Operation sequence fixed by

hydraulics

50A Type L

Min. Trip


Recloser Control: Electronic

Difference is recloser’s

interrupting time

• Curves identified by Numbers vs. Letters• Published curves: RESPONSE• CLEAR curves created by including

recloser’s interrupting time• Min. Trip current programmable• Open interval time programmable• Delayed curve programmable• Operation sequence programmable

Min. Trip


– Recloser must complete its multi trip / reclose sequence without fuse damage due to cumulative heating effects

– Care needed to account for intervening power transformer

– Device pair is critical yet not frequent– Not covered here

Coordinating Source-Side Fuse with Recloser


– Recloser must complete its fast operations without cumulative damage to fuse

– Recloser’s delayed operations should ensure positive fuse blowing before Lockout

– Device pair encountered frequently

Coordinating Recloser with Load-Side Fuse


RSource Load


– K-factor method used to verify coordination– Provides convenient, graphical solution– Factors are applied to the recloser’s FAST curve to ensure fuse-saving– Fuse must melt before recloser’s DELAYED curve to ensure lockout

coordination


1801575

L, 100Amp2A, 2C

40T

1500A Max Coord Current



• Recloser with Ground Trip Enabled• Follow same coordination process• Evaluate 2 new curves:

Recloser’s Ground Fast and Ground Delayed• Beware of possible encroachment

• Recloser will respond differently for ground faults.• Fuse responds the same regardless of fault type.



• Example• Choose the Ground Fast and

Ground Delayed curves• Use K-Factor = 1.35

1801750

50T

PHS: 400A, (2)#103, (2)#133GND: 200A, # ?, # ?

Coordinating Recloser and Ground Trip with Load-Side Fuse

240


1650A Max Coord Current


1801750

50T

PHS: 400A, (2)#103, (2)#133GND: 200A, # ?, # ?

240


1925A Max Coord Current:Improvement when faults involve ground

Take care to avoid ground curve encroachment here


1801750

50T

PHS: 400A, (2)#103, (2)#133GND: 200A, (2)#104, (2)#140

240


? QUESTIONS ?

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