Differences In Ansi-ieee And Iec Short Circuit Calculations And Their Implications

Institute of Integrated Electrical Engineers of the Philippines, Inc. 41 Monte de Piedad St., Cubao, Quezon City

A Technical Report on

Differences in ANSI/IEEE and IEC Short Circuit Calculations and Their Implications

___________________________________________________________________

Prepared by: Institute of Integrated Electrical Engineers, Inc. (IIEE) – Standards Committee 2011

Differences in ANSI/IEEE and IEC Short Circuit Calculations and Their Implications

Prepared by: IIEE Standards Committee March 19, 2011

i

Disclaimer It is not the intention of this paper to endorse over another the compared short-circuit calculations and standards. All discussions in this report are based on the featured system one line diagram only. The same parameters were considered for the American National Standards Institute/Institute of Electrical and Electronics Engineers (ANSI/IEEE) and the International Electro-technical Commission (IEC) calculations for result comparison. The values of these parameters, however, may vary from every project in terms of available utility short circuit levels, power system configuration, wiring method and all applicable factors to consider. IIEE and this Committee will not be responsible for any disputes that may arise out of referencing from this paper.

ii

Preface This technical report focuses on two of the most widely used short circuit calculation methods and standards/guidelines namely: American National Standards Institute/Institute of Electrical and Electronics Engineers (ANSI/C37/IEEE std 551) and the International Electrotechnical Commission (IEC 60909). To fully understand the analytical techniques of short circuit current analysis in industrial and commercial power system using both methods, a representative network model was exemplified and a comprehensive comparison between the two calculation methods was presented. For expediency, a short circuit calculating software was employed and the results were presented and evaluated at the end of the analysis. This technical report provides information and inculcates awareness to electrical practitioners in the country on the difference in the procedure of short circuit calculations and its implication between the standards cited. It is not intended to show the detailed short circuit current calculation for both methods. The reader is still recommended to consult technical books for reference on a complete and accurate calculation procedure. This paper starts off with a brief introduction on the current scenario in the Philippines and the importance of short circuit calculation in Chapter I and expounds on its basic principle in Chapter II. The equivalent short circuit schematic diagram is also available for analysis in simple calculation. Chapter III discusses the asymmetry current application focusing on the importance of determining the total available short circuit current in the design of electrical equipment such as circuit breakers, switches, transformers and fuses that are subjected to fault current. Chapter IV shows the different components in determining the short circuit calculation based on the two standard/guidelines, the ANSI/IEEE and the IEC. This is followed by Chapter V presenting the comparative matrix on both standards’ Calculation Method and Multiplying Factors with reference to the X/R ratio. Chapter VI clearly tabulates a comparison between the standards’ parameters particularly the device type, device capability and the calculated short circuit duty. In Chapter VII, an illustration of a sample network was configured consisting of two power transformers connected to a 13.2 kV bus wherein two different results from the ANSI/IEEE and IEC calculations were generated with the aid of short circuit calculating software. Chapter VIII presents the protective devices selection and evaluation focusing on the X/R ratio for breaker evaluation and on the short circuit test parameters while Chapter IX discusses the findings and results of the ETAP Total Bus Fault Short Circuit Study. The tables on the short circuit calculation clearly show the difference in values for the same parameters between ANSI/IEEE and IEC. This technical report was developed through the initiative of the IIEE Standards Committee. Any concern or contention as to its applicability, accuracy and completeness shall be addressed to the Institute of Integrated Electrical Engineers of the Philippines, Inc. for further validation and interpretation.

iii

Participants The following are the working group members of the Institute of Integrated Electrical Engineers of the Philippines, Inc. (IIEE) under the Standards Committee: Chairman: Gem J. Tan Fuji-Haya Audit Inspection and Maintenance Corporation Members: Arjun G. Ansay Technological University of the Philippines – Manila

Jesus C. Santos JC Santos and Associates

Arturo M. Zabala AC-DC-KV and Associates

Marites R. Pangilinan LJ Industrial Fabrication, Inc.

Edwin V. Pangilinan Total Power Box Solution, Inc.

Roderick T. Khu Airnergy and Renewables, Inc.

Frumencio T. Tan Safety Consultant

Samson D. Paden Department of Trade and IndustryBureau of Product Standards

Genesis A. Ramos Department of Energy

Vincent E. Jimenez Delta Power Engineering and Consulting

Gideon S. Tan Yu Eng Kao Electrical Supply and Hardware, Inc.

Wilson T. Yu Standards Committee Member

Jaime S. Jimenez Meralco Advisers: Arthur A. Lopez Private Consultant IIEE former president - year 2000 Willington K.K.C. Tan Columbia Wire and Cable Corporation IIEE former president - year 1990

Approved by the members of the IIEE Board of Governors on March 19, 2011: Armando R. Diaz, President

Virgilio S. Luzares, Region II

Jules S. Alcantara, VP- Internal Affairs

Roselyn C. Rocio, Region IV

Gregorio R. Cayetano, VP- External Affairs

Ronaldo D. Ebrada, Region V

Alex C. Cabugao, VP- Technical Affairs

Marlon T. Marcuelo, Region VI

Ma. Sheila C. Cabaraban, Secretary

Lelanie T. Mirambel, Region VII

Larry C. Cruz, Treasurer

Rey G. Paduganan, Region VIII

Florigo, C. Varona, Auditor

Victorianito E. Teofilo, Region IX

Francis R. Calanio, Region I

Gregorio Y. Guevarra, Immediate former President

iv

Table of Contents Chapter

Title

Page

I.

Introduction

1

II.

Basic Short-Circuit Discussion Figure 1 : Current Model for Asymmetry Figure 2 : Maximum Peak Asymmetrical Short Circuit Current

1 1 2

III.

Asymmetry Current Application

2

IV.

Short-Circuit Current Calculation Standard/Guideline

3

V.

Calculation Comparison Table 1 : Comparison Matrix of ANSI/IEEE and IEC

3 4

VI.

Comparison of Device Duty Rating and Short-Circuit Duty Table 2 : ANSI/IEEE Parameter Table 3 : IEC Parameter Table 4 : ANSI/IEEE vs. IEC Parameter

5 5 5 5

VII.

Sample Calculation using ANSI/IEEE and IEC Figure 3 : Single Line Diagram of the Sample Network Figure 4 : Single Line Diagram to consider IEC SC Result Figure 5 : Single Line Diagram to consider ANSI SC Result Figure 6 : Impedance Diagram for ANSI/IEEE SC Method

6 6 7 16 23

VIII.

Protective Devices Selection and Evaluation Table 5 : Circuit Breakers Short Circuit Breaking Capacity Table 6 : Circuit Breakers Interrupting Capacity

26 26 27

IX.

Findings and Results Table 7 : IEC Short Circuit Calculation Table 8 : ANSI Short Circuit Calculation

27 27 27

X.

Conclusion and Recommendation

28

XI.

References

29

Appendix ABB MCB S200 Technical Features

30

v

I.

Introduction

In the emerging world market place, Electrical Engineers should be familiar with the basic differences between the American National Standards Institute (ANSI) and the International Electro-technical Commission (IEC) with regards to short circuit current calculation procedures. Both the ANSI and the IEC Standards developed these procedures to provide rating for electrical equipment. These two standards are currently being applied by the electrical practitioners in the Philippines and it is important to determine the differences between these standards so that a more logical evaluation and breaker rating selection can be appropriated. IEC procedure requires significantly more detailed modeling of the power system short circuit contribution than ANSI. A short circuit calculation is an important task undertaken by a professional in power systems planning and operation. Circuit breaker and switchgear selection, protection settings and coordination require a comprehensive, detailed and accurate short-circuit calculation. The report focuses on the guidelines found in the following shortcircuit standards: the North American ANSI/IEEE standard and its European counterpart, IEC.

II.

Basic Short Circuit Discussion

To come up with a precise short circuit calculation requires a very complex computation. What is important is that whatever the short circuit calculation method used, it should be compared with the assigned (tested) fault current rating of the protective devices. The final equivalent short circuit schematic diagram is shown below. R

L

i(t)

~

√2 Esin(ωt + Ø)

Figure 1: Current Model for Asymmetry The circuit constitutes a series of resistance, inductance, and a switch connected to an ideal sinusoidal voltage source. The fault is simulated by closing the switch and the magnitude of the rms symmetrical short circuit current, I, is determined by the equation below.

I  where:

E Z

I = short circuit current (rms symmetrical) E = driving voltage (rms) Z = Thevenin’s equivalent system impedance from the fault point back to and including the source or sources of short-circuit currents for the distribution system.

The duration and magnitude of the asymmetrical current depends on the following parameters: a) The X/R ratio of the faulted circuit b) The phase angle of the voltage waveform at the time the short circuit occur 1

The asymmetrical fault current decay time is longer when X/R ratio is greater at the fault point. For specific X/R ratio, the angle of the applied voltage at the time of short-circuits initiation determines the degree of fault current asymmetry that will exist for that X/R ratio. The maximum asymmetrical short-circuit current occurs at the fault inception when the voltage sine wave is at zero point and not necessarily at the highest dc component.

Figure 2: Maximum Peak Asymmetrical Short Circuit Current

III. Asymmetry Current Application From the equipment design and application point of view, the phase with the largest fault peak current should be of major interest. This current subjects the equipment to the most severe magnetic force. The maximum magnetic force produced on a circuit element, such as a breaker, occurs at the instant the fault current through the circuit element is at a maximum. The largest fault peak typically occurs in the first cycle when the initiation of the shortcircuit current is near or coincident with the applied voltage passing through zero. This condition is called the condition of maximum asymmetry. Electrical equipment such as circuit breakers, switches, transformers and fuses that are subjected to carry fault current, the total available short circuit current must be determined. For correct equipment application, knowledge of the minimum test X/R ratio or maximum power factor of the applied fault current used in the acceptance test by ANSI, NEMA, UL and IEC is also required. Knowledge of peak fault current magnitudes are significant for some devices, such as low voltage breakers, while asymmetrical rms current magnitudes are equally significant for high voltage circuit breakers. This leads to the need to develop an X/R ratio dependent short circuit calculation for proper comparison to the equipment being applied. To determine the maximum peak or rms current magnitude that can occur in a circuit, every fault current calculation must consider the symmetrical ac component and the transient dc component of the calculated fault current. When the calculated fault X/R ratio is greater than the equipment X/R ratio, the higher X/R ratio must also be considered when evaluating or selecting the equipment.

2

IV. Short Circuit Calculation Standard / Guideline ANSI C37/IEEE Std. 551 The ANSI/IEEE method calls for determining the momentary network fault impedance which makes it possible to calculate the close and latch rating of the breaker. It also calls for identifying the interrupting network fault impedance which makes it possible to calculate the interrupting duty of the breaker. The interrupting network fault impedance value differs from the momentary network in that the impedance increases from the sub-transient to transient level. The IEEE standard permits the exclusion of 3 phase induction motors below 50 hp and all single phase motors. Hence no reactance adjustment is required for these sizes of motors. For detailed calculation requirements please refer to the applicable standards. IEC60909 The IEC method calls for the adjusted network impedance in calculating the symmetrical three phase fault (I” k) at a voltage higher than the nominal rating by a factor (c). The result is further manipulated to calculate peak current ip which is then compared to the breaker’s making capacity (I cm). Also, further manipulation of the calculated three-phase fault current I”k will result to the interrupting rating requirement that is compared to the selected breaker’s interrupting capacity (Ib). For detailed calculation requirements please refer to the applicable standards.

V.

Calculation Comparison

Table 1 presents a brief comparison of the ANSI/IEEE and IEC with regards to short circuit current calculation method and multiplying factors.

3

Table 1: Comparison of ANSI/IEEE and IEC Standard Calculation Method

ANSI/IEEE North America

IEC Europe Predominant

1. Voltage Source is equivalent to the pre-fault voltage at the location

4. Bolted Fault is assumed hence arc resistance is neglected

1. Pre-fault voltage is automatically adjusted by a factor ( c ) 2. Machines are represented by their internal impedances 3. Line capacitance of transmission lines and static loads are considered for unbalanced ground faults following a Shunt Admittance Model 4. System impedances are assumed balanced 3-phase 5. Uses symmetrical components for unbalanced fault calculations

5. System impedances are assumed balanced 3-phase

6. (I”k) Initial RMS Symmetrical SCC calculates through adjusted impedance network of synchronous

2. Machines are represented by their internal impedances 3. Line capacitance and static loads are neglected

machine Zk

6. Uses symmetrical components for unbalanced fault calculations

7. (ip) Peak Short circuit current =

7. Momentary calculates through sub-transient impedance network at half cycle

8. (Ib) Symmetrical Short-Circuit

8. Interrupting calculates through transient impedance network at 1.5 – 4 cycles 9. Steady-State calculates through steady-state impedance network at and beyond 30 cycles

k1*sqrt 2* I”k where k is determined by Method A, B or C Breaking Current = I”k for near generator faults and = u*I”k for synch machines = u*q*I”k for asynch. machines 9. Asymmetrical SC Breaking Current = I”k + Idc component current 10.Steady State SC current (Ik) accounts for power grid, generator and synch machine contributions (ip) Peak Short circuit current = k1*sqrt. 2 * I”k

Multiplying Factors

1. MF(m) Momentary multiplying factor – I mom. rms asym = I mom. rms sym * MF(m) 2. MF(p) Peak multiplying factor – I mom. peak = I mom. rms. Sym * MF(p) 4

1. C – pre-fault voltage factor (taken from IEC) 2. k – factors determined by IEC method A, B or C

VI. Comparison of Device Duty Rating and Short-Circuit Duty The tables below show the different parameters used in evaluating a protective device in terms of calculated short circuit duty of the ANSI/IEEE and IEC Standards. Table 2:

ANSI/IEEE Parameter

DEVICE TYPE HV BUS BRACING LV BUS BRACING HVCB LVCB Table 3:

Asymm. KA rms Symm. KA rms Symm. KA rms Asymm. KA rms C and L Capability KA rms C and L Capability KA Crest Interrupting KA

CALCULATED SHORTCIRCUIT DUTY (Momentary Duty) Asymm. KA rms Symm. KA rms Symm. KA rms Asymm. KA rms Asymm. KA rms Asymm. KA Crest Adjusted KA

Rated Interrupting KA

Adjusted KA

DEVICE CAPABILITY

IEC Parameter

DEVICE TYPE

CALCULATED SHORT-CIRCUIT DUTY (Momentary Duty) ip

DEVICE CAPABILITY Making

MVCB

AC Breaking

Ib ,symm

Making

LVCB Fuse

ip

Breaking

Ib ,symm

Breaking

Ib ,symm

Table 4: The ANSI/IEEE vs. IEC DEVICE TYPE DEVICE CAPABILITY ANSI

IEC

HVCB

MVCB

ANSI

IEC

C and L cap. KA rms

Making (ip)

C and L cap. KA rest

n/a

Interrupting KA

AC breaking (Isc) Ib asymm

CALCULATED SHORT CIRCUIT DUTY ANSI IEC Asymm. KA ip rms Asymm. KA rest Adjusted KA Ib symm Ib asymm

Idc LVCB

LVCB

Rated interrupting KA

Iohm

Ish

Breaking (Ib symm) ICU

Ib symm

Making peak (ICM)

ip

Ib asymm

Ib asymm

Ish

Ish

5

or Ik

VII. Sample Calculation using ANSI/IEEE and IEC Description of Sample network The sample network consists of two power transformers connected to a 13.2 KV bus. One of the transformers feeds a bus at a nominal voltage of 240 V, while the other transformer feeds a bus at a nominal voltage of 2.3 KV. The data of the transformer and other equipment and their principal characteristics are presented in Fig. 3. For the purpose of presenting a discussion on fault calculation, points B l and B2 are selected to have experienced a 3 phase bolted fault.

Figure 3: Single Line Diagram of the Sample Network

6

A. IEC SHORT CIRCUIT RESULT

Figure 4: Single Line Diagram to consider IEC SC Result 7

ETAP 6.0.0C

Project:

Page:

1

Date:

10-19-2010

Contract:

SN:

FUJIHAYAPH

Engineer:

Revision: Base

Location:

Study Case: SC

Filename: sample

Config.: Normal

Electrical Transient Analyzer Program Short-Circuit Analysis IEC 60909 Standard 3-Phase Fault Currents Maximum Short-Circuit Current

Number of Buses:

Number of Branches:

Swing 1

V-Control 0

Load 7

Total 8

XFMR2 2

XFMR3 0

Reactor 0

Line/Cable 0

Synchronous Generator Number of Machines:

0

Power Synchronous Induction Motor Machines Grid 1 0 5

Impedance 0

Tie PD 5

Lumped Load

Total

1

7

System Frequency: 60 Hz Unit System:

English

Project Filename:

sample

Output Filename:

D:\Etap6.0 Projects\SC sample attachments_2010_10_18\Untitled.SI1

8

Total 7

Adjustments Apply Adjustment

Individual /Global

Transformer Impedance:

Yes

Individual

Reactor Impedance:

Yes

Individual

Overload Heater Resistance:

No

Transmission Line Length:

No

Cable Length:

No

Tolerance

Percent

Apply Adjustment

Individual /Global

Degree C

Transformer Resistance:

Yes

Global

20

Cable Resistance:

Yes

Global

20

Temperature Correction

Bus Input Data Bus

Initial Voltage

ID

Type

Nom. kV

Base kV

Sub-sys

%Mag.

Ang.

B1

Load

0.240

0.240

1

100.00

0.00

B2

Load

2.300

2.300

1

100.00

0.00

Bus4

Load

0.240

0.240

1

100.00

0.00

Bus5

Load

2.300

2.300

1

100.00

0.00

Bus6

Load

2.300

2.300

1

100.00

0.00

Bus7

Load

2.300

2.300

1

100.00

0.00

Bus8

Load

2.300

2.300

1

100.00

0.00

UB

SWNG

13.200

13.200

1

100.00

0.00

8 Buses Total All voltages reported by ETAP are in % of bus Nominal kV. Base kV values of buses are calculated and used internally by ETAP

2-Winding Transformer Input Data Transformer

Rating

Z Variation

% Tap Setting

Adjusted

Phase Shift

ID

MVA

Prim. kV

T1

1.500

13.200

0.240

5.75

7.10

0

0

0

0

0

5.7500

Std Pos. Seq.

0.0

T2

5.000

13.200

2.300

7.15

12.14

0

0

0

0

0

7.1500

Std Pos. Seq.

0.0

Sec. kV

%Z

X/R

+5%

-5%

%Tol.

Prim.

Sec.

%Z

Type

Angle

Branch Connections CKT/Branch

Connected Bus ID

% Impedance, Pos. Seq., 100 MVAb

ID

Type

From Bus

To Bus

R

X

Z

T1

2W XFMR

UB

B1

51.58

366.13

369.74

T2

2W XFMR

UB

B2

11.76

142.82

143.31

CB6

Tie Breaker

B1

Bus4

CB7

Tie Breaker

B2

Bus5

CB8

Tie Breaker

B2

Bus6

CB9

Tie Breaker

B2

Bus7

CB10

Tie Breaker

B2

Bus8

9

Y

Power Grid Input Data Power Grid

Connected Bus

ID

ID

MVAsc

kV

U1

UB

720.000

13.200

R

% Impedance 100 MVA Base X"

R/X

0.00014

13.88889

0.00

Rating

Total Connected Power Grids ( = 1 ): 720.000 MVA

Induction Machine Input Data Induction Machine ID

Connected Bus

% Impedance (Motor Base)

Rating

ID

mFact.

Type

Qty

HP/kW

kVA

kV

Amp

PF

R

X"

R/X"

MW/PP

M2

Motor

1

Bus5

500.00

440.28

2.300

110.52

90.82

2.96

15.41

0.19

0.19

M3

Motor

1

Bus6

500.00

440.28

2.300

110.52

90.82

2.96

15.41

0.19

0.19

M4

Motor

1

Bus7

500.00

440.28

2.300

110.52

90.82

2.96

15.41

0.19

0.19

M5

Motor

1

Bus8

500.00

440.28

2.300

110.52

90.82

2.96

15.41

0.19

0.19

M1

Motor

1

Bus4

125.00

110.12

0.240

264.91

91.51

4.62

16.01

0.29

0.05

Total Connected Induction Machines ( = 5 ): 1871.3 kVA

Lumped Load Input Data Lumped Load Lumped Load

Connected Bus

Motor Loads Rating

ID

ID

kVA

kV

L1

B1

1000.0

0.240

% Load Amp

% PF

MTR

2405.63

85.00

60

Total Connected Lumped Loads ( = 1 ): 1000.0 kVA

10

% Impedance Machine Base

Loading

STAT 40

m Fact.

kW

kvar

R

X"

R/X"

MW/PP

510.0

316.1

6.46

15.37

0.42

0.51

SHORT - CIRCUIT REPORT B1

3-Phase fault at bus: Nomimal kV Voltage c Factor Peak Value Steady State

= = = =

0.240 1.10 181.348 68.754

(Maximum If) kA Method A kA rms

Contribution From Bus

To Bus

ID

ID

B1

Total

%V From Bus 0.00

UB

B1

Voltage and Initial Symmetrical Current (rms) kA kA X/R kA Real

Imaginary

Ratio

Magnitude

13.406

-78.631

5.9

79.766

96.12

9.232

-68.170

7.4

68.792

L1

B1

100.00

3.690

-8.782

2.4

9.526

M1

Bus4

100.00

0.485

-1.680

3.5

1.748

Bus4

B1

0.00

0.485

-1.680

3.5

1.748

Breaking and DC Fault Current (kA) Based on Total Bus Fault Current TD (S)

Ib sym

Ib asym

Idc

0.01

78.916

101.347

63.588

0.02

78.315

86.941

37.756

0.03

77.529

80.547

21.843

0.04

76.761

77.794

12.637

0.05

76.017

76.406

7.704

0.06

75.656

75.79

4.504

0.07

75.301

75.347

2.633

0.08

74.952

74.968

1.539

0.09

74.610

74.616

0.939

0.10

74.275

74.277

0.551

0.15

73.582

73.582

0.039

0.20

72.918

72.918

0.003

0.25

72.285

72.285

0.000

0.30

72.260

72.260

0.000

11

3-Phase fault at bus:

B2

Nomimal kV

= 2.300

Voltage c Factor

= 1.10

(Maximum If)

Peak Value

= 51.136

kA Method A

Steady State

= 17.417

kA rms

Contribution

Voltage and Initial Symmetrical Current (rms)

From Bus ID

To Bus ID

%V From Bus

kA Real

kA Imaginary

X/R Ratio

kA Magnitude

B2

Total

0.00

1.882

-20.420

10.9

20.506

UB

B2

90.44

1.297

-17.377

13.4

17.425

M5

Bus8

100.00

0.146

-0.761

5.2

0.775

M4

Bus7

100.00

0.146

-0.761

5.2

0.775

M3

Bus6

100.00

0.146

-0.761

5.2

0.775

M2

Bus5

100.00

0.146

-0.761

5.2

0.775

Bus5

B2

0.00

0.146

-0.761

5.2

0.775

Bus6

B2

0.00

0.146

-0.761

5.2

0.775

Bus7

B2

0.00

0.146

-0.761

5.2

0.775

Bus8

B2

0.00

0.146

-0.761

5.2

0.775

Breaking and DC Fault Current (kA) Based on Total Bus Fault Current TD (S)

Ib sym

Ib asym

Idc

0.01

20.014

28.877

20.816

0.02

19.722

25.04

15.429

0.03

19.441

22.464

11.254

0.04

19.174

20.857

8.208

0.05

18.921

19.955

6.342

0.06

18.799

19.373

4.679

0.07

18.681

18.997

3.453

0.08

18.566

18.74

2.548

0.09

18.456

18.564

2.001

0.10

18.349

18.409

1.486

0.15

18.145

18.148

0.336

0.20

17.954

17.954

0.076

0.25

17.775

17.775

0.017

0.30

17.769

17.769

0.004

12

3-Phase fault at bus:

Bus4

Nomimal kV

= 0.240

Voltage c Factor

= 1.10

(Maximum If)

Peak Value

= 181.348

kA Method A

Steady State

= 68.754

kA rms

Contribution

Voltage and Initial Symmetrical Current (rms)

From Bus ID

To Bus ID

%V From Bus

kA Real

kA Imaginary

X/R Ratio

kA Magnitude

Bus4

Total

0.00

13.406

-78.631

5.9

79.766

M1

Bus4

100.00

0.485

-1.680

3.5

1.748

UB

B1

96.12

9.232

-68.170

7.4

68.792

L1

B1

100.00

3.690

-8.782

2.4

9.526

B1

Bus4

0.00

12.921

-76.952

6.0

78.029

Breaking and DC Fault Current (kA) Based on Total Bus Fault Current TD (S)

Ib sym

Ib asym

0.01

78.916

101.347

63.588

0.02

78.315

86.941

37.756

0.03

77.529

80.547

21.843

0.04

76.761

77.794

12.637

0.05

76.017

76.406

7.704

0.06

75.656

75.790

4.504

0.07

75.301

75.347

2.633

0.08

74.952

74.968

1.539

0.09

74.61

74.616

0.939

0.10

74.275

74.277

0.551

0.15

73.582

73.582

0.039

0.20

72.918

72.918

0.003

0.25

72.285

72.285

0.000

0.30

72.26

72.260

0.000

13

Idc

3-Phase fault at bus:

UB

Nomimal kV

= 13.200

Voltage c Factor

= 1.10

(Maximum If)

Peak Value

= 90.256

kA Method A

Steady State

= 31.492

kA rms

Contribution

Voltage and Initial Symmetrical Current (rms)

From Bus ID

To Bus ID

%V From Bus

kA Real

kA Imaginary

X/R Ratio

kA Magnitude

UB

Total

0.00

0.142

-32.117

226.5

32.117

B1

UB

13.64

0.060

-0.167

2.8

0.178

B2

UB

13.86

0.081

-0.458

5.7

0.465

U1

UB

100.00

0.000

-31.492

99999.0

31.492

Breaking and DC Fault Current (kA) Based on Total Bus Fault Current TD (S)

Ib sym

Ib asym

Idc

0.01

32.048

55.226

44.977

0.02

32.004

55.166

44.934

0.03

31.959

54.943

44.692

0.04

31.915

54.723

44.452

0.05

31.874

54.998

44.82

0.06

31.853

54.889

44.701

0.07

31.833

54.781

44.583

0.08

31.814

54.674

44.464

0.09

31.795

55.076

44.971

0.10

31.777

55.024

44.921

0.15

31.74

54.801

44.674

0.20

31.706

54.581

44.427

0.25

31.673

54.362

44.182

0.30

31.672

54.164

43.939

14

Short Circuit Summary Report 3-Phase FaultCurrent

Bus ID B1

Device kV

ID

Type

Device Capacity (kA) Making Peak

Ib sym

Short-Circuit Current (kA)

Ib asym

Idc

I"k

ip

79.766

181.348

Ib sym

Ib asym

Idc

Ik

0.240

B1

Bus

0.240

CB2

CB

220.000

100.000

102.111

79.766

181.348

77.920

83.044

28.718

0.240

CB6

CB

176.000

80.000

80.426

79.766

181.348*

77.219

77.219

17.549

B2

2.300

B2

Bus

20.506

51.136

17.417

Bus4

0.240

Bus4

Bus

79.766

181.348

68.754

0.240

CB6

CB

79.766

181.348*

UB

13.200

UB

Bus

32.117

90.256

176.000

80.000

80.426

68.754

77.219

79.188

31.492

ip is calculated using method A Ib does not include decay of non-terminal faulted induction motors Ik is the maximum steady state fault current Idc is based on X/R from Method C and Ib as specified above LV CB duty determined based on ultimate rating. Total through current is used for device duty. *Indicates a device with calculated duty exceeding the device capability. # Indicates a device with calculated duty exceeding the device marginal limit ( 95 % times device capability)

Short Circuit Summary Report

Device Capacity

3-Phase Short-Circuit Current

Bus ID

Device ID

1thr (kA)

Tkr (sec.)

Ith (kA)

B1

CB2

100.000

1.00

75.613

B1

CB6

65.000

1.00

75.613*

Bus4

CB6

65.000

1.00

75.613*

1thr = Rated short-circuit withstand current Tkr = Rated short-time Ith = thermal equivalent short-time current *Indicates a device with calculated duty exceeding the device capability. # Indicates a device with calculated duty exceeding the device marginal limit ( 95 % times device capability )

15

17.549

B. ANSI SHORT CIRCUIT RESULT

FIGURE 5:

Single Line Diagram to consider ANSI SC Result 16

ETAP

Project: ANSI Calc Total Bus Fault Peak Current

Page:

1

Date:

10-19-2010

Contract:

SN:

FUJIHAYAPH

Engineer:

Revision: Ansi Breaker

6.0.0C

Location:

Study Case: SC

Filename: sample

Config.: Normal

Electrical Transient Analyzer Program Short-Circuit Analysis ANSI Standard 3-Phase Fault Currents

Swing Number of Buses:

Number of Branches:

1

XFMR2 2

V-Control 0

Load 7

XFMR3

Reactor 0

0

Total 8

Line/Cable Impedance 0 0

Synchronous Power Synchronous Induction Generator Grid Motor Machines Number of Machines:

0

1

0

5

Tie PD

Total

5

7

Lumped Load

Total

1

7

System Frequency:

60 Hz

Unit System:

English

Project Filename:

sample

Output Filename:

D:\Etap6.0 Projects\SC sample attachments_2010_10_18\Untitled.SA1

17

Adjustments Apply Adjustment

Individual /Global

Transformer Impedance:

Yes

Individual

Reactor Impedance:

Yes

Individual

Overload Heater Resistance:

No

Transmission Line Length:

No

Cable Length:

No

Tolerance

Percent

Apply Adjustment

Individual /Global

Degree C

Transformer Resistance:

Yes

Global

20

Cable Resistance:

Yes

Global

20

Temperature Correction

Bus Input Data Bus

Initial Voltage

ID

Type

Nom. kV

Base kV

Sub-sys

%Mag.

Ang.

B1

Load

0.240

0.240

1

100.00

0.00

B2

Load

2.300

2.300

1

100.00

0.00

Bus4

Load

0.240

0.240

1

100.00

0.00

Bus5

Load

2.300

2.300

1

100.00

0.00

Bus6

Load

2.300

2.300

1

100.00

0.00

Bus7

Load

2.300

2.300

1

100.00

0.00

Bus8

Load

2.300

2.300

1

100.00

0.00

UB

SWNG

13.200

13.200

1

100.00

0.00

8 Buses Total All voltages reported by ETAP are in % of bus Nominal kV. Base kV values of buses are calculated and used internally by ETAP

2-Winding Transformer Input Data Transformer

Rating

Z Variation

% Tap Setting

Adjusted

Phase Shift

ID

MVA

Prim. kV

T1

1.500

13.200

0.240

5.75

7.10

0

0

0

0

0

5.7500

Std Pos. Seq.

0.0

T2

5.000

13.200

2.300

7.15

12.14

0

0

0

0

0

7.1500

Std Pos. Seq.

0.0

Sec. kV

%Z

X/R

+5%

-5%

%Tol.

Prim.

Sec.

%Z

18

Type

Angle

Branch Connections CKT/Branch

Connected Bus ID

% Impedance, Pos. Seq., 100 MVAb

ID

Type

From Bus

To Bus

R

X

Z

Y

T1

2W XFMR

UB

B1

53.48

379.58

383.33

T2

2W XFMR

UB

B2

11.74

142.52

143.00

CB6

Tie Breaker

B1

Bus4

CB7

Tie Breaker

B2

Bus5

CB8

Tie Breaker

B2

Bus6

CB9

Tie Breaker

B2

Bus7

CB10

Tie Breaker

B2

Bus8

Power Grid Input Data % Impedance 100 MVA Base

Power Grid

Connected Bus

Rating

ID

ID

MVASC

kV

X/R

R

X

U1

UB

720.000

13.200

99999

0.00014

13.88889

Total Connected Power Grids ( = 1 ): 720.000 MVA

Induction Machine Input Data Induction Machine ID

Connected Bus

Rating

% Impedance (Motor Base)

X/R Ratio

Qty

ID

HP/kW

kVA

kV

RPM

M2

1

Bus5

500.00

440.28

2.300

1800

M3

1

Bus6

500.00

440.28

2.300

M4

1

Bus7

500.00

440.28

M5

1

Bus8

500.00

M1

1

Bus4

125.00

X"/R

X'/R

R

X"

X'

10.89

10.89

2.21

24.05

36.08

1800

10.89

10.89

2.21

24.05

36.08

2.300

1800

10.89

10.89

2.21

24.05

36.08

440.28

2.300

1800

10.89

10.89

2.21

24.05

36.08

110.12

0.240

1800

8.71

8.71

2.30

20.00

50.00

Motors

Total Connected Induction Machines ( = 5 ): 1871.3 kVA

Lumped Load Input Data Lumped Load Lumped Load Connected Bus

Motor Loads

Rating

% Load

Loading

X/R Ratio

Static Loads

% Imp. (Machine Base)

Loading

ID

ID

kVA

kV

MTR

STAT

kW

kvar

X"/R

X'/R

R

X"

X'

kW

kvar

L1

B1

1000.0

0.240

60

40

510.00

316.1

2.38

2.38

8.403

20.00

50.00

340.00

210.71

Total Connected Lumped Loads ( = 1 ): 1000.0 kVA

19

SHORT - CIRCUIT REPORT

B1

3-Phase fault at bus:

=

100.00% of nominal bus kV ( 0.240 kV ) 100.00% of base ( 0.240 kV )

Prefault voltage = 0.240 =

Contribution

1/2 Cycle

From Bus

To Bus

%V

kA

kA

Imag.

ID

ID

From Bus

kA Symm.

Real

Imaginary

/Real

Magnitude

B1

Total

0.00

10.893

-67.489

6.2

68.362

UB

B1

96.57

8.165

-60.047

7.4

60.600

L1

B1

100.00

2.577

-6.134

2.4

6.653

M1

Bus4

100.00

0.150

-1.307

8.7

1.316

*Bus4

B1

0.00

0.150

-1.307

8.7

1316

NACD Ratio = 1.00 # Indicates a fault current contribution from a three-winding transformer * Indicates a fault current through a tie circuit breaker If faulted bus is involved in loops formed by protection devices, the short-circuit contribution through these PDs will not be reported

3-Phase fault at bus:

B2

Prefault voltage = 2.300

= =

100.00% of nominal bus kV ( 2.300 kV ) 100.00% of base ( 2.300 kV )

Contribution From Bus

To Bus

ID

ID

B2

Total

1/2 Cycle %V

1.5 to 4 Cycle

kA

kA

Imag.

kA Symm.

From Bus 0.00

Real

Imaginary

/Real

Magnitude

1.368

-17.787

13.0

17.840

kA

kA

Imag.

kA Symm.

Real

Imaginary

/Real

Magnitude

0.00

1.311

-17.177

13.1

17.227

%V From Bus

UB

B2

91.20

1.201

-15.965

13.3

16.010

91.19

1.199

-15.962

13.3

16.007

M5

Bus8

100.00

0.042

-0.456

10.9

0.458

100.00

0.028

-0.304

10.9

0.305

M4

Bus7

100.00

0.042

-0.456

10.9

0.458

100.00

0.028

-0.304

10.9

0.305

M3

Bus6

100.00

0.042

-0.456

10.9

0.458

100.00

0.028

-0.304

10.9

0.305

M2

Bus5

100.00

0.042

-0.456

10.9

0.458

100.00

0.028

-0.304

10.9

0.305

* Bus5

B2

0.00

0.042

-0.456

10.9

0.458

0.00

0.028

-0.304

10.9

0.305

* Bus6

B2

0.00

0.042

-0.456

10.9

0.458

0.00

0.028

-0.304

10.9

0.305

* Bus7

B2

0.00

0.042

-0.456

10.9

0.458

0.00

0.028

-0.304

10.9

0.305

* Bus8

B2

0.00

0.042

-0.456

10.9

0.458

0.00

0.028

-0.304

10.9

0.305

20

NACD Ratio = 1.00 # Indicates a fault current contribution from a three-winding transformer * Indicates a fault current through a tie circuit breaker If faulted bus is involved in loops formed by protection devices, the short-circuit contribution through these PDs will not be reported

3-Phase fault at bus:

B4

Prefault voltage = 0.240

= =

100.00% of nominal bus kV ( 0.240 kV ) 100.00% of base ( 0.240 kV )

From Bus ID Bus4

Contribution To Bus ID Total

%V From Bus 0.00

kA Real 10.893

1/2 Cycle kA Imaginary -67.489

Imag. /Real 6.2

kA Symm. Magnitude 68.362

M1 UB L1

Bus4 B1 B1

100.00 96.57 100.00

0.150 8.165 2.577

-1.307 -60.047 -6.134

8.7 7.4 2.4

1.316 60.6 6.653

*B1

Bus4

0.00

10.743

-66.181

6.2

67.048

NACD Ratio = 1.00 # Indicates a fault current contribution from a three-winding transformer * Indicates a fault current through a tie circuit breaker If faulted bus is involved in loops formed by protection devices, the short-circuit contribution through these PDs will not be reported

3-Phase fault at bus:

UB

Prefault voltage = 13.200

= =

Contribution From Bus

To Bus

ID

100.00% of nominal bus kV ( 13.200 kV ) 100.00% of base ( 13.200 kV ) 1/2 Cycle

1.5 to 4 Cycle kA

kA

Imag.

kA Symm.

Real

Imaginary

/Real

Magnitude

0.00

0.037

-31.742

863.6

31.742

0.128

4.81

0.018

-0.052

2.8

0.055

0.289

6.50

0.018

-0.198

11.0

0.199

31.492

100.00

0.000

-31.492

99999.0

31.492

%V

kA

kA

Imag.

kA Symm.

ID

From Bus

Real

Imaginary

/Real

Magnitude

UB

Total

0.00

0.068

-31.901

470.9

31.901

B1

UB

11.24

0.041

-0.121

2.9

B2

UB

9.44

0.026

-0.288

11.0

U1

UB

100.00

0.000

-31.492

99999.0

%V From Bus

NACD Ratio = 1.00 # Indicates a fault current contribution from a three-winding transformer * Indicates a fault current through a tie circuit breaker If faulted bus is involved in loops formed by protection devices, the short-circuit contribution through these PDs will not be reported

21

Momentary Duty Summary Report 3-Phase Fault Currents: (Prefault Voltage = 100% of the Bus Nominal Voltage

Bus

Device

Momentary Duty

Device Capability

ID

kV

ID

Type

Symm. kA rms

X/R Ratio

M.F.

Asymm kA rms

Asymm. kA Crest

B1

0.240

B1

Bus

68.362

6.9

1.342

91.741

157.859

B2

2.300

B2

Bus

17.840

13.1

1.496

26.68

45.067

Bus4

0.240

Bus4

Bus

68.362

6.9

1.342

91.741

157.859

UB

13.200

UB

Bus

31.901

999.9

1.728

55.139

90.088

Symm kA rms

Asymm. kA rms

Method : IEEE - X/R is calculated from separate R and X networks. Protective device duty is calculated based on total fault current * Indicates a device with momentary duty exceeding the device capability

Interrupting Duty Summary Report 3-Phase Fault Currents:

Bus

(Prefault Voltage = 100% of the Bus Nominal Voltage

Device

Interrupting Duty CPT

ID

kV

B1

0.240

B2

2.300

Bus4

0.240

UB

13.200

ID CB6

CB6

Type Molded Case Molded Case

Test

Rated

Adjusted

Ratio

M.F.

kA rms

kV

PF

Int.

Int.

68.362

6.9

1.070

73.118

0.240

20.00

85.000

85.000

17.227

13.1

68.362

6.9

1.070

73.118

0.240

20.00

85.000

85.000

(Cy)

31.742

X/R

Device Capability Adj. Sym.

99184.7

Method: IEEE - X/R is calculated from separate R and X networks. HV CB interrupting capability is adjusted based on bus nominal voltage Short-Circuit multiplying factor for LV Molded Case and Insulated Case Circuit Breakers is calculated based on peak current. Generator protective device duty is calculated based on maximum through fault current. Other protective device duty is calculated based on total fault current. * Indicates a device with interrupting duty exceeding the device capability.

22

Asymm kA Crest

C. ANSI/IEEE Short Circuit Method (for Manual Calculation) Impedance Diagram Development @ 100 MVA base

XU RT2

RT1 XT1 RM1 XM1

where:

B2

B1

XT2 RM3

RM2

RL XL

XM2

XM3

HP(0.746) (Eff)(pf)(100) 500(0.746) (1000)(0.9325)(0.9082)

MOTOR (MVA) = RM4

RM5

XM4

XM5

M2 =

M2 = 0.440 MVA

Figure 6: Impedance Diagram

1. X U



2. R T1



3. X T1



4. R T2



5. X T2



6. R M1



7. X M1



8. R L



9. X L



10. X M2M5 11. R M2M5

100  j 0.13889 720 100 0.575costan 7.1  0.53463 1.5 100 0.575sin tan 7.1  j 3.79587 1.5 100 0.0715costan 12.14  0.11739 5 100 0.0715sin tan 12.14  j1.42157 5 100 0.2costan 8.707   20.74547 0.11 100 0.2sin tan 8.707   j180.63078 0.11 100 0.2costan 2.38  12.91214 1.00.6 100 0.2sin tan 2.38  j30.73089 1.00.6 100 0.24051sin tan 10.888  j54.43227  0.44 100 0.24051sin tan 10.888  12.91214  0.44 j

23

Solving for ½ cycle 3 phase fault at Z T B1



 Z

T2

 Z M2 Z M3 Z M4 Z M5   Z U  Z T1  Z M1 Z L

 0.56271  I T3 B

1



j3.44496



3.49062 80.72

B2

 Z M2 Z M3 Z M4 Z M5  0.10787

I T3 B 2



100 x 10 6  68.9 kA 3 240 3.49062 

Solving for ½ cycle, 3phase fault at Z T B2

B1



 Z

M1

Z L  Z T1   Z U  Z T2 

j1.40240  1.40655 85.6

100 x 10 6  17.85 kA 3 2300 1.40655 

IEC Short Circuit Calculation

1. XUK

 j0.13889

2. RT1K  K K

0.534630.965

 0.51592

 0.965 as per60909IECformula Cmax  0.965 ; ZK  ZT K 1  0.6XT 

Cmax  1.1 Table1 of 60909 0

3. XT1K  j3.795870.965  j3.66301

4. RT2K  0.117391.0

 0.11739

5. XT2

 j1.42517

 j1.425171.0

6. RM1K  20.745470.8

7. XM1K  j180.630780.8 8. RLK 9. XLK

 12.912140.77

 j30.730890.77

 16.596  j144.505  9.942  j23.66

10. XM2KM5K  j54.432270.64  34.837 11. RM2KM5K  4.999290.64 24

 3.199

Solving for 3 phase fault at Z TK B1



 Z

T2K

B1

 Z M2K Z M3 K Z M4K Z M5K   Z UK  Z T1K  Z M1K Z L

 0.54641  I"K B

1



I"K B

2

j3.22821 

100 x 10 6 1.1 3 240 3.27412 

Solving for 3 phase fault at Z TK B 2

, I "K

B2

3.27412 80.39

 80 kA

, I "K

 Z M2K Z M3K Z M4K Z M5K

 Z

 0.10307

 1.32948 85.6





j1.32547

M1K

Z LK  Z T1K   Z UK  Z T2K 

100 x 10 6 1.1  17.85 kA 3 2300 1.32948 

* It is therefore the basic inclusion of factors C m and k that increases the calculated short-circuit of IEC method when being compared to the result of the ANSI method.

25

VIII.

Protective Devices Selection and evaluation

X/R Ratio for Breaker Evaluation The fault point X/R ratio is a critical factor in the calculation of short circuit current when evaluating breakers. The X/R ratio determines the amount of dc component in the short circuit current and in the application to the circuit breaker withstands and interrupting time duties. ANSI/IEEE C37.010-1999 recommends a separate R and jX network reduction to determine the fault point X/R ratio while IEC 61909 allows several methods to provide a conservative X/R ratio. The peak current calculation that yields a very close approximation to the exact peak current and is conservative for most values of circuit X/R ratios greater than 0.81. The non-conservative errors for circuit X/R ratio around 10 are negligible. Please refer to equation below:     Half cycle  I ac peak 1  e X / R  or  

ANSI / IEEE

     2 I ac rms 1  e X / R   

3    Half cycle  I ac peak 1.02  0.98 e X / R  or  

IEC 60909

3     2 I ac rms 1.02  0.98 e X / R   

Circuit Breaker Short Circuit Test Parameters Based on IEC 60947-2, the circuit breakers short circuit breaking capacity, power factor and ratio, η, between short circuit making capacity and short circuit breaking capacity should be in accordance with Table 5. Table 5: Circuit Breakers Short Circuit Breaking Capacity Short circuit breaking capacity, Ib, kA rms 4.5 ≤ I ≤ 6 6 < I ≤ 10 10 < I ≤ 20 20 < I ≤ 50 50 < I

Lagging Power factor 0.7 0.5 0.3 0.25 0.2

X/R 1.02 1.73 3.18 3.87 4.9

Minimum value required for Short-circuit making capacity η = Short-circuit breaking capacity 1.5 1.7 2.0 2.1 2.2

Ratio η between Short-circuit making capacity and Short-circuit breaking capacity and related power factor or X/R ratio (for ac circuit breaker). 26

Based on NEMA AB1/UL489, the circuit breakers interrupting capacity, lagging power factor should be in accordance with Table 6. Table 6: Circuit Breakers Interrupting Capacity kA I ≤ 10 10 < I ≤ 20 20 < I All All

MCCB and ICB Power Circuit Breaker (Unfuse) Power Circuit Breaker (Fuse)

lagging pf 0.45 – 0.5 0.25 – 0.30 0.15 – 0.20 0.15 0.20

X/R 1.98 – 1.73 3.87 – 3.17 6.59 – 4.90 6.59 4.90

IX. Findings and Results From the result of ETAP Total Bus Fault Short Circuit Study, the following results were found: Table 7: IEC Short Circuit Calculation Bus ID

Device

B1

CB2

Device Capacity (kA) Making Ib sym Ib asym Peak 176

80

80.426

Short Circuit Calculation Result (kA) I"b

ip

Ib sym

Ib asym

79.8

181.348*

77.219

79.188

Note: Method A, Total Bus Fault

From the data in Table 7, the calculated short circuit current level of 79.8kA (I”k) is within the circuit breaker

capacity of 80 kA (Ib sym), however, other parameters such as peak short circuit current ( ip) is 181.348 kA exceeded the circuit breaker rating equivalent to 176 kA (making peak) only. Therefore, the selected IEC rated circuit breaker is not suitable for this particular application. The reason for this difference is that the calculated X/R ratio at 3-phase fault at point B1 is 5.9, which is greater than the device capacity X/R ratio of only 4.9 (see ETAP IEC method result above) applied during the testing of circuit breaker interrupting capacity or the Icu rating of the circuit breaker. Table 8: ANSI Short Circuit Calculation Bus ID

Device

B1

CB2

Device Capacity (kA) Rated Int.

Adj. Int

85.0

85.0

Short Circuit Calculation Result (kA) Sym Adj. Sym X/R ratio M.F rms rms 68.362 6.9 1.07 73.118

From the data in Table 8, the calculated symmetrical rms current of 68.362 kA needs to be adjusted by the multiplying factor (MF) of 1.070 (see computation below) resulting to 73.118 kA. This is because the calculated X/R ratio 6.9 is greater than the X/R ratio used in testing the circuit breaker interrupting capacity which is only 4.9 (Table 6). Comparing the adjusted symmetrical rms value of 73.118 kA against the selected NEMA rated device interrupting capacity of 85kA, the selected circuit breaker is suitable for the particular application. 27

MF 

1 e 1 e



R    X C R    X T

1 e 1 e

 1     6 .9  C  1     4 .9  T

 1.07

Where:

R  X

  T

R    X C

- Break test R/X ratio - Calculated R/X ratio at the point fault

MF - Multiplying factor

X.

Conclusion and Recommendation

From the above short circuit calculation examples, IEC method shows a higher value of short circuit current as compared to ANSI/IEEE calculation method. This is due to the differences in the consideration as mentioned above. Both methods are being used and internationally acceptable. In any electrical system, it is important to know the short circuit level of each of the protective equipment. However, we should not forget to verify the X/R ratio of the faulted bus against the circuit breaker test power factor or X/R ratio based on their product standard (e.g. UL/NEMA/ANSI or IEC). The example above illustrates clearly the importance of X/R ratio in evaluating or selecting the circuit breaker. Understanding the relationship between the product standards and electrical codes is of utmost importance. It is up to the engineers/designers to decide which method of short circuit calculation they are more comfortable with provided they have to take note of the different considerations in the selection of the protective equipment.

28

XI. References 1 IEEE Std 551-2006, IEEE Recommended Practice for Calculating Short-Circuit currents in Industrial and Commercial Power System. 2 IEEE Papers, Simplifying IEEE/ANSI and IEC Fault Point X/R Ratio for Breaker Evaluation by Ketut Dartawan and Conrad St. Pierre 3 IEC 60497-1:2009, Low-voltage switchgear and control gear - Part 1: General rules 4 IEC 60497-2:2009, Low-voltage switchgear and control gear - Part 2: Circuit-breakers 5 ANSI C37.5-1989, Calculation of Fault Currents for Application of Power Circuit Breakers Rated on a Total Current Basis 6 UL 489-1986, Molded Case Circuit Breaker and Circuit Breakers Enclosure 7 IEC 60909-0, Corrigendum 1 - Short-circuit currents in three-phase A.C. systems - Part 0: Calculation of currents 8 Electrical Transient Analyzer Program (ETAP) Software version 6.0

29

Appendix

Courtesy of ABB Phil., Inc.

proM Compact

Technical features

S 200

of MCBs S 200 series

Series Characteristics Rated current

[A]

Breaking capacity

[kA]

Reference standard IEC 23-3/EN 60898 IEC/EN 60947 - 2 Alternating current

Nr. Poles lcs lcu

1, 1P + N 2,3,4 2,3,4

lcs

1, 1P + N

B,C,D K,Z

S 200 P B,C,D K,Z

B,C,D K,Z

0.5 ≤ ln ≤ 63

0.2 ≤ ln ≤ 25

32 ≤ ln ≤ 40

50 ≤ ln ≤ 63

80≤ LN ≤ 100

6

10

25

15

15

6

133 230 230 400 500 690

20 10 20 10

25➇ 15➇ 25➇ 15➇

40 25 40 25

25 15 25 15

25 15 25 15

15 6 10 6

133

15

18.7➇

20

18.7

18.7

15

Ue [V] 230 / 400

S 200 B,C,D K,Z

S 200 M B,C,D K,Z

0.5 ≤ ln ≤ 63

30

S 280 B,C

(continued …)

2,3,4 2,3,4

IEC/EN 60497 - 2 Direct current T= lR≤ 5ms for all series except S280 UC and S800S-UC where T = lR <15ms

lcu

1, 1P + N

2

3,4

lcs

1, 1P + N

2

3,4

230 230 400 500 690

7.5 15 ➀ 7.5

11.2➇ 18.7➇ 11.2➇

12.5 20 12.5

11.2 18.7 11.2

7.5 18.7 7.5

6 10 6

24 60 125 250 48 125 250 500 600 800 375 500 750 1000 1200

20 10

10

15

10

10

10

20 10

10

15

10

10

10

24 60 125 250 48 125 250 500 600 800 375

20 10

10

15

10

10

10

20 10

10

15

10

10

10

31

(continued …) 500 750 1000 1200 UL 1077 / C22.2 No 235 Alternating current

lnt. cap.

1, 1P + N 2,3,4

UL 1077 / C22.2 No 235 Direct current UL 489/ C22.2 No 5 Alternating current

lnt. cap.

IEC / EN 60947 - 3

lcw

lnt. cap.

1, 1P + N 2,3,4 1 2,3,4

2 3,4

120 277 240 480Y / 277

10 6 10

10 10 10

10 10 10

10 10 10

6

10

10

10

60 125

10 10

240 277 240 480y / 277 800 1200

➇ <50 A

32