218538678 AP01200003E Fault Current Coordination Calculator

This software tool will allow the user to estimate short circuit fault currents on three types of power

sources: transformers (1), generators (1 - 5 in parallel) or a definite bus and will present Eaton

circuit breakers that are able to provide fully selective performance at the calculated short circuit

levels. The values displayed are RMS fault current values.

Where adjustable short time delay and pick up is provided the short time pick up is always set at

maximum, I2t in and the delay is set at minimum, except when one adjustable device is compared

above another similarly adjustable device. In that case the delay of the upstream device is set at a

Long time pick up is always set at maximum for all adjustable circuit breakers.

Ground fault settings are not considered in the analysis.

Tool identifies circuit breaker families that may meet the requirements. Circuit breakers are defined

by frame type and size, trip size or sensor and plug size where applicable. Circuit breakers may be

provided in various short circuit ratings, selectivity level used herein reflect the selectivity capability

of the highest rated CB within the family. A lower rated CB from the same family may be used if

suitable for the application.

Where devices have adjustable instantaneous trips the adjustment was set a maximum regardless

if the circuit breaker is evaluated as an upstream (main) or downstream (feeder) device.

Job Title

Company Name

Available Fault Current Calculation - Revsion 2, 05/29/08

Source Information

Generator kW:

Generator Voltage:

Generator Power Factor:

Generators in Parallel:

Generator Calculations

Total Generator kVA: 1,500

Generator Voltage 480

Enter Generator Subtransient (Z) 5.75 %

Nominal Secondary Current: 1,804 Amperes

Maximum Generator Short Circuit Current 31,379 Amperes

Motor Contributions 7,217 Amperes

Total Short Circuit Current: 38,596 Amperes

Enter Available Utility or Primary KVAS

Note: Primary KVA = Primary Voltage (kV) x Primary Current Ip (Amperes) x 1.743

Enter transformer KVA rating 1500 KVA

Enter transformer impedance (Z) 5.75 %

Select Secondary System Voltage

Transformer Calculations

Secondary Voltage 208 Volts

Secondary Current 4,164 Amperes

Maximum Secondary Protection per NEC 450.3(B) 5,205 Amperes

Recommended Secondary Breaker Rating 6000 Amperes

ISCA = Transformer 41,489 Amperes

ZU + ZT

Short Circuit Current (RMS symmeterical) 41,489 Amperes

@ Secondary (Line) Main MCCB Line Terminals

Motor Contributions 8,327 Amperes

Total Short Circuit Current @ LV Source Bus 49,816 Amperes

67,000 Amperes

Definite Bus Short Circuit Current 67,000 Amperes

Definite Bus Voltage 208 Volts

Select Conductor Data Between Line MCCB and Load MCCB

Select Conductor Type & Raceway

Charisteristics

Select Conductor Size

Enter Conductor Length 113 Feet

Enter Number of Conductors / Phase 1

Fault Current @ Terminals of Load MCCB 10,968 Amperes

Select Line MCCB

Select Load MCCB

Coordination Level 14,000 Amperes

Generators

Transformer

Enter Definite Bus Short Circuit Current

Bus Voltage

Select an appropriate Primary Protective device which provides selective

coordination with the selected secondary main breaker for all secondary faults.

Results Selectively Coordinated

Point to Point Method:

The application of the point to point method permits the determination of available short-circuit current

with a reasonable degree of accuracy at various points in an electrical distribution system.

Phase Neutral Select Conductor & Raceway

AWG AWG Copper in Non-metalic Raceway

14 14 Aluminium in Non-metalic Raceway

12 12 Copper in Metalic Raceway

10 10 Alumnium in Metalic Raceway

8 8

6 6 3 Raceway Selection

4 4 12,341 Phase Conductor Constant

3 3 7198 Neutral Constant

2 2

1 1

1/0 1/0

2/0 2/0

3/0 3/0

4/0 4/0

250 kcmil 250 kcmil f = 5.108

300 kcmil 300 kcmil

350 kcmil 350 kcmil M = 0.164

400 kcmil 400 kcmil

500 kcmil 500 kcmil

600 kcmil 600 kcmil

750 kcmil 750 kcmil 0

1000 kcmil 1000 kcmil

0

13 10 1

OOOO O 1

1.5

1

1.5

JG 100A CL

JG 160A CL

JG 250A CL

JD 70A

JD 125A

JD 250A

LCL 250 (125A)

LCL 250 (200A)

LCL 250 (250A)

LCL 400 (200A)

LCL 400 (300A)

LCL 400 (400A)

KD 100A

KD 200A

KD 400A

LD 300A

14,000

The application of the point to point method permits the determination of available short-circuit current

with a reasonable degree of accuracy at various points in an electrical distribution system.

Select Secondary

Main BreakerSelect Branch Breaker

EG(125 A) T/M BR, BAB, HQP & QC 15A 1

FD(100 A) T/M BR, BAB, HQP & QC 20A 2



FD(80 A) ETU BR, BAB, HQP & QC 50A 5



JD(70 A) T/M BR, BAB, HQP & QC 80A 8

JD(150 A) T/M BR, BAB, HQP & QC 90A 9

JD(250 A) T/M BR, BAB, HQP & QC 100A 10 10

JG(50 A) ETU BR, BAB, HQP & QC 125A 11 575

JG(100 A) ETU BR, BAB, HQP & QC 150A 12 34,500

JG(160 A) ETU BRH, QPHW, QBHW & QCHW 15A 13 34,500

JG(250 A) ETU BRH, QPHW, QBHW & QCHW 20A 14 25

KD(100 A) T/M BRH, QPHW, QBHW & QCHW 30A 15

K(D200 A) T/M BRH, QPHW, QBHW & QCHW 40A 16

KD(400 A) T/M BRH, QPHW, QBHW & QCHW 50A 17 2

KD(125 A) ETU BRH, QPHW, QBHW & QCHW 60A 18



LD(300 A) T/M BRH, QPHW, QBHW & QCHW 90A 21



LD(600 A) ETU BRH, QPHW, QBHW & QCHW 150A 24

LHH(150 A) T/M GHB / GHC 20A 25



LG(630 A) T/M GHB / GHC 70A 28

LG(250 A) ETU GHB / GHC 100A 29

LG(400 A) ETU GD 20A 30

LG(630 A) ETU GD 30A 31

N(150 A) ETU GD 50A 32 1

N(400 A) ETU GD 70A 33 0.0429

N(600 A) ETU GD 100A 34 0.0300

N(800 A) ETU FCL 15A 35 0.0231

N(1200 A) ETU FCL 30A 36 0.0200

R(800 A) ETU FCL 50A 37 0.0150

R(1000 A) ETU FCL 100A 38 0.0100

R(1200 A) ETU EG 15A 39 0.0060

R(1600 A) ETU EG 30A 40 0.0030

R(2000 A) ETU EG 50A 41 0.0429

R(2500 A) ETU EG 60A 42 EG 100A 43 0.1004

33 EG 125A 44

EG 15A CL 45

EG 30A CL 46

EG 50A CL 47

EG 60A CL 48

EG 100A CL 49

EG 125A CL 50

FD 15A 51

FD 40 A 52

FD 100A 53

FD 225A 54

JG 50A 55

JG 100A 56

JG 160A 57

JG 250A 58

JG 50A CL 59

JG 100A CL 60

JG 160A CL 61

JG 250A CL 62

JD 70A 63

JD 125A 64

JD 250A 65

LCL 250 (125A) 66

LCL 250 (200A) 67

LCL 250 (250A) 68

LCL 400 (200A) 69

LCL 400 (300A) 70

LCL 400 (400A) 71

KD 100A 72

KD 200A 73

KD 400A 74

LD 300A 75

LD 400A 76

LD 600A 77

LG 250A 78

LG 400A 79

LG 630A 80

LG 250A CL 81

LG 400A CL 82

LG 630A CL 83

N 400A 84

N 600A 85

N 800A 86

N 1200A 87

29

14,000

Select Three Phase

Primary Voltage

Select Three Phase

Secondary Voltage

Three Phase 208 Three Phase 208Y / 120

Three Phase 240 Three Phase 480Y / 277

Three Phase 480 1 1

Three Phase 575 208 208

Three Phase 2,400 208 x 1.732 Voltage Formula

Three Phase 4,160 4164 Transformer Secondary FLA

Three Phase 7,200

Three Phase 12,800 1.732 Phase

Three Phase 34,500 1.732 x L x Isca

120 EL-N

Voltage Formula

Transformer Primary FLA

Motor Contibution Factor

Utility / Primary KVA

35,000

50,000

65,000

75,000

100,000

150,000

250,000

500,000

Unlimited

Source Contribution Selection

Voltage selection

Voltage selection

Source Impedance Calcualtion

(ZU = KVABase / KVASource)

Source Impedance

Total Impedance (ZU+ZT)

Source Impedance Calcualtion

(ZU = KVABase / KVASource)

Select Three Phase

Definite Bus Voltage

Three Phase 208Y / 120

Three Phase 480Y / 277

Voltage selection

218538678 AP01200003E Fault Current Coordination Calculator

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