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# Short circuit current calculation at various point of electrical circuits (Isc)

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## Available fault current calculation

### Infinite Bus Method

#### 1. Fault Current At Transformer

##### Inputs:

• Transformer Kva
• Secondary Voltage of Transformer (Line-Line)
• Secondary Voltage of Transformer (Line-Neutral)
• Transformer Impedance (Zt)
• Transformer Secondary Full Load Current I (Line-Line)
• Transformer Secondary Full Load Current I (Line-Neutral)

• KVA Short Circuit At Primary Side
• Source Impedance (Zu)
• Total Impedance (Z =Zu+Zt)
• Short Circuit Current RMS Symmetrical
• Fault Current At Transformer Secondary ( Isc(L-L)=I (L-L)/Total Impedance)
• Fault Current At Transformer Secondary ( Isc(L-N)=I (L-N)/Total Impedance)

#### 2. Fault Current At Main Panel

##### Inputs:

• Cable Length from Transformer to Main Panel
• Type of Cable
• No of Conductor/Phase
• Size of Phase Conductor
• Size of Neutral Conductor
• Type of Race Way
• Phase Conductor Constant (C1)

• Neutral Conductor Constant (C2)
• F1(L-L) [F(L-L)=(1.732 X Length X Isc)/(C1 X No of Conductor X Volt)]
• F2(L-N) [F(L-L)=(1.732 X Length X Isc)/(C2 X No of Conductor X Volt)]
• M1(L-L) [M=(1/(1+F1)]
• M2(L-N) [M=(1/(1+F2)]
• Fault Current at Main Panel Disconnection (L-L) [Isc X M1]
• Fault Current at Main Panel Disconnection (L-N) [Isc X M2]

#### 3. Fault Current At Sub Panel

##### Inputs:

• Cable Length from Main Panel to Sub Panel
• Type of Cable
• No of Conductor/Phase
• Size of Phase Conductor
• Size of Neutral Conductor
• Type of Race Way
• Phase Conductor Constant (C1)

• Neutral Conductor Constant (C2)
• F1(L-L) [F(L-L)=(1.732 X Length X Isc)/(C1 X No of Conductor X Volt)]
• F2(L-N) [F(L-L)=(1.732 X Length X Isc)/(C2 X No of Conductor X Volt)]
• M1(L-L) [M=(1/(1+F1)]
• M2(L-N) [M=(1/(1+F2)]
• Fault Current at Sub Panel Disconnection (L-L) [Isc X M1]
• Fault Current at Sub Panel Disconnection (L-N) [Isc X M2]

#### 4. Fault Current At Distribution Board

##### Inputs:

• Cable Length from Sub Panel to Distribution Board
• Type of Cable
• No of Conductor/Phase
• Size of Phase Conductor
• Size of Neutral Conductor
• Type of Race Way
• Phase Conductor Constant (C1)

• Neutral Conductor Constant (C2)
• F1(L-L) [F(L-L)=(1.732 X Length X Isc)/(C1 X No of Conductor X Volt)]
• F2(L-N) [F(L-L)=(1.732 X Length X Isc)/(C2 X No of Conductor X Volt)]
• M1(L-L) [M=(1/(1+F1)]
• M2(L-N) [M=(1/(1+F2)]
• Fault Current at Distribution Board Disconnection (L-L) [Isc X M1]
• Fault Current at Distribution Board Disconnection (L-N) [Isc X M2]

 Software: Short Circuit Current Calculation at Various Point of Electrical Circuits (Isc) Version: – Developer: Jignesh Parmar Size: 85 Kb Price: Free Download: Right here | Video Courses | Membership | Download Updates

1. KUMAR
Dec 03, 2013

its not setisfied i need full calculation of short ckt current….

Aug 18, 2013

Can you please send me a format for calculating Isc for a panel fed from generator. (e.g. 2.75MVA CAT Genset feeds to a Panel of 4000A, 415V, 4C armored cables).

Best regards,

3. MILIND TAMBAT
Mar 21, 2013

I am not able to free down load free EL. ENG. Technical articles.
Thanks

• Edvard
Mar 21, 2013

Best regards,
Edvard

4. Allen
Jan 05, 2013

Could you please develop the Excel calculation sheet for sizing of Soft Starter with the curve appearance.

• Edvard
Jan 05, 2013

EEP is not the developer of any MS Excel Spreadsheet here. All spreadsheets are developed by engineers who wanted to share their entusiasm and knowledge with everybody.

5. fayinminu tosin
Feb 01, 2012

Hello, could you please solve the short circuit problem manually using point to point calculation. A better explanation on how you arrived at your answer would also be appreciated. Kindly send your reply to: [email protected] or [email protected].

• One 480V motor feeder, 100HP, 100m length, for both underground installation and offshore installation in cable trays. Assume MCC is fed from switchgear, on the secondary of a 750kVA transformer, 4160-480V. The check for Voltage drop should be for running and starting conditions
• One feeder cable to a Power Panel, 480V, 100kVA, 200 m distance
• One 250 HP, 4.16kV motor, 100m length for both underground and cable tray installation. Assume 4.16kV MCC is fed from 4.16kV switchgear having a short circuit rating of 200MVA, the feeder length is 50Ft.
• One remote 4.16kV-480V transformer feeder, 200m length, 500kVA.
• One line diagram for the system (4.16kV and 480V) shall also be prepared.
• Primary short circuit calculation (using reactance and resistances in ohms, not p.u.)
• Assume the generation is with 2+1 1250kVA, 4.16 kV Solar Saturn 20 gas turbine generators (sub transient reactance is 12.5%).

6. jbuda54
Jan 03, 2012

Do you have an AWG cable size equivalent excel file?

7. Edvard
Dec 15, 2011

I have sent you all an email with this tool. Hope it will help!

Cheers

8. GP
Dec 14, 2011

Please can you forward Short Circuit Current Calculation at Various Point of Electrical Circuits (Isc) excel sheet to me on my email address- [email protected]

Thanks

9. Simon
Dec 14, 2011

Hi Edvard,

Simon.

10. Sairaj
Dec 07, 2011

Sir,
Kindly send the excel tool for SC calculation as I am unable to download. My id: [email protected].. Thanks in advance..

11. RamaRaju
Dec 06, 2011

Dear Edvard,
Request you to send me a copy of the excel file for Short CKT Calcs as I am unable to download from the link.
My mail id: [email protected]
Thanks & Regards,
Raju

12. Marcus
Dec 04, 2011

Dear Sir, will you be able to send me a copy of the excel file? I am having trouble downloading it too. thanks heaps for your great work. [email protected]

13. Brkn
Dec 02, 2011

Dear Edvard,
Can you send to my e.mail too.
My e.mail is: [email protected]
Thanks.

14. S P Gupta
Nov 29, 2011

Please send the software for calculation of short circuit as it is not getting down-loaded. Thanks

• Edvard
Nov 29, 2011

I just checked and MS Excel tool is working very well, it’s downloadable. However, it’s my pleasure to se send it to you!

BR

Nov 28, 2011

sir, this short ckt. sheet is not getting downloaded on my system due to some network problem.so please send the Short Circuit Current Calculation at Various Point of Electrical Circuits (Isc) excel sheet me on my email address- [email protected]. i will be very much thankfull for your kind support.

• Edvard
Nov 28, 2011

No problem at all Ahmadgce04! I just sent you above mentioned XLS tool on your email.

BR