Calculate Transformer Losses (As per Test Results)


111

  • Calculate Form Factor at Full Load & Actual Load.
  • Calculate Core Losses at Full Load & Actual Load.
  • Calculate Copper Losses at Full Load & Actual Load.
  • Calculate Stray  Losses at Full Load & Actual Load.
  • Calculate Total Losses at Full Load & Actual Load.
  • Calculate Transformer Efficiency  at Full Load & Actual Load.

FREE DOWNLOAD

Advertisements

Pirating of Technical Works.


It has been observed that some people totally copy past of this blog and parallel republished all posts of this blog again on their Blog   .

Lots of time has been spent to read Books,Manuals,Handbooks and combined it with  practical experience to serve Handy Electrical tools,Notes to serve the Electrical Community.This Blog is a fusion of Theoretical and Practically knowledge to make all technical things easier to understand.

Please look at following totally copy past material of  this  Blog. 

After publishing Post on this Blog. Other Blogger republished the same post on their Blog .the blogger did not even change THE COLOR OF THE FONT while copy past and not even Chang the Title of the Post ….. All reader keeps their eyes on Date of original Post and date of copy past blog. Following blogger neither take any permission of the original blogger to republished the post nor give any credit by putting Reference of original post.

Blogger No-1

(1) Original post :https://electricalnotes.wordpress.com/2013/07/27/electrical-thumb-rules-part-1-2/

Copy past post of other blogger: http://myelectricalnote.blogspot.in/2013/08/electrical-thumb-rules.html

(2)Original post :https://electricalnotes.wordpress.com/2013/03/08/calculate-numbers-of-platepipestrip-earthing-for-system/

Copy past post of other blogger:http://myelectricalnote.blogspot.in/2013/04/calculate-numbers-of-platepipestrip.html

(3) Original post : https://electricalnotes.wordpress.com/2013/04/01/calculate-numbers-of-platepipestrip-earthings-part-3/

Copy past post of other blogger: http://myelectricalnote.blogspot.in/2013/04/calculate-numbers-of-platepipestrip_10.html

(4) Original post :https://electricalnotes.wordpress.com/2011/09/05/type-of-earthing-systems-in-electrical-distribution/

Copy past post of other blogger:http://myelectricalnote.blogspot.in/2013/05/type-of-electrical-power-distribution.html

(5) Original post :https://electricalnotes.wordpress.com/2012/07/17/parallel-operation-of-transformers/

Copy past post of other blogger: http://myelectricalnote.blogspot.in/2013/03/parallel-operation-of-transformers_7.html

Blogger No-2

(1) Original post :https://electricalnotes.wordpress.com/2013/10/01/electrical-thumb-rules-part-8/

Copy past post of other blogger http://www.electricalinfo.co.in/electrical-thumb-rules-part-8/

(2)Original post :https://electricalnotes.wordpress.com/2013/11/01/type-of-mcb-distribution-board/

Copy past post of other blogger:http://www.electricalinfo.co.in/difference-tpn-4p-spn-dp/#comment-1119

(3) Original post :https://electricalnotes.wordpress.com/2013/07/27/electrical-thumb-rules-part-1-2/

Copy past post of other blogger:http://www.electricalinfo.co.in/electrical-thumb-rules-part-1/

It is wast of time to put all lists of copy past items because this copy past list is long…………………..

Calculate Cable Size and Voltage Drop


Calculate Cable Size and Voltage Drop:

Calculate Voltage Drop and Size of Electrical cable for following data.

  •  Electrical Details: Electrical Load of 80KW, Distance between Source and Load is 200 Meter, System Voltage 415V Three Phase, Power Factor is 0.8,Permissible Voltage drop is  5%, Demand Factor is 1,
  • Cable Laying Detail: Cable is directed buried in Ground in trench at the depth of 1 meter. Ground Temperature is approximate 35 Deg. No of Cable per Trench is 1. No of Run of Cable is 1 Run.
  • Soil Details: Thermal Resistivity of Soil is not known. Nature of Soil is Damp Soil.

Calculation:

  • Consumed Load= Total Load x Demand Factor
  • Consumed Load in KW= 80 x 1 =80KW
  • Consumed Load in KVA= KW/P.F
  • Consumed Load in KVA =80/0.8=100KVA
  • Full Load Current= (KVAx1000) / (1.732xVoltage)
  • Full Load Current= (100×1000) / (1.732×415) = 139Amp.
  • Calculating Correction Factor of Cable from following data :
  • Temperature Correction Factor (K1) When Cable is in Air  is

Temperature Correction Factor in Air :K1

Ambient Temp©

Insulation

PVC

XLPE/EPR

10

1.22

1.15

15

1.17

1.12

20

1.12

1.08

25

1.06

1.04

35

0.94

0.96

40

0.87

0.91

45

0.79

0.87

50

0.71

0.82

55

0.61

0.76

60

0.5

0.71

65

0

0.65

70

0

0.58

75

0

0.5

80

0

0.41

  • Ground Temperature Correction Factor (K2):

Ground Temperature Correction Factor:K2

Ground Temp©

Insulation

PVC

XLPE/EPR

10

1.1

1.07

15

1.05

1.04

20

0.95

0.96

25

0.89

0.93

35

0.77

0.89

40

0.71

0.85

45

0.63

0.8

50

0.55

0.76

55

0.45

0.71

60

0

0.65

65

0

0.6

70

0

0.53

75

0

0.46

80

0

0.38

  • Thermal Resistance Correction Factor (K4) for Soil (When Thermal Resistance of Soil is known):

Ther.Resi Correction Factor: K4

Soil Thermal Resistivity: 2.5 KM/W

Resistivity

K3

1

1.18

1.5

1.1

2

1.05

2.5

1

3

0.96

  • Soil Correction Factor(K4) of Soil (When Thermal Resistance of Soil is not known):

Soil Correction Factor:K4

Nature of Soil

K3

Very Wet Soil

1.21

Wet Soil

1.13

Damp Soil

1.05

Dry Soil

1

Very Dry Soil

0.86

  • Cable Depth Correction Factor (K5):

Cable Depth Factor (K5)

Laying Depth(Meter)

Rating Factor

0.5

1.1

0.7

1.05

0.9

1.01

1

1

1.2

0.98

1.5

0.96

  • Cable Distance correction Factor (K6):

Cable Distance  Correction Factor(K6)

No of Circuit

Nil

cable Diameter

0.125m

0.25m

0.5m

1

1

1

1

1

1

2

0.75

0.8

0.85

0.9

0.9

3

0.65

0.7

0.75

0.8

0.85

4

0.6

0.6

0.7

0.75

0.8

5

0.55

0.55

0.65

0.7

0.8

6

0.5

0.55

0.6

0.7

0.8

  • Cable Grouping Factor ( No of Tray Factor) (K7):

No of Cable/Tray

(Cable Grouping factor K7 )==No of Tray

1

2

3

4

6

8

1

1

1

1

1

1

1

2

0.84

0.8

0.78

0.77

0.76

0.75

3

0.8

0.76

0.74

0.73

0.72

0.71

4

0.78

0.74

0.72

0.71

0.7

0.69

5

0.77

0.73

0.7

0.69

0.68

0.67

6

0.75

0.71

0.7

0.68

0.68

0.66

7

0.74

0.69

0.675

0.66

0.66

0.64

8

0.73

0.69

0.68

0.67

0.66

0.64

  • According to above Detail correction Factors are
  • Ground Temperature Correction Factor (K2) =0.89
  • Soil Correction Factor (K4)=1.05
  • Cable Depth Correction Factor (K5)=1.0
  • Cable Distance correction Factor (K6)=1.0
  • Total De rating Factor= k1x k2 x k3 x K4 x K5 x K6 x K7
  • Total De rating Factor= 0.93

Selection of Cable:

  • For selection of Proper Cable following Conditions should be satisfied
  • (1) Cable De rating Amp should be higher than Full Load Current of Load.
  • (2) Cable Voltage Drop should be less than Defined Voltage drop.
  • (3) No of Run of Cable >= (Full Load current / Cable De rating Current).
  • (4) Cable Short Circuit Capacity should be higher than System S.C Capacity at that Point.

Selection of Cable Case (1):

  • Let’s Select 3.5Core 70 Sq.mm cable for Single run.
  • Current Capacity of 70 Sq.mm cable is 170Amp,Resistance=0.57Ω/Km and Reactance=0.077 mho/Km
  • Total De rating Current of 70 Sq.mm Cable= 170×0.93 =159 Amp.
  • Voltage Drop of Cable= (1.732x Current x (RcosǾ+jsinǾ) x Cable Lengthx100) / (Line Voltage x No of Runx1000)
  • Voltage Drop of Cable= (1.732x139x(0.57×0.8+0.077×0.6)x200x100)/(415x1x1000)=5.8%
  • Voltage Drop of Cable=5.8%
  • Here Voltage drop for 70 Sq.mm Cable (5.8%) is higher than Define Voltage drop (5%) so either select higher size of cable or Increase no of Cable Runs.
  • If we Select 2 No’s of Run than Voltage drop is 2.8% which is within limit (5%) but to use 2 no’s of Run of cable of 70 Sq.mm Cable is not economical so It is necessary to use next higher size of Cable.

Selection of Cable Case (2):

  • Let’s Select 3.5Core 95 Sq.mm cable for Single run, S.C Capacity =8.2KA.
  • Current Capacity of 95 Sq.mm cable is 200Amp,Resistance=0.41Ω/Km and Reactance=0.074 mho/Km
  • Total De rating Current of 70 Sq.mm Cable= 200×0.93 =187 Amp.
  • Voltage Drop of Cable= (1.732x139x(0.41×0.8+0.074×0.6)x200x100)/(415x1x1000)=2.2%
  • Voltage Drop of Cable=2.2%
  • To decide 95Sq.mm Cable, Cable selection condition should be checked.
  • (1) Cable De rating Amp (187 Amp) is higher than Full Load Current of Load (139 Amp) =O.K
  • (2) Cable Voltage Drop (2.2%) is less than Defined Voltage drop (5%) =O.K
  • (3)No of Run of Cable (1) >= (139A / 187A =0.78) =O.K
  • (4) Cable S.C Capacity (8.2KA) is higher than System S.C Capacity at that Point (6.0KA) =O.K
  • 95 Sq.mm Cable satisfied all three condition so It is advisable to use 3.5 Core 95 Sq.mm cable

Calculate Fault current at various point of Distribution system(Excel).


  • ScreenHunter_01 Jan. 29 20.10Calculate Total impedance of upper stream.
  • Calculate Total impedance of Lower stream.
  • Calculate impedance of Transformer.
  • Calculate Fault current on Secondary of Transformer.
  • Calculate minimum size of Cable to withstand Isc.
  • Calculate Fault current at various location of Distribution System.
  • Calculate Min Size of Cable at various location of Distribution System.

FREE DOWNLOAD

%d bloggers like this: