Battery Sizing

March 12, 2018 | Author: pokiri | Category: Battery Charger, Volt, Battery (Electricity), Matrix (Mathematics), Electromagnetism

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Description

ELECTRICAL DESIGN PROCEDURES

BATTERY SIZING CALCULATIONS

DTP-E-GEN-1003-00

ROLTA INDIA LIMITED

EDS ELECTRICAL DESIGN PROCEDURES Battery Sizing Calculations Calculations DTP-E-GEN-1003-00 Revision History Revision Level

Revision Date

Revision Description

This Document and all contained herein are proprietary of ROLTA INDIA LIMITED and is subjected to confidentiality restrictions

between ROTLA INDIA LIMITED and the Recipient. Copyright Reserved.

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5 6

Description

Page no.

Purpose & Scope Applicability References Procedure 4.1 General 4.2 Methodology of Calculation 4.3 User’s Manual 4.4 Sample Output Battery Sizing & Battery Charger Sizing Sample Calculation of Battery Sizing

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3 3 3 5 6 6 9 10 25

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1. Purpose & Scope The purpose of this ETP is to describe the methods, which should be used to size, or to verify the sizing of batteries and battery chargers and to determine the short circuit current available from the battery and from the charger. The purpose of this procedure is to provide: 

A pre-approved calculation template to aid in calculating sizes and available short circuit currents for battery and charger.

User instructions for EL-105 “Battery Sizing, Battery Charger Sizing, and available Short Circuit Current,” for developing the user inputs and for performance of the calculation of the size and short circuit current contribution for battery and battery.

2. Applicability This procedure is applicable to all projects. 3. References 3.1 EL-105, “Battery & Battery Charger Sizing & Available Short Circuit Current,” Version 00, Level 00. 3.2 Mathcad Version 7, Mathsoft Inc., Cambridge, MA 3.3 “IEEE Recommended Practice for Sizing Lead-Acid Batteries for Stationary Applications,” IEEE Standard 485-1997. 3.4 “IEEE Recommended Practice for Design of the DC Auxiliary Power Systems for Generating Stations,” IEEE Standard 946-1992. 4. Procedure 4.1 General  The Electrical and Control Systems Engineer shall prepare a calculation to size batteries and chargers and to determine available short circuit currents for all project procured DC systems. DC components procured as part of a vendor supplied system (such as a fire alarm system) where others are responsible for determining the electrical loads, do not require the preparation of a calculation by the Engineer.

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4.2 Methodology of Calculation 

This ETP contains a pre-approved calculation EL-105, including battery sizing methodology adapted from IEEE 485, battery charger sizing methodology adapted from IEEE 946, and methodologies for calculating available short circuit current from the battery adapted from IEEE 946, Annex B, and available short circuit current from the battery charger adapted from IEEE 946, Annex D.

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DC system fault current analysis calculation.

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not included in the input data, the resulting short circuit current at the terminals

of the battery will be a conservatively higher value. The resistance values of inter-rack and battery terminal cables shall be included in the DC system fault current analysis calculation and are not included in this calculation. The heading and footer of the template can be modified, except that the left hand section of the footer, “EL 105 V00 L00” shall not be changed. MathCAD Version 7.0 or later and Windows 95 operating system are required to run EL-105. The Page Setup feature for the Mathcad files is set to ensure proper printing as follows: a) Letter 8.5 x 11 inch b) Portrait c) Margins are set: Left and Right are 1.0 inch; Top is 1.5 inch; Bottom is 1.0 inch 4.4. Sample Output EL-105 The entire output of EL-105 should be included as an attachment to a project calculation. In the Methodology section of the project calculation, the following text shall be included to describe the methodology used in EL105. Attachment A (Note: Attachment A should represent the actual battery and charger sizes calculated and not the appendix A example attached to this ETP) is the output of EL-105, “Battery Sizing, Battery Charger Sizing, and Available short Circuit Current,” a MathCAD template. Attachment A includes a run of sample battery sizing, charger sizing, and short circuit calculations. The battery data used is taken from the sample calculations in IEEE 485, Figures A1 and A4.

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5.

BATTERY SIZING CALCULATIONS

DTP-E-GEN-1003-00

BATTERY SIZING, BATTERY CHARGER SIZING AND AVAILABLE SHORT CIRCUIT CURRENT References: 1. IEEE 485 - 1997, “IEEE Recommended Practice for Sizing Lead-Acid Batteries for

Stationary Applications.” 2. IEEE 946 -1992, “IEEE Recommended Practice for the Design of DC Auxiliary Power Systems for Generating Stations.” I.

INPUT A. Load Duty Cycle The load duty cycle is developed per instructions contained in IEEE 485. Loading of each section of battery discharge, in Amperes ( Column 2 in IEEE 485, worksheet Figure A-4).

Time duration of each section of battery discharge, in minutes (Column 4 in IEEE 485,workshe -et Figure A-4).

320 100 280

A=

1 29 30 B=

200 40 120

60 59 1

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Note: Use CTRL "M" to insert or delete rows and columns in the above matrices. .Random A := 100 Random Current, A Random M :=1 Time duration of random current, minutes B. Design, Aging Margin, & Battery Room Temperature

DesignMargin ----------------AgingFactor ----------------Electrolutye temp Low-------C. Battery Type

1.15 1.25 65 °F

(USER TO MODIFY - TEXT IN QUOTES)

The battery manufacturer's type of cell is selected as follows: Reference -------------------- "ABC-123" Manufacturer----------------- "ABC" Cell Type-------------------"XYZ" Cell Voltage-----------------2.00 Volts-per-cell, nominal open circuit. Minimum_Cell_Voltage--1.75 ----- Volts-per-cell Total Number Cells = 60 R factor for battery: 1 st Column is the time duration associated with a specific R factor. 2 nd Column is R factor (Item 6A of Column 6 discharge period in IEEE 485, Sample Worksheet Figure A-4).

Cell Type ="XYZ" Available battery sizes, in terms of the total number of plates and Ampere-hour ratings for an 8 hour . 1

R=

104

11

30 55.4

13

59 40

15

60 40

17

TotalPlates=

90 32.5 119 27.5

19 21

120

27.5

23

150

24.0

25

179

21.5

27

180

21.5

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400

480 560

Batt Size_Ah=

640 720 800

880 960

64

1040

Note: Use CTRL "M" to insert or delet rows and columns in theabove matrices Select two points on the manufacturer's initial voltage curve (V1,I1) and (V2, I2) that will be used for the calculation of short circuit current: (Ref. IEEE 946-1992, Fig. B.1) V1

1.90

V2

1.50

Volts

I1=60

Volts

I1=370

Amperes per positive plate Amperes per positive plate

D. Battery Charger Design Parameters(Reference IEEE 946-1992, Sample A.3) Tc8

Time to recharge the battery to approximately 95% of capacity (in hours) (This is same as the symbol "T" in equation 1 of IEEE Std 946, which was modified to avoid confusion with the use of "T" in battery sizing).

C=1.1

Constant that compensates for battery losses.

L c 50

Continuous dc load (Amperes), including future load growth (1.30 factor), in Amperes.

L n 60

The largest combination of noncontinuous loads in Amperes (as defined in IEEE Std 485) that would likely be connected to the bus simultaneously during normal plant operations. 3 6 12 25 50 75

100 150

Standard Charger Sizes, Amperes DC

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200 300 400 432 500 600 800 1000

II. Calculation A. Template Parameters

the

see= rows A)

sec 6

i= 1 sec

j= 1 sec

m= 1 sec

n= 1 sec

Lookup num A1 A2) = for return

S

ORIGIN=1

i €1 last A1)

This defines a function called Vector "A,"

A2 if

value in the is returned.If "A",then the messa -ge "NF" (not found) is returned.

A1inum

i "NF"

Replicate A s) =

k

0 for

i €1 last A)

Creates a function called "Replicate" which doubles the size of matrix A, repeating the value of each element.

for j €1  s TkjAi k k 2

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+ T

LookupCol Vector sF) = for

i €1 last Vector)

return

S

Similar to "Lookup" function, except only the first column is used. Vector if

"Out of Range"

B Duty Cycle Curve Plot CREATING THE "CURRENT" VECTOR AA

= Replicate (A, 2)

Double the size of the current "A" matrix and call it "AA" matrix.

AA rows (AA)+1 : = 0 q :=1 ( rows AA)+1 )

Add an additional element to "AA" matrix at the end and set it equal to zero so that current curve will return to zero.

AAAq :=if ( q =1,0,AA q-1

Current Vector"AAAq"

CREATING THE "TIME" VECTOR

r:= 2 rows (M) time1 := M1

Set first element of "time" matrix to first element of "M" Add the next element of "M" matrix to the previous element of "time" matrix.

timer : =Mr + time r-1 Dbl_time := Replicate (time ,2 )

q := 1 ( rows (Dbl_time)+1 )

"Time" matrix is now doubled and called "Dbl_time."

Add additional element to "Dbl_time" matrix at the beginning, and set it equal to 0.

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Dbl_timeplusq := if (q =1, 0

DTP-E-GEN-1003-00

Dbl_time q-1)

q := 1 ( rows (Dbl_timeplus) + 1 )

element. DDbl_timeplusq := if (q= 1, 0Dbl_timeplus q-1) C. Change in Load

∆Ai :=if [i = 1, Ai,Ai - A (i-1) ] Change in load Amperes of present section load compared with the previous section load (Column 3 in IEEE 485 example.

320 -220

180

∆A =

-80

 80

∆A_testi : = if (i= sec, Ai, Ai – Ai+1) 220

∆A_test section



160

-80 120

D. Time to End of Section (minutes) T(i i) := 0 T1, j := if [ j= 1, M1Mj + T1(j -1) Ti,j :=if [ i= 1 ,Ti,jT(i – 1j) – M (i-1)] . Tij := if ( Ti,j ≤ 0,0, Ti,j ) Ti,j := if ( ∆ - testj < 0,0,Ti,j )

Eliminates section calculation if load duration of

the next section is greater than present section,

i.e., Ai+1 is greater than Ai

1 0 60 120 0 180 ime to end of section, in minutes. 0 0 30 90 0 150 Columns represent each section;

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ELECTRICAL DESIGN PROCEDURES T=

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rows represent the period within each section.

0 0 0 60 0 120 0 0 0 0 0 60 0 0 0 0 0 1

E. IEEE 485 Temperature Correction Factors The first column is the electrolyte temperature in degrees F. The second column is the correction factor from Table 1 of IEEE 485.

Table 1a =

25

1.520

78

0.980

30

1.430

79

0.987

35

1.350

80

0.980

40

1.300

81

0.976

45

1.250

82

0.972

50

1.190

83

0.968

55

1.150

84

0.964

60

1.110

85

0.960

65

1.080

86

0.956

66

1.072

87

0.952

67

1.064

88

0.948

Table 1b =

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1.056

89

0.944

69

1.048

90

0.940

70

1.040

95

0.930

71

1.034

100

0.910

72

1.029

105

0.890

73

1.023

110

0.880

74

1.017

115

0.870

75

1.011

120

0.860

76

1.006

125

0.850

77

1.000

DTP-E-GEN-1003-00

Table1 := stack (Table 1a,Table1b ) TempCorrFactor := Lookup ( ElectrolyteTempLow Table11 ) TempCorrFactor 1.11 F. Battery Size - Positive Plate Method (R Factor) R1 : =R Rmatrix i,j

R2 := R

Divides the 2 column matrix, "R," into two vectors.

: = if ( Ti,j = 0, 0,Lookup (Ti,j ,R1,R2 ))

This is matrix of R factor of each value of time in the matrix ‘T’. If the time in “T” is zero, then the value in “RMatrix” is set to zero. If a value in “T” is not found in matrix “R”, an input, then “NF” (Not Found) is reported. The user has to then to correct his input matrix R by inserting missing value(s).

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This replicates DA into a matrix of identical columns.

This calculates the required section size (Column 7 in IEEE 485) , the number of positive plates for each period in each section.

This is the section size of each section.The subtotal of each column of matrix “Col 7” in Ampere-hours. MaximumSectionSize = max (SubtotalCol7) This is maximum section size, in positive plates. MaximumSectionSize 7.1748

Positive plates, maximum section size

Random A

This is the number of positive plates

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RandomSectionSize 0.962

DTP-E-GEN-1003-00

UncorrSizeRFactor: = MaximumSectionSize + RandomSectionSize UncorrSizeRFactor: = 8.136 Uncorrected total number of positive plates. PositivePlatesRq: = UncorrSizeRFactor X TempCorrFactor X DesignMargin X AgingFactor  PositivePlatesRq: = 12.63 PositivePlates: = ceil (PositivePlatesRq) PositivePlates: = 13 Total number of positive plates required. Plates: = (2 X PositivePlates) + 1 Plates = 27 Total number of plates required. AmpHour_SizeR:= Lookup (Plates TotalPlates BattSze_Ah) AmpHour_SizeR = 1040 Ampere-hour size of battery required (R factor) G. Charger Size

Charger size based on Ampere-hours discharged from the battery:

Total ampere hours discharged from the battery during its specified duty cycle, Ampere-Hours. I 1= L c + C Ah

I1 = 144.971

Minimum required charger size,Ampere

Tc I 2 = Lc + L n

(Equation 1 from IEEE 946 ). I2 = 21.78

I 3= if (I 1, I 2I 1 I 2 )

Sum of continuous and noncontinuous loads, Amperes (Equation 2 from IEEE 946). Larger of the two above sizes.

I3 = 144.971

Charger_Size:= LookupCol (StdCharger I 3 1) Charger_Size 150

Amperes DC, based on Ampere-Hours discharged from the battery.

Charger size based on the rated size of the selected battery: Minimum required charger size, based on Ampere-hours size of selected battery © Copyright 2008. Rolta India Limited. All Rights Reserved.

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(Equation 1 from IEEE 946).

Sum of continuous & noncontinuous loads, Amperes (Equation 2 from IEEE 946) Larger of the two above sizes.

Selected_Charger_Size:= LookupCol( StdCharger , I 5 , 1) Selected_Charger_Size 200

Amperes DC, based on rated Ampere-hours of the selected battery.

H. DC SOURCE SHORT CIRCUIT CONTRIBUTION Battery (Based on IEEE Standard 946, Annex B): The internal resistance of a cell is calculated from the slope of the initial volts line of the Published discharge characteristic curve of the manufacturer. The internal resistance is Determined as follows: PositivePlates = 13 Rp=( V1 (I2

Number of positive plates

- V2)

Rp =1.29 x10-9

I1) Rp= Rp Positive plates

Ohms per positive plate.

-

Rt =9.926 x10-5

Rb Rt Total_Number_Cells

Total internal resistance of cell

Rb 5.955 x10-3 Ohms,total battery resistance.

The short circuit current available at the cell terminals is found from Ohm's law as follows: CellVoltage 2.00

Volts/cell, nominal cell voltage

Batt_Voltage = CellVoltage Total_Number_Cells Batt_Voltage 120

Volts, nominal battery voltage

Ic1 20150

Amperes, available short circuit current

2. Battery Charger (Based on IEEE Standard 946, Annex D): The maximum battery charger available continuous short circuit current is 1.5 times the full load current rating of the charger. Charger Voltage: = Batt_Voltage Charger Voltage = 120 Volts, DC © Copyright 2008. Rolta India Limited. All Rights Reserved.

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Charger based on the larger of the the Ampere-hours discharged from the battery or the combination of continuous and non-continuous loads: Charger_Size 150 Amperes Icharger_fault=1.5 charger_Size Icharger_fault =225 Amperes Charger based on the larger of the rated Ampere-hour size of the battery or the combination of continuous and non-continuous loads: Selected_Charger_Size = 200 Amperes Icharger_Selected_fault:= 1.5 Selected_Charger_Size. Icharger_Selected_fault = 300 Amperes

A. Battery Size: 1. Inputs: Load Duty Cycle Section

Amperes Time (minutes)

320 1 100 29 280 A=

M=

30

200

60 59

40 1 120

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For load duration curve see the following curve-----

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DesignMargin =1.15 AgingFactor =1.25 ElectrolyteTempLow =65 Degrees F, lowest electrolyte temperature TempCorrFactor =1.08 2. Results:

Minimum_Cell_Voltage =1.75

Volts per cell end voltage

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Total_Number_Cells =  60

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Total number of cells

PositivePlates =13

Number of positive plates

Plates =27

Total number of plates required.

AmpHour_SizeR =1040

Ampere-hours for an 8 hour discharge to the specified Volts-per-cell end voltage.

Manufacturer ="ABC"

Cell_Type ="XYZ"

B. Battery Charger Size: 1. Inputs: T c= 8

Hours, recharge time

C =1.1

Recharging efficiency constant

L c =50

L n= 60

Amperes, largest combination of noncontinuous loads

2. Results: Charger_Size =150

Amperes DC, based on the larger of the the Ampere-hours discharged from the battery or the combination of continuous and non-continuous loads.

Selected_Charger_Size =200

Amperes DC, based on the larger of the rated Ampere-hour size of the selected battery or the combination of continuous and non-continuous loads.

C. Short Circuit Current Available 1. Inputs: CellVoltage =2.00 Volts per cell, nominal

Initial Voltage Curve Data V1 = 1.90

Volts

I1 = 60

Amperes per positive Plate.

V2 = 1.50

Volts

I2 = 370 Amperes per positive Plate.

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a. Battery Short Circuit Current Batt Voltage = 120 Volts, DC, nominal battery short circuit voltage. Ic1 = 20150

Amperes, available battey short circuit current

b. Battery Charger Short Circuit Current Charger Voltage = 120 Volts, DC, nominal charger short circuit voltage. Charger based on the larger of the Ampere-hours discharged from the battery or the combination of continuous and non-continuous loads. Icharger Fault = 225

Amperes, available charger short circuit current

Charger based on the larger of the rated Ampere-hour size of the battery or the combination of continuous & non-continuous loads: Icharger Selected Fault = 300 Amperes, available charger short circuit current.

6.SAMPLE CALCULATION OF BATTERY SIZING 1.0 Site and system Conditions Ambient temp. : Max: 46.6°C, Min: -0.7°C Design ambient temp. : Max: 45°C, Min: 10°C (for battery sizing) Maximum voltage : 220, +10% 242V (as per Bid package)

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ELECTRICAL DESIGN PROCEDURES Minimum voltage End cell voltage

BATTERY SIZING CALCULATIONS

DTP-E-GEN-1003-00

: 220, -10% = 198 V (as per Bid. package) : 1.16V (as per Bid package)

2.0. Battery sizing calculation 2.1 No of cells Number of battery cells shall be based on the following No.of cells : Maximum allowable system voltage/Float charging voltage per cell =242V/ 1.41 = 171.63 = 172 Minimum system voltage ≥ No of cells x End cell voltage = 172 x 1.16= 199.52V No of cells selected : 172 2.2 Calculation of load cycle 2.2.1 Calculation of continuous electrical loads (I2)

S.NO

DESCRIPTION

QTY

TOTAL NO OF PANEL

1

Indicating lamps for HV sw.bd (6.6kV & 33kV)

3 per panel

34

2.5

255

2

Indicating lamps for MV sw.bd

3 per breaker feeder

70

2.5

525

3

86 relay

2 per sw.bd

10

3.0

60

4

Aux.relay

1 per bkr feeder

100

3

300

5

Motor protection relay

50% of HV and MV motors

13

15

195

6

Motor diff. relay

As per project design data

3

15

45

7

Under voltage relay

4nos per sw.bd

5

15

300

8

ELR for motors rated above 22KW

50% of motors

I2

3

36

9

As per design data

10

As per plan layout

-

-

2200

11

As applicable

-

-

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-

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ELECTRICAL DESIGN PROCEDURES

BATTERY SIZING CALCULATIONS

12

-

-

-

1000

13

Owner’s DC load for Elect. Control

.

-

-

2000

14

15

DTP-E-GEN-1003-00

2000 -

-

-

-

Total load = 8916 watts TotaI current (I2) 40.55 Amps 2.2.2 Calculation of electrical load (I4) S.NO

DESCRIPTION

QTY

TOTAL NO OF PANEL

1

HV incomer bkr tripping on U/V

2 no. per swbd

2

300

600

2

MV incomer bkr tripping on U/V

2 no. per swbd

7

200

1400

3

Breaker fed motor tripping on U/V

50% HV and MV motors

13

6 nos. - 300W (HV) & 7 nos. – 200W(MV)

3200

4

Aux.relay

1 per HV panel + 4 per PCC / EPMCC

46

3

138

5

Closing of EPMCC incomer

1No.

1

200

200

6

-

-

-

-

Total load = 5538 watts TotaI current (I4) = 25.173 Amps 2.2.3 Calculation of electrical load (I5)

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ELECTRICAL DESIGN PROCEDURES

BATTERY SIZING CALCULATIONS

DTP-E-GEN-1003-00

DESCRIPTION

QTY

TOTAL NO OF PANEL

I

Closing of main HV incomer bkr

2 nos. per substation

2

300

600

2

Closing of main MV incomer bkr

2 nos. per substation

2

200

400

3

Breaker spring charging motor

2 nos. per substation

2

400

800

4

Aux.relay

1 per HV panel + 4 per PCC / EPMCC

46

3

138

5

-

-

-

-

S.NO

Total load = 1938 watts TotaI current (I5) = 8.809 Amps 2.24 Calculation of random electrical load (IR) IR = load expected during any period of the duty cycle = NIL Amps. Electrical Loads for various duty cycle are First minute duty cycle I1 =I2 + I4 = 40.53 + 25.173 = 65.703 for duration of’ M 1 minutes 66A for 1 min. Next duty cycle I2 = I2 = 40.53 A for duration of M2 minutes = Approx. 41A for 118 min cycle I3=I2+I5 = 40.53 + 8.809 = 49.339 for duration of’ M3 minutes = Approx. 50A for 1 min IR = lR for duration of MR minutes - NIL

= Approx. Last minute duty Random load if any

Loads and time duration is tabulated as shown below

2.3 Duty cycle diagram S. NO

DURATION(MIN)

1.0

I1

1

66

REMARKS

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ELECTRICAL DESIGN PROCEDURES

BATTERY SIZING CALCULATIONS

Issue Date: Uncontrolled When Reproduced

DTP-E-GEN-1003-00

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