Force Calculation -28 Mva

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

1.1.2 PEAK ASYMETRICAL SHORT CIRCUIT CURRENT: 1.1.2.1 MEANING OF ABREVIATIONS: Iph = RATED PHASE CURRENT ZT = PER UNIT IMPEDANCE OF TRANSFORMER ZS = PER UNIT IMPEDANCE OF TRANSFORMER K1 = K x √2 (IEC 60076-5 1976 AND IT’S AMMENDMENT) EZ = TOTAL PER UNIT IMPEDANCE %X = PERCENT RECTANCE OF TRANSFORMER %R= PERCENT RESISTANCE OF TRANSFORMER

1.1.2.2 CALCULATIONS:

ZT

=

12.216

ZS(HV) = RATED MVAFAULT MVA = 5010000= 0.005 ; EZ(HV) = 0.12216 + 0.005 = 0.12716 ZS(LV) = RATED MVAFAULT MVA = 501000= 0.05 0.17216

%X%R

=

12.210.4044

=

; EZ(LV) = 0.12216 + 0.05 =

30.19 ; K1 = K x √2 = 1.8 x √2 = 2.55

ISC(HV) = IphHV× K1 EZ(HV) = 157.83× 2.55 0.12716 = 3165 ISC(LV) =IphLV× K1 EZ(LV) = 874.44× 2.55 0.17216 = 12957

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

1.1.3 AXIAL IMBALANCE FORCE (as per IEEMP (M.A Waters)): 1.1.3.1 MEANING OF ABREVIATIONS: Dm = MEAN DIA OF WINDING Isc = SHORT CIRCUIT CURRENT N= TURN OF WINDING H = HEIGHT OF WINDING Ka = CONSTANT (SEE ANEX-A)

1.1.3.2 CALCULATIONS:

Fa(hv) = 4π2 ×Ka×N(hv)×Isc(hv)2×DmH×10-7 Newton =4π2 ×0.1387×1334×31652×9122115×10-7 =4.2×106 Newton

Fa(lv) = 4π2 ×Ka×N(lv)×Isc(lv)2×DmH×10-7 Newton =4π2 ×0.1387×241×129572×6762115×10-7 =1.7×106 Newton 1.1.3.3 CONCLUSION:

The result axial imbalance force for winding hv and lv are listed below: winding

CALCULATED VALUE

Fa(hv)

4.2×106 Newton

Fa(lv)

1.7×106 Newton

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

1.1.4 AXIAL COMPRESSIVE FORCE (as per IEEMP (M.A Waters)): 1.1.4.1 MEANING OF ABREVIATIONS: KVA = RATING OF THE JOB %Z = SHORT CIRCUIT IMPEDANCE HW= HEIGHT OF WINDING

1.1.4.2 CALCULATIONS:

Fc

=

34×KVAHw×%Z×9964×10-3 Newton

=34×50,000211.5×.1221×9964×10-3 Newton =0.655×106 Newton

Fc(HV) = 13×Fc= 0.218×106 Newton Fc(LV) = 23×Fc= 0.437×106 Newton

1.1.4.3 CONCLUSION:

The result axial compressive force for winding hv and lv are listed below: winding

CALCULATED VALUE

Fa(hv)

0.218×106 Newton

Fa(lv)

0.437×106 Newton

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

1.1.5 AXIAL COMPRESSIVE STRESS : 1.1.5.1 MEANING OF ABREVIATIONS: FC= AXIAL COMPRESSIVE FORCE OF WINDING

n = NO OF CONDUCTOR RADIALLY t= THICKNESS OF CONDUCTOR w= WIDTH OF KEYBLOCK s = NO OF BLOCK/CIRCLE

1.1.5.2 CALCULATIONS:

Qc

=

Fcn×t×w×sN/mm 2

Qc(HV) = 0.218×1062×2.55×40×24 N /mm2 =44.52 N/mm 2 Qc(LV) =0.437×10612×2.7×40×16 N /mm2 =21 N/mm 2 1.1.5.3 CONCLUSION:

The result required no of vertical support for winding hv and lv are listed below: winding

CALCULATED VALUE

PERMITTED LIMIT

comment

Qc(HV)

44.52 N/mm2

20 N/mm2

NOT OK

Qc(LV)

21 N/mm2

20 N/mm2

NOT OK

1.1.6

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

BENDING STRESS ON CLAMPING RING: 1.1.6.1 MEANING OF ABREVIATIONS: BS= BENDING STRESS FC= TOTAL AXIAL FORCE OF WINDING (IN TON)

n = NO OF JACKING POINTS t= THICKNESS OF PERMAWOOD RING b= WIDTH OF PERMAWOOD RING Dout = O/D OF PERMAWOOD RING Din= I/D OF PERMAWOOD RING 1.1.6.2 CALCULATIONS:

FC = Fa-13 Fc = (4.2×106-0.218×106) N = 3.982×106 N=399.63 TON b =(Dout-Din)2cm= (115-60.0)2cm =27.5

cm

6×π×Fc×D8×t2×n2×b MT/cm2 3×1158×62×102×27.5 MT/cm2=0.00109 MT/cm2 BS(MAX)

=

=

6×π×399.63×10-

1.1.6.3 CONCLUSION:

The result of bending stress on clamping ring listed below: winding

CALCULATED VALUE

PERMITTED LIMIT

BS(MAX

0.00109 MT/cm2

1.1 MT/cm2

1.1.7 COMPRESSIVE STRESS ON WINDINGS: 1.1.7.1

comment OK

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

MEANING OF ABREVIATIONS: PI= COMPRESSIVE STRESS ON INNER WINDING POUT= COMPRESSIVE STRESS ONOUTER WINDING FC= AXIAL COMPRESSIVE FORCE OF WINDING( HV & LV) Fa= AXIAL IMBALANCE FORCE OF WINDING FI = MAX COMPRESSIVE FORCE ON INNER SPACERS FOUT = MAX COMPRESSIVE FORCE ON OUTER SPACERS

Asin= TOTAL SUPPORTED AREA OF INNERWINDING SPACERS Asout = TOTAL SUPPORTED AREA OF OUTER WINDING SPACERS w= WIDTH OF KEYBLOCK b= LENGTH OF KEYBLOCK n = NO OF BLOCK/CIRCLE

1.1.7.2 CALCULATIONS:

FI = Fa+13 Fc = (4.2×106+0.218×106) N = 4.418×106 N = 443.4 ×103 kg FOUT = Fa+23 Fc = (4.2×106+0.437×106) N = 465.37 ×103 kg Asin = w×b×n= 4×9.6×16 cm2= 614.4 cm2 Asout = w×b×n= 4×8×24 cm2= 768 cm2

continued………………………….

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

PI =FiAin= 443.4 ×103 614.4=721.67 kgcm2 Pout=FoutAout= 465.37 ×103 768=605.95kgcm2

1.1.7.3 CONCLUSION:

The result of compressive stress on windings for winding hv and lv are listed below: winding

CALCULATED VALUE

PERMITTED LIMIT

comment

PI(lv)

721.67 kg/cm2

500 kg/cm2

NOT OK

Pout(hv)

605.95 kg/cm2

500 kg/cm2

NOT OK

1.1.8 CRITICAL RESISTANCE TO COLLAPSE:

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

1.1.8.1 MEANING OF ABREVIATIONS: E= MODULUS OF ELASTICITY OF COPPER= m= TOTAL NO OF PARALLEL CONDUCTORS Dm= MEAN DIA OF WINDING( HV & LV) Iph/cond= PHASE CURRENT PER CONDUCTOR OF THE WINDING t = THICKNESS OF THE CONDUCTOR FOUT = MAX COMPRESSIVE FORCE ON OUTER SPACERS

As= TOTAL SUPPORTED AREA OF SPACERS J = CURRENT DENSITY WCR= CRITICAL RESISTANCE TO COLLAPSE

1.1.8.2 CALCULATIONS:

WCR =1.05×E×m×Iph/cond2t×Dm×J2+4500×As×t3×JIph/cond

WCR(LV) =1.05×1.13×106×12×72.920.27×67.6×249.62+4500×614.4×0.273×249.672.9kg cm2 =66.543×103+ 186.325×103 kgcm2 = 252.868×103kgcm2

WCR(HV =1.05×1.13×106×2×78.920.22×91.2×3072+4500×768×0.223×30778.9kgcm2 =7.818 ×103+143×103kgcm2

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

=151×103kgcm2

the total compressive force of the inner and outer spacers must be less than these critical resistance to collapse

1.1.8.3 CONCLUSION:

The result of compressive stress on windings for winding hv and lv are listed below: wcr

winding

CALCULATED VALUE

PI(lv)

721.67 kg/cm2

252.868×103 kg/cm2

OK

Pout(hv)

605.95 kg/cm2

151×103 kg/cm2

OK

1.1.9 HOOP STRESS: 1.1.9.1

comment

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

MEANING OF ABREVIATIONS:

hoop = HOOP STREES Rdc= DC RESISTANCE OF WINDING IN CM HW= WINDING HEIGHT K(CU) = 0.03 × K x √22.55

2

= 0.03

1.1.9.2 CALCULATIONS:

hoop(HV)

=K(CU)

0.127162×211.5

hoop(LV)

×Rdc_hv×Iph_hv2EZ(hv)

= 1029.22

2×Hw

= 339.58

0.03×4.71×157.832

Kg/cm2

= K(CU) ×Rdc_lv×Iph_lv2EZ(lv) 2×Hw

0.172162×211.5

=

=

0.03

×0.0928×874.442

Kg/cm2

1.1.9.2 CONCLUSION:

The result of hoop stress for hv and lv are listed below:

winding

Calculated value

Permissible value

comment

HV

1029.22 Kg/cm2

1250 Kg/cm2

O.K

LV

339.58 Kg/cm2

1250 Kg/cm2

O.K

1.1.10

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

REQUIRED NO OF SUPPORT FOR RADIAL FORCE: 1.1.10.1 MEANING OF ABREVIATIONS: Dm = MEAN DIA OF WINDING t = THICKNESS OF CONDUCTOR OF THE RELATED WINDING EO = MODULUS OF ELASTICITY OF COPPER =1.136 ×106

Ns= REQUIRED NO OF VERTICAL SUPPORT FOR WINDING 1.1.10.1 CALCULATIONS:

Ns(hv) =Dm t×12Xhoop(HV) EO =1100.29×12X1029.22 1.136 ×106 = 39.55 ≅40

Ns(lv) =Dm t×12Xhoop(lV) EO =67.600.27×12X339.58 1.136 ×106 = 14.99 ≅15

1.1.10.2 CONCLUSION:

The result required no of vertical support for winding hv and lv are listed below:

winding

Required supports Available supports

comment

HV

40

24

NOT OK

LV

15

16

OK

ANNEXTURE-A:

20/28 MVA, 33/11 SHORT CIRCUIT KV, Dyn11

FORCE CALCULATION

CALCULATION OF CONSTANT Ka:

15 mm.

HV TAP 746

HV M

LV

2115

1490

=H

T = 2x746+623

HV TAP746

d1 =118 d2 =212

Kt=ATS OF TAPATS OF MAIN+ATS OF TAP=5041334+504=0.274 X1 = 15mm

; d1x1=11815=7.86

X2=H-T4+X1= 2115-14924+15= 170.75 mm

Ka= 1-Kt1+d1x12 + & HV)

Kt21+d2x22

; d2x2=212170.75=1.241

= 0.09162+0.0471=0.1387 (FOR LV