52189101 Busbar Calculation

CLIENT: - M/S PEPSICO HOLDING PVT. LTD. PROJECT: - AQUFINA (PHASE-III) PLANT

AT

MAHUL- MUMBAI.

Bus Bar Calculation for Main LT Panel

A.

Bus Bar size calculation for 3200A Rating Panel: -

CONDITIONS Rating Current:

3200Amp.

System:

415Vac, TPN, 50Hz.

Fault Level:

50KA. For 1 Sec.

Operation Temp:

40°C rise over 45°C ambient.

CONSIDERATION Enclosure size:

1400mm. wide X 400mm. height

Bus bar Size:

2:200x10 per Ph., 1:200x10 for Neutral.

Bus bar material:

Electrolytic gr. Al. (IS 63401/AA6101)

CALCULATION 1.

 AC Current rating for Dual Al. Flats 200x10mm considered considered = 4750Amp. (As per Table – 8.4 as INDAL hand  book   )

2.

 Ambient correction factor (k1) factor (k1) 45°C rise over 35°C (ambient) = .88 (As per Table – 5 as INDAL hand book   )

If ambient Temp. 45°C instead of 35°C than De-rating Factor = 1-θ ° C x α θ α

= Temp difference = 45°C - 35°C = 10 = Resistance-Temp. Coefficient for Al. Bus= 0.00403

k1A

= 1-10 x 0.00403 = 0.96

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3.

Enclosure correction factor (k2) ratio of total conductor bus bar crosssection to enclosure cross-section. (3 x 2 x 200 x 10) x 100 --------------------------------= 2% 1400 x 400 De-rating factor for enclosure = 0.82 ( As per Table – 5 as INDAL hand book )

4. 5.

6.

Correction factor (k3) for busbar material = 1 Up-rating factor (k4) for PVC Sleeving bus bar = 1

Total Combined De-Rating factor

= k1xK1Axk2xk3xk4 = 0.88 x 0.96 x 0.82 x 1 x 1 = 0.693

So, actual rating of considered busbar = 4750 x 0.693 = 3291Amp. Conclusion: - 

It means 2:200x10mm Al. Bus Bar is much sufficient for  3200A Rating as per actual operating conditions.

B.

Minimum Conductor size for Stand 50KA Fault: While considering short circuit condition, assuming a steady state average temperature of 75°C and final temperature of 160 °C then required bus section: CALCULATION: (As per table – 17)

Let

θ θ

f I

 A T Isc

=Final conductor temp after the fault = 160°C. = Initial conductor temp before the fault = 75°C. = Cross sectional area of conductor (Sq. inch) =? = Duration of fault (sec.) = 1 Sec. = Short circuit current = 50KA. A

Or

θ

f + 258

Isc = 14 x 10 ------  log10 ---------------T



θ

I + 258

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Isc x T ---------------------------------------------θ f + 258 

Or

A=

14 x 10





log10 ---------------θ

50,000 x Or

A=

A=

1



---------------------------------------------- = 0.93 in 160 + 258



14 x 10

Or

I + 258



600 mm



.



log10 ---------------75 + 258

Considered bus section = 2x200x10 = 4000mm

.



Conclusion: - 

It means 2:200x10mm Al. Bus Bar is much sufficient for  stand 50KA Fault Current for 1Sec.

C.

TEMPERATURE CONDUCTORS: -

RISE

CALCULATION

OF

Max. Temperature at full Load condition: i.e. When 3200Amp. Flows thru steady state temperature of 45 C. 

Full Load Current T max = Ambient X ------------------------------------------------------- X Allow Trise Actual Current Rating of used Conductors 45 + (3200 / 3291) [45+40].



x 40 = 82.8

C which is within the limit of 85 C





Summary: Hence the designed bus bar for Main Panel is OK & within the safe limit. Reference:

INDAL hand book  And IS: 8623 (Part – 1) of 1993.

MILESTONES SWITCHGEARS PVT. LTD. Tel: (0124) 4002970, 5002971, Telefax: (0124) 4002973.

Bus Bar Calculation for Bus Duct

A. Bus Bar size calculation for 3200A Rating Bus Duct: CONDITIONS Rating Current:

3200Amp.

System:

415Vac, TPN, 50Hz.

Fault Level:

50KA. For 1 Sec.

Operation Temp:

40°C rise over 45°C ambient.

CONSIDERATION Enclosure size:

750mm. wide X 450mm. height

Bus bar Size:

2:200x10 per Ph., 1:200x10 for Neutral.

Bus bar material:

Electrolytic gr. Al. (IS 63401/AA6101)

CALCULATION 1.  AC Current rating for Dual Al. Flats 200x10mm considered = 4750Amp. (As per Table – 8.4 as INDAL hand book   )

2.  Ambient correction factor (k1) 45°C rise over 35°C (ambient) = .88 (As per Table – 5 as INDAL hand book   )

If ambient Temp. 45°C instead of 35°C than De-rating Factor = 1-θ° C x α θ α

= Temp difference = 45°C - 35°C = 10 = Resistance-Temp. Coefficient for Al. Bus= 0.00403

k1A

= 1-10 x 0.00403 = 0.96

MILESTONES SWITCHGEARS PVT. LTD. Tel: (0124) 4002970, 5002971, Telefax: (0124) 4002973.

3. Enclosure correction factor (k2) ratio of total conductor bus bar cross-

section to enclosure cross-section. (3 x 2 x 200 x 10) x 100 --------------------------------= 3.5% 750 x 450 De-rating factor for enclosure = 0.78 ( As per Table – 5 as INDAL hand book )

4. Correction factor (k3) for bus bar material = 1 5. Up-rating factor (k4) for Black Matt Painted bus bar = 1.2

6. Total Combined De-Rating factor = k1xK1Axk2xk3xk4 = 0.88 x 0.96 x 0.78 x 1 x 1.2 = 0.79 So, actual rating of considered bus bar = 4750 x 0.79 = 3752Amp. Conclusion: - 

It means 2:200x10mm Al. Bus Bar is much sufficient for  3200A Rating as per actual operating conditions.

Summary: Hence the designed bus bar for Bus Duct is OK & within the safe limit. Reference:

INDAL hand book  And IS: 8623 (Part – 1) of 1993.

Bus Bar Calculation for Other Panels [Main Bus]

Sl. No.

1.0 2.0 3.0

Used Current Rating in Amp. 1600Amp . 800Amp. 630Amp.

Used Bus Bar Size:

2x100x10 – For Ph. 1x100x10 – For N. 100x10 – For Ph. 100x6 – For N. 80x10 – For Ph. 80x6 – For N.

Current Rating as per INDALHand Book  Table No. 8.4 in Amp.

Max. [Approx]  Total DeRating Factor

Actual Current Rating

2650Amp.

0.7

1855Amp

1565Amp.

0.7

1095Amp

1250Amp.

0.7

875Amp

MILESTONES SWITCHGEARS PVT. LTD. Tel: (0124) 4002970, 5002971, Telefax: (0124) 4002973.