Take Home Assignment - Transformer Calculations PDF

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Transformer Calculations...

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Take Home Assignment Transformer Calculations Name: Deanne Aira P. Pimentel

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Date: August 4, 2020

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Please calculate the question below in the space provided. Be sure to show all of your work!! 1) 35KVA, 600v Primary, 120/208v Secondary, 3 Phase 4 wire system.(12 Marks)

Assuming Dry−type Transformer :

a) What is the size of the Primary Fuse? (3 marks)

I primary =

KVA ×1000 Eline ×1.73

=

35 ×1000 =33.7 A 600 V ×1.73

MaximumCalculated Fuse Rating:

Rule 26 −254 ( 1)

PrimaryFuse Rating Max. =I primary × 1.25 ¿ 33.7 A ×1.25 ¿ 42.1 A Suggested Primary Fuse ¿ 42.1 A Stand ard Primary Fuse ¿ Table 13 ¿=40 A , ans .

b) What size Disconnect? (3 marks)

I primary =

KVA ×1000 Eline ×1.73

=

35 ×1000 =33.7 A 600 V ×1.73

Suggested Primary Fuse ¿ 33.7 A × 1.25=42.1 A

Use 40 A fused disconnects , ans .

C) What size T90 conductors for Line side AND Load Side?(3 marks)

Minimum Ampacity Rating : Rule26 −256 (1)(a) ¿ Ip×

1.25

¿ 33.7 A ×1.25 ¿ 42.1 A

Table 2 Conductor ¿ (¿ ):Three¿ 8 AWG T 90 Copper , ans .

D) What size T90 conductors from Transformer to Panel(Secondary feeder)? (3 marks)

I secondary=

35× 1000 =97.3 A 208× 1.73

Minimum Ampacity Rating=I s ×1.25=97.3 A × 1.25=121.6 A Conductor ¿Table 2 ¿ : Four ¿ 2 T 90 Copper , ans .

Please calculate the question below in the space provided. Be sure to show all of your work!! 2) 45KVA, 600v Primary, 120/208v Secondary, 3 Phase 4wire system(12 marks)

Assuming Dry−type Transformer :

a) What size T90 copper conductor from Transformer to Panel?(3 marks)

I s=

45 ×1000 =125.1 A 208× 1.73

Minimum Ampacity Rating=125.1 A × 1.25=156.4 A Table 2 Conductor ¿ (¿ ):Four ¿ 1∅ T 90 Copper , ans .

b) Size conduit from Disconnect to Transformer? (3 marks)

Ip=

45× 1000 =43.4 A 600× 1.73

Minimum Ampacity Rating=I p × 1.25=43.4 A × 1.25=54.25 A Table 2 Conductor ¿(¿):Three¿ 8 T 90Coppe r

Table 6 K '' Conduit ¿(¿):Use 3 / 4 ∨21mm conduit , ans .

C) Size conduit from Transformer to Panel?

¿a¿ Table 2 Conductor ¿(¿):Four 1∅ T 90 Copper Table 6 K Conduit ¿(¿):Use 2'' ∨53 mm conduit , ans .

D) Bonding conductor from Secondary Side? (3 marks)

¿a¿

Minimum Ampacity Rating=156.4 A Bonding Conductor (Table 16):¿ 6 AWG Copper , ans .

Please calculate the question below in the space provided. Be sure to show all of your work!!

3) 80 KVA, 600v Primary, 120/208v Secondary, 3 Phase 4 wire system.(24 marks)

Assuming Dry−type Transformer :

a) Primary fuse size? (3 marks)

I primary =

KVA ×1000 Eline ×1.73

=

80 ×1000 =77.1 A 600 V × 1.73

MaximumCalculated Fuse Rating:

Rule 26 −254 ( 1)

PrimaryFuse Rating Max. =I primary × 1.25 ¿ 77.1 A ×1.25 ¿ 96.4 A Suggested Primary Fuse S ize=96.4 A Standard Primary Fuse S ize=90 A , ans .

b) Size of disconnect? (3 marks)

I primary =

KVA ×1000 Eline ×1.73

=

80 ×1000 =77.1 A 600 V × 1.73

Suggested Primary Fuse ¿ 77.1 A × 1.25=96.4 A

Use 90 A Fused Disconnects , ans . c) Size of T90 Copper Conductor from:(6 marks) i) Main power to Disconnect(2 marks)

Ip=

80× 1000 =77.1 A 600× 1.73 Minimum Ampacity Rating=I p × 1.25=77.1 A × 1.25=96.4 A

Table 2 Conductor ¿(¿):Three¿ 3 AWG T 90 Copper ,ans .

ii) Load side of Disconnect (2 marks)

Minimum Ampacity Rating=I p × 1.25=77.1 A × 1.25=96.4 A Table 2 Conductor ¿(¿):Three¿ 3 AWG T 90 Copper ,ans .

iii) Transformer to Panel (2 marks)

I s=

80 ×1000 =222.3 A 208× 1.73 Minimum Ampacity Rating=I s ×1.25=222.3 A × 1.25=277.9 A

Table 2 Conductor ¿(¿):Four 250 kcmil T 90 Copper , ans .

d) Size of Panel? (3 marks)

I secondary=

KVA ×1000 Eline × 1.73

=

80 ×1000 =222.3 A 208 V ×1.73 Rule 26 −254 ( 1)

MaximumCalculated Fuse Rating:

Secondary Fuse Rating Max.=I s × 1.25

¿ 222.3 A × 1.25=277.9 A

Table 13 Standard Primary Fuse ¿ (¿)=250 A , ans . e) Size of conduit from disconnect to Transformer? (3 marks)

Minimum Ampacity Rating=I p × 1.25=77.1 A × 1.25=96.4 A Table 2 Conductor ¿(¿):Three ¿ 3 T 90 Copper Table 6 K Conduit ¿(¿):Use 35 mm conduit , ans .

f) Size of conduit from Transformer to Panel? (3 marks)

Minimum Ampacity Rating=I s ×1.25=222.3 A × 1.25=277.9 A Table 2 Conductor ¿ (¿ ):Four 250 kcmil T 90 Copper Table 6 K Conduit ¿(¿):Use 78 mm conduit , ans .

g) Secondary Bonding conductor? (3 marks)

Minimum Ampacity Rating=I s ×1.25=222.3 A × 1.25=277.9 A Bonding Conductor ( Table 16 ) :¿ 4 AWG Copper , ans ....