Table of the electric currents of a 3-phase motor

An electric motor has specifications: voltage is 380 V, 3 phase, frequency is 50 Hz, 1500 rpm, cos phi is 0.8 and real power on the name plate is 22 kW. Convert to HP (Horse Power) and calculate, how many current of electricity will flow into the motor?

Connection of 3-Phase Motor

:catat: Answer:
1HP = 0.75 kW --> 22 kW / 0.75 kW x 1 HP = 29.33 HP
--> 22 kW ≈ 30 HP
:catat: The power of the motor is 30 HP

V = 380 V 3 fase
f = 50 Hz
Cos φ = 0.8
P = 22 kW = 22000 W
I = ...?

The formula of real power electricity in 3-phase:
P = √3 x V x I x Cos φ --> I = P / (√3 x V x Cos φ)
--> I = 22000 / (√3 x 380 x 0.8)
--> I = 41.78 A
:catat: The current of electricity will flow into the motor is 41,78 A

For reference, here is a table of the electric currents of a 3-phase motor, 380 V, cos phi 0.8

kW	HP	A
0.4	0.5	0.8
0.75	1	1.4
1.1	1.5	2.1
1.5	2	2.8
2.2	3	4.2
3	4	5.7
3.7	5	7
4.5	6	8.5
5.5	7.5	10.4
7.5	10	14.2
9	12	17.1
11	15	20.9
15	20	28.5
18.5	25	35.1
22	30	41.8
30	40	57
37	50	70.3
45	60	85.5
55	75	104.5
75	100	142.4

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Octal fractions to decimal numbers

This post is explain how to convert octal fractions to decimal numbers. The picture below is show octal fraction to decimal, form 1st position to 5th position of the digit, before and after the octal point.

Octal fractions to decimal

Example 1:
Convert Octal number 0.725 to decimal number

Completion:
0.725 ₍₈₎ = ... ₍₁₀₎
1st digit after octal point: 7 → 7 × (1/ 8¹) = 7 × 0.125 = 0.875
2nd digit after octal point: 2 → 2 × (1/ 8²) = 2 × 0.015625 = 0.03125
3rd digit after octal point: 5 → 5 × (1/ 8³) = 5 × 0.001953125 = 0.009765625
sum all → 0.875 + 0.03125 + 0.009765625 = 0.916015625

0.725 ₍₈₎ = 0.916015625 ₍₁₀₎

Example 2:
Convert octal number 105.2063 to decimal number

Completion:
105.2063 ₍₈₎ = ... ₍₁₀₎

before octal point
1st digit: 5 → 5 × 8⁰ = 5 × 1 = 5
2nd digit: 0 → 0 × 8¹ = 0 × 8 = 0
3rd digit: 1 → 1 × 8² = 1 × 64 = 64
sum all → 5 + 0 + 64 = 69

after octal point
1st digit: 2 → 2 × (1/ 8¹) = 2 × 0.125 = 0.25
2nd digit: 0 → 0 × (1/ 8²) = 0 × 0.015625 = 0
3rd digit: 6 → 6 × (1/ 8³) = 6 × 0.001953125 = 0.01171875
4th digit: 3 → 3 × (1/ 8⁴) = 3 × 0.000244141 = 0.000732423
sum all → 0.25 + 0 + 0.01171875 + 0.000732423 = 0.262451173

501.2063 ₍₈₎ = 69.262451173 ₍₁₀₎

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Binary fractions to decimal numbers

This post is explain how to convert binary fractions to decimal numbers. The picture below is show binary fraction to decimal, form 1st position to 5th position of the digit, before and after the binary point.

Binary fractions to decimal

Example 1:
Convert binary number 0.1101 to decimal number

Completion:
0.101 ₍₂₎ = ... ₍₁₀₎
1st digit after binary point: 1 → 1 × (1/ 2¹) = 1 × 0.5 = 0.5
2nd digit after binary point: 0 → 0 × (1/ 2²) = 0 × 0.25 = 0
3rd digit after binary point: 1 → 1 × (1/ 2³) = 1 × 0.125 = 0.125
sum all → 0.5 + 0 + 0.125 = 0.625

0.101 ₍₂₎ = 0.625 ₍₁₀₎

Example 2:
Convert binary number 1110.11011 to decimal number

Completion:
1110.11011 ₍₂₎ = ... ₍₁₀₎

before binary point
1st digit: 0 → 1 × 2⁰ = 0 × 1 = 0
2nd digit: 1 → 1 × 2¹ = 1 × 2 = 2
3rd digit: 1 → 1 × 2² = 1 × 4 = 4
4th digit: 1 → 1 × 2³ = 1 × 8 = 8
sum all → 0 + 2 + 4 + 8 = 14

after binary point
1st digit: 1 → 1 × (1/ 2¹) = 1 × 0.5 = 0.5
2nd digit: 1 → 1 × (1/ 2²) = 1 × 0.25 = 0.25
3rd digit: 0 → 0 × (1/ 2³) = 0 × 0.125 = 0
4th digit: 1 → 1 × (1/ 2⁴) = 1 × 0.0625 = 0.0625
5th digit: 1 → 1 × (1/ 2⁵) = 1 × 0.03125 = 0.03125
sum all → 0.5 + 0.25 + 0 + 0.0625 + 0.03125 = 0.84375

1110.11011 ₍₂₎ = 14.84375 ₍₁₀₎

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