Transformer

Reference data and engineering information about transformer for electrical applications.

transformerCalculator

Overview

A transformer transfers electrical energy between circuits through electromagnetic induction. It can step voltage up or down while conserving power (ideally).

Formula

$\frac{V_1}{V_2} = \frac{N_1}{N_2}$

Calculator

Notes

Results are approximate and should be verified for critical applications
Input values should be within reasonable engineering ranges

Single Phase Transformer Full Load Current

For a single-phase transformer, the full load current can be calculated using:

$I = \frac{S \times 1000}{V}$

where:

$I$ = full load current (A)
$S$ = transformer apparent power (kVA)
$V$ = voltage (V)

Three Phase Transformer Full Load Current

For a three-phase transformer, the full load current is:

$I = \frac{S \times 1000}{\sqrt{3} \times V}$

Single Phase Transformer Ratings

23 rows

Single-phase transformer full load current vs. kVA rating
Rating(kVA)	120 V(A)	240 V(A)	480 V(A)
0.05	0.42	0.21	0.1
0.075	0.63	0.31	0.16
0.1	0.83	0.42	0.21
0.15	1.25	0.63	0.31
0.25	2.08	1.04	0.52
0.5	4.17	2.08	1.04
0.75	6.25	3.13	1.56
1	8.33	4.17	2.08
1.5	12.5	6.25	3.13
2	16.7	8.33	4.17
3	25	12.5	6.3
5	41.7	20.8	10.4
7.5	62.5	31.3	15.6
10	83.3	41.7	20.8
15	125	62.5	31.3
25	208	104.2	52.1
37.5	313	156.3	78.1
50	417	208.3	104.2
75	625	313	156
100	833	417	208
167	1392	696	348
200	1667	833	417
250	2083	1042	521

Source: engineeringtoolbox.com

Three Phase Transformer Ratings

14 rows

Three-phase transformer full load current vs. kVA rating
Rating(kVA)	240 V(A)	480 V(A)
3	7.2	3.6
6	14.4	7.2
9	21.7	10.8
15	36.1	18
22	53	26.5
30	72.2	36.1
45	108	54.1
75	180	90.2
112.5	271	135
150	361	180
225	541	271
300	722	361
500	1203	601
750	1806	903

Source: engineeringtoolbox.com

Interactive Charts

transformer - primary and secondary coil

Three-phase transformer full load current vs. kVA rating

References

Original Source

Source: engineeringtoolbox.com