Distribution transformers are used to step down the electric energy supplied from the electric grid from medium voltage to low voltage level MV / LV. They are produced with 3 different technologies that include the conservator, hermetic and dry type. The used voltage levels range between 2kV up to 40.5Kv.
Although the transformer are widely used between 25kVA and 2.500kVA, it is also possible to produce higher and lower powers.
Transformers made of aluminum or copper conductor in line with the desired losses, expansion tank, and transformer type. Generally, ONAN cooling models are used, while models with fan are preferred for dry type transformers.
For more details on LV Transformers seeReference Library.
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LV Transformer Selections and Calculations
Transformer Selection Table
Input Type
Input Unit
Output
Selected Transformer Type
Primary Voltage
Secondary Voltage
Impedance
Connection
Cooling (#)
Primary Calculated Load Tables:
(To Transfer To MV Process Equipment Schedule, Save the LV Transformer)
kWatts
Amps
kVA
kVAr
Secondary Calculated Load Tables:
(Transfered From Panelboard Loads)
kWatts
Amps
kVA
Transformer Circuit Protection
(Primary Only)
Fuse Size
Circuit Breaker
125% of Total Circuit Amps
125% of Total Circuit Amps
Enter Panelboard Information
Panelboard Inputs
Input
Panelboard ID
Panelboard Function
kWatts
Secondary Amps
kVA
Note: Complete the Transformer Selection Table on
the Transformer Page Before Entering Panelboard Information.
Secondary Panelboard Loads
Panelboard ID
Panelboard Function
kWatts
Sec. Amps
kVA
Delete
Primary Power Cable Calculator:
Cable Type - 3 Phase
Unit
Selection
Output
Conductor No
Cable Type - Single Phase
Unit
Selection
Output
Cable Type
Transformer Primary Inputs
Unit
Selection
Output
Full Load Amps
Voltage
Cable Temperature Rating
Material
Cable Length (Feet). Use Quick Metric Calculator to convert
to Meters
Choose Cable Size (#)
Primary Voltage Drop Output
Unit
Output
Ohms/Ft
Circular Mils
Voltage Drop (#)
End of Run Volts
% of Drop
Allowable Volt Drop
Secondary Power Cable Calculator:
Transformer Secondary Inputs
Unit
Selection
Output
Full Load Amps
Voltage
Cable Temperature Rating
Material
Cable Length (Feet). Use Quick Metric Calculator to convert
to Meters
Choose Cable Size (#)
Secondary Voltage Drop Output
Unit
Output
Ohms/Ft
Circular Mils
Voltage Drop
End of Run Volts
% of Drop
Allowable Volt Drop
Select Ampacity Table
NEC Single Conductor Ampacity Table
Cable
Copper
Aluminum
Size
60
75
90
60
75
90
14
25
30
35
-
-
-
12
30
35
40
25
30
35
10
40
50
55
35
40
50
8
60
70
80
45
55
60
6
80
95
105
60
75
80
4
105
125
140
80
100
110
3
120
145
165
95
115
130
2
140
170
190
110
135
150
1
165
195
220
130
155
175
1/0
195
230
260
150
180
205
2/0
225
265
300
175
210
235
3/0
260
310
350
200
240
275
4/0
300
360
405
235
280
315
250
340
405
455
265
315
355
300
375
445
505
290
350
395
350
420
505
570
330
395
445
400
455
545
615
355
425
480
500
515
620
700
405
485
545
600
575
690
780
455
540
615
700
630
755
855
500
595
675
750
655
785
885
515
620
700
800
680
815
920
535
645
725
900
730
870
985
580
700
785
1000
780
935
1055
625
750
845
1250
890
1065
1200
710
855
960
1500
980
1175
1325
795
950
1075
1750
1070
1280
1445
875
1050
1185
2000
1155
1385
1560
960
1150
1335
NEC Three Conductor Ampacity Table
Cable
Copper
Aluminum
Size
60
75
90
60
75
90
14
20
20
25
-
-
-
12
25
25
30
20
20
25
10
30
35
35
25
30
35
8
40
50
55
30
40
45
6
55
65
75
40
50
60
4
70
85
95
55
65
75
3
85
100
110
65
75
85
2
95
115
130
75
90
100
1
110
130
150
85
100
115
1/0
125
150
170
100
120
135
2/0
145
175
195
115
135
150
3/0
165
200
225
130
155
175
4/0
195
230
260
150
180
205
250
215
255
290
170
205
230
300
240
285
320
190
230
255
350
260
310
350
210
250
280
400
280
335
380
225
270
305
500
320
380
430
260
310
350
600
355
420
475
285
340
385
700
385
460
520
310
375
420
750
400
475
535
320
385
435
800
410
490
555
330
395
450
900
435
520
585
355
425
480
1000
455
545
615
375
445
500
1250
495
590
665
405
485
545
1500
520
625
705
435
520
585
1750
545
650
735
455
545
615
2000
560
665
750
470
560
630
CEC Single Conductor Ampacity Table
Cable
Copper
Aluminum
Size
60
75
90
60
75
90
14
25
30
35
-
-
-
12
30
35
40
25
30
35
10
40
50
55
35
40
45
8
60
70
80
45
55
60
6
80
95
105
65
75
85
4
105
125
140
85
100
115
3
120
145
165
95
115
130
2
140
170
190
115
135
150
1
165
195
220
130
155
175
1/0
195
230
260
150
180
205
2/0
220
265
300
175
210
235
3/0
260
310
350
200
240
270
4/0
300
360
405
235
280
315
250
340
405
455
265
315
355
300
375
445
500
295
350
395
350
425
505
570
330
395
445
400
455
545
615
355
425
480
500
520
620
700
405
485
545
600
580
690
780
455
545
615
700
630
755
850
500
595
670
750
655
785
885
520
620
700
800
680
815
920
540
645
725
900
730
870
980
585
700
790
1000
785
935
1055
630
750
845
1250
890
1065
1200
715
855
965
1500
985
1175
1325
795
950
1070
1750
1070
1280
1445
880
1050
1185
2000
1160
1385
1560
965
1150
1295
CEC Three Conductor Ampacity Table
Cable
Copper
Aluminum
Size
60
75
90
60
75
90
14
15
20
25
-
-
-
12
20
25
30
20
20
25
10
30
35
40
25
30
35
8
40
50
55
35
40
45
6
55
65
75
40
50
55
4
70
85
95
55
65
75
3
85
100
115
65
75
85
2
95
115
130
75
90
100
1
110
130
145
85
100
115
1/0
125
150
170
100
120
135
2/0
145
175
195
115
135
150
3/0
165
200
225
130
155
175
4/0
195
230
260
150
180
205
250
215
255
290
170
205
230
300
240
285
320
195
230
260
350
260
310
350
210
250
280
400
280
335
380
225
270
305
500
320
380
430
260
310
350
600
350
420
475
285
340
385
700
385
460
520
310
375
420
750
400
475
535
320
385
435
800
410
490
555
330
395
445
900
435
520
585
355
425
480
1000
455
545
615
375
445
500
1250
495
590
665
405
485
545
1500
525
625
705
435
520
585
1750
545
650
735
455
545
615
2000
555
665
750
470
560
630
Motor CAD/Export Generator
All LV Transformer drawings, from Single Lines, AC and DC Schematics, to Wiring Diagrams, can be generated from here!