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Transformers are useful where the available voltage must be changed to accommodate the voltage required by the load. For many electrical circuits, the National Electrical Code (NEC) requires a separately derived neutral secondary connection provided by Delta-Wye connected transformers. Typical applications include:
• Hospitals
• Office Buildings
• Industrial Plants
• Schools
• Commercial Buildings
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• Shopping Centers
• Apartment Buildings
• High Rise Buildings
• Institutional Buildings
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SolaHD offers a broad range of transformers to meet many applications. These dry-type transformers are offered encapsulated, ventilated or non-ventilated, 600 Volt Class, isolation type, single and three phase, through 500 kVA. Indoor and outdoor models are available.
To help you determine the type of transformer you need, use the online selector or the Selection Steps, Full Load Current and Motor Charts below. |
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Not sure of what you need? Click here to use our Transformer Product Selector
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General purpose transformers can be located close to
the load. No vaults are required for installation and no long, expensive feeder lines are needed. Common applications include inductive and resistive loads such as motors,
lighting and heating.
SolaHD general purpose transformers are manufactured to meet applicable industry standards, are listed in accordance with UL 506 and UL 1561 specifications and are classified as isolation transformers. The family of transformers includes:
Distribution Transformers - Ventilated 15 kVA to 500 kVA
General Purpose
These industry workhorses feature dry type construction and are classified as isolation
transformers.
Low
Temperature Rise
A high efficiency, low loss design minimizes operating costs.
K-Factor
Designed to reduce the heating effects of harmonic currents created by solid state loads.
Copper Wound
SolaHD general purpose transformers have standard aluminum coil windings. As an option, we offer a selection with copper windings.
Automation Transformers -
Non-Ventilated 50 VA to 45 kVA, Drive Isolation 7.5 kVA to 440 kVA and Industrial Control 50 VA to 10 kVA
General Purpose
Dry-type transformers, 600 Volt Class, isolation type, single and three phase.
Indoor and outdoor models available.
Hazardous
Location (Encapsulated)
Comply with Article 500 of the NEC for Class I, Division 2, Group A-D locations.
Buck-Boost
Used for outdoor or designer low voltage lighting. When connected properly, these
transformers can be used to raise or lower the supply voltage to match the needs of the
load.
Drive
Isolation
Designed to handle to the mechanical stresses, voltage demands and harmonics associated
with SCR applications.
Industrial Control
The units supply inrush current demands of electromagnetic loads without the secondary
voltage dropping below 85% of nominal.
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- Find the electrical
load requirements. These are:
- Load
operating voltage.
- Load
frequency (expressed in Hz).
- Determine
load size - usually expressed in kVA, amperage or horsepower.
- Is
the load designed to operate on single phase or three phase
power?
This information is
available from the equipment manufacturer and is typically listed on the nameplate of the
equipment.
- Know the supply
voltage conditions:
- Available source voltage.
- Available source frequency
(A transformer will not change frequency.
The frequency of the supply voltage and the needed load voltage must be equal).
- Number of phases on power
source.
-
Determine the
transformer kVA rating:
- If the load is expressed in
kVA, select the appropriate transformer from the following selection charts (make sure the
selected transformer's kVA rating is equal to or greater than the required load kVA).
- If the load is expressed in
amperage, use either the appropriate kVA formula listed below or the appropriate sizing
chart.
kVA
(1Ø) = (Volts x Amps) / 1000
kVA
(3Ø) = (Volts x Amps x 1.732) / 1000
- If the load is expressed in
wattage, either utilize the formula below to convert to kVA or refer to the equipment
nameplate to obtain amperage requirement.
kVA
= Wattage / (1000 x Power Factor of the load)
- If the load is a motor and
expressed in horsepower, refer to the following Full
Load Current and Motor Horsepower charts
Some sizes may require an
optional weather shield for outdoor use.
Always size the
transformer to the load requirements.
Are there any special application considerations?
- For ambient conditions over 40°C, derate the transformer nameplate KVA by 8% for each 10°C above 40°C.
- For high altitude applications, derate the transformer nameplate KVA by 0.3% for every 330 feet over 3300 feet above sea level. This assures proper transformer convection cooling.
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Some applications may require a transformer design that limits the BTU output of the unit at full load or a design to withstand and mitigate specific electrical anomalies.
For these applications, see the Special Application Transformers section (Chapter 7) or the following transformers:
- Low Temperature Rise
- K-Factor
- Copper Wound
Three things to keep in mind:
- Motor horsepower charts are based on 1800 RPM squirrel cage induction motors. If using another type of motor, check running amperage against the chart and adjust as necessary.
- Increase required transformer KVA by 20% if motors are started more than once per hour.
- If your motor service factor is greater than 1, proportionally increase full load amperage.
(i.e. – if service factor is 1.10, increase full load amperage by 10%.)
Single Phase: Full Load
Current Chart
| kVA Rating |
120 V |
208 V |
240 V |
277 V |
480 V |
600 V |
Amperes |
| .050 |
.42 |
.24 |
.21 |
.18 |
.10 |
.08 |
| .075 |
.63 |
.36 |
.31 |
.27 |
.16 |
.13 |
| .100 |
.83 |
.48 |
.42 |
.36 |
.21 |
.17 |
| .150 |
1.3 |
.72 |
.63 |
.54 |
.31 |
.25 |
| .250 |
2.1 |
1.2 |
1.0 |
.90 |
.52 |
.42 |
| .500 |
4.2 |
2.4 |
2.1 |
1.8 |
1.4 |
.83 |
| .750 |
6.3 |
3.6 |
3.1 |
2.7 |
1.6 |
1.3 |
| 1 |
8.3 |
4.8 |
4.2 |
3.6 |
2.1 |
1.7 |
| 1.5 |
12.5 |
7.2 |
6.3 |
5.4 |
3.1 |
2.5 |
| 2 |
16.7 |
9.6 |
8.3 |
7.2 |
4.2 |
3.3 |
| 3 |
25.0 |
14.4 |
12.5 |
10.8 |
6.3 |
5.0 |
| 5 |
41.7 |
24.0 |
20.8 |
18.1 |
10.4 |
8.3 |
| 7.5 |
62.5 |
36.1 |
31.3 |
27.1 |
15.6 |
12.5 |
| 10 |
83.3 |
48.1 |
41.7 |
36.1 |
20.8 |
16.7 |
| 15 |
125.0 |
72.1 |
62.5 |
54.2 |
31.3 |
25.0 |
| 25 |
208.3 |
120.2 |
104.2 |
90.3 |
52.1 |
41.7 |
| 37.5 |
312.5 |
180.3 |
156.3 |
135.4 |
78.1 |
62.5 |
| 50 |
416.7 |
240.4 |
208.3 |
180.5 |
104.2 |
83.3 |
| 75 |
625.0 |
361.0
|
313.0 |
271.0 |
156.0 |
125.0 |
| 100 |
833.0 |
481.0 |
417.0 |
361.0 |
208.0 |
167.0 |
| 167 |
1392.0 |
803.0 |
696.0 |
603.0 |
348.0 |
278.0 |
200 |
1667.0 |
962.0 |
833.0 |
722.0 |
417.0 |
333.0 |
| 250 |
2083.0 |
1202.0 |
1042.0 |
903.0 |
521.0 |
417.0 |
Three Phase: Full Load Current Chart
| kVA Rating |
208 V |
240 V |
480 V |
600 V |
Amperes |
| 3 |
8.3 |
7.2 |
3.6 |
2.9 |
| 6 |
16.7 |
14.4 |
7.2 |
5.8 |
| 9 |
25.0 |
21.7 |
10.8 |
8.7 |
| 15 |
41.6 |
36.1 |
18.0 |
14.4 |
| 30 |
83.3 |
72.2 |
36.1 |
28.9 |
| 45 |
125.0 |
108.3 |
54.1 |
43.3 |
| 75 |
208.2 |
180.4 |
90.2 |
72.2 |
| 112.5 |
312.0 |
271.0 |
135.0 |
108.0 |
| 150 |
416.0 |
361.0 |
180.0 |
144.0 |
| 225 |
625.0 |
541.0 |
271.0 |
217.0 |
| 300 |
833.0 |
722.0 |
361.0 |
289.0 |
| 500 |
1388.0 |
1203.0 |
601.0 |
481.0 |
Single Phase Motor Chart: AC, Motor Horsepower Amperage
Horse
Power |
115 V |
208 V |
230 V |
460 V |
575 V |
Min Tfmr.
kVA |
Std. NEMA
kVA Size |
| 1/6 |
4.4 |
2.4 |
2.2 |
1.1 |
.9 |
.53 |
.750 |
| ¼ |
5.8 |
3.2 |
2.9 |
1.4 |
1.2 |
.70 |
.750 |
| 1/3 |
7.2 |
4.0 |
3.6 |
1.8 |
1.4 |
.87 |
1.0 |
| ½ |
9.8 |
5.4 |
4.9 |
2.5 |
2.0 |
1.2 |
1.5 |
| ¾ |
13.8 |
7.6 |
6.9 |
3.5 |
2.8 |
1.7 |
2 |
| 1 |
16.0 |
8.8 |
8.0 |
4.0 |
3.2 |
1.9 |
2 |
| 1½ |
20.0 |
11.0 |
10.0 |
5.0 |
4.0 |
2.4 |
3 |
| 2 |
24.0 |
13.2 |
12.0 |
6.0 |
4.8 |
2.9 |
3 |
| 3 |
34.0 |
18.7 |
17.0 |
8.5 |
6.8 |
4.1 |
5 |
| 5 |
56.0 |
30.8 |
28.0 |
14.0 |
11.2 |
6.7 |
7.5 |
| 7.5 |
80.0 |
44.0 |
40.0 |
21.0
|
16.0 |
9.6 |
10 |
| 10 |
100.0 |
55.0 |
50.0 |
26.0 |
20.0 |
12.0 |
15 |
Three Phase Motor Chart: AC, Motor Horsepower Amperage
Horse
Power |
208 V |
230 V |
460 V |
575 V |
Min Tfmr.
kVA |
Std. NEMA
kVA Size |
| ½ |
2.2 |
2.0 |
1.0 |
0.8 |
0.9 |
3.0 |
| ¾ |
3.1 |
2.8 |
1.4 |
1.1 |
1.2 |
3.0 |
| 1 |
4.0 |
3.6 |
1.8 |
1.4 |
1.5 |
3.0 |
| 1½ |
5.7 |
5.2 |
2.6 |
2.1 |
2.1 |
3.0 |
| 2 |
7.5 |
6.8 |
3.4 |
2.7 |
2.7 |
3.0 |
| 3 |
10.7 |
9.6 |
4.8 |
3.9 |
3.8 |
6.0 |
| 5 |
16.7 |
15.2 |
7.6 |
6.1 |
6.3 |
9.0 |
| 7½ |
24.0 |
22.0 |
11.0 |
9.0 |
9.2 |
15.0 |
| 10 |
31.0 |
28.0 |
14.0 |
11.0 |
11.2 |
15.0 |
| 15 |
46.0 |
42.0 |
21.0 |
17.0 |
16.6 |
30.0 |
| 20 |
59.0 |
54.0 |
27.0 |
22.0 |
21.6 |
30.0 |
| 25 |
75.0 |
68.0 |
34.0 |
27.0 |
26.6 |
30.0 |
| 30 |
88.0 |
80.0 |
40.0 |
32.0 |
32.4 |
45.0 |
| 40 |
114.0 |
104.0 |
52.0 |
41.0 |
43.2 |
45.0 |
| 50 |
143.0 |
130.0 |
65.0 |
52.0 |
52.0 |
75.0 |
| 60 |
170.0 |
154.0 |
77.0 |
62.0 |
64.0 |
75.0 |
| 75 |
211.0 |
192.0 |
96.0 |
77.0 |
80.0 |
112.5 |
| 100 |
273.0 |
248.0 |
124.0 |
99.0 |
103.0 |
112.5 |
| 125 |
342.0 |
312.0 |
156.0 |
125.0 |
130.0 |
150.0 |
| 150 |
396.0 |
360.0 |
180.0 |
144.0 |
150.0 |
150.0 |
| 200 |
528.0 |
480.0 |
240.0 |
192.0 |
200.0 |
225.0 |
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