Sola/Hevi-Duty 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. Sola/Hevi-Duty offers a broad range of both distribution and automation transformers.
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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.
Hevi-Duty 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 Hevi-Duty offers a selection of general purpose transformers with copper windings. Automation Transformers - Non-Ventilated 50VA to 45kVA, Drive Isolation 7.5kVA to 440kVA and Industrial Control 50VA to 10kVA General Purpose Dry-type transformers (encapsulated, ventilated or non-ventilated), 600 Volt Class, isolation type, single and three phase, through 500 KVA. Indoor and outdoor models available. Hazardous Location (Encapsulated) Comply with Article 500 of the NEC for Class I, Division 2, Group 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.

Selection Steps

1. Find the electrical load requirements. These are: 
   
   1. Load operating voltage.
   2. Load frequency (expressed in Hz).
   3. Determine load size - usually expressed in kVA, amperage or horsepower.
   4. 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.

2. Know the supply voltage conditions:
    
   1. Available source voltage.
   2. Available source frequency (A transformer will not change frequency.
      The frequency of the supply voltage and the needed load voltage must be equal).
   3. Number of phases on power source.
      
      
3. Determine the transformer kVA rating:
    
   1. 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).
      
   2. 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
       
   3. 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)
       
   4. 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.

Full Load Current Charts

Are there any special application considerations?

1. For ambient conditions over 40^°C, derate the transformer nameplate KVA by 8% for each 10^°C above 40^°C.
2. 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.
3. 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:

1. 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.
2. Increase required transformer KVA by 20% if motors are started more than once per hour.
3. 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

Three Phase: Full Load Current Chart

 

Motor Horsepower Charts

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

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