Transformers Selection Steps

Product catalog summary

Specifications and Procedures:
1. Load Conversion: If the load is expressed in wattage, convert to kVA using the formula: kVA (1Ø) = Volts x Amps / 1000 or kVA (3Ø) = Volts x Amps x 1.732 / 1000. For motor loads expressed in horsepower, refer to the motor horsepower charts.
2. Transformer Sizing: Always size the transformer to the load requirements. Use the online product selector or follow manual steps to determine the electrical load requirements, including operating voltage, frequency, load size, and phase type.
3. Supply Voltage Conditions: Know the available source voltage, frequency, and number of phases.
4. kVA Rating Determination: Select a transformer with a kVA rating equal to or greater than the required load kVA. Use the appropriate formula or sizing chart if the load is expressed in amperage.

Norms and Recommendations:
1. Motor Considerations: Motor horsepower charts are based on 1800 RPM squirrel cage induction motors. Adjust for different motor types and increase transformer kVA by 20% if motors start more than once per hour.
2. Service Factor: If the motor service factor is greater than 1, proportionally increase full load amperage.
3. Special Applications: For ambient conditions over 40°C, derate the transformer kVA by 8% for each 10°C above 40°C. For high altitude applications, derate by 0.3% for every 330 feet over 3300 feet above sea level.

Charts and Data:
1. Full Load Current Charts: Provide amperage values for various kVA ratings across different voltages for both single and three-phase systems.
2. Motor Horsepower Amperage Charts: Detail amperage requirements for motors at different horsepower levels and voltages, with corresponding transformer kVA sizes.

Catalog excerpts

Selection Steps A. An online transformer product selector is available in the Transformer section of our website or you can use the following steps below to manually select a trans former.B. Find the elec trical load re quire ments. These are:1. Load operating voltage.2. Load frequency (ex pressed 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 equip ment.C. Know the supply voltage con ditions:1. Available source voltage.2. Available source fre quency (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.D. 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 transformers 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 on the next page. kVA =Wattage(1000 x Power Factor of the load) 4. If the load is a motor and expressed in horse power, refer to the motor horsepower charts on the next page.Some sizes may require an optional weather shield (order separately) for outdoor use. 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 (1Ҙ) =Volts x Amps1000 kVA (3) =Volts x Amps x 1.7321000 > Visit our website at www.solaheviduty.com or contact Technical Services at (800) 377-4384 with any ques tions. 179 >

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Transformers Selection Steps

Transformers Selection Steps

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