There are two way to search for a Micron stock standard transformer:
- If you know the transformer catalog number, enter it in the Product Search window at the top left of every page and hit <enter>. You can enter just the first part of a catalog number to view all transformers that start with that number.
- To find Micron's control transformers matching the criteria for your application, answer the five questions on the search page.
The search will result in a listing of all the stock standard transformers that match your search. You may re-sort your results be clicking on any of the column headings. (Note that the sorting is alpha-numeric so there may be cases when 230 appears before 24.) Click on the catalog number to view a PDF file containing dimensions, ratings, a product drawing and schematic of that product. The PDF file is viewable with Adobe Acrobat Reader already installed on most browsers. (If you don't have Acrobat Reader, you may download it for free).
If no results are received, the product you are looking for may be a custom or specialty product. Call Micron at 800 664-4660 for unparalleled responsiveness to your specific application needs.
Micron provides rapid response by providing their products in either Ready to Ship or Standard Shipping options.
Quick Ship Products These products are available for next day shipping.
Standard Ship Products These products require assembly and thus are available for our traditional rapid response shipping of 7 to 10 days.
Selecting a transformer for industrial control circuit applications requires knowledge of the following terms:
Capacity is the Transformer VA rating. View "selection of a transformer" below.
Input or Primary Voltage is the voltage available from the electrical distribution system and its operational frequency, which is connected to the transformer supply voltage terminals. Note that industry equivalencies are built into our search tool. Thus, if you search on an input voltage of 110, you will also receive results for 115 and 120, and likewise for other voltage equivalencies.
Output or Secondary Voltage is the voltage required for load operation which is connected to the transformer load voltage terminals. Note that industry equivalencies are built into our search tool. Thus, if you search on an input voltage of 110, you will also receive results for 115 and 120, and likewise for other voltage equivalencies.
CE Marked signifies the compliance to the applicable requirements of a particular product as outlined by the International Electrotechnical Commission (IEC) and by mutual agreement is recognized throughout the European Union. See the Industrial Standards page in the Tech Support & Resources section for more information.
Primary Fusing - In compliance with the requirements of UL508 and the National Electrical Code, ImperviTRAN and ValuTRAN transformers, rated 50 VA and larger, can be ordered with the provision for factory mounted dual primary class cc fusing capability. Indicate fusing preference with the radio button selector.
Secondary Fusing - Micron offers a variety of secondary fusing options to meet most applications for Impervitran and Valutran transformers.
SELECTION OF A TRANSFORMER
In order to select a transformer, you will need to determine the circuit variables including the Inrush VA and sealed VA.
Inrush VA is the product of load voltage (V) multiplied by the current (A) that is required during circuit start-up. It is calculated by adding the inrush VA requirements of all devices (contactors, timers, relays, pilot lights, solenoids, etc.), which will be energized together. Inrush VA requirements are best obtained from the component manufacturer.
SEALED VA is the product of load voltage (V) multiplied by the current (A) that is required to operate the circuit after initial start-up or under normal operating conditions. It is calculated by adding the sealed VA requirements of all electrical components of the circuit that will be energized at any given time. Sealed VA requirements are best obtained from the component manufacturer. Sealed VA is also referred to as steady state VA.
Once the circuit variables have been determined, transformer selection is a simple 5-step process as follows:
- Determine the Application Inrush VA by using the following industry accepted formula:
-
Refer to the Regulation Data Chart. If the primary voltage is basically stable and does not vary by
more than 5% from nominal, the 90% secondary voltage column should be used. If the primary voltage
varies between 5 and 10% of nominal, the 95% secondary voltage column should be used.
Regulation Data Chart Inrush VA at 20% Power Factor Transformer
VA RatingNEMA/IEC
95% Sec.
VoltageNEMA/IEC
90% Sec.
VoltageNEMA/IEC
85% Sec.
Voltage25 100/--- 130/--- 150/--- 50 170/190 200/220 240/270 75 310/350 410/460 540/600 100 370/410 540/600 730/810 150 780/860 930/1030 1150/1270 200 810/900 1150/1270 1450/1600 250 1400/1540 1900/2090 2300/2530 300 1900/2090 2700/2970 3850/4240 350 3100/3410 3650/4020 4800/5280 500 4000/4400 5300/5830 7000/7700 750 8300/9130 11000/12100 14000/15400 1000* 15000/--- 21000/--- 27000/--- 1000** 9000/--- 13000/--- 18500/--- 1500 10500/--- 15000/--- 20500/--- 2000 17000/--- 25500/--- 34000/--- 3000 24000/--- 36000/--- 47500/--- 5000 55000/--- 92500/--- 115000/--- To comply with NEMA standards, which require all magnetic devices to operate successfully at 85% of rated voltage, the 90% secondary voltage column is most often used in selecting a transformer.
* For units with class 105c insulation systems
** For units with class 180c insulation systems
- After determining the proper secondary voltage column, read down until a value equal to or greater than the Application Inrush VA is found. In no case should a figure less than the Application Inrush VA be used.
- Read left to the Transformer VA Rating column to determine the proper transformer for this application. As a final check, make sure that the Transformer VA Rating is equal to or greater than the total sealed requirements. If not, select a transformer with a VA rating equal to or greater than the total sealed VA.
- Use the transformer selector to determine the proper catalog number based on the transformer VA, and primary and secondary voltage requirements.