TEMCo Single Phase Control Transformer Selection GuideTEMCo Industrial Control Transformers are used to convert all standard international voltages. Many models are dual frequency rated for 50 and 60 Hz. TEMCo's transformers are built to last, guaranteed! That's why we back these with a decade long warranty. Our industrial control transformers change supply voltages for the operation of components such as contactors, solenoids, relays, and timers. They accommodate momentary current inrush produced when electromagnetic components are energized without compromising secondary voltage stability. Maximum Safety is assured through the secondary control circuit which is isolated from the primary line circuit. Voltage regulation of TEMCo Industrial Control Transformers exceeds standards recommended by the National Electrical Manufacturers Association. Secondary circuit voltage drop between no-load and momentary overload remains exceptionally low maintaining excellent voltage regulation. TEMCo has the capability to wind your custom control transformer with no penalty for small quantity. Please call us with your requirements for a Fast Turnaround Quote. |
IndexGlossary of Technical Terms »Features & Specifications » How to Select a Control Transformer » View Products »  |
Features & Specifications
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• Built to order FAST in 1 week. |
Primary (Input) Voltages: 600, 575, 550, 480, 240/480, 460, 230/460, 440, 220/440, 416, 208/416, 400, 380, 347/380, 347, 277, 240, 120/240, 230, 115/230, 220, 110/220, 208, 200, 130, 120, 115, and 110. |
How to Select a Control Transformer
To properly select a control transformer, you must analyze the load, which involves all electrically energized part in the control circuit.
All electromagnetic control devices have two current requirements. First, it must energize the coil. Second, it must maintain the contact for a specific period of time. It takes 5 to 20 milliseconds to initally energize the coil. The current required for this is many times more than normal. This is called volt-ampere inrush. It is immediately followed by sealed volt-amperes, which is the amount of current needed to hold the contact in the circuit.
Easy 5 Step Selection Guide
1) Determine the voltage and frequency of the supply circuit (i.e. 600 volts, 60 Hz).
2) Determine the total inrush VA of the control circuits from the manufacturer data or the contactor data table. Don't forget to account for the current requirements of indicating lights and timing devices that don't have an inrush VA but are energized at the same time as the other components in the circuit. Their total VA should be added to the total inrush VA.
3) See the regulation data chart. If the supply circuit voltage (Step 1) is relatively stable and varies no more than +/- 5%, see the 90% Secondary Voltage column. If it varies as much as +/- 10%, see the 95% Secondary Voltage column. Go down the column you selected until you get to the inrush VA that is closest to (but not less than) the inrush VA of your control circuit.
4) Follow that value to the far left side of the chart to select the continuous nominal VA rating of the transformer you will need. The secondary voltage that will be delivered under inrush conditions will either be 85%, 90%, or 95% of the rated output voltage, depending on the column you selected from the regulation data chart. The total sealed VA of the control cicuit must not be more than the nominal VA rating of the
5) Refer to the product selection below to find the transformer you need according to the required continuous nominal VA and primary/secondary voltages.
| Table 1 - Inrush VA | ||||||
| Nominal VA Rating | Inrush VA @ 20% & 40% Power Factor | |||||
| 85% Secondary Voltage | 90% Secondary Voltage | 95% Secondary Voltage | ||||
| 20% P.F. | 40% P.F. | 20% P.F. | 40% P.F. | 20% P.F. | 40% P.F. | |
| 50 | 362 | 224 | 289 | 179 | 217 | 134 |
| 75 | 579 | 354 | 462 | 283 | 345 | 211 |
| 100 | 839 | 522 | 664 | 413 | 489 | 304 |
| 150 | 1326 | 842 | 1003 | 637 | 679 | 431 |
| 250 | 3447 | 2281 | 2462 | 1629 | 1477 | 977 |
| 300 | 3894 | 2618 | 2812 | 1890 | 1731 | 1163 |
| 350 | 5418 | 3689 | 3870 | 2635 | 2322 | 1581 |
| 500 | 6496 | 4575 | 4691 | 3304 | 2887 | 2033 |
| 750 | 8377 | 5811 | 5913 | 4102 | 3449 | 2393 |
| 1000 | 11329 | 9005 | 7789 | 6191 | 4248 | 3377 |
| 1500 | 25519 | 18803 | 18013 | 13273 | 10508 | 7742 |
| 2000 | 28178 | 21600 | 19372 | 14850 | 10566 | 8100 |
| 3000 | 34797 | 28391 | 24562 | 20041 | 14328 | 11690 |
| 5000 | 138500 | 84542 | 10000 | 61058 | 61550 | 37574 |
| Table 2 - Typical Magnetic Motor Starter & Contactor Data (60 Hz, 120 Volts, 3-Pole) | ||||||||||
| Contactor | NEMA Size | |||||||||
| 00 | 0 | 1 | 2 | 3 | 4 | 5 | ||||
| A | L | |||||||||
| Allen Bradley | 500 Series | - | 192 | 192 | 240 | 660 | 1225 | 2040 | 1490 | VA Inrush |
| - | 29 | 29 | 29 | 45 | 69 | 110 | 96 | VA Sealed | ||
| K Series | 53 | 110 | 175 | 240 | 580 | 1000 | 1950 | VA Inrush | ||
| 15 | 20 | 22 | 31 | 43 | 65 | 98 | VA Sealed | |||
| ASEA | Heavy Duty Series | 85 | 85 | 100 | 150 | 490 | 900 | 1200 | VA Inrush | |
| 9 | 9 | 11.5 | 15 | 35 | 55 | 65 | VA Sealed | |||
| Furnace | 218 | 218 | 218 | 218 | 310 | 957 | 1518 | VA Inrush | ||
| 25 | 25 | 25 | 25 | 26 | 75 | 116 | VA Sealed | |||
| General Electric | 151 | 151 | 151 | 528 | 1152 | 1248 | 2580 | VA Inrush | ||
| 24 | 24 | 24 | 60 | 83 | 86 | 191 | VA Sealed | |||
| Joslyn Clark | 210 | 210 | 210 | 210 | 724 | 880 | 1790 | VA Inrush | ||
| 18 | 18 | 18 | 18 | 30 | 39 | 295 | VA Sealed | |||
| Siemens-Allis formerly ITE Gould) | 76 | 76 | 76 | 194 | 365 | 530 | 1630 | VA Inrush | ||
| 12 | 12 | 12 | 21 | 35 | 40 | 110 | VA Sealed | |||
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Square D |
165 | 245 | 245 | 311 | 700 | 1185 | 2970 | VA Inrush | ||
| 33 | 27 | 27 | 37 | 46 | 85 | 212 | VA Sealed | |||
| Westinghouse | 160 | 160 | 160 | 160 | 625 | 625 | 1700 | VA Inrush | ||
| 25 | 25 | 25 | 25 | 50 | 50 | 180 | VA Sealed | |||
| Cutler Hammer (Citation Line) |
A1 Series | 87 | 103 | 103 | - | - | - | 1158 | VA Inrush | |
| 15 | 20 | 20 | - | - | - | 100 | VA Sealed | |||
| B1 Series | 102 | 103 | 103 | 140 | 390 | 1158 | 1158 | VA Inrush | ||
| 13 | 20 | 20 | 24 | 50 | 100 | 100 | VA Sealed | |||
Product Selection
Below is a list of all the single phase control transformer configurations we offer. Find the primary voltage you need. Then, click on the link to view the full product selection for that primary voltage.
Secondary voltages offered: 240, 120/240, 230, 115/230, 220, 110/220, 120, 115, 110, 48, 36, 32, 24, 16, and 12.
Control Transformer VA Range offered: 25, 50, 100, 150, 200, 250, 350, 500, 750, 1000, 1500, 2000, 3000, 5000, and 7000.
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