Single Phase Control Transformer Selection Guide

TEMCo Single Phase Control Transformer Selection Guide

TEMCo 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.

TEMCO 1 Phase Control Transformer

Features & Specifications

• Built to order FAST in 1 week.
• 10 Year Warranty - Guaranteed to last.
• Copper Windings - Standard on all units.
• 130°C Insulation class, 80°C temperature rise (25-1000 VA models).
• 155°C Insulation class, 100°C temperature rise (1500-7500 VA models).
• Easy Wiring - Solid terminals with combination screw connections.
• Clear Terminals Marking - identified with additive polarity markings.
• Versatile - Models with multi-voltage primary and secondary increase applications possible.
• Silicon Steel Lamination - Minimize core losses and increase efficiency.
• Excellent Regulation - Designs incorporate precision wound coils layers and exceed NEMA requirements.
• High Efficiency and Heat Dissipation - Every coil is precision bobbin-wound.
• Versatile Mounting - Vertically or horizontally.
• CSA Certified & UL Listed
• CE verified up to and including 5000 VA.

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.
Secondary (Output) Voltages: 240, 120/240, 230, 115/230, 220, 110/220, 120, 115, 110, 48, 36, 32, 24, 16, and 12.
Phase: Single
Frequency: 60(some units are rated 50/60 Hz)
VA: 25, 50, 100, 150, 200, 250, 350, 500, 750, 1000, 1500, 2000, 3000, 5000, and 7500.
K Rating: 1
Reverse Connectable: No
Winding Material: Copper
Electrostatic shielded: No
Temperature Rise: 80°C (25-1000 VA), 100°C (1500-7500 VA)
Insulation System: 130°C (25-1000 VA), 155°C (1500-7500 VA)
Enclosure Rating: Open
Construction Style: Open - Core & Coil
Mounting Type: Base/Panel
Cooling: Air/dry
Agency Approvals: UL Listed, CSA Approved, CE Marked (up to and including 5000 VA)
Warranty: 10 Years


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

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.

Full Product Selection
Primary (Input) Voltage View products
600 Click here »
575 Click here »
550 Click here »
480 Click here »
240/480 Click here »
460 Click here »
230/460 Click here »
440 Click here »
220/440 Click here »
416 Click here »
208/416 Click here »
400 Click here »
380 Click here »
347/380 Click here »
Full Product Selection
Primary (Input) Voltage View products
347 Click here »
277 Click here »
240 Click here »
120/240 Click here »
230 Click here »
115/230 Click here »
220 Click here »
110/220 Click here »
208 Click here »
200 Click here »
130 Click here »
120 Click here »
115 Click here »
110 Click here »