Control Transformers

Catalogs > Industrial Controls Catalog > Power Supplies > Control Transformers > Bulletin 1497A — Machine Tool Transformers

Bulletin 1497A — Machine Tool Transformers

Introduction Standards Compliance and Certifications Cat. No. Explanation Product Selection Approximate Dimensions
Product Selection

Selecting a Machine Tool Transformer

For proper transformer selection, three characteristics of the load circuit must be determined in addition to the minimum voltage required to operate the circuit. These are total steady-state (sealed) VA, total inrush VA, and inrush load power factor.

  • Total steady-state (sealed) VA is the volt-amperes that the transformer must deliver to the load circuit for an extended period of time — the amount of current required to hold the contact in the circuit.


  • Total inrush VA is the volt amperes that the transformer must deliver upon initial energization of the control circuit. Energization of electromagnetic devices takes 30…50 milliseconds. During this inrush period, the electromagnetic control devices draw many times normal current — 3…10 times normal is typical.


  • Inrush load power factor is difficult to determine without detailed vector analysis of all the load components. Such an analysis is generally not feasible. Therefore, a safe assumption is 40% power factor.



  • Selection Process

    1.  Determine the total inrush VA of the control circuits from the table below. Do not neglect the current requirements of indicating lights and other devices that do not have an inrush VA but are re-energized at the same time as the other components in the circuit. Their total VA should be added to the total inrush VA.

    2.  Refer to the table below, Regulation DataInrush VA. If the supply circuit voltage (Step 1) is reasonably stable and fluctuates not more than ± 5%, refer to the 90% secondary voltage column. If it fluctuates as much as ± 10%, refer to the 95% secondary voltage column. Go down the column selected until at the inrush VA closest to, but not less than, the inrush VA of the control circuit.


    3.  Read to the far left side of the chart. The transformer’s continuous nominal VA rating is now selected. The secondary voltage that will be delivered under inrush conditions will be either 85%, 90%, or 95% of the rated secondary voltage, depending on the column selected from the table below, Regulation DataInrush VA. The total sealed VA of the control circuit must not exceed the nominal VA rating of the transformer selected from the table below.

    4.  Refer to the specification tables on the following pages to select a transformer according to the required continuous nominal VA, and primary and secondary voltage combinations.


    Regulation Data — Inrush VA

    Inrush VA at 40% Power Factor Power Factor Adjustments
    Nominal VA Rating 85% 90% 95% Power Factor Multiply By
    50 158 139 116 100% 0.63
    75 242 213 177 90% 0.65
    100 346 302 249 80% 0.70
    150 528 461 379 70% 0.75
    200 869 743 585 60% 0.82
    250 1057 904 719 50% 0.90
    300 1418 1200 937 40% 1.00
    350 1620 1361 1047 30% 1.12
    500 2681 2221 1648 20% 1.27
    750 4560 3718 2700 10% 1.45
    1000 7568 6118 4185
    1500 15724 12423 8203
    2000 16941 13660 9484
    3000 25680 20180 13797
      

    Transformer without Primary or Secondary Fuse Block/Clip§ 

    Continuous VA Cat. Nos.
    Primary
    220x440V, 230x460V, 240x480V (50/60 Hz)
    Primary
    230/460/575V (50/60 Hz)
    Primary
    208/277/380V (50/60 Hz)
    Primary
    208/230/480V (50/60 Hz)
    Primary
    240X480V (50/60 Hz)
    Click to enlarge - 1497_Diagram01 Click to enlarge - 1497_Diagram02 Click to enlarge - 1497_Diagram03 Click to enlarge - 1497_Diagram12 Click to enlarge - 1497_Diagram13
    Secondary
    110, 115, 120V
    Secondary
    115/95V
    Secondary
    115/95V
    Secondary
    120/24V
    Secondary
    48V
    50 1497A-A1-M6-0-N 1497A-A1-M7-0-N 1497A-A1-M8-0-N 1497A-A1-M18-0-N 1497A-A1-M19-0-N
    75 1497A-A2-M6-0-N 1497A-A2-M7-0-N 1497A-A2-M8-0-N 1497A-A2-M18-0-N 1497A-A2-M19-0-N
    100 1497A-A3-M6-0-N 1497A-A3-M7-0-N 1497A-A3-M8-0-N 1497A-A3-M18-0-N 1497A-A3-M19-0-N
    150 1497A-A4-M6-0-N 1497A-A4-M7-0-N 1497A-A4-M8-0-N 1497A-A4-M18-0-N 1497A-A4-M19-0-N
    200 1497A-A5-M6-0-N 1497A-A5-M7-0-N 1497A-A5-M8-0-N 1497A-A5-M18-0-N 1497A-A5-M19-0-N
    250 1497A-A6-M6-0-N 1497A-A6-M7-0-N 1497A-A6-M8-0-N 1497A-A6-M18-0-N 1497A-A6-M19-0-N
    300 1497A-A7-M6-0-N 1497A-A7-M7-0-N 1497A-A7-M8-0-N 1497A-A7-M18-0-N 1497A-A7-M19-0-N
    350 1497A-A8-M6-0-N 1497A-A8-M7-0-N 1497A-A8-M8-0-N 1497A-A8-M18-0-N 1497A-A8-M19-0-N
    500 1497A-A9-M6-0-N 1497A-A9-M7-0-N 1497A-A9-M8-0-N 1497A-A9-M19-0-N
    750 1497A-A10-M6-0-N 1497A-A10-M7-0-N 1497A-A10-M8-0-N 1497A-A10-M19-0-N
    1000 1497A-A11-M6-0-N 1497A-A11-M7-0-N 1497A-A11-M8-0-N 1497A-A11-M19-0-N
    1500 1497A-A12-M6-0-N 1497A-A12-M7-0-N 1497A-A12-M8-0-N
    2000 1497A-A13-M6-0-N 1497A-A13-M7-0-N 1497A-A13-M8-0-N
    3000 1497A-A14-M6-0-N
      
    § Secondary Fuse Block/Clip: Transformers rated 350 VA and below use secondary fuse clips. Transformers rated above 500 VA use secondary fuse blocks.

    Transformer with 1 Secondary Fuse Block/Clip§ 

    Continuous VA Cat. Nos.
    Primary
    220x440V, 230x460V, 240x480V (50/60 Hz)
    Primary
    230/460/575V (50/60 Hz)
    Primary
    208/277/380V (50/60 Hz)
    Primary
    208/230/480V (50/60 Hz)
    Primary
    240X480V (50/60 Hz)
    Click to enlarge - 1497_Diagram01 Click to enlarge - 1497_Diagram02 Click to enlarge - 1497_Diagram03 Click to enlarge - 1497_Diagram12 Click to enlarge - 1497_Diagram13
    Secondary
    110, 115, 120V
    Secondary
    115/95V
    Secondary
    115/95V
    Secondary
    120/24V
    Secondary
    48V
    50 1497A-A1-M6-1-N 1497A-A1-M7-1-N 1497A-A1-M8-1-N 1497A-A1-M18-1-N 1497A-A1-M19-1-N
    75 1497A-A2-M6-1-N 1497A-A2-M7-1-N 1497A-A2-M8-1-N 1497A-A2-M18-1-N 1497A-A2-M19-1-N
    100 1497A-A3-M6-1-N 1497A-A3-M7-1-N 1497A-A3-M8-1-N 1497A-A3-M18-1-N 1497A-A3-M19-1-N
    150 1497A-A4-M6-1-N 1497A-A4-M7-1-N 1497A-A4-M8-1-N 1497A-A4-M18-1-N 1497A-A4-M19-1-N
    200 1497A-A5-M6-1-N 1497A-A5-M7-1-N 1497A-A5-M8-1-N 1497A-A5-M18-1-N 1497A-A5-M19-1-N
    250 1497A-A6-M6-1-N 1497A-A6-M7-1-N 1497A-A6-M8-1-N 1497A-A6-M18-1-N 1497A-A6-M19-1-N
    300 1497A-A7-M6-1-N 1497A-A7-M7-1-N 1497A-A7-M8-1-N 1497A-A7-M18-1-N 1497A-A7-M19-1-N
    350 1497A-A8-M6-1-N 1497A-A8-M7-1-N 1497A-A8-M8-1-N 1497A-A8-M18-1-N 1497A-A8-M19-1-N
    500 1497A-A9-M6-1-N 1497A-A9-M7-1-N 1497A-A9-M8-1-N 1497A-A9-M19-1-N
    750 1497A-A10-M6-1-N 1497A-A10-M7-1-N 1497A-A10-M8-1-N 1497A-A10-M19-1-N
    1000 1497A-A11-M6-1-N 1497A-A11-M7-1-N 1497A-A11-M8-1-N 1497A-A11-M19-1-N
    1500 1497A-A12-M6-1-N 1497A-A12-M7-1-N 1497A-A12-M8-1-N
    2000 1497A-A13-M6-1-N 1497A-A13-M7-1-N 1497A-A13-M8-1-N
    3000 1497A-A14-M6-1-N
      
    § Secondary Fuse Block/Clip: Transformers rated 350VA and below use secondary fuse clips. Transformers rated 500VA and above use secondary fuse blocks.

    Note:Refer to Selecting a Machine Tool Transformer for information on how to select a machine tool transformer.

    Transformer with 2 Primary and 1 Secondary Fuse Block/Clip§ 

    Continuous VA Cat. Nos.
    Primary
    220x440V, 230x460V, 240x480V (50/60 Hz)
    Primary
    230/460/575V (50/60 Hz)
    Primary
    208/277/380V (50/60 Hz)
    Primary
    208/230/480V (50/60 Hz)
    Primary
    240X480V
    (50/60 Hz)
    Click to enlarge - 1497_Diagram01 Click to enlarge - 1497_Diagram02 Click to enlarge - 1497_Diagram03 Click to enlarge - 1497_Diagram12 Click to enlarge - 1497_Diagram13
    Secondary
    110, 115, 120V
    Secondary
    115/95V
    Secondary
    115/95V
    Secondary
    120/24V
    Secondary
    48V
    50 1497A-A1-M6-3-N 1497A-A1-M7-3-N 1497A-A1-M8-3-N 1497A-A1-M18-3-N 1497A-A1-M19-3-N
    75 1497A-A2-M6-3-N 1497A-A2-M7-3-N 1497A-A2-M8-3-N 1497A-A2-M18-3-N 1497A-A2-M19-3-N
    100 1497A-A3-M6-3-N 1497A-A3-M7-3-N 1497A-A3-M8-3-N 1497A-A3-M18-3-N 1497A-A3-M19-3-N
    150 1497A-A4-M6-3-N 1497A-A4-M7-3-N 1497A-A4-M8-3-N 1497A-A4-M18-3-N 1497A-A4-M19-3-N
    200 1497A-A5-M6-3-N 1497A-A5-M7-3-N 1497A-A5-M8-3-N 1497A-A5-M18-3-N 1497A-A5-M19-3-N
    250 1497A-A6-M6-3-N 1497A-A6-M7-3-N 1497A-A6-M8-3-N 1497A-A6-M18-3-N 1497A-A6-M19-3-N
    300 1497A-A7-M6-3-N 1497A-A7-M7-3-N 1497A-A7-M8-3-N 1497A-A7-M18-3-N 1497A-A7-M19-3-N
    350 1497A-A8-M6-3-N 1497A-A8-M7-3-N 1497A-A8-M8-3-N 1497A-A8-M18-3-N 1497A-A8-M19-3-N
    500 1497A-A9-M6-3-N 1497A-A9-M7-3-N 1497A-A9-M8-3-N 1497A-A9-M19-3-N
    750 1497A-A10-M6-3-N 1497A-A10-M7-3-N 1497A-A10-M8-3-N 1497A-A10-M19-3-N
    1000 1497A-A11-M6-3-N 1497A-A11-M7-3-N 1497A-A11-M8-3-N 1497A-A11-M19-3-N
    1500 1497A-A12-M6-3-N 1497A-A12-M7-3-N 1497A-A12-M8-3-N
    2000 1497A-A13-M6-3-N 1497A-A13-M7-3-N 1497A-A13-M8-3-N
    3000 1497A-A14-M6-3-N
      
    § Secondary Fuse Block/Clip: Transformers rated 350VA and below use secondary fuse clips. Transformers rated 500VA and above use secondary fuse blocks.

    Fuse Sizing Charts

    Important: Select the fuse to protect the control circuit conductors in accordance with the National Electrical Code.

    Primary Fuse Sizing Chart (When only primary protection is used)

    Maximum Amp rating for current limiting Class C fuses based on transformer primary voltage and the National Electrical Code

    VA 115V 120V 200V 208V 220V 230V 240V 277V 380V 400V 415V 440V 460V 480V 500V 550V 575V 600V
    50 1.25 1.25 0.75 0.6 0.6 0.6 0.6 0.5 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.25 0.25 0.25
    75 1.8 1.8 1.125 1 1 0.75 0.75 0.75 0.5 0.5 0.5 0.5 0.4 0.4 0.4 0.4 0.3 0.3
    100 2.5 2.5 1.5 1.4 1.25 1.25 1.25 1 0.75 0.75 0.6 0.6 0.6 0.6 0.6 0.5 0.5 0.5
    150 3.5 3.5 2.25 2 2 1.8 1.8 1.6 1.125 1.125 1 1 0.75 0.75 0.75 0.75 0.75 0.75
    200 5 5 3 2.8 2.5 2.5 2.5 2 1.5 1.5 1.4 1.25 1.25 1.25 1.125 1 1 1
    250 3.5 3.2 3.5 3.5 3.2 3.2 3 2.5 1.8 1.8 1.8 1.6 1.6 1.5 1.5 1.25 1.25 1.25
    300 4 4 4.5 4 4 3.5 3.5 3.2 2.25 2.25 2 2 1.8 1.8 1.8 1.6 1.5 1.5
    350 5 4.5 5 5 4.5 4.5 4 3.5 2.5 2.5 2.5 2.25 2.25 2 2 1.8 1.8 1.6
    500 7 6.25 4 4 3.5 3.5 3.2 5 3.5 3.5 3.5 3.2 3.2 3 3 2.5 2.5 2.5
    750 10 10 6.25 6 5.6 5 5 4.5 5.6 5.6 5 5 4.5 4.5 4.5 4 3.5 3.5
    1000 12 12 8 8 7 7 6.25 6 4 4 4 3.5 3.5 3.2 3.2 5 5 5
    1500 20 15 12 12 10 10 10 9 6.25 6.25 6 5.6 5 5 5 4.5 4 4
    2000 20 20 12 12 10 12 12 12 8 8 8 7 7 6.25 6.25 6 5.6 5
    3000 30 30 15 15 15 15 15 12 12 12 12 10 10 10 10 9 8 8
      

    Primary Fuse Sizing Chart (When primary and secondary protection is used)

    Maximum Amp rating for current limiting fuses based on transformer primary voltage and the National Electrical Code

    VA 115V 120V 200V 208V 220V 230V 240V 277V 380V 400V 415V 440V 460V 480V 500V 550V 575V 600V
    50 1 1 0.6 0.6 0.5 0.5 0.5 0.4 0.3 0.3 0.3 0.25 0.25 0.25 0.25 0.2 0.2 0.2
    75 1.6 1.5 0.75 0.75 0.75 0.75 0.75 0.6 0.4 0.4 0.4 0.4 0.4 0.3 0.3 0.3 0.3 0.3
    100 2 2 1.25 1.125 1.125 1 1 0.75 0.6 0.6 0.6 0.5 0.5 0.5 0.5 0.4 0.4 0.4
    150 3.2 3 1.8 1.8 1.6 1.6 1.5 1.25 0.75 0.75 0.75 0.75 0.75 0.75 0.75 0.6 0.6 0.6
    200 4 4 2.5 2.25 2 2 2 1.8 1.25 1.25 1.125 1.125 1 1 1 0.75 0.75 0.75
    250 5 5 3 3 2.8 2.5 2.5 2.25 1.6 1.5 1.5 1.4 1.25 1.25 1.25 1.125 1 1
    300 6.25 6.25 3.5 3.5 3.2 3.2 3 2.5 1.8 1.8 1.8 1.6 1.6 1.5 1.5 1.25 1.25 1.25
    350 7 7 4 4 3.5 3.5 3.5 3 2.25 2 2 1.8 1.8 1.8 1.6 1.5 1.5 1.4
    500 10 10 6.25 6 5.6 5 5 4.5 3.2 3 3 2.8 2.5 2.5 2.5 2.25 2 2
    750 15 15 9 9 8 8 7 6.25 4.5 4.5 4.5 4 4 3.5 3.5 3.2 3.2 3
    1000 20 20 12 12 10 10 10 9 6.25 6.25 6 5.6 5 5 5 4.5 4 4
    1500 30 30 15 15 15 15 15 12 9 9 9 8 8 7 7 6.25 6.25 6.25
    2000 40 40 25 20 20 20 20 15 12 12 12 10 10 10 10 9 8 8
    3000 45 45 35 35 30 30 30 25 15 15 15 15 15 15 15 12 12 12
      

    Secondary Fuse Sizing Chart

    Maximum Amp rating for current limiting midget fuses based on the National Electrical Code

    VA 23V 24V 25V 85V 90V 95V 100V 110V 115V 120V 125V 130V 220V 230V 240V
    50 3.5 3.2 3.2 0.75 0.75 0.75 0.75 0.75 0.6 0.6 0.6 0.6 0.3 0.3 0.3
    75 5 5 5 1.4 1.25 1.25 1.25 1.125 1 1 1 0.75 0.5 0.5 0.5
    100 7 6.25 6.25 1.8 1.8 1.6 1.6 1.5 1.4 1.25 1.25 1.25 0.75 0.6 0.6
    150 10 10 10 2.8 2.5 2.5 2.5 2.25 2 2 2 1.8 1.125 1 1
    200 12 12 12 3.5 3.5 3.5 3.2 3 2.8 2.5 2.5 2.5 1.5 1.4 1.25
    250 15 15 15 4.5 4.5 4 4 3.5 3.5 3.2 3.2 3.2 1.8 1.8 1.6
    300 20 20 20 5.6 5 5 5 4.5 4 4 4 3.5 2.25 2 2
    350 20 20 20 6.25 6.25 6 5.6 5 5 4.5 4.5 4 2.5 2.5 2.25
    500 9 9 8 8 7 7 6.25 6.25 6.25 3.5 3.5 3.2
    750 12 12 12 12 10 10 10 10 9 5.6 5 5
    1000 15 15 15 15 15 12 12 12 12 7 7 6.25
    1500 25 25 25 25 20 20 20 20 15 10 10 10
    2000 35 35 35 30 30 25 25 25 25 15 12 12
    3000 45 40 40 40 35 20 20 20