Express Transformers & Controls Ltd

Resistors

Express Transformers manufactures a range of wire wound power resistors ranging from 130 watts to 750 watts in a standard range. We also produce special resistors up to 900 watts to order.

A Selection of Resistors

The resistors are close wound on a sturdy ceramic former using nickel/copper wire to BS 115. The stability is obtained by using oxidised wire enabling close winding which prevents shorted turns and turn movement on the former.

The ohmic valus shown in the table below are the maximum obtainable for each gauge of wire within a tolerance of +/- 10%. A tapping band is provided to obtain intermediate values, extra bands can be provided if required.

The current ratings shown produce a temperature rise of approximately 300^oC on the surface of the wire when the resistor is mounted vertically in an ambient temperature of 20^oC.

For each 15^oC increase in the ambient temperature the current ratings should be reduced by 5%.

All the terminals used are nickel silver bands with nickel plated brass screws and nuts and have the facility for either a solder or a screw type extra connection.

Each resistor can be supplied open or cement coated.

To Specify a Resistor

To specify your choice of resistor take the Resistor Type Code followed by the Resistor Number and, should cement coating be required, add the suffix 'C'.

Example
If a 185 Ohm 300 Watt cement coated resistor is required, it would be specified as follows:-
300 Watts = ET/300/8
185 Ohms = Resistor No. 16
Cement Coated = C
Therefore the part number would be ET/300/8-16-C

Technical Data

130 to 300
Watts.

400 to 450
Watts.

600 to 750
Watts.

Slider
Clips.

Dimensions.

130 to 300 Watts
To Index

Power 130 Watts 200 Watts 300 Watts

Resistor Resistor ET/130/6- Resistor ET/200/6- Resistor ET/300/8-

1 7.50 Ohms 0.50 Ohms 0.72 Ohms

2 10.40 Ohms 0.73 Ohms 1.05 Ohms

3 14.70 Ohms 1.10 Ohms 1.49 Ohms

4 21.95 Ohms 1.50 Ohms 2.16 Ohms

5 34.90 Ohms 2.16 Ohms 3.12 Ohms

6 45.0 Ohms 3.16 Ohms 4.58 Ohms

7 60.0 Ohms 5.13 Ohms 7.41 Ohms

8 83.0 Ohms 8.70 Ohms 12.70 Ohms

9 105.0 Ohms 12.05 Ohms 17.41 Ohms

10 150.0 Ohms 17.21 Ohms 24.86 Ohms

11 192.0 Ohms 25.68 Ohms 37.09 Ohms

12 251.0 Ohms 40.40 Ohms 58.34 Ohms

13 302.0 Ohms 53.00 Ohms 76.00 Ohms

14 383.0 Ohms 70.00 Ohms 102.0 Ohms

15 481.0 Ohms 98.00 Ohms 142.0 Ohms

16 620.0 Ohms 128.0 Ohms 185.0 Ohms

17 876.0 Ohms 175.0 Ohms 253.0 Ohms

18 1091.0 Ohms 225.0 Ohms 324.0 Ohms

19 1531.0 Ohms 296.0 Ohms 427.0 Ohms

20 2225.0 Ohms 361.0 Ohms 521.0 Ohms

21 3413.0 Ohms 446.0 Ohms 644.0 Ohms

22 4370.0 Ohms 562.0 Ohms 812.0 Ohms

23
731.0 Ohms 1056.0 Ohms

24
961.0 Ohms 1388.0 Ohms

400 to 450 Watts
To Index

Power 400 Watts 450 Watts

Resistor Resistor ET/400/10- Resistor ET/450/12-

1 0.94 Ohms 1.17 Ohms

2 1.38 Ohms 1.70 Ohms

3 2.09 Ohms 2.58 Ohms

4 2.82 Ohms 3.49 Ohms

5 4.09 Ohms 5.05 Ohms

6 5.98 Ohms 7.39 Ohms

7 9.69 Ohms 11.97 Ohms

8 16.61 Ohms 20.52 Ohms

9 22.77 Ohms 28.13 Ohms

10 32.51 Ohms 40.16 Ohms

11 48.50 Ohms 59.91 Ohms

12 76.30 Ohms 94.25 Ohms

13 100.0 Ohms 123.0 Ohms

14 133.0 Ohms 165.0 Ohms

15 186.0 Ohms 230.0 Ohms

16 242.0 Ohms 299.0 Ohms

17 331.0 Ohms 410.0 Ohms

18 424.0 Ohms 524.0 Ohms

19 599.0 Ohms 690.0 Ohms

20 681.0 Ohms 842.0 Ohms

21 842.0 Ohms 1041.0 Ohms

22 1062.0 Ohms 1311.0 Ohms

23 1382.0 Ohms 1707.0 Ohms

24 1815.0 Ohms 2242.0 Ohms

600 to 750 Watts
To Index

Power 600 Watts 750 Watts

Resistor Resistor ET/600/12- Resistor ET/750/14-

1 1.44 Ohms 1.71 Ohms

2 2.08 Ohms 2.49 Ohms

3 3.18 Ohms 3.79 Ohms

4 4.31 Ohms 5.13 Ohms

5 6.22 Ohms 7.40 Ohms

6 9.10 Ohms 10.83 Ohms

7 14.83 Ohms 17.57 Ohms

8 25.27 Ohms 30.09 Ohms

9 34.63 Ohms 41.23 Ohms

10 49.63 Ohms 58.88 Ohms

11 73.78 Ohms 87.83 Ohms

12 116.00 Ohms 138.17 Ohms

13 152.0 Ohms 181.0 Ohms

14 203.0 Ohms 242.0 Ohms

15 283.0 Ohms 337.0 Ohms

16 368.0 Ohms 438.0 Ohms

17 504.0 Ohms 601.0 Ohms

18 646.0 Ohms 769.0 Ohms

19 850.0 Ohms 1012.0 Ohms

20 1037.0 Ohms 1239.0 Ohms

21 1282.0 Ohms 1526.0 Ohms

22 1655.0 Ohms 1923.0 Ohms

23 2102.0 Ohms 2501.0 Ohms

24 2761.0 Ohms 3287.0 Ohms

Slider Clips
To Index

Each resistor comes with one slider clip fitted - extra's can be purchased as required.

Slider Clip Type Resistor Type Code Used on Resistor No.

SC 01 ET/130/6 1 - 22

SC 02 ET/200/6 7 - 24

SC 02 ET/300/8 7 - 24

SC 02 ET/400/10 7 - 24

SC 02 ET/450/12 7 - 24

SC 03 ET/200/6 1 - 6

SC 03 ET/300/8 1 - 6

SC 03 ET/400/10 1 - 6

SC 06 ET/600/12 All

SC 06 ET/750/14 All

Dimensions
To Index

Dimensions in millimeters

Resistor A B C D E F G

ET/130/6 153 32 194 176 32 28 5.4 x 9

ET/200/6 153 42 208 178 47 51 6.2 x 13

ET/300/8 204 42 259 230 47 51 6.2 x 13

ET/400/10 254 42 309 280 47 51 6.2 x 13

ET/450/12 305 42 356 330 47 51 6.2 x 13

ET/600/12 305 54 356 330 54 78 6.3 x 12.7

ET/750/14 356 54 407 381 54 78 6.3 x 12.7

For further details or literature please contact

Sales Department

Technical Department

For a quote please send us a full electrical specification of your requirements