U400 TTELEC | Alldatasheet

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Technical content

  • Very low resistance values
  • Choice of terminations and mounting styles
  • High overload capability Dimensions (mm) Type A B C D E F G H J max max nom nom nom max max max U412 53 28 13 5.7 6.8 26.5 M4 85 39 U413 116 28 13 5.7 6.8 26.5 M4 150 39 U414 102 36 19 7 98 32 M6 134 43 U415 152 36 19 7 9.8 32 M6 184 43 U416 216 36 19 7 98 32 M6 248 43 U417 267 36 19 7 9.8 32 M6 299 43 General Note Welwyn Components reserves the right to make changes in product specification without notice or liability. All information is subject to Welwyn’s own data and is considered accurate at time of going to print. © Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com 127 Physical Data Issue D · 08.04 A subsidiary of TT electronics plc Welwyn Components General Information The U400 Series of resistors is particularly suitable for overload applications, due to the large energy absorption capability of the heavy tape element and careful matching of tube and enamel thermal characteristics. The Welwyn range is based on six sizes of tube, each of which has a recommended dissipation which limits operating surface temperature to a maximum of 350°C. The resistors may be fitted with tapping bands as required; these may also be used as adjusting bands. Each style is available with the following choice of terminations:- a) Lugs for soldered or screwed connection Style U b) Pigtails for flexible connection Style UP c) Ferrules, permitting connection via spring mounting clips Styles UC and UCB The U400 Series is designed for use with Welwyn type MD40 mounting brackets. and the UC400 Series with spring mounting clips See figs 2 to 6 for illustrations Electrical Data U412 U413 U414 U415 U416 U417 Power rating at 20°C* watts 30 60 125 140 275 375 Resistance range ohms 0R09 to 2R25 0R27 to 6R8 0R28 to 7R2 0R48 to 12R4 0R76 to 19R0 0R96 to 39R0 TCR range (-55 to +200°C). ppm/°C Typically: +75 Maximum: +200 Resistance tolerance % 10 Values Any value within the specified resistance range Ambient temperature range °C -55 to +350 *Mounted horizontally with unobstructed bore. U400_D.qxd 8/9/04 4:55 PM Page 1

© Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com 129 Issue D · 08.04 Welwyn Components Application Notes The recommended dissipation for the resistor hot spot temperature applies to resistors mounted horizontally. If the bore is completely blocked a 15% derating is recommended. However, wherever possible, resistors should be mounted vertically with unobstructed bore and under these conditions can be up-rated by 10%. This makes best use of the chimney effect of the heated tube and will encourage a cooling system of air through the bore. Appreciable reduction of hot spot temperature can be achieved by arranging that resistors are subjected to some measure of forced draught. In general, it is effective to extract air from the resistor enclosure and arrange that an air inlet is adjacent to the bottom of the tubes. Ordering Procedure Specify the type reference and quantity in units. Mounting Devices MD5 and 6 have an ear formed in the bottom surface of the bracket to prevent rotation on the mounting plate. The auxiliary locking springs ensure positive retention of the tube under severe mechanical shock conditions. See figure 8. Ordering Procedure Mounting clips (and auxiliary locking springs, when required): specify the type reference and quantity in units. Mounting Clip dimensions (mm) Fig. 8 Auxiliary locking Resistor Bracket A B C D E F G H J K spring ref. type nom. max nom. max max max ±0.2 dia dia nom ref Mounting bracket dimensions (mm) Fig. 7 Resistor Bracket A B C D E ref. type nom. nom. max max nom U412 MD42 70 81 20 25 5.2 U413 MD42 133 144 20 25 5.2 U414 MD43 124 140 28 30 5.2 U415 MD43 174 190 28 30 5.2 U416 MD43 238 255 28 30 5.2 U417 MD43 290 306 28 30 5.2 U400_D.qxd 8/9/04 4:55 PM Page 3

© Welwyn Components Limited Bedlington, Northumberland NE22 7AA, UK Telephone: +44 (0) 1670 822181 · Facsimile: +44 (0) 1670 829465 · Email: info@welwyn-tt.com · Website: www.welwyn-tt.com Issue D · 08.04 Welwyn Components Type U412 2R25 J Resistance value (IEC62 code) Tolerance (IEC62 code) F1 % G2 % J5 % Ordering Procedure Specify type reference, value and tolerance as shown in this example of U412 2R25 5%: U400_D.qxd 8/9/04 4:55 PM Page 4