RES-250 OHMITE | Alldatasheet
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1-866-9-OHMITE • Int’l 1-847-258-0300 • Fax 1-847-574-7522 • www.ohmite.com • info@ohmite.com110
250 Series
‘Thin’ Stackohm® Vitreous Enamel Power Series Wattage Ohms Max. Voltage* F10 10 1.0-15K 187 F20 20 1.0-50K 815 F30 30 1.0-10K 281 F40 40 1.0-25K 655 F55 55 1.0-30K 1405 Adjustable versions and other sizes available; Consult Ohmite Also available in low cost Centohm or Silicone coating; Consult Ohmite. * Maximum Voltage is based on Ohm’s Law [V=√P*R] as limited by the resis- tance value of specified product
- Small size-to-power ratio.
- Stackable
- Integral mounting bracket conducts heat to mounting surface.
- Low profile for use in equipment where space is limited.
- All-welded construction.
- RoHS compliant product available. Add “E” suffix to part number to specify. When limited space is a consideration, choose Ohmite’s “thin” stackable 250 Type resistors. These oval-shaped ceramic-core resistors feature a low profile to permit installation in spaces with height restrictions. They are also equipped with integral mounting brackets so they can be fastened to a chassis and stacked in locations with limited surface area. When properly fastened, the mounting brackets add a heat sinking benefit resulting in a smaller size per watt. Durable 250 Type resistors are fully welded and coated with lead free vitreous enamel. Coating Lead free vitreous enamel Core Ceramic Terminals Tinned lug with hole. RoHS solder composition is 96% Sn, 3.5% Ag, 0.5% Cu Derating Linearly from 100% @ +25°C to 0% @ +350°C Tolerance ±5% (J) Power rating Based on mounting a single resistor on a metal surface measuring 10” (254mm) square by 0.04” (1.016mm) thick. Reduce rating by 15% when mounting on non-metallic surface Overload 10x rated wattage for 5 seconds if max. voltage is not exceeded Temperature coefficient 1 to 20Ω: ±400 ppm/°C Over 20Ω: ±260 ppm/°C Dielectric with- standing voltage 500 VAC: 10 and 20 watt rating. 1000 VAC: 30, 40 and 55 watt rating (mea- sured from lug to mounting bracket) Max. amps To calculate, use the formula √P/R characteriSticS SerieS SPeciFicatiONS
FeatureS
1-866-9-OHMITE • Int’l 1-847-258-0300 • Fax 1-847-574-7522 • www.ohmite.com • info@ohmite.com 111 Series Wattage Length L Length A F10 10 0.750 / 19.050 1.000 / 25.400 F20 20 2.000 / 50.800 2.313 / 58.750 F30 30 1.250 / 31.750 2.000 / 50.800 F40 40 2.000 / 50.800 2.750 / 69.850 F55 55 3.500 / 88.900 4.250 / 107.950 0.625" 15.875 mm0.031" 0.794 mm 0.125" 3.175 mmDiam. 0.063" 1.588 mm Diam. 0.125" 3.175 mm L A0.110": 2.776 mm 0.250" 6.350 mm 0.375" 9.525 mm 10W & 20W 0.125" 3.175 mm 0.188" 4.763 mmDiam. 0.109" 2.776 mm Diam. 0.196" 4.979 mm L A0.250" 6.350 mm 0.125" 3.175 mm 0.438" 11.113 mm 30W, 40W & 55W 0.375" 9.525 mm 0.125" * 3.175 mm 1.000" 25.400 mm 0.250" * 6.350 mm 0.938" 23.813 mm 0.375" 9.525 mm *Reference dimension only; varies according to resistance value. Note: When resistors are stacked, use washers or spacers as required to insure clearance and improve power dissipa - tion. ‘Thin’ Stackohm® Vitreous Enamel Power dimeNSiONS (in. / mm) 0.625" 15.875 mm0.031" 0.794 mm 0.125" 3.175 mmDiam. 0.063" 1.588 mm Diam. 0.125" 3.175 mm L A0.110": 2.776 mm 0.250" 6.350 mm 0.375" 9.525 mm 0.125" 3.175 mm 0.188" 4.763 mmDiam. 0.109" 2.776 mm Diam. 0.196" 4.979 mm L A0.250" 6.350 mm 0.125" 3.175 mm 0.438" 11.113 mm T T B W W B 0.094" 2.381 mm 0.125" 3.175 mmDiam. 0.063" 1.588 mm Diam. 0.196" 4.979 mm L A 0.125" 3.175 mm 0.438" 11.113 mm T B 0.813" 20.638 mm Core size Core size Core size 0.125" 3.175 mm 0.188" 4.763 mmDiam. 0.109" 2.776 mm Diam. 0.196" 4.979 mm L A 0.125" 3.175 mm 0.438" 11.113 mm (SS) T B W Core size 0.188" 4.763 mm 0.250" 6.350 mm 0.531" 13.494 mm (SSH) 0.125" 3.175 mm 0.188" 4.763 mmDiam. 0.109" 2.776 mm 0.156" x0.313" 3.969 x 7.938 mm Slot L A 0.5" 12.7 mm T B W Core size 0.188" 4.763 mm Brackets cemented in core mOuNtiNg In addition to the standard box bracket, stud type brackets are available for stacking the standard size resistors. Stud type brackets are available in two heights: standard (SS, SSH stud is recommended when stacking the adjustable Type 260, as it assures clearance for the adjustable lugs to pass mended for use with the miniature adjustable and fixed resis- tors to provide clearance, as explained above, or increased wattage. See chart. Derating for stacked mounting Stacked resistors should be derated to prevent excessive tem- peratures due to proximity. Approximate ratings are given in the table. 2 70 70 75 3 60 60 69 4 50 50 60 Miniature with 0.094” (2.381 mm) Spacer WasherMiniatureStd. or Inter. Percent of Single Unit Rating No. of Resistors (continued)
1-866-9-OHMITE • Int’l 1-847-258-0300 • Fax 1-847-574-7522 • www.ohmite.com • info@ohmite.com112 ‘Thin’ Stackohm® Vitreous Enamel Power cOre aNd termiNal SelectiON For Made to Order Type 250 Stackohm Resistors Miniature Intermediate Standard ‡ TE 5 5.250” (133.350mm) 0.938” (23.813mm) 57 Free Air Wattage Rating* Length L Width W Thickness T Code for Core Dia. Min. Ohms Max. Practical Ohms Standard Terminal Fig. No. Dimension A Dimension B *Based on mounting on steeel panel 10” (254mm) x 10” x 0.040” (1.016mm). Core Dimensions† ‡These sizes are Ohmicone (silicone-ceramic) coated–type 450-460. **User supplies brackets. 20 –––20RE 30 –––30RE 40 –––40RE 150 –––150E 300 –––300E 800 –––800E 5,000 –––5K0E 6,000 –––6K0E 7,500 –––7K5E 15,000 –––15KE 20,000 –––20KE 25,000 –––25KE 40,000 –––40KE = Standard values; check availability at www.ohmite.com Ohmic value F10J––– 10 F20J––– 20 F30J––– 30 F40J––– 40 Wattage Part No. Prefix Suffix F55J––– 55 Ohmic value F10J––– 10 F20J––– 20 F30J––– 30 F40J––– 40 Wattage Part No. Prefix Suffix F55J––– 55 Wattage Ohmic value F10J––– 10 F20J––– 20 F30J––– 30 F40J––– 40 Part No. Prefix Suffix F55J––– 55 See web- site for custom core info Tolerance F= 1% H= 3% J= 5% K= 10% Ohms 1R0 = 1Ω 250 = 250Ω 1K0 = 1,000Ω 25K = 25,000Ω 25K5 = 25,500Ω RoHS CompliantSeries WattageCoating Blank =V itreous C= Centohm S= Silicone Ohms Example: 1R00 = 1Ω 250R = 250Ω 1K00 = 1,000Ω 25K0 = 25,000Ω 25K5 = 25,500Ω Series Vitreous enamel: 25 = 250 Fixed 26 = 260 Adjustable Silicone ceramic: 45 = 450 Fixed 46 = 460 Adjustable Wattage & Core Code See “Core and Terminal Selection” Terminal Type See “Resistor Terminals for Tubular Cores” Mounting Brackets (user supplies bracket for core TB) B= Stacking box S= Stacking stud, std. height H= Stacking stud high U= Unit type RoHS Compliant Tolerance J= 5%