250 Series ‘Thin’ Stackohm® Vitreous Enamel Power 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. F e at u r e s • 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. S ERIE S S P ECI F ICATI O N S Series F10 F20 F30 F40 F55 Wattage 10 20 30 40 55 Ohms 1.0-15K 1.0-50K 1.0-10K 1.0-25K 1.0-30K Max. Voltage* 187 815 281 655 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 resistance value of specified product characteristics 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 1 to 20Ω: ±400 ppm/°C coefficient Over 20Ω: ±260 ppm/°C Dielectric with- 500 VAC: 10 and 20 watt rating. 1000 VAC: 30, 40 and 55 watt rating (meastanding voltage sured from lug to mounting bracket) Max. amps To calculate, use the formula √P/R 110 1-866-9-OHMITE • Int’l 1-847-258-0300 • Fax 1-847-574-7522 • www.ohmite.com • [email protected] 250 Series ‘Thin’ Stackohm® Vitreous Enamel Power d i m e ns i ons 0.125" 3.175 mm Diam. 0.063" 1.588 mm Diam. 0.125" 3.175 mm 0.110": 2.776 mm 0.625" 15.875 mm 0.375" 9.525 mm 0.031" 0.794 mm 10W & 20W Series Wattage L A 0.125" * 3.175 mm 0.188" 4.763 mm Diam. 0.196" 4.979 mm 0.250" 6.350 mm 30W, 40W & 55W 1.000 / 25.400 F30 30 1.250 / 31.750 2.000 / 50.800 20 F40 2.000 / 50.800 40 F55 2.313 / 58.750 2.000 / 50.800 55 2.750 / 69.850 3.500 / 88.900 4.250 / 107.950 1.000" 25.400 mm Diam. 0.109" 2.776 mm 0.750 / 19.050 Note: When resistors are stacked, use washers or spacers as required to insure clearance and improve power dissipation. 0.938" 23.813 mm 0.125" 3.175 mm Length A 10 *Reference dimension only; varies according to resistance value. 0.375" 9.525 mm 0.250" 6.350 mm Length L F10 F20 0.375" 9.525 mm (in. / mm) L A 0.250" * 6.350 mm 0.125" 3.175 mm 0.438" 11.113 mm Mo u n t i n g Derating for stacked mounting Stacked resistors should be derated to prevent excessive temperatures due to proximity. Approximate ratings are given in the table. Percent of Single Unit Rating 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, 0.437”/11.113mm) and high (SSH, 0.531”/13.494mm). The SSH stud is recommended when stacking the adjustable Type 260, as it assures clearance for the adjustable lugs to pass eachother. Spacer washer No. 6027 (O.D. 0.219”/5.556mm, I.D. 0.125”/3.175mm, thickness 0.094”/2.381mm) is recommended for use with the miniature adjustable and fixed resistors to provide clearance, as explained above, or increased wattage. See chart. 0.031" 0.794 mm Diam. 0.125" 3.175 mm 0.110": 2.776 mm 0.125" 3.175 mm Diam. 0.063" 1.588 mm 0.625" 15.875 mm 0.094" 2.381 mm B W L A T Core size 0.375" 9.525 mm 0.250" 6.350 mm 0.125" 3.175 mm Diam. 0.196" 4.979 mm 0.250" 6.350 mm 0.125" 3.175 mm 0.188" 4.763 mm Diam. 0.109" 2.776 mm L A 70 60 50 B 0.813" 20.638 mm Core size B Core size 0.156" x0.313" 3.969 x 7.938 mm Slot 0.188" 4.763 mm 75 69 60 0.188" Diam. 4.763 mm 0.109" 2.776 mm Diam. 0.196" 4.979 mm 0.250" 6.350 mm 0.188" 4.763 mm Diam. 0.109" 2.776 mm Miniature with 0.094” (2.381 mm) Spacer Washer 70 60 50 B W L A 0.125" 3.175 mm 0.438" 11.113 mm 0.125" 3.175 mm Miniature 0.125" 3.175 mm T 0.125" 3.175 mm T Std. or Inter. 2 3 4 0.125" 3.175 mm Diam. 0.063" 1.588 mm Diam. 0.196" 4.979 mm 0.188" 4.763 mm W L A No. of Resistors T Core size 0.438" 11.113 mm Brackets cemented in core B W L A T 0.438" 0.531" 11.113 mm 13.494 mm (SS) (SSH) Core size 0.5" 12.7 mm (continued) 1-866-9-OHMITE • Int’l 1-847-258-0300 • Fax 1-847-574-7522 • www.ohmite.com • [email protected] 111 250 Series ‘Thin’ Stackohm® Vitreous Enamel Power Co r e a n d T e r m i n a l S e l e c t i on For Made to Order Type 250 Stackohm Resistors Free Air Wattage Rating* Max. Min. Practical Ohms Ohms Core Dimensions† Code for Core Dia. Fig. No. Standard Terminal Length L Width W Thickness T 10 0.750” (19.050mm) 0.375” (9.525mm) 0.125” (3.175mm) 1 15,000 TA 1 1.000” (25.400mm) 0.375” (9.525mm) 51 15 1.000” (25.400mm) 0.375” (9.525mm) 0.125” (3.175mm) 1 25,000 TA 1 1.250” (31.750mm) 0.375” (9.525mm) 51 20 2.000” (50.800mm) 0.375” (9.525mm) 0.125” (3.175mm) 1 50,000 TA 1 2.313” (58.750mm) 0.375” (9.525mm) 51 12 0.688” (17.463mm) 0.594” (15.081mm) 0.234” (5.953mm) 1 20,000 TB ** Dimension A Dimension B Miniature 51 Intermediate 21 1.000” (25.400mm) 0.813” (20.638mm) 0.250” (6.350mm) 1 8,000 TD 2 1.313” (33.350mm) 0.594” (15.081mm) 51 25 1.500” (38.100mm) 0.813” (20.638mm) 0.250” (6.350mm) 1 15,000 TD 2 1.813” (46.050mm) 0.594” (15.081mm) 51 30 1.250” (31.750mm) 1.000” (25.400mm) 0.250” (6.350mm) 1 10,000 TE 5 3, 4 1.750” (44.450mm) 2.000” (50.800mm) 0.938” (23.813mm) 57 40 2.000” (50.800mm) 1.000” (25.400mm) 0.250” (6.350mm) 1 25,000 TE 5 3, 4 2.500” (63.500mm) 2.750” (69.850mm) 0.938” (23.813mm) 57 4.000” (1.1.600mm) 4.250” (107.950mm) 0.938” (23.813mm) 57 Standard 55 3.500” (88.900mm) 1.000” (25.400mm) 0.250” (6.350mm) 1 30,000 TE 5 3, 4 70 4.750” (120.650mm) 1.000” (25.400mm) 0.250” (6.350mm) 1 120,000‡ TE 5 3, 4 5.250” (133.350mm) 5.500” (139.700mm) 0.938” (23.813mm) 57 1 ‡ TE 5 3, 4 6.500” (165.100mm) 6.750” (171,450mm) 0.938” (23.813mm) 57 95 6.000” (152.400mm) 1.000” (25.400mm) 0.250” (6.350mm) 150,000 *Based on mounting on steeel panel 10” (254mm) x 10” x 0.040” (1.016mm). ‡These sizes are Ohmicone (silicone-ceramic) coated–type 450-460. †Inside dimensions of core are: 0.250” (6.350mm) x 0.047” (1.191mm) for TA; 0.406” **User supplies brackets. (10.319mm) x 0.047” (1.191mm) for TB; 0.438” (11.113mm) x 0.063” (1.588mm) for TD; 0.672” (17.069mm) x 0.063” (1.588mm) for TE. o r d e r i n g i nfo r m a t i on Made-to-order Parts Tolerance F = 1% H = 3% J = 5% K = 10% See website for custom core info Ohms 1R0 = 1Ω 250 = 250Ω 1K0 = 1,000Ω 25K = 25,000Ω 25K5 = 25,500Ω Series Vitreous enamel: 25 = 250 Fixed 26 = 260 Adjustable Silicone ceramic: 45 = 450 Fixed 46 = 460 Adjustable Standard Values 112 1,500 2,000 2,500 3,000 4,000 5,000 6,000 7,500 10,000 15,000 20,000 25,000 40,000 –––1K5E –––2K0E –––2K5E –––3K0E –––4K0E –––5K0E –––6K0E –––7K5E –––10KE –––15KE –––20KE –––25KE –––40KE F30J––– 30 –––50RE –––75RE –––100E –––150E –––200E –––250E –––300E –––400E –––500E –––750E –––800E –––1K0E –––1K25E F20J––– 20 50 75 100 150 200 250 300 400 500 750 800 1,000 1,250 Part No. Prefix Suffix F10J––– 10 Ohmic value Ohmic value F55J––– 55 F55J––– 55 F40J––– 40 Ohms Example: 1R00 = 1Ω 250R = 250Ω 1K00 = 1,000Ω 25K0 = 25,000Ω 25K5 = 25,500Ω Wattage F40J––– 40 F30J––– 30 F20J––– 20 F20J––– 20 Part No. Prefix Suffix F10J––– 10 F10J––– 10 –––1R0E –––1R5E –––2R0E –––3R0E –––4R0E –––5R0E –––7R5E –––10RE –––15RE –––20RE –––25RE –––30RE –––40RE Mounting Brackets (user supplies bracket for core TB) B = Stacking box S = Stacking stud, std. height H = Stacking stud high U = Unit type 1 1.5 2 3 4 5 7.5 10 15 20 25 30 40 Wattage & Core Code See “Core and Terminal Selection” Wattage Part No. Prefix Suffix Ohmic value Wattage Tolerance RoHS Compliant J = 5% Terminal Type See “Resistor Terminals for Tubular Cores” F30J––– 30 Coating Wattage Blank = Vitreous C = Centohm S = Silicone F55J––– 55 RoHS Compliant F40J––– 40 Series 1-866-9-OHMITE • Int’l 1-847-258-0300 • Fax 1-847-574-7522 • www.ohmite.com • [email protected] = Standard values; check availability at www.ohmite.com