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.
Features
- 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.
Specifications
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
Dimensions
(in./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 dissipation.
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, 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.
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
Core and Terminal Selection
For Made to Order Type 250 Stackohm Resistors
*Based on mounting on steeel panel 10” (254mm) x 10” x 0.040” (1.016mm).
†Inside dimensions of core are: 0.250” (6.350mm) x 0.047” (1.191mm) for TA; 0.406” (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.
‡These sizes are Ohmicone (silicone-ceramic) coated–type 450-460.
**User supplies brackets.
