250 Datasheet, PDF (1/3 Pages) CTS Corporation – Commercial Composition 9mm Diameter Variable Resistors

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
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
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 (mea-
standing voltage sured from lug to mounting bracket)
Max. amps To calculate, use the formula √P/R
110
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