250 Series
‘Thin’ Stackohm®
Vitreous Enamel Power
F ꢁ at u ꢀ ꢁ S
Whenꢀlimitedꢀspaceꢀisꢀaꢀconsideration,ꢀchooseꢀ
Ohmite’sꢀ“thin”ꢀstackableꢀ250ꢀTypeꢀresistors.ꢀTheseꢀ
oval-shapedꢀceramic-coreꢀresistorsꢀfeatureꢀaꢀlowꢀ
profileꢀtoꢀpermitꢀinstallationꢀinꢀspacesꢀwithꢀheightꢀ
restrictions.ꢀTheyꢀareꢀalsoꢀequippedꢀwithꢀintegralꢀ
mountingꢀbracketsꢀsoꢀtheyꢀcanꢀbeꢀfastenedꢀtoꢀaꢀ
chassisꢀandꢀstackedꢀinꢀlocationsꢀwithꢀlimitedꢀsurfaceꢀ
area.
Whenꢀproperlyꢀfastened,ꢀtheꢀmountingꢀbracketsꢀ
addꢀaꢀheatꢀsinkingꢀbenefitꢀresultingꢀinꢀaꢀsmallerꢀsizeꢀ
perꢀwatt.ꢀDurableꢀ250ꢀTypeꢀresistorsꢀareꢀfullyꢀweldedꢀ
andꢀcoatedꢀwithꢀleadꢀfreeꢀvitreousꢀenamel.
•ꢀSmallꢀsize-to-powerꢀratio.
•ꢀStackable
•ꢀIntegralꢀ mountingꢀ bracketꢀ conductsꢀ heatꢀtoꢀ
mountingꢀsurface.
•ꢀLowꢀprofileꢀforꢀuseꢀinꢀequipmentꢀwhereꢀspaceꢀisꢀ
limited.
•ꢀAll-weldedꢀconstruction.
•ꢀRoHSꢀcompliantꢀproductꢀavailable.ꢀAddꢀ“E”ꢀsuffixꢀtoꢀ
partꢀnumberꢀtoꢀspecify.
SꢁꢀꢂꢁS SPꢁcꢂFꢂcatꢂONS
Series
Wattage
10
Ohms
1.0-15K
1.0-50K
1.0-10K
1.0-25K
1.0-30K
Max. Voltage*
187
F10
F20
F30
F40
F55
20
30
40
55
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 resis-
tance value of specified product
chaꢀactꢁꢀꢂStꢂcS
Lead free vitreous enamel
Coating
Core
Ceramic
Tinned lug with hole. RoHS solder composition is 96% Sn, 3.5% Ag, 0.5% Cu
Linearly from 100% @ +25°C to 0% @ +350°C
±5% (J)
Terminals
Derating
Tolerance
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
10x rated wattage for 5 seconds if max. voltage is not exceeded
1 to 20Ω: ±400 ppm/°C
Over 20Ω: ±260 ppm/°C
Overload
Temperature
coefficient
500 VAC: 10 and 20 watt rating. 1000 VAC: 30, 40 and 55 watt rating (mea-
Dielectric with-
sured from lug to mounting bracket)
standing voltage
To calculate, use the formula √P/R
Max. amps
1-866-9-OHMITE • Int’l 1-847-258-0300 • Fax 1-847-574-7522 • www.ohmite.com • info@ohmite.com
110