Ohmite F55H1R0E Thin stackohm vitreous enamel power Datasheet

250 Series
• All-welded construction.
• RoHS compliant product available. Add “E” suffix to part number to specify.
‘Thin’ Stackohm®
Vitreous Enamel Power
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0.031"
0.794 mm
Diam.
0.063"
1.588 mm
Diam.
0.125"
3.175 mm
0.110":
2.776 mm
0.125"
3.175 mm
0.625"
15.875 mm
0.375"
9.525 mm
10W & 20W
L
A
0.125" *
3.175 mm
0.375"
9.525 mm
0.250"
6.350 mm
0.125"
3.175 mm
Diam.
0.109"
2.776 mm
Diam.
0.196"
4.979 mm
0.250"
6.350 mm
0.188"
4.763 mm
30W, 40W & 55W
L
A
1.000"
25.400 mm
Material
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.
Electrical
Tolerance: ±5% (J)
Power rating: Based on mounting a single resistor on a metal
surface measuring 10” (254mm)
square by 0.04” (1.016mm)
F eat u r es
thick. Reduce rating by 15%
when mounting on non-metallic
• Small size-to-power ratio.
surface.
• Stackable
Overload:
10x rated wattage for
• Integral mounting bracket con5 seconds if max. voltage is not
ducts heat to mounting surface.
exceeded.
• Low profile for use in equipment
Temperature
coefficient:
where space is limited.
1 to 20Ω: ±400 ppm/°C.
Over 20Ω: ±260 ppm/°C
ordering infO
Dielectric withstanding
Series
RoHS Compliant
voltage: 500 VAC: 10 and
20 watt rating. 1000 VAC:
30, 40 and 55 watt rating (measured from lug to
Coating
Wattage Tolerance Ohms
Blank = Vitreous
F = 1%
1R0 = 1 Ω
mounting bracket)
C = Centohm
H = 3%
250 = 250 Ω
To calculate max. amps:
S = Silicone
J = 5%
1K0 = 1,000 Ω
K = 10% 25K = 25,000 Ω
use the formula √P/R
0.375"
9.525 mm
S pe c i f i c at i ons
0.938"
23.813 mm
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.
0.250" *
6.350 mm
0.125"
3.175 mm
0.438"
11.113 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.
25K5 = 25,500 Ω
Made-to-order parts
Terminal Type
See website for See “Resistor Terminals for Tubular Cores”
custom
core info
Tolerance RoHS
Compliant
J = 5%
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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”
Mounting Brackets
(user supplies bracket for core TB)
B = Stacking box
S = Stacking stud, std. height
H = Stacking stud high
U = Unit type
Ohms
Example:
1R00 = 1 Ω
250R = 250 Ω
1K00 = 1,000 Ω
25K0 = 25,000 Ω
25K5 = 25,500 Ω
Dimensions (in. /mm)
Max.
Length L
Length A Voltage*
0.750 / 19.050
1.000 / 25.400
187
2.000 / 50.800
2.313 / 58.750
815
1.250 / 31.750
2.000 / 50.800
281
2.000 / 50.800
2.750 / 69.850
655
3.500 / 88.900
4.250 / 107.950
1405
Series Wattage Ohms
F10
10
1.0-15K
F20
20
1.0-50K
F30
30
1.0-10K
F40
40
1.0-25K
F55
55
1.0-30K
Adjustable versions available. Consult Ohmite.
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
S ta n d a r d pa rt n u m b e r s f o r 2 5 0 s e r i e s
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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
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F55J––– 55
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F40J––– 40
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F30J––– 30
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F20J––– 20
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–––50RE
–––75RE
–––100E
–––150E
–––200E
–––250E
–––300E
–––400E
–––500E
–––750E
–––800E
–––1K0E
–––1K25E
Part No.
Prefix 
Suffix
F10J––– 10
50
75
100
150
200
250
300
400
500
750
800
1,000
1,250
Ohmic value
Ohmic value
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F55J––– 55
F55J––– 55
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F40J––– 40
F40J––– 40
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F30J––– 30
F30J––– 30
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F20J––– 20
F20J––– 20
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F10J––– 10
F10J––– 10
–––1R0E
–––1R5E
–––2R0E
–––3R0E
–––4R0E
–––5R0E
–––7R5E
–––10RE
–––15RE
–––20RE
–––25RE
–––30RE
–––40RE
Part No.
Prefix 
Suffix
Wattage

1
1.5
2
3
4
5
7.5
10
15
20
25
30
40
Wattage

Part No.
Prefix 
Suffix

Ohmic value
Wattage
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 = Standard values; check availability
using the worldwide inventory
search at www.ohmite.com
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Ohmite Mfg. Co. 1600 Golf Rd., Rolling Meadows, IL 60008 • 1-866-9-OHMITE • Int’l 1-847-258-0300 • Fax 1-847-574-7522 • www.ohmite.com • [email protected]
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