Ohmite F55 Stackable Datasheet

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

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
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
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












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
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






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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
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
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