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60
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PILKOR components
Carbon composition resistors SR25/37/37L/52
Dimensions ( mm )
TYPE D
0.8
L 1
0.8
L 2
Max.
d
(0.05)
SR25 2.7 6.5 7.5 0.6
SR37 3.7 9.0 12 0.7
SR37L 3.7 11 13 0.7
SR52 6.0 16.5 18.5 0.8
QUICK REFERENCE DATA
VALUE
DESCRIPTION
SR25 SR37 SR37L SR52
resistance range 10Ωto 9.1 ㏀
resistance tolerance 5%, 10% ( E12, E24 series )
temperature coefficient 600 ppm / ℃
rated dissipation
at Tamb = 70 ℃ 0.25 W 0.5 W 1 Ws 1W
max. working voltage 250 V 350 V 500 V 750 V
max. overload voltage 500 V 700 V 1000 V 1500 V
basic specifications IEC 60 115-1B
climatic category (IEC60) 55 / 155 / 56
stability, R/Rmax after
load : 1000 hours 5% 0.1Ω
soldering heat 3% 0.1Ω
FEATURES
Non inductive
High pulse loading capability.
APPLICATIONS
Application for overload and high
voltage surge hazard circuits.
DESCRIPTION
A carbon film is deposited on a high
grade ceramic body. After that caps
are applied to the rods and copper
wire are welded to these end caps.
The resistors are coated with a brown
and blue non fl
ammable lacquer witch
provides electrical, mechanical and
climatic protection.
copper are welded to the end-caps.
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PILKOR components
Carbon composition resistors SR25/37/37L/52
ORDERING INFORMATION
Ordering code indicating resistor types and packing
Table 1
Type Bandolier
width Packing
Quantity
Resistance
range
Tol.
% Ordering code
SR25
( 0.25W ) 52mm ammo 5000 10Ωto 9.1 ㏀ 5
10
PPSR 241 43xxx
PPSR 241 73xxx
Table 2
Type Bandolier
width Packing
Quantity
Resistance
range
Tol.
% Ordering code
SR37
( 0.5W ) 52mm ammo 1000 10Ωto 9.1 ㏀
5
10
15
PPSR 242 33xxx
PPSR 242 15xxx
PPSR 242 22xxx
Table 3
Type Bandolier
width Packing
Quantity
Resistance
range
Tol.
% Ordering code
SR37L
( 1Ws ) 64mm ammo 1500 10Ωto 9.1 ㏀ 5
10
PPSR 243 13xxx
PPSR 243 14xxx
Table 4
Type Bandolier
width Packing
Quantity
Resistance
range
Tol.
% Ordering code
SR52
( 1W ) 64mm ammo 500 10Ωto 9.1 ㏀ 5
10
PPSR 250 11xxx
PPSR 250 14xxx
Table 5. Last digit of 12NC
Resistance decade
Last digit
1 to 9.76Ω 8
10 to 97.6Ω 9
100 to 976Ω 1
1 to 9.76 ㏀ 2
Ordering Example
The ordering code of a SR37- 0.5W resistor, value 4.7 ㏀ 10%, taped on a bandolier of
1000 units in ammopack is: PPSR 242 15472.
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PILKOR components
Carbon composition resistors SR25/37/37L/52
Limiting values
Table 6
TYPE LIMITING VOLTAGE( 1 )
(V)
LIMITING POWER
(W)
SR25 250 0.25
SR37 350 0.5
SR37L 500 1 (small)
SR52 750 1
Note
1. the maximum voltage that may be continuously applied to the resistor element, see
“IEC publication 60 115-1”
The maximum permissible hot – spot temperature is 155 ℃.
DERATING
The power that the resistor can dissipate depends on the operating temperature : Fig. 1
Fig. 1 Maximum dissipation (Pmax) in percentage of rated power as a function of the
ambient Temperature (Tamb)
50
100
-
55
50
70
100
155
0
T
amb
(
℃
)
P
max
( % )
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PILKOR components
Carbon composition resistors SR25/37/37L/52
Surge resistance characteristics
Fig. 2 Maximum allowed peak surge voltage in accordance with “IEC 60065 chapter
14.1” 50 discharges form a 1nF capacitor
charged to Vmax ; 12 discharges / minute
Application information
SR25 - 0.25W
%
0
-5
-10
-15
0 2KV 4KV 6KV 8KV 10KV 12KV 14KV
0.25W
1Ws
1W
Fig. 3 Hot – spot temperature rise (
T ) as
a function of dissipated power
Fig.4 Temperature rise (
T ) at the lead end
of the lead (soldering point) as a f
function of dissipated Power at various
lead lengths after mounting
0.5W
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PILKOR components
Carbon composition resistors SR25/37/37L/52
SR37 – 0.5W
SR37L – 1Ws
Fig. 5 Hot – spot temperature rise (
T ) as
a function of dissipated power
Fig.6 Temperature rise (
T ) at the lead end of
the lead soldering point as a function
of dissipated power at various lead
lengths after mounting
Fig. 7 Hot – spot temperature rise (
T ) as
a function of dissipated power
Fig.8 Temperature rise (
T ) at the lead end of
the lead soldering point as a function
of dissipated power at various lead
lengths after mounting
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PILKOR components
Carbon composition resistors SR25/37/37L/52
SR52 – 1W
MECHANICAL DATA
Table 7. Mass per 100 units
TYPE MASS ( g )
SR25 - 0.25W 25
SR37 - 0.5W 42
SR37L - 1Ws 67
SR52 - 1W 148
MARKING
The nominal resistance and tolerance are marked on the resistor using four or five colored
Bands in accordance with IEC publication 60 062 “color codes for fixed resistors”
Table 8. BODY COLORS
TYPE COLORS
SR25
– 0.25W Brown
SR37
– 0.5W Brown
SR37L
– 1Ws Brown
SR52
– 1W Blue
Fig.10 Temperature rise (
T ) at the lead end of
the lead soldering point as a function
of dissipated power at various lead
lengths after mounting
Fig. 9 Hot – spot temperature rise (
T ) as
a function of dissipated power
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PILKOR components
Carbon composition resistors SR25/37/37L/52
TEST AND REQUIREMENTS
Table 9. Test procedures and requirements
REQUIREMENTS
TEST PROCEDURE
SR25 SR37 SR37L SR52
robustness of
terminations:
tensile all
samples
bending half
number of
samples
torsion other
half number
samples
φ0.6 / 0.7 / 0.8 mm
: load 10N:10s
φ0.6 / 0.7 / 0.8 mm
: load 5N: 4x90
3x360in opposite
directions
number of failures < 10 -6
number of failures < 10 -6
no damage
0.25% 0.05
solderability 2 s ; 235℃ flux 600 good tinning; no damage
soldering heat Thermal shock: 3 s; 360℃
6mm from body 3% +0.1
rapid change of
temperature
30 minutes at –55℃ and
30 minutes at +155℃;5cycles
2% +0.05
vibration
frequency 10 to 500 Hz;
displacement 1.5mm or
acceleration 10g; 3 directions
total 6 hours(3x2 hours)
no damage
1% +0.05
Climatic sequence
dry heat
damp heat
(accelerated)
1st cycle
cold
low air pressure
damp heat
(accelerated)
remaining cycles
16 hours;155℃
24hours;55℃; 90 to 100% RH
2 hours; - 55℃
2 hours;8.5 Kpa; 15 to 35℃
5 days;55℃;95 to 100% RH
Rins min; 1000 ㏁
2% + 0.05
damp heat 56 days; 40 ℃; 90 to 95% RH
dissipation 0.01 Pn 3% + 0.1
endurance 1000 hours at 70 ℃;
Pn or Vmax 5% + 0.1
temperature
coefficient between –55 ℃and +155 ℃ 600 ppm/ ℃
dielectric
withstanding
voltage
500VRMS SR25
700VRMS SR37,SR37L and
SR52 during 1 min.
V- block method
no breakdown
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PILKOR components
Carbon composition resistors SR25/37/37L/52
TEST AND REQUIREMENTS
REQUIREMENTS
TEST PROCEDURE
SR25 SR37 SR37L
SR52
insulation
resistance
500VDC during 1 minute ;
V – block method min. : 1000 ㏁
short time
overload
rated voltage x 2.5
5 s on 45 s off ( V2 x Vmax)
10 cycles
2.5% + 0.1
overload test rated voltage x 2.5
during 1 min. 10% + 0.1
high voltage
surge test
50 discharges from a 1 nF capacitor
charged to Vmax ;12 discharges / minute
SR25 SR37 SR37L SR52
10Ω-3.3 ㏀:
2 KV
10Ω-3.3 ㏀:
7 KV
3.6 ㏀-9.1 ㏀:
3 KV
3.6 ㏀-9.1 ㏀:
10 KV
10Ω- 9.1 ㏀:
10 KV
10Ω- 9.1 ㏀:
10 KV
no evidence of flash
over, mechanical
damage, arcing or,
insulation breakdown.
10 % + 0.1
1000 pF
10KV
Switch
1
㏀
Circuits
