PILKOR components
Carbon composition resistors
SR25/37/37L/52
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 flammable lacquer witch
provides electrical, mechanical and
climatic protection.
copper are welded to the end-caps.
TYPE
SR25
SR37
SR37L
SR52
D
0.8
2.7
3.7
3.7
6.0
Dimensions ( mm )
L1
0.8
6.5
9.0
11
16.5
L2
Max.
7.5
12
13
18.5
d
(0.05)
0.6
0.7
0.7
0.8
QUICK REFERENCE DATA
VALUE
DESCRIPTION
SR25
resistance range
resistance tolerance
temperature coefficient
rated dissipation
at T
amb
= 70
℃
max. working voltage
max. overload voltage
basic specifications
climatic category (IEC60)
stability,
R/R
max
after
load : 1000 hours
soldering heat
0.25 W
250 V
500 V
SR37
SR37L
SR52
10Ωto 9.1
㏀
5%, 10%
( E12, E24 series )
600 ppm /
℃
0.5 W
350 V
700 V
1 Ws
500 V
1000 V
1W
750 V
1500 V
IEC 60 115-1B
55 / 155 / 56
5%
0.1Ω
3%
0.1Ω
- 60 -
PILKOR components
Carbon composition resistors
ORDERING INFORMATION
Ordering code indicating resistor types and packing
Table 1
Type
SR25
( 0.25W )
Bandolier
width
52mm
Packing
ammo
Quantity
5000
Resistance
range
10Ωto 9.1
㏀
Tol.
%
5
10
SR25/37/37L/52
Ordering code
PPSR 241 43xxx
PPSR 241 73xxx
Table 2
Type
Bandolier
width
Packing
Quantity
Resistance
range
10Ωto 9.1
㏀
Tol.
%
5
10
15
Ordering code
PPSR 242 33xxx
PPSR 242 15xxx
PPSR 242 22xxx
SR37
( 0.5W )
52mm
ammo
1000
Table 3
Type
SR37L
( 1Ws )
Bandolier
width
64mm
Packing
ammo
Quantity
1500
Resistance
range
10Ωto 9.1
㏀
Tol.
%
5
10
Ordering code
PPSR 243 13xxx
PPSR 243 14xxx
Table 4
Type
SR52
( 1W )
Bandolier
width
64mm
Packing
ammo
Quantity
500
Resistance
range
10Ωto 9.1
㏀
Tol.
%
5
10
Ordering code
PPSR 250 11xxx
PPSR 250 14xxx
Table 5. Last digit of 12NC
Resistance decade
1 to 9.76Ω
10 to 97.6Ω
100 to 976Ω
1 to 9.76
㏀
Last digit
8
9
1
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.
- 61 -
PILKOR components
Carbon composition resistors
Limiting values
Table 6
TYPE
SR25
SR37
SR37L
SR52
Note
LIMITING VOLTAGE
( 1 )
(V)
250
350
500
750
SR25/37/37L/52
LIMITING POWER
(W)
0.25
0.5
1 (small)
1
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
P
max
( %)
100
50
-55
0
50
70
100
T
amb
(
℃
)
155
Fig. 1 Maximum dissipation (P
max
) in percentage of rated power as a function of the
ambient Temperature (T
amb
)
- 62 -
PILKOR components
Carbon composition resistors
Surge resistance characteristics
SR25/37/37L/52
%
0
0.25W
-5
0.5W
1Ws
1W
-10
-15
0
2KV
4KV
6KV
8KV
10KV
12KV
14KV
Fig. 2 Maximum allowed peak surge voltage in accordance with “IEC 60065 chapter
14.1” 50 discharges form a 1nF capacitor
charged to V
max
; 12 discharges / minute
Application information
SR25 - 0.25W
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
- 63 -
PILKOR components
Carbon composition resistors
SR37 – 0.5W
SR25/37/37L/52
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
SR37L – 1Ws
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
- 64 -
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