WELWYN ULW2

UL Recognised
Wirewound Resistors
Welwyn Components
ULW Series
· UL1412 recognised fusible resistor *
· Failsafe mains fusing at 120 / 240Vrms
· Inrush and surge withstanding
· UL94-V0 flameproof coating
· SMD leadform option available
· RoHS compliant
* UL file number E234469.
Electrical Data
ULW2
ULW3
ULW4
Power rating at 25°C
watts
2
3
4
5 second overload rating at 25ºC
watts
10
15
20
ohms
22 to 100
Inrush / surge performance
See Pulse Performance graphs
Resistance range
TCR
10 to 100
ppm/°C
Isolation voltage
±200
volts
Resistance tolerance
250
350
%
UL recognised standard values
ohms
Thermal impedance
500
5
22, 33, 47, 68, 100
10, 22, 27, 33, 47, 68, 100
10
110
82
62
°C/watt
Ambient temperature range
10
°C
-55 to +155
Note - no limiting element voltage applies; maximum continuous voltage is √(P.R)
Physical Data
Dimensions (mm) and weight (g)
Type
L Max
D Max
f min
ULW2
9.0
3.6
19.8
ULW3
14.5
5.2
24.6
ULW4
13
5.6
22.8
d nom
PCB
mount
centres
Min
bend
radius
12.7
0.8
20.3
18.9
Min
bend
radius
0.5
1.2
1.1
d
D
L
f
1.0
Construction
A high purity ceramic rod is assembled with interference fit end caps to which are welded the terminations. The surge withstanding resistive element
is wound on the rod and welded to the caps. Flameproof fusible cement coating is applied prior to marking with indelible ink. The components are
then leadformed if required and packed.
Marking
ULW2 & ULW3 resistors are marked with five colour bands. The first four indicate value and tolerance in conformance with IEC62. The fifth yellow
band denotes defined fusibility. ULW4 resistors are legend marked with type, value and tolerance.
General Note
Welwyn Components reserves the right to make changes in product specification without notice or liability.
All information is subject to Welwyn’s own data and is considered accurate at time of going to print.
A subsidiary of
TT electronics plc
© Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0)1670 822181 · Facsimile: +44 (0)1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com
03. 09
UL Recognised Wirewound Resistors
Welwyn Components
ULW Series
Terminations
Material: Strength: Solderability: Hot tin dipped copper wire
The terminations meet the requirements of IEC 68.2.21
The terminations meet the requirements of IEC 115-1 Clause 4.17.3.2
Solvent Resistance
The body protection and marking are resistant to all normal industrial cleaning solvents suitable for printed circuits.
Flammability
The resistor coating will not burn or emit incandescent particles under any condition of applied temperature or power overload.
Performance Data
Maximum
Typical
5
3
Load at rated power (1000 hours @ 25°C)
ΔR%
Short term overload (5 x Pr for 5 seconds)
ΔR%
5
1
Pulse (see Pulse Performance graphs)
ΔR%
5
2
Climatic
ΔR%
5
2
Long term damp heat (56 days)
ΔR%
5
1
Temperature rapid change
ΔR%
5
1
Dry heat (1000 hours @ 200°C)
ΔR%
5
3
Climatic category
55/200/56
Vibration
ΔR%
5
1
Robustness & solder heat
ΔR%
5
1
Thermal Performance
Derating Curve
Body Temperature Rise
Temperature Rise (°C)
Proportion of Rated Power (%)
250
ULW3
100
80
60
40
20
0
ULW2
200
ULW4
150
100
50
0
0
50
100
150
200
250
300
0
1
Am bient Tem perature (°C)
2
3
4
Pow er (W)
© Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0)1670 822181 · Facsimile: +44 (0)1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com
03. 09
UL Recognised Wirewound Resistors
Welwyn Components
ULW Series
Pulse Performance
Pulse Energy Limit
(single or low repetition rate,
1.2/50µs Peak Voltage Limit
R<5%)
8
ULW3
7
5
6
5
Peak Voltage (kV)
Pulse Energy (J)
(10 pulses at 10s intervals, R<5%)
Note the voltage show n is the nett voltage across the
resistor. The generator open circuit voltage w ill be higher
due to the generator's internal impedance.
4
3
ULW2
2
1
ULW3
4
3
ULW2
2
1
0
0
0
10
20
30
40
50
60
70
80
90
0
100
10
20
30
40
50
60
70
80
90
100
Value (ohm s)
Value (ohms)
ULW4-10RJ has an energy limit of 4.3J and a 1.2/50 s peak voltage limit of 1.1kV.
Fusing Performance
Maximum Fusing Time (s)
ULW2 Fusing Characteristic
60
50
40
30
20
10
0
30
35
40
45
50
55
60
Initial Power (W)
Maximum Fusing Time (s)
ULW3 & ULW4 Fusing Characteristic
60
50
40
30
20
10
0
50
60
70
80
90
100
110
120
Initial Power (W)
Notes:
1. Typical fusing times are around 1/3 of the maximum figures.
2. After fusing the resistance value is >100 times the initial nominal value.
3. Suitable for fusing at voltages up to 264Vrms.
© Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0)1670 822181 · Facsimile: +44 (0)1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com
03. 09
UL Recognised Wirewound Resistors
Welwyn Components
ULW Series
Application Notes
Application Notes
1. If the resistors are to dissipate full rated power, it is recommended that the terminations should not be
soldered closer than 4mm from the body.
2. Due to operating temperature limits imposed by some PCB materials, derating may be necessary. An
estimate of the temperature rise to be expected can be calculated using the thermal impedance figures
given under Electrical Data.
3. For the purposes of UL approval, the following points should be observed:
3.1 To protect against fire under all conditions of overload, a positive clearance of at least
13mm should be provided between the body of the resistor and any combustible materials.
3.2 A positive clearance of 13mm should be provided between the resistor body or terminations
and uninsulated parts of opposite polarity or uninsulated dead metal parts.
3.3 Limited Short Circuit testing should be performed in the complete appliance.
Packaging
The standard packaging for ULW is taped. The critical dimensions are shown in Figure 1. The component wires will not protrude beyond the outside
edge of the tapes. Taped product is then packed into ammo boxes. Alternative packaging is available by request. Pre-formed resistors are supplied
loose packed in plastic bags or boxes. For SMD leadformed option, see the Z-form datasheet.
Figure 1 F
Dimensions (mm)
Type
b
C
ULW2
52
5
ULW3
67
10
C
f1
6
ULW4
63
b
f2
6
Body location f1 - f2 <1.4mm
10
Ordering Procedure
Example: ULW2 at 33 ohms and 5% tolerance in ammo pack box of 2500 pieces ULW2 – 33R J
A25
Type
Value (use IEC62 code)
Tolerance (use IEC62 code)
J
5%
Packing
A25
A1
Ammo
ULW2
2500/box
ULW3, ULW4
1000/box
Standard
© Welwyn Components Limited · Bedlington, Northumberland NE22 7AA, UK
Telephone: +44 (0)1670 822181 · Facsimile: +44 (0)1670 829465 · Email: [email protected] · Website: www.welwyn-tt.com
03. 09