Datasheet

UL Recognised
Wirewound Resistors
ULW Series
Fusing Performance
ULW3 & ULW4 Fusing Characteristic
0
10
20
30
40
50
60
50 60 70 80 90 100 110 120
Initial Power (W)
Maximum Fusing Time (s)
ULW5 Fusing Characteristic
0
10
20
30
40
50
60
80 100120 140160 180200
Initial Power (W)
Maximum Fusing Time (s)
Notes:  1.Typicalfusingtimesarearound1/3ofthemaximumgures.
2. After fusing the resistance value is >100 times the initial nominal value.
3. Suitable for fusing at voltages up to 264Vrms.
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.
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General Note
TT electronics reserves the right to make changes in product specification without notice or liability.
All information is subject to TT electronics’ own data and is considered accurate at time of going to print.
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02.12