FUSIBLE RESISTORS
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In order to meet the growing demand worldwide for resistors to fuse or blow as a safety measure, HTR can provide fusible resistors which fuse or blow if they are subjected to an abnormal spike of voltage / current.
Physical configuration
FLAME RETARDANT SILICONE COATED TYPE -please
refer to HTR type H1 to H10
| Test | Performance |
| Resistance tolerance | ± 10% [K]: ± 5% [J] [ < 1ohms ± 0.05 ohms] |
| Di-electric withstanding voltage | Max DR ± [ 2% ± 0.05 ohms] |
| Insulation resistance | >1000 M [ Dry] |
| Temperature co-efficient | ± 550 ppm/°C |
| Short time overload | Max D R ± [2%+ 0.05 ohms] |
| Moisture resistance | Max D R ± [5%+ 0.05 ohms] |
| Load life | Max D R ± [5%+ 0.05 ohms] |
| Ambient operating temperature range | -25 °C to + 155° C |
| Flame test | Specifications laid down by UL have been met satisfactorily |
NOTE:
Contrary to popular belief, fusible resistors are not standard
resistor types and each type of fusible resistor must be tailor designed to suit a
particular application.
ORDERING INFORMATION:
In order that we can design a fusible resistor suitable to your
needs, we need the following data from you:-
- Power rating in terms of watts.
- Resistance in ohms.
- Tolerance.
- Maximum continuous working voltage across the resistor, at which the resistor must continue to function.
- Fusing voltage - The voltage at which the resistor must fuse or blow.
- Fusing time - The duration within which the resistor must fuse or blow, on being subjected to the fusing voltage.
- In case, lead preforming is required, we need a drawing. This service is provided, upon a minimum order of 5000 pieces.
- These resistors can also be provided in taped form.
NOTE :
Generally speaking as per international standards, a
fusible resistor fuses on being given fusing voltage from instantaneously to 45 seconds
without any flame.
At HTR if no special data is provided, we assume that if a fusible resistor is
ordered, it should fuse on being given voltage calculated at 16 times power from
instantaneously to 45 seconds.
Precautions to be taken : Before conducting this test the voltage must be correctly set /
adjusted by first using a dummy piece which should then be discarded.
TYPICAL APPLICATIONS
As mentioned previously a fusible resistor is a tailor made dual
purpose component -
(a) In normal conditions it functions as a resistor.
(b) In high overload conditions it acts as a fuse/safety device.
