characteristics

standard

test methods

1.

 resistance temperature coefficient

 (ppm/℃)

±300ppm/℃

natural resistance change per temperature degree centigrade.

(ppm/℃)

r1: resistance value at reference temperature. (t1)

r2: resistance value at reference temperature. (t2)

t1: room temperature

t2: t1±100℃

2.

 dielectric

 withstanding

 voltage

 no evidence of flashover, mechanical damage or arcing or, insulation break down.

resistors shall be subjected to an approximately sinusoidal test potential (as below) 60hz applied between both terminals connected together and a  90° v-block extending beyond the end of the resistor.

resistor wattage

dc volts

1/2w(1ws)

1w,2w above

350

600

3.

 solderability

 90% covered min.

the terminal lead shall be dipped into molten solder s at 3.2 to 4.8mm from the body of resistor.the temp. and time as below:

a. 260±5℃for 2±0.5 seconds

b. 350±10℃for 2±0.5seconds

4.

 resistance to soldering

no evidence of mechanical damage

△    r/r±5%

the terminal of the resistor is dipped into the molten solder of 350±10℃for 3±0.5 seconds. then put the resistor in the room temperature. for min.3 hours.

5.

 humidity load life

±5% max./1000hours

resistance change after 1000 hours ( 1.5 hours on  0.5 hours off)at rated continuous working voltage in a humidity chamber controlled at 40±2℃and 90~95% relative humidity .

6.

load life

±5% max./1000hours

permanent resistance change after 1000 hours  operating at rated continuous working voltage with a duly cycle of 1.5 hours on 0.5 hours off at 70 ± 2℃ambient .

7.

 temperature cycling

δ r/r at±1% max.no evidence of mechanical damage.

resistance change after continuous five cycles for duty cycle as specified below.

step

temperature

time

1

-30℃

30 minutes

2

+25℃

10~15 minutes

3

+85℃

30 minutes

4

+25℃

10~15 minutes

characteristics

standard

test methods

8.

 short time   overload

δr/r at±2% max. with no evidence of arcing burning, or charring

permanent resistance change after the application of a potential of 2.5 times rated continuous working voltage for 5 seconds at room temperature.

9.

terminal strength

no  evidence  of  mechanical damage or loosening terminals

direct load resistance to 2.5kg direct load 30±5 seconds twist test, for axial leads unit only. terminal lead shall be bent through at a right angle at a point of 6.35mm from the body edge of resistor and shall be rotated through at a right angle about the original axis of the bent terminal in alternating direction for a total 3 rotations.