无感封闭式水泥电阻 卧式脚片水泥电阻

characteristics

standard

test methods

1.

temperature

 coefficient of    resistors

 (ppm/℃)

wire wound  –80~+900

natural resistance change per temperature degree centigrade.

(ppm/℃)

r1: resistance value at reference temp. (t1)

r2: resistance value at reference temp. (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

ac or rms volts

1w above

500

3.

solderability

90% covered min.

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

a. 235±5℃for 2±0.5seconds

b. 270±10℃for2±0.5seconds

4.

resistance to soldering

no evidence of mechanical damage ?r / r at±2% max

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 3 min.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 duty cycle of 1.5 hours on 0.5 hours off at 70 ±2℃ambient

7.

temperature cycling

±2% max with no evidenceofmechanical damage

resistance change after continuous 5 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

?r / r at±3% 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 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 of   3 rotations.

10.

burn out

the arcing and  or flaming duration is less than 2seconds and the flame height is less than 1/2 inch.

resistors burning out or opening up for overloads in excess of 10 times rated wattage (regardless of how it is applied)