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Carbon Film Resistors (RD)
Fusible Film Resistors (RF)
Cement Resistors (RG)
Metal Glaze Resistors (RM)
Metal Film Resistors (RN)
Metal Oxide Resistors (RS)
Wire Wound Resistors (RW)
Insulated 0Ω Resistors (RZ)
Metal Plate Resistors (MPC)
Anti-burst Fusible Resistor
(RFB)


 

Wire Wound Resistors (RW)


1. Scope of the coverage:
 This specification is pertinent to the application of wire wound resistors (designated as RW).
2 .Temperature range of the application:
 -40℃ ~ +155℃。
3. Type:
 Two types of wire wound resistors are available: one is normal size and the other one is small
 size. These two types are distinguished by the color of the coating resin. The color of the resin for
 the normal size is gray and that for the small size is pinkish red.
4.Marking and illustration: ref. To Fig.1, Fig.2:
 Two types of designation are used to distinguish wire wound resistors with or without inductance.
 The one with inductance is: (RWU/S) and the one without (low) inductance is : (NWU/S).
 With inductance---------- >1/2W、1W、2W、3W、S1W、S2W、S3W、S5W (Fig.1)
 Without inductance ------------>1/2W、1W、2W、3W、S1W、S2W、S3W、S5W (Fig.2)
 (without inductance means low inductance or inductance is <1μH)
 
 
 
5.Dimension, voltage, resistance range: listed in the following Table

Rated

Power

(W)

Type

Resistance Range

(Ω)

2
J ( ±5%)
L
ι
1/4
Normal
0.1~150
6±0.3
2.4±0.1
28±2
0.6±0.05
1/2
Small
0.1~150
6±0.3
2.4±0.1
28±2
0.6±0.05
Normal
0.1~150
9±0.5
3.0±0.5
30±3
0.6±0.05
1
Small
0.1~330
9±0.5
3.0±0.5
30±3
0.8±0.05
Normal
0.1~330
4.0±0.5
38±3
0.8±0.05
2
Small
0.1~680
4.0±0.5
38±3
0.8±0.05
Normal
0.1~680
5.5±0.5
38±3
0.8±0.05
3
Small
0.1~1K
5.5±0.5
38±3
0.8±0.05
Normal
0.1~1K
8.5±0.5
38±3
0.8±0.05
5
Small
0.1~1K
8.5±0.5
38±3
0.8±0.05
7
Small
0.1~15K
8.5±0.5
38±3
0.8±0.05
10
Small
0.1~27K
8 (MAX)
44 (MAX)
38±3
0.8±0.05
 P/S:7W、10W is for Philips specification only.
 
6.Coating
 
 6.1 The body of the resistor is covered by nonflammable silicon resin.
 6.2 The maximum length of the lead wire covered by the resin is 2mm.
 6.3 The maximum area of the end cap which is not covered by the resin is half of the diameter of
 6.3 the cap.
 6.4 The status of coating condition described by 6.2 and 6.3 are acceptable.
 
7.Characteristics of electrical performance
 7.1 Rated power
 The rated power indicates the maximum power the resistor can endure continuously when the
 ambient temperature is equal to or lower than 70℃. When the ambient temperature is higher than
 70℃, the rated power of the resistor is determined by the derating curve described in the following
 figure.
 
 7.2 Rated voltage
 The rated voltage of a resistor is either a continuous DC voltage or an AC rms voltage which can
 be calculated by the following formula. If the calculated rated voltage is higher than the highest
 working voltage then the highest working voltage should be used as the rated voltage.
  P: Rated power (W) R: Nominal resistance (Ω) E: Rated voltage (V)
 
 7.3 Insulation resistance (Ref. JIS C5202 5.6)
 Equipment: Insulation resistance tester
 The body of the resistor is wrapped around by the aluminum foil without extending beyond the
 resistor body. Clap one electrode on the aluminum foil and the other electrode on the lead wire.
 Apply 500V from the tester for 1 min. and the measured resistance value should be larger than
 1,000MW.
 
 7.4 Dielectric strength (Ref. JIS C5202 5.7)
 Equipment: Dielectric strength tester
 The body of the resistor is wrapped around by the aluminum foil without extending beyond the
 resistor body. Clap one electrode on the aluminum foil and the other electrode on the lead wire.
 Apply 500V from the tester to the resistor for 1 min.. No flash-over, burning or breakdown should be
 observed.
 
 7.5 Short time overload (SOL) (Ref. JIS C5202 5.5)
 Equipment: S.O.L. tester.
 Apply voltage of to the resistor for 5 sec., After the test, stabilize the resistor at room
 temperature for 30 min. then measure its resistance. Compare the resistance before and after the
 test. The acceptable change of the resistance is: ±(2%+0.05Ω).
 
 7.6 Flame proof (Ref. JIS C5202 7.12 3.4(2)c)
 Equipment: AC power supply
 Apply 2 times, 4 times, 8 times, 16 times and 32 times of rated voltage sequentially. The duration
 for each voltage application is 1 min.. The resistor should not demonstrate arcing, burning or melt
 down except when the applied voltage exceeds 10 times of rated power. Under this circumstance
 of applied more than 10 times of rated power, arcing or burning is acceptable but the duration
 should be less than 5 sec. And the height of flame should be less than 3.5mmv.
 
8.Environmental tests
 8.1 Load life test (Endurance with rated load) (Ref. JIS C5202 7.10)
 Equipment: High temperature chamber and DC power supply
 The resistors are put in a fixture where no interference will be allowed. Put the fixture in a 70±3℃
 chamber and apply rated voltage with a cycle of 90 min. ON and 30 min. OFF for hours.
 After 240, 480, 720 and 1,000 hours, the resistors are taken out and stabilize at room temperature
 for 30 min. and then the resistance is measured. Upon each step of resistance measurement, the
 change of the resistance should not exceed ±(5%+0.05Ω) and the appearance should show no
 remarkable abnormality and legibility of marking.
 
 8.2 Resistance to damp heat (Ref. To JIS C5202 7.2)
 Equipment: Constant temperature and humidity chamber
 The resistors are put in a 40±2℃ chamber with RH=90~95% for 240±4 hours. After the test, take
 the resistors out and stabilize in room temperature for 1 - 4 hour. Measure the resistance. The
 acceptable change of resistance should not exceed ±(2%+0.05Ω) and the appearance should
 show no remarkable abnormality and legibility of marking.
 
 8.3 Endurance under damp heat and load (Ref. JIS C5202 7.9)
 Equipment: Constant temperature and humidity chamber, DC power supply
 The resistors are put in a fixture where no interference will be allowed. Put the fixture in a 40±2℃
 chamber with RH=90~95% and apply voltage equal 1/10 of rated power with a cycle of 90 min. ON
 and 30 min. OFF for hours. Water drops should avoid dripping on the resistors. After 240
 and 1,000 hours, the resistors are taken out and stabilize at room temperature for 1 hour and then
 the resistance is measured. Upon each step of measurement, the change of the resistance
 should not exceed ±(5%+0.05Ω) and the appearance should show no remarkable abnormality and
 legibility of marking.
 
 8.4 Temperature coefficient (TCR) (Ref. JIS C5202 5.2)
 Equipment: High temperature chamber
 Measure the resistance at room temperature. Put the resistor in a chamber with the temperature
 of RT+100℃ for 30 - 45 min. to stabilize. Measure the resistance again. Compare the resistance
 at these two temperatures with the following equation and the acceptable value is:
 ≦1Ω±500 PPM/℃ or >1Ω±300 PPM/℃
 
 R = Resistance at T T = RT + 100℃ Ro = Resistance at To  To =room temperature
 
 8.5 Thermal shock
 Equipment: DC power supply, low temperature chamber
 Measure the resistance at room temperature then take it to -30 ℃ low temperature chamber for 15
 min.. Take it out and stabilize at room temperature for 2 hours. Measure he resistance . Compare
 the resistance before and after test. The acceptable change of resistance is ±(2%+0.05Ω). The
 appearance should show no remarkable abnormality and legibility of marking.
 
 8.6 Temperature cycling (Ref. JIS C5202 7.4)
 Equipment: High temperature chamber, low temperature chamber
 Measure the resistance before the test. Put the resistor to -55℃ chamber for 30 min. then take it
 out at room temperature for 2 to 3 min.. Put the resistor to +85℃chamber for 30 min. then take it
 out at room temperature for 2 to 3 min. This completes a cycle. Repeat the cycle 5 times. Put
 resistors at room temperature for 90 min. and then measure the resistance. Compare the
 resistance before and after test. The acceptable change of resistance is ±(1%+0.05Ω). The
 appearance should show no remarkable abnormality and legibility of marking.
 
9.Mechanical performance
 9.1 Resistance to soldering heat (Ref. JIS C5202 6.4)
 Equipment: Solder bath
 Measure the resistance before the test. Immerse part of the lead wire which is 4±0.8mm away from
 the body to the flux for 5 - 10 sec. Take the resistor out and immerse resistors in the solder bath of
 350±10℃ for 3.5±0.5 sec.. Stabilize at room temperature for 1 hour and then measure the
 resistance value. Compare the resistance values before and after the test, The acceptable change
 is ±(1%+0.05Ω)
 
 9.2 Solderability (Ref. JIS C5202 6.5)
 Equipment: Solder bath
 Immerse part of the lead wire which is 4±0.8mm away from the body to the flux for 5 - 10 sec. Take
 the resistor out and immerse resistors in the solder bath of 245±5℃ for 3.5±0.5 sec.. Take the
 resistor out and inspect the lead wire visually. The acceptable level is the coverage of the new
 
 9.3 Robustness of terminals (Ref. JIS C5202 6.1)
 9.3.1 Tensile strength of termination
 Equipment: Weight gauge
 Fixed the resistor and apply axially along the lead wire of 2.5Kg (0.8φ lead wire) or 1.0Kg (0.6φ
 lead wire) for 30 sec.. The lead wire should not break or detached from the resistor and the change
 of the resistance should be less than ±(0.5%+0.05Ω).
 
 9.3.2 Torsional strength
 Equipment: Torsion tester
 Bend the terminal 6.4mm away from the body according to Fig-a to 90 degree with a curvature of
 0.75mm~0.80mm. The lead wire should be clamped at a point of 1.2mm away from the bending
 point by a fixture which can rotate 360 degree according to Fig-b. Rotate the resistor 360 degree
 clockwise and counter clockwise for 1 cycle. The rotation speed is 360 degree per 5 sec.. Perform
 3 cycles for the lead wire diameter of 0.8φ and 1.5 cycles for that of 0.6φ. The terminal should not
 break down or detached from the body. The acceptable change of resistance is ±(0.5%+0.05Ω).
  
 

 

 

 

 

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