NON-INDUCTIVE METAL OXIDE FILM RESISTORS, FLAMEPROOF(NRSN)
1.
Applicable Scope:
This NRSN standard specification is for use in consumer electronics, computers,
telecommunications, control instruments...etc.
2. Part Number:
It is composed by Type, Rated Wattage, Terminal Form, Nominal Resistance, Tolerance
and package. e.g.
NRSN
2W
10Ω
MG
Bulk
J
Type Rated Wattage Nominal Resistance Terminal Form Package Tolerance
2.1 Type :
Non-Inductive Metal Oxide Film Resistors, Flameproof are called "NRSN" &
"NRSS"(small size).
2.2 Rated Wattage:
Shown by "W", such as 1/4W, 1/2W, 1W, 2W, 3W, 4W,
2.3 Nominal Resistance:
Ω,
KΩ are its unit, which be in accordance with JIS-C6409 article 6 (EIA RS-196A)
series.
2.4 Terminal Form:
Upon the shape of terminal, there are "axial" form
，"F"
forms and "MG" form.
2.5 Package:
T/R＝tape & reel ; T/B＝tape in box; Bulk.
2.6 Tolerance:
It is measured by Bridge-method at room temperature and expressed by a capital letter.
G＝± 2% , J＝± 5% .
3. Rated Power:
Rated power is the value of Max load voltage specified at the ambient temperature of 70℃,
and shall meet the functions of electrical and mechanical performance. When the ambient
temperature surpasses above mentioned temperature, the value declines as per following
DERATING CURVE.
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NON-INDUCTIVE METAL OXIDE FILM RESISTORS, FLAMEPROOF(NRSN)
4.2.4 Marking:
Marking is made on resistors surface, either by color coding or marked with Type
of Resistor, Rated Wattage, Nominal Resistance, Tolerance, "NON-IND" code and
Maker's trade mark (TY-OHM).
5. Operating Temperature Range: -55℃∼155℃
6. Mechanical Performance
6.1 Terminal tensile:
To fix the resistor body, a static load of 2.5kgs. (under 1/2W:1kg.)is to be gradually
applied into the terminal for 10 seconds without causing any looseness and fall.
6.2 Twist withstand:
To bend the lead wire at the point of about 6mm from resistor body to 90°, then catch
the wire at 1.2± 0.4mm apart from the bent point end and turn it (clockwise) by 360
degrees perpendicular to the resistor axis at speed of 5 seconds per turn, and do the
same counterclockwise again which constitute a whole turn. Repeat the turn 2 times
without causing any break and looseness.
7. Electrical Performance
7.1 Resistance Temperature Coefficient:
It shall be within
±200ppm/℃.
T.C (ppm/℃) =〔(R2－R1)÷ R1〕×
〔1÷
(T2－T1)〕× 10
R1: resistance value at reference temperature
R2: resistance value at test temp.
T1: reference temp. (usu. 25℃)
T2: test temp. (about 75℃)
7.2 Temperature Cycle:
Following temp. cycles are to be made 5 times and then put at room temp. for one hour,
the resistance value change rate between pre-and-post test shall be within
±
1%
Steps
1
st
step
2
nd
step
3
rd
step
4
th
step
Temperature(℃)
-55±3
Room temp.
155±3
Room temp.
Time (minutes)
30
3
30
3
where
7.3 Short Time Over Load:
When the resistors are applied 2.5 times as much as rated voltage for 5 seconds
continuously, it shows no evidence of arc, flame...etc. Removing the voltage and
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NON-INDUCTIVE METAL OXIDE FILM RESISTORS, FLAMEPROOF(NRSN)
place the resistors to the normal condition for 30 minutes, the resistance value change
rate between pre-and-post test shall be within
±
1%(RSS＝±2%).
7.4 Insulation Character :
Resistors are located in a V-shaped metal trough. Using the DC500V mega instrument
2 poles to clutch either side of lead wires and metal trough, measuring the Insulation
Resistance which shall be over 1000MΩ.
7.5 Voltage Withstanding:
Resistors are located in a V-shaped metal trough. Applying Max Working Voltage for
one minute and should find no physical damage to the resistors, such as arc,
char ...etc.
7.6 Load Life:
The resistors arrayed are sent into the 70℃ oven, applying rated voltage at the cycle
of 1.5 hours ON, 0.5 hour OFF for
hours in total. Then, after removing the
voltage, take the resistors out of the oven and left under normal temp. for one hour
cooling. The resistance value change rate between pre-and-post test shall be within
±
5%.
7.7 Moisture-proof Load Life:
The resistors arrayed are placed into a constant temp./humidity oven at the temp. of 40
±
2℃ and the humidity of 90∼95%, then rated power is applied for 1.5 hours and cut
off for 0.5 hour. The similar cycle will be repeated for 500
hours in total (including
cut-off time). Then remove the voltage, taking the resistors out of the oven and leaving
them at room temp. for one hour. The resistance value change rate between
pre-and-post test shall be within
±
5%. There also shall be no evidence of remarkable
change on appearance, and the marking shall not be illegible.
7.8 Solder-ability:
The leads with flux are dipped in a melted solder of 235± 5℃ for 2 seconds, more than
95% of the circumference of the lead wires shall be covered with solder.
7.9 Incombustibility:
The resistors are applied the power of 16 times the rated wattage for 5 min. and shall
not get flame.
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