इंटरनेट
मानक
Disclosure to Promote the Right To Information
Whereas the Parliament of India has set out to provide a practical regime of right to
information for citizens to secure access to information under the control of public authorities,
in order to promote transparency and accountability in the working of every public authority,
and whereas the attached publication of the Bureau of Indian Standards is of particular interest
to the public, particularly disadvantaged communities and those engaged in the pursuit of
education and knowledge, the attached public safety standard is made available to promote the
timely dissemination of this information in an accurate manner to the public.
“जान1 का अ+धकार, जी1 का अ+धकार”
“प0रा1 को छोड न' 5 तरफ”
“The Right to Information, The Right to Live”
“Step Out From the Old to the New”
Mazdoor Kisan Shakti Sangathan
Jawaharlal Nehru
IS 8872-4-4 (1984): Variable Resistors, Part 4: Preset,
Section 4: Type VRT 4 P [LITD 5: Semiconductor and Other
Electronic Components and Devices]
“!ान $ एक न' भारत का +नम-ण”
Satyanarayan Gangaram Pitroda
“Invent a New India Using Knowledge”
“!ान एक ऐसा खजाना > जो कभी च0राया नहB जा सकता ह”
है”
ह
Bhartṛhari—Nītiśatakam
“Knowledge is such a treasure which cannot be stolen”
IS : 8872 ( Part 4/Set 4 ) - 1984
UDC: 621.316.82
( Reaffirmed 2002 )
India/z Standard
SPECIFICATION FOR VARIABLE RESISTORS
PART 4 PRESET
Section 4 Type VRT 4 P
0. General - This standard shall be read in conjunction with IS : 88?2 ( Part 1 ) - 1977 ‘Specification for
variable resistors: Part 1 General requirements and methods of tests’.
c‘
1
~scope
_- This standard covers the requirements of cermet (non-wire wound ) multi-turn presets.
The outline, drawing and dimensions shall be according to Fig. 1.
2. Outline, Drawing aud Dimensions
2tl.5
FiG. 1 OUTLINE,
DRAWING
AND DIMENSIONS
Gr. 5
@ May 1985, IS1
Adopted SO November 1984
I
I
INDIAN
STANDARDS
INSTITUTION
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI-l 10002
IS : 8872 ( Part 4/Set 4 ) - 1984
2.1 Characteristics
a) Climatic category
55/100/56
b) Low air pressure
2 kPa
c) Acceleration
1 km/s2
d) Bump
4 000 bumps
e) Vibration
10 to 2 000 Hz, 200 m/s2
f) Shock
1 km/s2
g) Preferred resistance values
See Table 1
h) Rated working voltage
See Table I
j) Selection tolerance
f 10 percent
k) Rated dissipation at 70°C
0.5 W (see Note)
f
m) Temperature characteristic
of resistance
f 2 percent
n) Stability after endurance
electrical
p)
100 ppm/“C, f 250 ppmrC
125°C
Maximun surface temperature
q) Effective electrical travel
15 turns Min
20 turns Max
r) Typical construction
Cermet ( non-wire-wound
Note -
For ratings at temperatures
TABLE
1 PREFERRED
)
other than 7O”C, reference shall be made to the derating curve shown in 3.
RESISTANCE
VALUES
AND RATED
WORKING
VOLTAGES
Rated Working
Voltage
Resistance
V
7
100 D
200 n
10.5
470 sz
15.3
lk
22’4
2.2k Q
33.2
4*?k bb
48.5
10k B
70.7
22k Q
105
47k 9
153
1OOk n
224
220k rlz
250
470k Q
250
IM D
250
-
2
IS : 8872 ( Part 4/Set 4 ) - 1984
3. Derating:Curve
0
20
40
140
4. Marking - See 6 of IS : 8872 ( Part 1 ) - 1977. In addition, the temperature
marked.
160
co-efficient
shall also be
5. Material, Construction and Workmanship - See 5 of IS : 8872 ( Part 1 ) - 1977.
6. Tests
6.1 ClassiJca tion
ofTests
6.1.1 Type tests -
The sequence of type tests and requirements shall be in accordance with Table 3.
6.1.1.1 The manufacturers shall submit 48 samples in each style for which the approval is required,
having the numbers and values as follows :
a) 14 samples of the highest value, and 2 spares;
b) 14 samples of the lowest value, and 2 spares; and
c) 14 samples of the middle value, and 2 spares.
Note - When approval to variable resistors of closer temperature characteristic of resistance is desired, two specimens
each of the highest, the middle and the lowest resistance value shall be submitted for approva! testing and these shall be
subjected to the tests of Group 0 and VII.
6.1.2 Routine tests every resistor :
The following shall constitute the routine tests and shall be carried out on each and
a) Visual examination,
b) Continuity,
c) Element resistance, and
d) Sealing.
6.1.3 Acceptance tests - For the purpose of the acceptance of the lot, all samples shall be subjected to the
tests as given in 6.1.2. The following two groups of samples Group A and Group B) shall be drawn and the
resistors in each group shall be subjected to the tests as speci Bed in the Table 2.
IS : 8872 (Part 4ISec 4) - 1984
TABLE 2 SCHEDULE
Clause Ref
in IS : 8872
(Part l)-1977
51
No.
Tests
(1)
(2)
9
Group A
Voltage
(4)
D/ND
(5)
(6)
9.1.1
proof (2 seconds)
Operating
Contact
TESTS
Inspection*
Level
AQL
(Percent
Defective)
(3)
Dimensions
ii)
OF ACCEPTANCE
8.9
torque
9.2
resistance variation
II
ND
s:;
ND
8.12.4
Group B
Sub-group B I
Solderability
9.8.3
Sub-group B 2
Resistance
to soldering
Rohustness
heat
9.8.4
of terminations
9.7
Endurance (mechanical)
(200 cycles)
11.3
Resistance
11.1
to solvents
s3
D
s3
D
s3
ND
Sub-group B 3
Settability
Bump
9.10
Climatic
10.1
Sub-grdup B 4
Endurance
(electrical)
D=Destructive,
Note
-
* Sea IS
(168 h)
11.4
ND-Non-destructive.
: 10673-1984 Sampling
6.2 General Conditions for Tests-
plans
TABLE
(11
i)
Test
(2)
and procedures
for inspection by attributes
for electronic
items.
See 7 of IS : 8872 ( Part 1 > - 1977.
6.2.1 The test schedule and the requirements
61
No.
4
shall be in accordance with Table 3,
3 TEST SCHEDULti
Clause Ref
in IS : 8872
( Part 1 ) - 1977
AND REQUIREMENTS
Condition
of
Test
(4)
(3)
Requirements
(5)
0 Group ( 48 Samples )
a) Visual examination
-
9.1
The
condition, workmanship
and finish shall be satisfactory.
Marking
shall be legible and
indelible.
( Continued )
4
IS : 8872 ( Part 4/Set 4 ) - 1984
TABLE
SI
No.
3 TEST
SCHEDULE
Co&
Requirements
(5)
(4)
(3)
(21
-
Condition
of
Test
Clause Ref
in IS : 8872
(Part
1) - 1977
Test
(1)
AND REQUIREMENTS
The
adjustment
be
operated
slowly.
device
steadily
shall
and
The change in resistance shall
be smooth continuous and unithroughout
the
directional
actual effective electrical level.
b)
Continuity
8.1
c)
Dimensions
9.1.1
The dimensions of the resistors
and their terminations
shall
confirm to the values given in
Fig. 1.
d)
Element resistance
8.2
l%is shall be within the selection tolerance of f 10 percent.
c)
Terminal resistance
8.3
The end
resistance
at either
end of the resistor shall not
exceed 20 Sz or f 2 percent of
the total
resistance
value
whichever is greater..
f)
Minimum effective resistance
and angle of ineffective rotation
8.5
g)
h)
jj
k)
-
8.5.1
This is the angle between the
two positions recorded above.
Value of minimum effective
resistance. (from termination n j
8.5.1
This is the resistance
measured above.
Angle of effective rotation
and value of minimum
effective resistance ( from
termination c )
8.5.2
Voltage proof
Insulation resistance
Integrity
Perpendicular
Operatiog
torque
value as
-
8.6
The angle of effective
shall be :
15 Turns, Min
20 Turns, Max
rotation
8.9
900 V rms for one minute.
rhere shall be no breakdown
or flashover shall occur.
8.10
500 v.
rhe value shall
than 1000 8.
be not
less
Resistors shall be mounted on
an appropriate
mounting fixture with their bodies restrained
from movement .
of shaft
-
1) Pull force
m)
The resistance value at angular
positions are recorded for information only.
Angle of ineffective rotation
( from termination a )
Effective resistance and angle of
effective rotation
2)
-
A force of 23 N shall be applied
Resistors
shall
be examined
for evidence of shaft breakage.
iz force of 10 N shall be applied
in a direction perpendicular to
the axis of the operating shaft
for 1 minute, Min.
Resistors
shall be examined
for evidence of shaft breakage.
along the axis of the operating
shaft, away from the body of the
resirtor. The force
shall be
maintained for one minute, Min.
force
9.2
The operating
torque
to operate the contact
approximately
10, 50
percent of the actual
electrical travel shall
mined.
required
arm at
and 90
effective
be deter-
The operating
be a maximum
torque
shall
of 10 mNm.
(
5
Continued
)
IS : 8872 ( Part 4/Set 4 ) - 1984
TABLE 3 TEST SCHEDULE AND REQUIREMENTS - Contd
Teat
i!.
i2)
(1)
n)
Clutch operation
p)
Sealing
q) Contact resistance
ii)
Condition
of
Teat
Clause Ref
in IS : 8872
( Part 1) - 1977
(4)
(3)
-
9.4.2
-
11.5.2
8.12.4
Requirements
(5)
arm shall idle
The
contact
against the stop without electrical discontinuity or evidence
of mechanical damage.
The
travel of the contact arm shall
also be capable of reversing
directon.
No bubbling shall occur.
Number of cycles-6
The
contact
resistance variation shall not exceed 3 percent or 352 whichever is greater.
First Croup ( 12 Samples)
a) Settability
-
b) Solderability
9.8.3
c) Robustners of terminations
9.7
Tensile : 10 N. In addition, the
test shall be carried out in the
opposite direction,
bending :
$z bend, to be bent through
0
d) Bump+
9.10
4 000 bumps
The resistor wiper shall be set
at approximately 30, 50 and 75
percent of mechanical rotation.
A dc voltage of up to 2.5 V shall
be applied across the end terminals, and the wiper shall
then be adjusted
smoothly
without abrupt voltage change
at each test point.
The settability error shall be within the
limits specified.
-
The settability
error
within * 1 pe:cent
shall be
As in IS
: 8872 (Part l)-1977.
As in IS
: 8872 (Part l)-1977.
1)
Setting stability
-
-
The change shall not exceed
f 1 percent
2)
Continuity
8.1
-
As in Sl No. (i) (b) .
3)
Klement resistance
8.2
-
The change in the resistance
from the initial value shall
not exceed f (1 percent +
0.059).
9.1
-
There
shall
be no fracture,
loosening of parts or other
mechanical damage.
4) Visual examination
e) Vibration*
9.9
10 to 2 000 Hz, 200 m/s2
1) Setting stability
The
f
2) Continuity
8.1
3) Element resistance
8.2
change
shall
1 percent.
not
exceed
As in Sl No. (i) (b).
-
The change in the resistance
from the initial value shall not
exceed f
( 1 percent + 0.05
0).
*Throughout the test the resistors shall be connected to a suitable monitoring- device to determine electrical discontinuity.
It is desirable that the detecting equipment shall detect any interruption with a duration of 0.1 millisecond or greater.
( Continlled)
6
IS : 8872 ( Part 4/Set 4 ) - 1984
TABLE
3 TEST
Test
BE.
(2)
(11
AND
-
Conld
Clause Rof
in Is : 8872
( Part 1 )-1977
Condition
of
Test
Raqoircmerts
(3)
(4)
(5)
-
There
shall be
no
loosening
of parts
mechanical damage.
fracture,
or other
1 km/s’
9.11
Shock*
1) Setting
REQUIREMWTS
9.1
4) Visual examination
f)
SCHEDULE
-
stability
The
f
shall
change
1 percent.
not
exeeed
2) Continuity
8.1
As in Sl No. (i) (b) .
3) Element
8.2
The change in resistance
from
the initial value shall not exceed i (1 percent + 0.05 Sz )
resistance
g) Acceleration*
1) .Setting
There
shall
be Fno fracture,
loosenmg
of parts or other
mechanical damage.
9.1
4) Visual examination
1 km/s*
9.12
The
f
stability
change
shall
1 percent.
.not
exceed
2) Continuity
8.1
As in Sl No. (i) (b).
3) Element resistance
8.2
The change in resistance
from
the initial
value
shall
not
exceed i ( 1 percent + 0.05
51).
4) Visual examination
9.1
There shall
be
no
loosening
of parts
mechanical
damage.
-
The
change shall
at 1 percent.
fracture,
or other
551125
10.5
h) Rapid ehange of temperature
-
1) Setting stability
not
exceed
2) Continuity
8.1
-
As in Sl No. (i) (b).
3) Element
8.2
-
‘The change in resistance from
the initial value shall not exceed f 1.5 percent.
9.1
-
There shall
be no
loosening of parts
mechanical damage.
10
-
resistance
4) Visual examination
j) Climatic
tests
1) Dry heat
2) Damp heat ( accelerated
3) Cold test
4) Operating
torque
5) Low air pressure
)
-
10.1.2
At + lOO”C, 16 h
10.1.3
One cycle
10.1.4
At -
55W,
2 kPa
‘The voltage proof test shall
be done at 350 V rms.
10.1.5
-
2 h
-
9.1
fracture,
or other
The
value shall
not
exceed
1.5 times the maximum value
specifiedin Sl NO. (i) (m).
There shall be no breakdown
or flashover
*Throughout
the test the resistors shall be connected to a suitable monitoring
device to determine electrical
discontinuity.
It is desirable that the detecting equipment shall detect any interruption with a duration of O-1 millisecond or greater.
( Confinued )
7
IS : 8872 ( Part 4/Set 4 ) - 1984
TABLE
SI
No.
Test
(1)
(2)
10.l.G
-_
Con&f
Requirements
(5)’
(4)
-
5 Cycles
The voltage to be applied shall
be the rated voltage.
There
thall be no
or flashover.
breakdown
:
1) Visual examination
9.1
There shall
be
no corrosion
fracture, loosening of parts or
mechanical
damage.
other
Marking shall be legible and
indelible.
2) Continuity
8.1
As in Sl No. (i) (b).
3) Element
8.2
‘The change in resistance
from
the initial value shall not cxteed f 2 percent.
resistance
4) Insulation
5) Voltage
iii) Second Grouj
Resistance
proof
8.10
The value shall
than 1OOMP.
8.9
There shall be no
or flashover.
be
not
less
breakdown
(6 Samples)
10.2
a) Damp heat (long term)
i) Working
iv)
)
-
Condition
of
Test
(3)
test
Final Meamrcmentr
AND REQUIREMENTS
Clause Ref
in IS :8872
( Part 1 )- 1977
6) Damp heat ( accelerated
remaining cycles
i) Working
3 TEST SCHEDULE
-
test
A dc voltage of 20 f 2 V shall
be apphed to half the specimens between termination
‘b’
and the external metal parts
( termination
being positive )
and no voltage shall be applied for the other half specimens.
The voltage to be applied
be the rated voltage.
shall
-
_
‘There shall be no
or flashover.
There shall be no
corrosion
fracture, loosening of parts or
mechanical
damage.
other
Marking shall be legible and
indelible.
1) Visual examination
9.1
2) Elcrnent resistance
8.2
3) Insulation
8.10
-
‘The value
shall
than 100 M Q.
4, Voltage proof
8.9
--
There shall be no
or flashover.
5) Solderability
9.8.3
resistance
breakdown
The change in resistance from
the initial value shall not exceed f 2 percent.
be
not
less
breakdown
As in Sl No. (ii) (b).
l’hird Groub ( 6 Samfiles)
a) Bndurancc
( mechanical
)
11.3
200 cycles. 1 cycle in 2.0 +=
O-5 minutes.
The specimens shall be mounted by their normal mounting
means on a I.6 mm thick glass
epoxy laminate. The specimens
shall be ganged in pairs and
each pair shall be connected
in series so that a nominally
constant current flows through
the resistors, irrespective
of
the contact arm position during the turning
of the lead
screw actuator.
( Continued)
8
IS: 8872 ( Part 4/Set 4 ) - 1984
TABLE
Sl
No.
Test
(
SCHEDULE
AND
REQUIREMENTS
Requirementm
(5)
(4)
1j Visual examination
-
There shall
be
no
loosening
of parts
mechanical damage.
2) Continuity
8.1
-
As in Sl No. (i) (b).
resistance
fracture,
or other
The change in resistance from
the initial value shall not exceed f 2 percent.
8.2
Fourth Group ( 6 Samples )
a) Endurance
( electrical
)
1) Vilual cxaminatlon
At + 7o” c.
The specimens shall he preconditioned
at the test temperature
for a period of 8
hours before the start of the
test. The specimens shall be
normal
their
mounted
hy
means on a 1.6 mm thick glass
epoxy laminate. The specimens
shall be so arranged that the
temperatnre of any one specimen shall not appreciably
influence the temperature of any
other specimen,
There
shall
he no undue draft over the
resistors.
11.4
-
9.1
There shall be no fracture,
or
any other ‘mechanical damage.
Marking shall be legible and
indelible.
2) Continuity
8.1
As in Sl No. (i) (b).
3) Element
8.2
The change in resistance from
the initial
value shall
not
exceed f 2 percent.
resistanee
4) Insulation
resistance
5) Voltage proof
-
8.10
7) Operating
torque
h) Flammability
As in Sl No. (i) (j)
There
shall be
or flashover.
8.9
The
f
6) Setting stahility
no
change shall
1 percent.
breakdown
not
exceed
9.2
-
The value shall not exceed 1’5
the
maximum
value
times
specified in Sl. No. (i) (m).
11.2
-
As in IS
: 8872 (Part I)-1977.
10.4
-
As in IS
: 8872 (Part 1)“1977.
11.1
-
As in IS
: 8872
Fayth Group ( 3 Samples )
a) Mould growth
vii)
Conrd
9.1
3) Element
vi)
-
Coadition
of
Test
Clause Ref
in IS : 8872
Part 1 ) - 1977
(3)
(2)
v)
3 TEST
Sixtlr &or@ ( 3 SampleJ 1
a) Resistance
to solvents
h) Resistance
to soldering heat
9.8.4
-
1) Visual examination
9.1
-
2) Element resistance
8.2
(Part l)-1977.
There
shall
be no fracture,
loosening of parts or other mechanical deterioration.
The change in resistance
from
the initial value shall not excecd f 1 percent + O-50)
( Continued)
9
IS: 8872 ( Part 4/Set 4 ) - 1984
TABLE
SCHEDULE
AND REQUIREMENTS -
Test
in IS : 8872
( Part 1 ) - 1977
(2)
(3)
f.1)
Requirements
of
Test
(4)
(5)
Seventh Groufi ( 6 Sampfcs )
a) Temperature
characteristic
of
8.11
‘Drying
as per procedure
resistance
b) Salt mist
1) Visual
II’
The
value
shall
ppm/‘C
or 250
applicable.
be f
ppm/“C
100
as
10.3
examination
2) Element
ti)
Conrd
Condition
C1aosc Rcf
SI
No.
viii)
3 TEST
resistance
9.1
There
shall bc
no
corrosion,
loosening
of parts
or other
mechanical
deterioration.
Marking
shall
be legible
and
indelible.
8.2
As in Sl No. (i) (c).
As in Sl No. (i) (j).
3) Insulation
resistance
8.10
4) Operating
torqoe
9.2
-
.4s in Sl No.
(i) (m).
Spares ( 6 Samples)
10
Printed
lt.DcIhi
Priotm.
lhlbi.
India