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 8872-2-1 (1979): Variable Resistors, Part 2: General
Purpose, Section 1: Type VRG1C [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”
UDC
621.31692
: 62148~038
IS : 8872 (Part
Indian
SPECIFICATION
1
Is1
I
II
GENERAL
Section
1) - 1979
( Reaffirmed 2002 )
Standard
FOR VARIABLE
PART
II/Set
RESISTORS
PURPOSE
1 TypeVRGlC
0. General - This standard shall be read in conjunction
with IS : 8872 ( Part I) - 1977 ‘ Specification
for variable resistors:
Part I General requirements
and methods of fesfs’.
1. Scope -Covers
non-wire
commercial
applications.
2. Outline
to Fig. 1.
Drawing
wound,
general
purpose
-
outline
and Dimensions
The
variable
drawing
resistors
of rotary type required
and dimensions
shall
be according
--__--
8
..
0
1A
16-mm Variable
ResistojtchSingle
with*
and Without
1B
16-mm Variable
*Switch
23.mm
shown
-Tandem
Without
-----------
----__
IC
Resistor
Switch
Variable Resistor - Single
and Without Switch
in interrupted
1D
with*
23-mm Variable
Resistor -Tandem
and Without Switch
outline.
All
FIG.
INDIAN
MANAK
1
dimensions
OUTLINE
in millimetres.
DRAWING
STANDARDS
BHAVAN,
9
NEW
BAHADUR
DELHI
AND DIMENSIONS
INSTITUTION
SHAH
110002
ZAFAR
MARG
for
with*
IS: 8872 ( Part ll/Sec
3. Ratings
1 )- 1979
and Characteristics
a) Electrical ratings
b) Mechanical characteristics
Cl Selection tolerance
d)
e)
f)
9)
h)
See Table 1
See Table 2
f 20 percent
Stability class:
1) Electrical
2) Mechanical
Temperature
characteristic
of resistance
Maximum surface temperature
Mechanical endurance
Typical construction
TABLE
Rated
Dissipation
at 40°C
Style
VRGI C-0*25A
VRGIC-0*125B
VRGI C-O-1 A
VRGIC-0.05B
4. Climatic
4
b)
cl
d)
4
f)
9)
h)
W
0.25
0.125
0.1
0.05
ELECTRiCAL
to
to
to
to
4’7
4.7
4.7
4.7
Rated Limiting
Element Voltage
vdc Or Vrms
(4)
(3)
100 a
1 kQ
100 a
1 k B
M B
M a
M a
M .Q
Law
Law
Law
Law
(carbon
track)
RATINGS
Resistance
Law
Resistance
Range
(E3 Series)
(2)
(1)
1
XII IO percent
5 15 percent
-f 1 200 ppm/“C
1oo”c
10 000 cycles
Nonwire-wound
A
B
A
B
( linear)
(forward
(linear)
(forward
(5)
log)
log )
250
250
250
250
Angle of
Effective
Rotation
(6)
235
235
235
235
to 250”
to 250°
to 250”
to2500
Severeties
Temperature
severity
Damp heat severity
Bump
Vibration
Shock
Acceleration
Low air pressure
Rapid change of temperature
1o/70
21 days
4000, log
IO-55 Hz, 10 g, 3 x 2 hours
Not applicable
Not applicable
Not applicable
Not applicable
Derating
-Variable
resistors covered by this standard are derated linearly
from 100 percent
rated dissipation
at 40°C to zero dissipation
at 100°C through 50 percent dissipation
at 70°C. The
dissipation
at temperatures
below 40°C is the rated dissipation.
Reference should
be made to the
derating curve shown below to find out dissipation
at other temperatures.
5.
TABLE
2
MECHANICAL
CHARACTERISTICS
[ Clause 3 (b) ]
Style
(1)
(2)
VRGl C-0.25A
Tandem
iii)
iv) Tandem
VRGl C-O.1256
Tandem
iii)
iv) Tandem
VRGIC-O*lA
i) Single
W
ii)
iii)
VRGlC-0.05B
Single
Tandem
i) Single
ii) Single
iii)
*IS :4586
with switch
without
with
switch
length
(Part
Tandem
with
switch
without
with
switch
switch
without
with
without
without
with
switch
switch
switch
switch
switch
without
switch
( Part l/Set
( Part IjSec
3)-1978:
4 )-1976:
(5)
(6)
(7)
kg.cm
kg.cm
g.cm
5”
35 -
500
8
12.5
35 -
500
8
12.5
35 -
500
8
12.5
300 f
5O
270 f
5’
Part 1 Spindles,
Part I Spindles,
Section
Section
3 Flatted
4 Slotted
Torque
(4)
5”
5O
Switching
g.cm
35 -
500
8
12.5
35 -
Not
applicable
400 - 800
Not applicable
400 - 800
500
a
12.5
35 - 500
8
12.5
400 - 800
500
8
12.5
Not applicable
8
12.5
300 f
5”
35 -
300 f
5O
35 - 500
Not applicable
400 - 800
270 f
5”
35 -
500
3.5
10~0
270 f
5”
35 -
500
3.5
IO.0
300 f
5”
35 - 500
3.5
10.0
Not applicable
270 f
5”
35 - 500
3.5
10.0
Not applicable
270 f
5”
35 - 500
3.5
IO.0
300 + 5”
35 - 500
3.5
IO.0
of spindle (L,), flat length
(L,)
for flatted
spindle
and slot dimensions
l/Set 3)-1976* and IS: 4535 (r’art
l/Set 4)-1979*,
for the corresponding
Dimensions
of spindles and mounting arrangements
( Part l/Set 2)-1978:
Part I Spindles,
Section 2 Plain
Locking
Torque
(Max)
270 f
270 & 5”
switch
End Stop
Torque
(Max)
Starting
Torque
270 f
300 f
switch
0 Single without
ii) Single
Mechanical
Rotation
(3)
i) Single without switch
ii) Single
Note-Mounting
Set 2)-1975*,
IS:4536
Total
Type
of spindle operated
round spindles.
spindle.
spindle.
electronic
for sloted spindle,
spindle diameter.
components,
shall
be chosen
Not applicable
150 -400
150-400
Not
from
applicable
IS:4586
( Part I/
IS : 8872 ( Part
6. Marking
-
II/Set
1) - 1979
See 6 of IS : 8872 ( Part I ) - 1977.
7. Material,
Construction
and Workmanship
-
See 5 of IS : 8872 ( Part I ) - 1977.
8. Tests
6.1 Classification
of Tests
8.1.1 Type tests - The sequence
in accordance
with Table 3.
of type tests and grouping
TABLE
Title
SI
of Test
rM-----_Highest
Value
NO.
(2)
(1)
i) Group
TYPE
Number
for type approval
shall
examination
b) Dimensions
Electrical
d) Total
TESTS
of Samples
IS
-------7
Middle
Value
Clause Ref in
: 887f9gart I
)-
Lowest
Value
(4)
(5)
(3)
16
16
16
9.1
9.1.1
continuity
resistance
e) Terminal
resistance
8.1
8.2
8.3
f ) Attenuation
8.4
g) Effective resistance and
angle of effective rotation
8.6
h) Resistance
law
a.7
] ) Matching
of resistance
law
( for tandem types only )
8.14
k) Switch
contact
resistance
(for types with switch only )
a.8
m) Voltage
8.9
proof
n) Insulation
resistance
8.10
8.12
p) Noise
q) Operating
torque
9.2
r) Switching
torque
9.3
s)
be
0
a) Visual
c)
(3)
3
of samples
End-stop
t) Locking
u) Thrust
torque
torque
and pull on spindle
9.4
9.5
9.6
( Continued )
IS: 8872 ( Part Il/Sec
TABLE
SI
No.
Title
of Test
ii) Group
TESTS
-
Contd
IS
Lowest
Value
(3)
(4)
(5)
4
4
4
Clause Ref in
: 8872 ( Part I )1977
(6)
1
a) Robustness
of terminations
9.1
b) Solderability
9.8.3
c) Bump
9.10
d) Vibration
9.9
e) Climatic
iii)
TYPE
Number of Samples
~~~~~~~__~~h~___-~~~-~~~
Middle
Highest
Value
Value
(2)
(1)
3
1 ) - 1979
sequence
10.1
Group 2
Damp heat (long
term
)
2
2
2
10.2
2
2
2
11.3
2
2
2
11.4
2
2
2
9.8.4
2
2
2
8.11
2
2
2
iv) Group 3
Mechanical
v) Group
4
Electrical
vi) Group
endurance
5
endurance
3
Resistance
vii)
Group
to soldering
heat
6
Temperature
characteristic
of resistance
Spares
given
8.1.1.1The
below:
manufacturer
shall
submit
Highest
Middle
8.1.2 Routine
4
Visual
fesfs -
value
dissipation,
of samples
as
16*
value
16*
Lowest value
16*
The following
the number
tests shall
be carried
out on each and every resistor:
more than
10 percent
of the lot fails,
examination,
b) Electrical
c) Total
for each rated
continuity,
and
resistance.
8.1.2.1If during
rejected.
routine
tests,
the entire
lot may
be
8.1.3 Acceptance tests - For the purpose of the acceptance of the lot, all the resistors shall be
this two groups of samples ( Group A and B )
subjected to the tests as given in 8.1.2. Following
shall be selected and the resistors shall be subjected to the tests specified in Tabie 4 in the Q iven
order.
*Of these 16 samples,
14 are required
for
carrying
out the type tests
5
and two are to be kept as spare.
IS : 8872 ( Part II/Set
1) - 1979
8.2 General Conditions
for Tests -See
7 of IS : 8872 (Part
be used for any one test but not necessarily
for all tests.
I j-1977.
The same measuring
8.2.1 The test schedule
with test conditions
and requirements
after each test
variable resistors covered by this standard shall be in accordance with Table 5.
set shall
applicable
to
TABLE 4 ACCEPTANCE TESTS
Test
Clause
t?:.
IS
(1)
Ref in
: 8872 ( Part I )-1977
(3)
(2)
law
proof
)
d) Operating
e) Locking
f)
(two
seconds
1 percent
II
4 percent
s3
4 percent
53
(9)
9.2
torque
9.5
8.12
B
Bl
9.8.3
a) Solderability
Subgrcup
B2
a) Resistance
to soldering
Robustness
Cl Endurance
d)
(5)
8.9
torque
Sub-group
b)
D/ND
8.7
Noise
ii) Group
Inspection
Level
9.1.1
b) Resistance
c) Voltage
duration
Defective)
(4)
i) Group A
a) Dimensions
AQL
( Percent
9.8.4
heat
of terminations
( mechanical
9.7
)
11.3
End stop torque
Subgroup
9.4
B3
Subgroup
electrical
D = Destructive,
11.4
(t68h)
and
ND = Non-destructive.
Note-For
4 percent
s3
10.1
sequence
B4
a) Endurance
s3
9.9
a) Vibration
b) Climatic
4 percent
each group/sub-group,
separate
samples
shall
6
be drawn.
_
D
IS : 8872 ( Part II/See
TABLE
5
TEST
SCHEDULE
AND
1 ) - 1979
REQUIREMENTS
( Clause 8.2.1 )
SI
Test
Clause Ref
in IS : 8872
( Part I )-I977
(2)
(3)
(4)
9.1
-
The workmanship
be satisfactory.
shall be legible
9.1.1
-
The dimensions
of the resistors
and
their
terminations
shall
conform to values given in Fig. 1
8.1
-
There shall
8.2
-
The resistance
value
correspond
with
resistance
taking
the tolerance
NO.
(1)
I) All
Visual
b)
Dimensions
examination
Cl Electrical
4 Total
continuity
resistance
resistance
8.3
Attenuation
(for
Law
B
variable
resistors
having
values > 1 k Q only )
8.4
and
resistance
angle of effective rotation
8.6
4 Terminal
9) Effective
h)
of Test
Requirement
(5)
Samples
a)
f)
Condition
Resistance
law
8.7
be no discontinuity
-
Shall
be greater
As in Table
Setting
in percent of total
electrical rotation
Output
shall
Matching
of resistance
law
( for tandem types Only )
1
ratio in percent
the limits:
i) 40-60 for resistance
resistance
< 220 k D
2 220 k Sz
i) l-5-8
i) 30-36
ii)
ii) 64-70
j)
than 50 dB
resistance
not exceed
ii) 35-65 for
2) Law B
at 25’C shall
the
rated
into account
The minimum
terminal
resistance
at either end of the resistor
shall
not exceed the values
given in
Appendix
A
47 to 63
1) Law A
and finish shall
The
marking
8.14
-
IO-40
The ratio of the two voltages or the
differences
expressed in decibles
shall be within the limits:
i) Law A
At any point between 10yO and 90%
of the total resistance
value the
ratiosg(
or%)
of
either
of
the two variable
resistors
shall
not exceed l-25 times the corresponding
momentary
ratio of the
other variable
resistor
ii)
Law 13
Vab
20 tog Vat
O-20 dB
20-30 dB
30-40 dB
Over 40 dB
Maximum
permissible difference
between the
attenuation
of the
two
section
2dB
3dB
4dB
No requirements
( Continued)
7
IS : 8872 ( Part ll/Sec
1 )- 1979
TABLE
SI
No.
5
TEST
SCHEDULE
Test
Clause Ref
in IS : 8872
( Part I )-1977
(2)
(3)
(1)
k) Switch
contact
resistance
(tor
types
with
switch
only )
m) Voltage
AND
REQUIREMENTS
Condition
1) For variable
resistors
2) For switch
Requirement
(5)
For spindle
> 16 mm
Less than
25 m ohms
For spindle
616mm
Less than
20 m ohms
There
sha!l
flashover
8.9
proof
Contd
of Test
(4)
-
8.8
-
8.9.2
Test voltage
50 Hz shall
8.9.3
i) For spindle
diameter
< 16 mm test voltage
500 v
be no
breakdown
or
of 1 000 V at
be applied
ii) For spindle
diameter
> 16 mm test voltage
2 000 V ac at 50 Hz
n) Insulation
p) Contact
resistance
resistance
variation
8.10
-
i) For carbon
> 1 000 MS
ii) For switch
,100 MQ
8.12.4
-
Contact resistance shall not exceed
for
i) Law A 6 percant of Rn
ii) Law B 8 percent of Rn
-
35-500 g.cm
q) Operating
torque
9.2
r ) Switching
torque
9.3
track
i) 150-400 g.cm for 16 mm resistor
ii) 400-800 g.cm for 23 mm resistor
s)
9.4
End stop torque
i) 33 kg.cm
ii) 8 kg.cm
t) Locking
-
9.5
torque
Max for 16 mm resistor
Max for 23 mm resistor
i) 10 kg.cm Max for 16 mm resistor
ii) 12.5 kg.cm Maxfor
U)
Thrust
and pull on spindle
1) Visual
examination
2) Electrical
3) Total
continuity
resistance
9.6
-
9.1
-
8.1
There shall
23mm
be no visible
There shall be
tinuity
resistor
damage
no electrical
discon.
8.2
The change
in
resistance
value
shall not exceed *2 percent
9.7
There shall
ii) First Group
a) Robustness
nations
of
termi-
b) Solderability
9.8.3
-
c) Bump
9.10
4 000, 10 g
1) Visual
examination
2) Electrical
3) Total
continuity
resistance
d) Vibration
1) Visual
examination
2) Electrical
3) Total
continuity
resistance
damage
There
shall be no visible damage
and the tinning shall be good
9.1
-
There
8.1
-
There shall
tinuity
8.2
-
9.9
IO-55 Hz, 10 g, 6 h
9.1
-
There shall
8.1
-
There shall
continuity
8.2
be no visible
shall
be no visible
damage
be no electrical
discon-
The change
in resistance
value
shall not exceed f 2 percent
be no visible
be no
Change in resistance
exceed f 2 percent
damage
electrical
value shall
disnot
( Confinued
8
)
IS : 8872 ( Part II/Set
TABLE
5
TEST
SCHEDULE
SI
No.
Test
Clause Ref
in IS : 8872
( Part I )-I977
(1)
(2)
(3)
e) Climatic
10.1.2
1) Dry heat
examination
2) Damp heat
ted ) first
Visual
(acceleracycle
examination
10.1.4
3) Cold
i) Visual
examination
ii) Operating
iii)
Switching
torque
torque
9.1
5) Damp heat (accelerated ) remaining
cycles
10.1.6
ii) Total
iii)
examination
resistance
Insulation
resistance
iv) Switch
contact
resistance
v) Electrical
vi) Operating
vii)
Voltage
continuity
torque
At
upper
perature
(5)
category
tem( + 70°C)
-
After
recovery
visible
damage
be legible
-
there shall
be no
and marking
shall
-
One cycle
of
24 h at
55 &2”C
and
RH
of
95-100
percent
with
no voltage
applied
There
shall
be
no
damage
marking
shall be legible
-
There
shall
be no
damage
marking shall be legible
During the last 5 minutes
of the
test,
voltage
proof
test
shall
be
carried out subject to
the air pressure ( low)
voltage limitation
Switching
torque
times the initial
shall not exceed two
requirement
During and after this test there shall
be no sign of breakdown
or flashover
-
-
There
shall
be no visible
damage
and the marking shall be legible
-
The change in resistance
not exceed &20 percent
value shall
The insulation
resistance
shall
not
be less than 25 MQ for carbon track
and 2 MS for switch
a.8
The switch contact
resistance
not exceed 40 m.ohms
a.1
There shall
tinuity
proof
a.9
( long term)
10.2
and
Operating
torque
shall
not
exceed
three times the initial requirement
a.10
9.2
and
-
At lower category
temperature ( - 10°C )
9.1
a.2
Requirement
-
9.3
10.1.5
Contd
of Test
9.2
4) Low air pressure
i) Visual
iii)
9.1
-
(4)
9.1
10.1.3
REQUIREMENTS
Condition
10.1
sequence
Visual
AND
1) - 1979
-
shall
be no electrical
discon-
There shall be no breakdown
over
or flash-
Initial
limits
Second Group
a) Damp heat
Half the number of specimens shall be loaded
with a direct voltage of
20 V between the movable contact
and case
(movable contact being
positive )
-
(Continued)
9
IS : 8872 ( Part II/Set
1 )-1979
TABLE
SI
No.
5
TEST
SCHEDULE
Clause Ref
in IS: 8872
(Part
I )-1977
Test
AND
Condition
REQUIREMENTS
-
Contd
Requirement
of Test
(5)
(3)
(4)
9.1
-
There shall be no damage
marking shall be legible
8.2
-
The change of resistance
exceed f 20 percent
8.10
-
4) Switch contact
resistance
8.8
-
Resistor : 25 MQ, Min
Switch :
2 MS, Min
The switch
contact
resistance
not exceed 40 m.ohms
5) Electrical
continuity
8.1
-
6) Operating
torque
9.2
(1)
(2)
1) Visual
2) Total
examination
resistance
3) Insulation
resistance
7) Contact resistance
variation
a-12.4
-
8) Voltage
8.9
-
proof
and the
shall
There shall be no electrical
tinuity
Initial limits
Law A 4 4 percent
Law B 4 8 percent
There
shall
flashover
be
not
shalt
discon-
of Rn
of Rn
no
breakdown
or
iv) Third Group
a) Mechanical
endurance
11.3
resistor
10.3.1
1) Variable
-
rate of
-
i) Visual
examination
9.1
There shall
ii) Total
resistance
8.2
The change in resistance
value
not exceed & 15 percent
-
iii)
Terminal
resistance
resistance
torque
vi)
continuity
vii)
viii)
ix)
Electrical
Thrust
spindle
Voltage
and
pull
Contact
variation
resistance
on
proof
2) Switch
i) Visual examination
ii) Operating
torque
iii) Insulation
resistance
iv) Switch
contact
resistance
v) Fourth
8.10
9.2
8.1
1000
be no visible
8.9
There shall be no breakdown
over
-
Shall
8.9
endurance
11.4
-
shall
-
-
8.12.4
10.3.2
9.1
9.2
8.10
8.8
damage
MS& Min
9.6
proof
v) Voltage
-
a.3
iv) Insulation
v) Operating
There
Initial
Shall
Shal I
be within
initial
or flash-
limits
shall be no visible damage
limits
not be less than inital limits
not exceed 200 m.ohms
There
shall
flashover
be
no
breakdown
or
Group
a) Electrical
i) Visual
ii) Total
iii)
10000 cycles at the
IO-15 cycles/Min
-
examination
resistance
Insulation
resistance
iv) Contact
resistance
variation
-
9.1
There
a.2
Change in resistance
exceed &IO percent
8.10
Shall not be less than 10 000 MQ, for
variable resistors
-
8.12.4
Shall
shall
be no damage
be within
value shall not
the inital
limits
vi) Fifth Group
a) Resistance
heat
to soldering
i) Visual examination
ii) Total resistance
vii)
Shf/~
-
9.8.4
9.1
8.2
-
There shall be no visible
Change
in resistance
not exceed f2 percent
8.11
-
rt 1 200 ppm/“C
Group
Temperature
characteristic
of resistance
10
damage
value
shall
IS : 8872 ( Part II/Set
APPENDIX
1) - 1979
A
[ Table 5, SI No. l(e)]
TABLE
SI No.
’
6
TERMINAL
RESISTANCE
Rated
Resistance
Greater
Than
Maximum
Less Than or
Equal to
Clockwise
and
Counter
Clockwise
Law
---I
A
Value of Minimum
Resistance
Counter
Clockwise
Law
B
Clockwise
Law
B
-__
(1)
(2)
(3)
(4)
i)
-
50052
ii)
50052
iii)
(5)
(6)
5oQ
-
-
1 kQ
5oQ
552
5052
1 kG?
5 ka
5052
552
10052
iv)
5 kS
IO kfi
509
IOSZ
20052
v)
IOka
25 ka
5052
IOQ
44052
vi)
25 kQ
50 kn
5052
508
1 ka
vii)
50 kQ
0.1 MB
10052
1 OOB
2 kQ
0’1 fv?sz
0.25 MB
22oS1
2208
4.4 kS?-,!
ix)
0.25
Ma
0.50 MSZ
4708
47OQ
9.4 kfi
x)
0.50
MS1
1 Ma
1 kP
1 kn
20 kB
1 Ma
2.5 MSZ
2.2 kSZ
2.2 k0
4.4 kQ
2.5 Ma
5MSZ
4.7 kQ
4’7 kQ
94 kSZ
viii)
xi)
xii)
11
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