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Bakelit-graphite products
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Collecting brushes maded
bakelit-graphite semimanufactured, have the following
features: high electrical and mechanical rezistivity, big difference between
rezistivity measured
on perpendicular and parallel plane of press direction. Electrical brushes,
maded bakelit-graphite semimanufactured, have: low and very low friction
coefficient, high falling voltage at the sliding contact,
a good swiching, good rezistivity at sparkling. These brushes are good for
current decrease in short
circuit for motors with smooth commutator. Bakelit-graphite semimanufactured
are produced
in five qualities: BGR-1, BGR-2, BGR-3, BGR-4, BGR-5.
Bakelit-graphite
brushes assure slide contact for electrical machines of A.C. with collector
type Schrape-Richter, motors of D.C. till 30 kW, motors type Lawrence Scott
of high power,
fractionary motors, hand tool motors, auxiliary motors of traction.
Table
with parameters of running recommanded for
bakelit graphite materials in normal conditions of
running
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Group
of semimanufactured
|
Mark
|
Density
of curent
|
Peripheral
speed max.
|
Pressure
on brush
|
|
|
A/cm²
|
m/s
|
kN/m²
|
|
0
|
1
|
2
|
3
|
4
|
|
BAKELIT
GRAPHITE
|
BGR
- 1
|
max.
10
|
max.
10
|
18
- 21
|
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BGR - 2
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BGR
- 3
|
|
BGR
- 4
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BGR
- 5
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Phisical characteristics
of the bakelit-graphite materials could be determined using a tubes
of sizes 4x8x32 mm or 10x10x64 mm according to STAS 10223/1-75.
Fuctional characteristics: falling voltage, friction coefficient and middle
wear speed values
are determinated in laboratory conditions on two pieces of testing brushes
on sizes
12,5x25x40 mm according to STAS 10223/3-84. For the folling voltages, friction
coefficient
and medium wear speed values (point 6,7 and 8) are necesary the following conventional
conditions of testing:
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TESTING
CONDITIONS
|
VALUES
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peripheral
speeds
|
25 m/s
|
|
density
of current
|
8
A/cm²
|
|
pressure
on brush
|
22
kN/m²
|
|
current
|
continous
|
|
temperature
|
60°C
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