BS 7744:1994
Superseded
A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.
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Guide to artificial pollution tests on high voltage insulators to be used on d.c. systems
Hardcopy , PDF
30-04-2015
English
15-03-1994
Committees responsible
National foreword
Introduction
Section 1. General
1.1 Scope
1.2 Normative references
1.3 Definitions
Section 2. General test requirements
2.1 Test methods
2.2 Arrangement of the insulator for the test
2.3 Requirements for the test circuit
Section 3. Salt fog method
3.1 Salt solution
3.2 Spraying system
3.3 Conditions before starting the test
3.4 Preconditioning process
3.5 Withstand test
3.6 Acceptance criteria for the withstand test
Section 4. Solid layer method
4.1 Composition of the contaminating suspension
4.2 Main characteristics of the inert material
4.3 Application of the pollution layer
4.4 Determination of the degree of pollution of the
test insulator
4.5 Test procedure
4.6 Withstand test and acceptance criteria
Section 5. Withstand characteristic of insulators
5.1 Determination of the withstand characteristics of
insulators
Annexes
A. (informative) Method for checking the uniformity
of the layer
B. (informative) Additional recommendations concerning
the solid layer method procedures
C. (informative) Information to check equipment for
artificial pollution tests
Tables
1. Salt-fog method: correspondence between the value
of salinity, volume conductivity and density of the
solution at a temperature of 20 deg C
2. Correspondence between the solution temperature
and the factor b
3. Approximate correspondence between the SD and
sigma 20 for kaolin compositions
4. Main characteristics of kaolin used in the solid
layer suspension
Figures
1. Ripple amplitude and actual mean voltage, measured
on a resistive load absorbing 100 mA
2. Voltage drop and voltage overshoot and leakage
current
3. Typical construction of fog spray nozzle
4. Test layout for inclined insulators
A.1 Arrangement of the probe electrodes
A.2 Circuit diagram of the meter
B.1 Determination of layer conductance and evaluation
of its rise time Tc = t2 - t1
C.1 (Provisional)
Provides a methodology for undertaking tests but world experience is too limited to know if these procedures cover all voltages adequately.
Committee |
PEL/36
|
DevelopmentNote |
Also numbered as IEC 61245 Supersedes 92/28034 DC (10/2005)
|
DocumentType |
Standard
|
Pages |
24
|
PublisherName |
British Standards Institution
|
Status |
Superseded
|
SupersededBy | |
Supersedes |
BS EN 61325:1996 | Insulators for overhead lines with a nominal voltage above 1000 V. Ceramic or glass insulator units for d.c systems. Definitions, test methods and acceptance criteria |
BS EN 60507:2014 | Artificial pollution tests on high-voltage ceramic and glass insulators to be used on a.c. systems |
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