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BS 7744:1994

Superseded

Superseded

A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.

View Superseded by

Guide to artificial pollution tests on high voltage insulators to be used on d.c. systems

Available format(s)

Hardcopy , PDF

Superseded date

30-04-2015

Superseded by

PD IEC TS 61245:2015

Language(s)

English

Published date

15-03-1994

€231.38
Excluding VAT

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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