1 Scope
This part of GB/T 16927 is applicable to the following on-site test voltages and in service stresses, which are in relation to GB/T 16927.1:
——direct voltage;
——alternating voltage;
——lightning impulse voltage of aperiodic or oscillating shape;
——switching impulse voltage of aperiodic or oscillating shape.
For special tests the following voltages are used:
——very low frequency voltage;
——damped alternating voltage.
This standard is applicable to equipment with a nominal voltage of 3kV and above. The selection of on-site test voltages, test procedures and test voltage levels for apparatus, equipment or installations is under the responsibility of the relevant technical committee. For special applications, on-site test voltages different from those described in this standard may be specified by the relevant technical committee.
Note 1: The different voltage waveforms listed above do not necessarily provide equal stress on the test object (insulation).
Note 2: The selection of the test voltage levels should take the larger tolerances and measuring uncertainties into account.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB 311.1-1997 Insulation co-ordination for high voltage transmission and distribution equipment (neq IEC 60071-1:1993)
GB/T 2900.19-1994 Electrotechnical terminology - High-voltage test technique and insulation coordination (neq IEC 60071-1:1993)
GB/T 16927.1-1997 High-voltage test techniques - Part 1: General test requirements (eqv IEC 60060-1:1989)
GB/T 16927.2-1997 High-voltage test techniques - Part 2: Measuring systems (eqv IEC 60060-2:1994)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply. For all other definitions relating to testing procedures, see GB/T 16927.1 and GB/T 16927.2.
3.1
on-site test
test at the place of use of the apparatus, equipment or installation that is to be tested, and with the test object as far as possible in its service condition
3.2
impulse voltage
intentionally applied aperiodic or oscillating transient voltage, which usually rises rapidly to a peak value and then its enveloping curve falls more slowly to zero
(GB/T 2900.19-1994, 4.12, modified)
3.3
lightning and switching impulse voltage
a distinction is made between lightning and switching impulse voltages on the basis of duration of the front. Impulses with front duration up to 20μs are defined as lightning impulse voltages and those with longer fronts are defined as switching impulse voltages
Generally, switching impulse voltages are also characterized by total durations considerably longer than those of lightning impulse voltages.
(GB/T 2900.19-1994, 3.32, 4.13 and 4.25, modified)
3.4
characteristics of the test voltage
those characteristics specified in this standard for designating the different types of voltage variation that define the test voltage
3.5
prospective characteristics of a test voltage
the characteristics which would have been obtained if no disruptive discharge had occurred. When a prospective characteristic is used, this shall always be stated
3.6
actual characteristics of a test voltage
characteristics that occur during the test at the terminals of the test object
3.7
value of the test voltage
as defined in the relevant clauses of the present standard
3.8
classification of insulation in test objects
insulation systems of apparatus and high-voltage structures must basically be classified into self-restoring and non-self-restoring insulation and may consist of external and/or internal insulation
3.8.1
external insulation
distances in atmospheric air, and the surfaces in contact with atmospheric air of solid insulation of the equipment which are subject to dielectric stresses and to the effects of atmospheric and other external conditions such as pollution, humidity, vermin, etc.
(GB/T 2900.19-1994, 3.24)
3.8.2
internal insulation
internal solid, liquid or gaseous insulation, which are protected from the effects of atmospheric and other external conditions
(GB/T 2900.19-1994, 3.25)
3.8.3
self-restoring insulation
insulation that completely recovers its insulating properties after a certain time interval following a disruptive discharge caused by the externally applied voltage
(GB/T 2900.19-1994, 3.28, modified)
3.8.4
non-self restoring insulation
insulation that loses its insulating properties, or does not recover them completely, after a disruptive discharge caused by the externally applied voltage
(GB/T 2900.19-1994, 3.29, modified)
Note: In high-voltage apparatus, parts of both self-restoring and non-self-restoring insulation often operate in combination and some parts may be degraded by repeated or continued voltage applications. The behaviour of the insulation in this respect shall be taken into account by the relevant technical committee when specifying the test procedures to be applied.
3.9
measuring system and their components
3.9.1
measuring system
complete set of devices suitable for performing a high-voltage measurement
(GB/T 16927.2-1997, 3.1.1, modified)
Note 1: A measuring system is usually comprised of the following components: a converting device with the leads required for connecting this device to the test object and the connections to earth, a transmission system connecting the output terminals of the device to the indicating or recording instruments with its attenuating, terminating and adapting impedance or networks, and indicating or recording instruments together with any connections to the HV source.
These components may be arranged in one compact unit together with the HV source. This usually applies to portable test equipment for medium-voltage apparatus.
Note 2: Measuring systems which are based on non-conventional principles are acceptable if they meet the accuracy requirements specified in this standard.
Note 3: The environment in which a measuring system functions, its clearances to live and earthed structures and the presence of electric or magnetic fields may significantly affect its accuracy.
3.9.2
record of performance of a measuring system
detailed record, established by the user, describing the system and containing evidence that the requirements given in this standard have been met. This evidence shall include the results of the initial acceptance test and the schedule and results of each subsequent performance test and performance check
(GB/T 16927.2-1997, 3.1.2)
3.9.3
approved measuring system
a measuring system that is shown to comply with the requirements of this standard by:
——an initial performance test;
——successive performance checks and performance tests;
——inclusion of the results of these tests in the record of performance.
The system is approved only for the arrangements and operating conditions included in its record of performance.
(GB/T 16927.2-1997, 3.1.3, modified)
Foreword i
Introduction ii
1 Scope
2 Normative references
3 Terms and definitions
4 Normal and special service conditions
5 Common tests and checks on a measuring system
6 Tests with direct voltage
7 Tests with alternating voltage
8 Tests with lightning impulse voltage
9 Tests with switching impulse voltage
10 Tests with very low frequency voltages
11 Tests with damped alternating voltages
