IEC 60034-15:1995 pdf Rotating electrical machines – Part 15: Impulse voltage withstand levels of rotating a.c. machines with form-wound stator coils

IEC 60034-15:1995 pdf Rotating electrical machines – Part 15: Impulse voltage withstand levels of rotating a.c. machines with form-wound stator coils
1 Scope
This part of IEC 34 specifies the rated phase-to-earth impulse voltage withstand levels of rotating a.c. machines having rated voltages from 3 kV to 15 kV inclusive and incorporating form-wound stator coils, together with the test procedures and voltages to be applied to the main and interturn insulation of sample coils to prove the compliance of the machine.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of IEC 34. At the time of publication, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this part of IEC 34 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. Members of IEC and ISo maintain registers of currently valid International Standards.
IEC 34-1: 1994, Rotating electrical machines – Part 1: Rating and performance
IEC 60-1: 1989, High-voltage test techniques 一Part 1: General definitions and test requirements
IEC 71-1: 1993, Insulation co-ordination – Part 1: Definitions, principles and rules
3 Definitions
For the purpose of this part of IEC 34 the following definitions apply.
3.1 random sample test: Test carried out on coils which adequately represent the configuration of the finished item to be used in the machine, for the purpose of evaluating the basic design, type of materials, manufacturing procedures and processes incorporated in the insulation system.
3.2 routine test: Test carried out on all coils of the machine.
3.3 form-wound stator coil: Coil which is preformed to shape before insertion into the stator.
4 Impulse voltage withstand levels
Rated impulse voltage withstand levels for rated voltages from 3 kV to 15 kV shall be obtained by application of the formulae given in notes 2 and 4 of table 1, the values obtained being rounded off to the nearest whole number. Table 1 gives the rated impulse voltage withstand levels for some common rated voltages, together with the corresponding rated power-frequency withstand voltage (r.m.s.) according to IEC 34-1.
5 Tests
5.1 Random sample tests
5.1.1 General
These tests are carried out as an indirect proof as explained in A.3.2 of annex A. The test coils shall be fully processed, including corona protection, if provided, and shall be either embedded in slots or fitted with the slot portion wrapped in earthed conducting tape or foil.
The number of sample coils shall be two, unless agreed otherwise between the manu-facturer and the purchaser.
All tested coils shall fulfil the requirements given below and, in the case of a failure,investigations shall be carried out to determine the cause.
5.1.2 Impulse test of the interturn insulation
5.1.2.1 The impulse test of the interturn insulation shall be carried out by applying a voltage between the two terminals of the sample coils.
5.1.2.2 The interturn test voltage shall be generated by the damped oscillatory discharge of a capacitor. The number of capacitor discharges shall be five, unless agreed otherwise between the manufacturer and the purchaser. The front time of the first voltage peak shall be 0,2 μs with a tolerance of + 0,3 μs/ -0,1 μs. .
5.1.2.3 The voltage peak between the terminals of the sample coil shall have the values given in table 1, column 3, as appropriate, or the values obtained by application of the formula in note 4 of table 1 and rounded off to the nearest whole number.
5.1.3 Impulse test of the main insulation
The impulse withstand level of the main insulation is tested by applying either a power-frequency voltage (see 5.1 .3.1) or an impulse voltage (see 5.1.3.2).
5.1.3.1 Power-frequency voltage test
The rated power-frequency withstand voltage (2 UN + 1 kV) shall be applied for 1 min between coil terminals and earth. The applied voltage shall then be increased at the rate of 1 kV/s up to 2 (2 UN + 1 kV), and then immediately be reduced at a rate. of at least 1 kV/s to zero. There shall be no failure during the sequence. The corresponding impulse withstand level of the main insulation and the overhang corona protection are then considered to fulfil at least the requirements of table 1.