8) This describes the essential skills and knowledge and their level, required for this unit. Evidence shall show that knowledge has been acquired of safe working practices and rewinding three phase induction machines rated for high voltage above 3.3 kV. All knowledge and skills detailed in this unit should be contextualised to current industry practices and technologies. KS01-EG156A High voltage three phase motor winding techniques rated above 3.3 kV Evidence shall show knowledge and skills of high voltage three phase motor winding techniques rated above 3.3 kV to an extent indicated by the following aspects: T1 HV winding conductors and their applications. T2 HV winding wire connection methods encompassing: Conductor handling Conductor preparation Connection mediums T3 Insulation types and methods T4 Critical details and measurements when stripping a stator encompassing: Winding types Note. Example are hairpin wound stator and lap wound stator Winding diagram Wedges of a radially ventilated machine Factors to be considered when selecting cables for a stator. T5 Procedures for checking the condition of a stripped in preparation for rewind encompassing: Manufacturers' specifications. Sequence of events between the removal of the old winding and the start of rewinding. Core loss test, the effect this test may have on the core and expected test results Methods of overcoming hot spots in a stator core. Level of insulation required to insulate the steel bracing rings that support the overhang. Difference between the slot liners and packers of a 6.6 kV machine. T6 Procedures for the fitting of coils to core, wedging and bracing. Significance of the slot portion of coils for machines above 3.3 kV Method of inserting the coils of a ribbon winding into slots. Effects of undue mechanical stress on B stage insulated coils. Importance of coil pitch and why it is important. Sequence of events in fitting the first pole pitch group of coils in a lap winding Sequence of events in fitting the coils of a concentric winding Purpose and location of the excess packing in a slot. Difference between the wedges for a lap and hairpin winding. Method of fitting a wedge. Difference that may be encountered between the wedges for a radial ventilated and the wedges for an axially ventilated machine. Methods used to brace and strengthen the overhang of a lap winding and a hairpin winding T7 Procedures for making inter turn and inter coil connections on a hairpin winding and inter coil connections on a lap and bar winding encompassing: Sequence of events in making turn to turn connections, and insulating the turns of a lap winding Note. Connection methods include silver solder or brazing and soft solder Sequence of events, from hand forming the coil to final insulation, in making the turn to turn connections in a hairpin winding, using a welded joint. Sequence of events in making the coil to coil connections in a bar winding. T8 Testing according to British and IEC standards. Note. Examples of testing are 6.6 kV B stage insulated winding and VPI winding test. T9 Materials, procedures, tests and precautions required during and after the impregnation of completed windings according to Australian, British and IEC standards. Precautions to be taken when handling and using varnishes and resins. Important features of an oven used to cure large impregnated machines. Application and features of various impregnating materials Note. Examples are water based varnish, Xylol base varnish and 100% solids resin Method of carrying out a gel test on a resin and a viscosity test on a varnish Typical quality procedures carried out on an impregnating varnish. Procedure and precautions for carrying out the a hot dip impregnation, a flood coat impregnation and a VPI impregnation Tests to be carried out after impregnation and bake on a a 6.6 kV B stage insulated winding and a VPI winding T10 Winding to terminal connections according to British and IEC standards. Criteria for selection of winding to terminal cables Note. Examples are voltage rating, full load current and fault capacity. Common types of terminal boxes and their structure. Note. Example are phase segregated, phase separated and phase insulated Method of making the joint between winding and terminal cables and insulating such a joint. T11 Procedures and precautions to be followed when performing static electrical testing of a completed rewind according to Australian, British and IEC standards encompassing: Types and purpose of tests Testing safety precautions Testing procedures Note. Examples of tests are repetitive surge test, loss tangent test, polarisation index (PI) test, cold resistance test and polarity test. Interpretation of test results Calculation of winding cold resistance and line and phase resistance |