Objective: To obtain Two-phase supply from Three-phase and to conduct load test. Preview:
The concept of 3phase to 2-phase connection follows from the voltage phasor diagram of balanced 3-phase supply. If the point M midway on Vbc could be located then VAM leads Vbc by 900. A 2-phase supply could be thus obtained by means of two transformers; one connected across AM, called the teaser transformer and the other connected across the lines B &C. Since VAM = ?3Vbc/2, the transformer primaries must have ?3N1/2 (teaser) and N1 turns;this would mean equal voltage / turn in each transformer. A balanced two phase supply could then be easily obtained by having both secondaries with equal number of turns N2. The point M is located midway on the primary of the transformer connected across the lines B & C. The connection of two such transformers, known as the Scott Connection, is shown in Fig with its phasor diagram of two phase supply in the secondary. Equipment Required: All the measuring instruments associated with each experiment are industrial grade. These instruments are housed in an elegant cabinet as a package. Range of instruments and accessories (standard format) 1. Transformer 1? 1KVA Capacity, Primary: 230V(tapings at 86.6%,50%), Secondary: 115V ? Two numbers
2. Suitable Loading rheostat for the above single phase ? two numbers
3. Suitable Variac ? three phase
4. Suitable digital ammeters of different ratings AC
5. Suitable digital voltmeters of different ratings AC
6. Suitable digital wattmeter |
