Experiment No.: 5
Experiment Name:
Determine the regulation & efficiency of single-phase transformer by direct loading method.
Objective:
To determine
- Regulation of single-phase transformer by direct loading method
- Efficiency of single-phase transformer by direct loading method
Theory:
Although two chief difficulties which do not warrant the testing of large transformer by direct load test are:
- Large amount of energy has to be wasted in such a test.
- It is stupendous (impossible for large transformer) task to arrange a load large enough for direct loading. Yet this test can be performed to find out the efficiency & voltage regulation of small rating transformers.
Efficiency, η = Output Power / Input Power
% η =((P2) / (P1)) × 100
% Voltage regulation up= ((No load voltage – Full load voltage)/Full load voltage)×100
% Voltage regulation down= ((No load voltage – Full load voltage)/No load voltage)×100
Circuit Diagram:
Observation Table:
Calculation:
Apparatus Used:
| Sl. No. | Name of Apparatus | Quantity | Specification | Makers name |
| 1. | Single phase wattmeter | 2 | 0-750-1500-3000 W 150-300-600 V 5-10 A | MECO-G |
| 2. | Single Phase Transformer | 1 | 230/115 V | |
| 3. | Ammeter | 1 | 0-5 A, MI type | KEW |
| 4. | Ammeter | 1 | 0-10 A, MI type | Sushama |
| 5. | Voltmeter | 1 | 0-300 V, MI type | Sushama |
| 6. | Digital Multimeter | 1 | 0-750 V AC, 0-1000 V DC, 0-10 A | Akademika |
| 7. | Rheostat | 1 | 0-100 W, 1kW |
Remarks: This method is not applicable for large rated transformer as a large amount of energy has to be wasted in such a test. During this test we should cautious about the heat radiated by the resistive load.
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