ALTERNATING CURRENT MACHINES – I(Practical:)

https://jpilms.gnomio.com/pluginfile.php/1051/mod_book/chapter/235/A%20C%20M-1%28Job.%20no-4.%29%20Regulation.pptx

 Determine the voltage regulation of single phase transformer by direct loading.

4.1 Sketch the necessary circuit diagram.

4.2 List the tools, equipment & materials required.

4.3 Connect the meters according to the diagram.

4.4 Connect the source to the primary keeping the secondary open and record no load

voltage (Vo).

4.5 Connect full load on the secondary & record the load voltage.

4.6 Calculate the voltage regulation from the formula:

Voltage Regulation of a Transformer

When the transformer is loaded with continuous supply voltage, the terminal voltage of the transformer varies. The variation of voltage depends on the load and its power factor.

Mathematically, the voltage regulation is represented as

The equation for the voltage regulation of transformer, represented in percentage, is

where,

E₂ – secondary terminal voltage at no load
V₂ – secondary terminal voltage at full load

The voltage regulation by considering the primary terminal voltage of the transformer is expressed as,

Aim: 

To determine Regulation and Efficiency of a single phase (1 Ф) Transformer by direct loading test. Apparatus: -

 Single phase dimmer stat, Ammeter (AC), Voltmeter (AC) Single phase transformer, Wattmeter, Resistive Load Bank

Regulation is defined as the ratio of change in terminal voltage from no load to full load to the no load voltage. 

Efficiency is defined as the ratio of output power to the input power of the transformer. Efficiency of a transformer varies with power factor at different loads. 

LOAD TEST: 

The load on a large power transformer in a sub-station will vary from a very small value in the early hours of the morning to a very high value during the heavy peaks of maximum industrial and commercial activity. The transformer secondary voltage will vary somewhat with the load, and because motors, incandescent lamps, and heating devices are all quite sensitive to voltage changes, transformer regulation is of considerable importance. The secondary voltage also depends upon whether the power factor of the load is leading, lagging, or unity. Therefore, it should be known how the transformer will behave (its voltage regulation) when connected to a capacitive, an inductive, or a resistive load.

This test is performed to determine the efficiency and regulation of a transformer at different load conditions. Usually, this test is performed for low, power, rating of transformers. This test gives accurate results as compared to the above tests. In this test, measurements are taken on HV side and LV side at different load conditions.

 PROCEDURE: 

 Make the connections as the circuit diagram in Figure 3.  Keep the switch on secondary side open so that load is zero to measure no load voltage. Also keep knob of auto transformer at zero output voltage position.  Now increase the voltage through auto transformer until the voltage at secondary winding at its rated value.  Adjust the switches on the Resistive Load module to successively increase the loading factor.  For each resistance value, record the readings from Wattmeter, Voltmeter, & Ammeter.  Switch off the AC-Supply.