Separation of No Load Losses in a Single Phase Transformer

SEPARATION OF NO LOAD LOSSES IN A SINGLE PHASE TRANSFORMER

AIM:

• To separate no load losses of a transformer in to eddy current loss and hysteresis loss.

APPARATOUS REQUIRED:

MACHINES DETAILS:

THEORY : 

It is seen that the core losses of transformer includes,

• Hysteresis loss
• Eddy current loss

       For a given volume and thickness of laminations, these losses depend on the operating frequency, maximum flux density in the core and the voltage.

       The hysteresis loss is given by Steinmet’z relation,

              P_h = K_h B_m^1.67 f v    watts

i.e.          P_h = A B_m^1.67 f    watts                                                            …………..(1)

       Practically conduct two tests on transformers at two different frequencies f₁ and f₂, keeping maximum flux density in the core same. Thus the core losses i.e. iron losses can be separated into hysteresis and eddy current losses.

PRECAUTIONS:

• The motor field rheostat should be kept at minimum resistance position.
• The alternator field rheostat should be kept at maximum resistance position.

PROCEDURE:

• Connections are given as per the circuit diagram.
• Supply is given by closing the DPST switch.
• The DC motor is started by using the 3 point starter and brought to rated speed by adjusting its field rheostat.
• By varying the alternator filed rheostat gradually the rated primary voltage is applied to the transformer.
• The frequency is varied by varying the motor field rheostat and the readings of frequency are noted and the speed is also measured by using the tachometer.
• The above procedure is repeated for different frequencies and the readings are tabulated.
• The motor is switched off by opening the DPST switch after bringing all the rheostats to the initial position.

CIRCUIT DIAGRAM

TABULAR COLUMN:

SAMPLE GRAPH :

RESULT: