Transformer study : EXP400050 or EXP400051
Référence : EXP 400 050
This kit, designed for transformer experimental study, comprises a magnetic circuit and a series of various coils and accessories : two 250-turn coils, two 500-turn coils, one 1000-turn coil, one 135-turn coil, one 5-turn coil, one pair of poles, one hardened steel part and one soft iron part, as well as a hollow turn. All coils are equipped with Ø 4 mm safety sockets and are covered with an insulating plastic cover preventing access to the windings.
CHECKING THE RELATIONSHIP BETWEEN VOLTAGES AT THE TERMINALS OF EACH COILS
A single-phase transformer consists of two main parts : a magnetic circuit (“iron”) and two copper coils that are placed on each circuit leg. A first coil is supplied by sinusoidal voltage, and thus becomes the primary voltage. The transformer transfers the power transmitted by the primary to the secondary by magnetic induction, thus allowing the voltage at the secondary terminals to be measured. By modifying the number of primary and secondary turns, we can measure the different voltage ratios and check experimentally their equality with the ratios of the number of turns (i.e. the turns ratio).
TRANSFORMER LOSS STUDY
The single-phase transformer is not an ideal transformer. By connecting various loads (via a rheostat) at the secondary
output, we can measure efficiency between power absorbed and power restored by the primary to the secondary. This
measurement example highlights the presence of losses at transformer level. The open-circuit transformer study (i.e.
no load behind the secondary) determines iron losses (due to hysteresis and eddy currents). A series of measurements
can be performed by alternating the number of primary and secondary coil turns and by varying supply voltage.
Based on voltage, current and phase-shift measurements (conducted by the oscilloscope and the clamp ammeter),
we can calculate iron losses and show their linearity as a function of the average voltage’s square root. Finally, a
second study, in short-circuit this time, determines losses due to the copper winding resistances of each coil: these
are the Joule effect losses.
MAGNETISM EXPERIMENTS
A series of accessories supplied with the single-phase transformer is used to reveal a number of physical phenomena related to magnetism. For example, by placing the hollow coil around one of the transformer legs, its overheating is observed when it is subjected to the magnetic field generated by a coil, thus proving the induction heating principle. In turn, the 5-turn coil generates high currents and proves the spot welding principle. Finally, the eddy current device shows the behaviour of material subjected to a magnetic field. Slowdown of the aluminium solid disk confirms presence of the eddy currents induced in metal materials subjected to a variable magnetic field, and forms an approach to the eddy current braking principle.
SUBJECTS APPROACHED
»»Transformer study
»»Hysteresis losses
»»Eddy current losses
»»Joule effect losses
»»Turns ratio
NECESSARY EQUIPMENT
COMPOSITION
EXP400051 Study of the transformer (BASIC)
| Reference | Description | quantity |
| PED021370 | Kit for the study of the transformer | 1 | | PAM067690 | Kit for Eddy current | 1 |
COMPOSITION
EXP400051 Study of the transformer (COMPLETE)
| Reference | Description | quantity |
| PED021370 | Kit for the study of the transformer | 1 | | PAM067690 | Kit for Eddy current | 1 | | PMM062012 | Autotransformer | 1 | | PMM062220 | Dual adjuastable power supply | 1 | | PEM080030 | Black cords, Ø 4 mm, 100 cm - set of 10 | 1 | | PEM080031 | Red cords, Ø 4 mm, 100 cm - set of 10 | 1 | | EMD018015 | Digital oscilloscope, 2x100 MHz | 1 | | PMM062332 | Ammeter probe | 1 | | PMM064000 | Rheostat, 320 W | 1 | | PEM063700 | Adaptater, BNC/4-mm socket | 2 |
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