The power and other characteristics of the transformer are indicated on the information plate attached by the manufacturer to each device. But what if this plate is worn out or lost? When the type of transformer and its parameters are unknown, they can be determined using an autometer and simple calculations.
Necessary
- - avometer (multimeter);
- - source of power;
- - thin wire;
- - knife, sewing needle;
- - calculator
Instructions
Step 1
Using a multimeter (autometer), determine the location of the terminals of all windings of the transformer and measure their resistance. The primary winding is the one with the greatest resistance. This is the easiest way to determine the primary winding.
Step 2
If the investigated transformer has more than two windings, first take any winding with low resistance as the primary one. Apply a low AC voltage (such as 10 volts) to it using a power source. Measure the voltage on all windings. Based on the results of the measurements, determine the real primary winding of the transformer. Check yourself by repeating measurements while applying more voltage to the windings.
Step 3
Then, observing the gap between the coil and the magnetic circuit, wind a thin wire over the windings, thus creating another winding. The more turns of wire are wound, the higher the accuracy of the final results will be. If there is no free space in the transformer for another winding, use part of the existing outer winding. To do this, carefully remove the outer insulation layer of the coil to gain easy access to the last layer of the existing winding.
Step 4
Find the end of the opened winding and count any number of turns from it. Remember that this number of turns directly affects the calculation results. On the last loop, carefully peel off some of the enamel. Having prepared the multimeter, with one of its leads, touch the bare turn of the winding using a sewing needle for this. After applying voltage to the primary winding, measure the voltage on the winding you created or on the counted turns.
Step 5
Calculate the number of turns in each winding. To do this, multiply the voltage on the tested winding by the number of turns made by yourself or counted on the last layer. Divide the result by the voltage applied to the tested winding.
Step 6
After calculating the number of turns in all standard transformer windings, calculate the cross-sectional area of the magnetic circuit. To do this, multiply the voltage on the primary winding by 50 and divide by the number of turns of this winding. The result will be the area of the core of the magnetic circuit, expressed in square centimeters.
Step 7
To calculate the power of the investigated transformer, square the obtained cross-sectional area of the magnetic circuit and divide by 1, 3. The result will show the power of the device in watts.
