Como para medir indutância com a multímetro

Detecção de Cor Código Indutores

Lugar o multímetro em R × At first gear, connect the red and black pens to either end of the color code inductor, and the pointer should swing to the right. According to the measured resistance value, there are three specific situations for identification:

The resistance value of the tested color code inductor A is zero, and there is an internal short-circuit fault. The DC resistance value of the tested color code inductor is directly related to the diameter of the enameled wire used for winding the inductor coil and the number of windings. As long as the resistance value can be measured, the tested color code inductor can be considered normal.

A Set the multímetro to R × First gear, check the on-off condition of each winding one by one according to the pin arrangement rule of each winding of the mid cycle transformer, and then judge se it is normal.

B Teste isolamento desempenho

Place o multímetro em R × 10k gear, perform the following status tests:

(1) A resistência valor entre o primário enrolamento e o secundário enrolamento;

(2) The resistance value between the primary winding and the casing;

(3) A resistência valor entre a secundária enrolamento e a caixa.

(1) O resistência valor é infinito: normal;

(2) Zero resistance: there is a short-circuit fault;

(3) Resistência valor menor que infinito mas maior que zero: lá está um vazamento falha.

3. Detecção de potência transformador

Verifique se há há óbvia anormalidades observando a aparecido de o transformador. For exemplo, se a bobina leads estão quebrados, dessoldados, se há há queimados marcas em o isolamento material, se o fixação parafusos de o ferro núcleo são soltos, se o silicon aço folha está enferrujado, e se o enrolamento bobina está exposto.

B Isolamento teste. Usando a multímetro R × Medida a resistência valores entre o núcleo e primário, primário e secundário, core e secundário, eletrostático blindagem camada e secundário, e secundário enrolamento at 10k gear. O multímetro ponteiro deveria ser fixo at infinito. Caso contrário, it indica poor insulation performance of the transformer.

C bobina on/off detection. Place the multimeter in R × In gear 1, during the test, if the resistance value of a certain winding is infinite, it indica that there is an open circuit fault in the winding.

Distinguish between primary and secondary coils. The primary and secondary pins of the power transformer are generally led out from both sides, and the primary winding is often marked with the word 220V, while the secondary winding is marked with the rated voltage value, such as 15V, 24V, 35V, etc. Then identify based on these markings.

E. Detection of no-load current. (a) Direct measurement method. Open all secondary windings, Place the multimeter in the AC current range (500mA) and connect it to the primary winding in series. When the plug of the primary winding is inserted into a 220V AC mains supply, the multimeter indicates the no-load current value. This value should not be greater than 10 percent to 20 percent of the transformer's full load current. Generally, the normal no-load current of power transformers for common electronic equipment should be around 100mA. If it exceeds too much, it indicates that the transformer has a short-circuit fault. (b) Indirect measurement method. Connect a 10 Ω/5W resistor in series in the primary winding of the transformer, and all secondary windings are still unloaded. Set the multimeter to AC voltage. After powering on, use two probes to measure the voltage drop U at both ends of resistance R, and then use Ohms