For electronic components to detect this basic skills, this is the power engineer and then familiar, but can say how accurate and effective detection of components related parameters to determine whether the normal components, not a single thing, must be based on Different components using different methods to determine the normal components or not. Especially for beginners, the mastery of commonly used components of the detection methods and experience is necessary, the following commonly used electronic components testing experience and methods for the test for the test.
Inductor, transformer detection method
Electronic Components Here we first explain the color code inductor detection, where the test method is that we need to put the multimeter in the R × 1 block, red and black pen each color code inductor any of the leading end, this time The pointer should swing to the right. According to the measured value of the resistance value, can be divided into the following three cases to identify: A measured color code inductor resistance is zero,Electronic Components the internal short-circuit fault. B measured color code inductor DC resistance value and wound inductor coil used in the enamel wire diameter, the number of circle circle is directly related, as long as the resistance can be measured, you can think that the color sensor is measured in the normal The
Electronic Components The following description is the detection of the transformer in the week, A. will be allocated to the R × 1 block multimeter, according to the transformer in the winding of the winding rules, one by one check the winding off the situation, and then determine whether it is normal. (2) the resistance between the primary winding and the shell; (2) the resistance between the primary winding and the secondary winding; (2) the resistance between the primary winding and the shell; (2) the resistance between the primary winding and the secondary winding; 3) the resistance between the secondary winding and the housing. The above test results are divided into three cases: (1) resistance is infinite: normal; (2) resistance is zero: a short circuit fault; (3) resistance is less than infinity, but greater than zero: a leakage fault.
Detection of the power transformer A Inspect the appearance of the transformer to check for abnormalities. Such as whether the coil wire break, desoldering,Electronic Components insulation materials are scorched traces, the core fastening screw is loose, silicon steel sheet with or without corrosion, winding coil is exposed and so on. B Insulation test. With a multimeter R × 10k block were measured core and primary, primary and secondary, core and the secondary, electrostatic shielding and pantal secondary, secondary resistance between the windings, multimeter pointer should be in the infinity position is not move. Otherwise, the transformer insulation performance is bad. C. coil on and off detection. The multimeter placed in the R × 1 block, the test, if a winding resistance is infinite, then this winding has a circuit fault. D. Identify the primary and secondary coils. Power transformer primary and secondary pins are generally derived from both sides, and the primary winding with more than 220V words, the secondary winding is marked with rated voltage, such as 15V, 24V, 35V and so on. And then according to these markers to identify. E No-load current detection. (A) direct measurement method. (500mA, string into the primary winding. When the primary winding plug into the 220V AC mains, the multimeter is indicated by the no-load current value. This value should not be More than 10% to 20% of the full load current of the transformer. General common electronic equipment Power transformer normal no-load current should be about 100mA. If too much, then the transformer has a short circuit fault. (B) Indirect measurement method. In the transformer The primary winding in series with a 10 / 5W resistance, the secondary still all the no-load. The multimeter dial to the AC voltage block. After power, with two test leads R measured resistance R across the voltage drop U, and then use Ohm law to calculate no load Current U space, that is, I = U / R.F no-load voltage detection. The power transformer of the primary 220V mains, with a multimeter AC voltage followed by measuring the winding no-load voltage (U21, U22, U23 , U24) should meet the requirements, the allowable error range is generally: high voltage winding ≤ ± 10%, low voltage winding ≤ ± 5%, with the center of the two groups of symmetrical winding voltage difference ≤ ± 2% .G. General low power Power transformer The temperature of the insulation is 40 ° C to 50 ° C, and if the quality of the insulating material used is good,Electronic Components the temperature rise is allowed to be increased. H Detection of the same end of each winding In the case of using a power transformer, sometimes in order to obtain the desired secondary Voltage, two or more secondary windings can be used in series.Using the series method to use the power transformer, the series connected to the same terminal must be properly connected, can not make mistakes. Otherwise, the transformer can not work. The main symptoms of the short circuit fault of the power transformer are the serious heat generation and the abnormal output voltage of the secondary winding.Therefore, the more the short-circuit point between the turns of the coil, the greater the short-circuit current, and the higher the heat of the transformer The more accurate way to determine whether a power transformer has a short-circuit fault is to measure the no-load current (the test method has already been described above.) Transformers with short-circuit faults will have a no-load current value greater than 10% of the full load current. severe short circuit,Electronic Components the transformer will heat rapidly within a few tens of seconds after the load is powered, hand-to-core will be Hand feel. At this point you can not measure the load current transformer short circuit judge points exist.