How to detect a transformer?
In circuit schematics, the transformer is usually represented by the letter " T ". Such as " T1 " denotes a transformer numbered 1. When detecting a transformer, we can first check the appearance of the transformer to see if there is any obvious abnormality. For example, if the coil leads are broken or welded, whether the insulation material has charred marks, whether the core fastening screws are loose or not, and whether the silicon steel sheet is corroded or not, whether the winding coil is exposed, etc.
( 1 ) Coil on-off detection puts the multimeter on the resistance value between the two terminals of the RX 1 block detection coil winding. If the resistance of a winding is infinite, it means that the winding has circuit breakdowns. If the resistance is very small, it can not measure the no-load current at this time.
( 2 ) Discriminating the primary and secondary winding pins of the primary and secondary windings of the power transformer are usually drawn from both sides, and one. The secondary winding is marked with the words 220V, and the secondary winding is marked with rated voltage value, such as 6V,9V,12V and so on. For a step-down transformer, the secondary winding resistance is usually greater than the secondary winding resistance ( the secondary winding is smaller than the secondary winding ). Detection of insulation performance.
(3)Measuring the transformer core and the first side, the first side and the two side, the resistance value between the electrostatic shielding layer and the two side windings should be greater than 100 Mega or the finger needle in the infinity insulation performance of the device is bad.
(4) detection of no-load current
The two side windings are all opened, and the multimeter is placed in an alternating current block (usually 500mA block), and is connected to the primary winding. The current value of the multimeter is the no-load current value when the plug of the secondary winding is connected to the 220V power supply. This value should not exceed 10% 20% of the full load current of the transformer too much, indicating that the transformer has a short circuit fault.
(5) Distinguishing the same name
When using a power transformer, sometimes two or more two side winding can be used in series to obtain the required two side voltage. When the power transformer is used in series, the same end of the series winding must be connected correctly. Otherwise, the transformer will burn up or not work properly.
The method of distinguishing the same name is as follows: a 1.5V dry battery is connected to any set of windings in the transformer (when the number of transformer winding turns is few, 9~15V battery can be used), and the rest of the winding coils are connected to the positive and negative ends of the DC milli voltmeter or the DC milli meter. When there are not many watches, each winding can be measured sequentially by multimeter. When the 1.5V power is connected, the pointer of the meter will swinging quickly, if the pointer is deflected in the positive direction. The line head of the positive electrode of the battery is the same name as the line head of the positive control line of the ammeter; if the pointer is reversed, the line head of the positive electrode of the battery is the same name as the line head of the negative connection standard of the electric meter.
In addition, the direct electrifying method can be used to distinguish the transformer from the secondary circuit, and the voltage of each winding of the secondary side is measured, and any end of any two windings is connected in one-up, use the multimeter to measure the other two ends of voltage, such as the sum of two windings, then connected together for a different name; if the sum of the two windings is lower than the sum of two windings ( if the voltage of the two windings is equal, it may be 0V ), the ends of which are connected together or both of the pen and pen ends are of the same name. Others and so on. ( it should be noted in the measurement that the same winding can not be connected at both ends, otherwise it will short circuit and burn out the transformer.
( 6 ) Detection of no-load voltage will connect the primary side of the power transformer to 220V, and measure the no-load voltage of each winding in turn with the AC voltage of the multimeter, the allowable error range is as follows : 10 % for HV winding, 5 % for low voltage winding, and 2 % for symmetrical winding with center tap.
If you want to know more, our website has product specifications for transformers, you can go to ALLICDATA ELECTRONICS LIMITED to get more information