Working principle of programmable DC switching power supply
1. The AC power input is converted into DC by rectification and filtering.
2. Control the switching tube through a high-frequency pulse width modulation signal, and add DC to the primary of the switching transformer.
3. The secondary of the switching transformer induces a high-frequency voltage, which is rectified and filtered to supply the load.
4. The output part feeds back to the control circuit through a certain circuit to control the pulse width modulation duty cycle to achieve stable output.
When AC power is input, it usually filters the interference on the power-off network through loops, etc., and it also filters the interference of the power supply on the grid.
When the power of the programmable DC switching power supply is the same, the higher the switching frequency, the smaller the size of the switching transformer, but the higher the requirements for the switching tube; the secondary of the switching transformer can have multiple windings, or one winding can have multiple tap to obtain the desired output. Under normal circumstances, some protection circuits should also be added, such as no-load protection and short-circuit protection, otherwise the switching power supply may burn out.
How to deal with blown DC power transformer fuses
(1) How to deal with a blown DC power transformer. Check whether the appearance and sound of the transformer are normal.
(2) If it is a low-voltage fuse; check whether the low-voltage line is faulty; check whether the fuse melted due to a small load or a large load; if the operation is convenient and safe, the fault inspection light can also be used to test the break on the fuse fu 2 to determine the line Check whether there is a fault in the circuit: bright or red, the line may be normal; normal light. The line may be abnormal. The load should be disconnected during the test and the internal resistance of the fault check light should not be too high. If everything is fine, you can replace the melt and send it once.
(3) If it is a high-voltage fuse: If the phase fuse, the transformer is normal, and the low-voltage side line is not faulty, it can be replaced once for power transmission; if a two-phase or two-phase fuse is used, the transformer should stop running, check and shake the insulation resistance, Find out the cause of the malfunction and power on again.
(4) When the fuse is blown and there is an abnormal sound or the transformer is sprayed with oil, the power circuit breaker should be opened when the power transformer is turned on.
