Switch transformer ” is the transformer that points to to use inside ” of “ switch power source commonly, the job is in ten to a few hertz even below the pulse condition of frequency of at present of hundreds of kilohertz, core uses ferrite data commonly. Transformer of switch power source is the power source transformer that joined switch canal, alternate besides the voltage of common transformer in circuit function, still hold an insulation concurrently to keep apart as deferent as power function to be used in the switch power source situation that involves high frequency circuit commonly.

 

Action of transformer of switch power source

 

Transformer of switch power source and switch canal form one each to stimulate together (or he is stimulated) the intermittent oscillator of type, become modulation of input volts d.c. thereby voltage of a high frequency pulse.

 

Be delivered to energy since and change intention. In stimulating type circuit instead, when switch the canal guides when connecting, transformer can store electric energy changeover into magnetic field rise, release when switch canal ends. In stimulating type circuit, when switch the canal guides when connecting, input voltage furnishs to load directly and store energy in store can in inductance. When switch canal ends, again by store can inductance undertakes follow on current is delivered to load.

 

Change the volts d.c. of the input into all sorts of needs low pressure.

 

Switch transformer principle

 

To switch power source, the working principle of the working principle of switch transformer and common transformer is different. Of the alternating voltage that common transformer inputs or electric current, owing half cycle body is semmetry, and input voltage and voltaic weaveform be successive commonly, it is in a cycle, the average that inputs voltage and electric current is equal to 0, the basic characteristic; that this is principle of common transformer job and switch transformer is the job commonly at switch condition, its input voltage or electric current is not successive commonly, however spiccato, input voltage or electric current are in great majority is not equal to an average in cycle 0, accordingly, switch transformer also calls pulse transformer, this is the biggest distinction of switch transformer and common transformer in working principle respect.

 

Pass PWM (pulse width modulation) control switch canal, undertake the volts d.c. after rectification high frequency switch guides, make what high frequency electric current flows into switch power source high frequency transformer former edge, it is transformer thereby deputy edge generation is faradic, the voltage that needs through can reaching after rectification or multichannel voltage.

 

Switch transformer stand or fall detects

 

1, whether to have apparently unusual appearance through observing the appearance of transformer will check its:

 

If whether coil down-lead ruptures, sealing off, whether does insulating material have scorch trace, whether does screw of core close solid have become loose, silicon steel piece have without rustily, whether does winding coil have appear etc.

 

2, insulating properties checks:

 

Block with avometer R&TImes;10k measure respectively core and primary, primary layer of as sub as each sub, core and each, electrostatic screen and vent in the sides of a garment are sub, sub the resistance between each winding, avometer finger all should show in infinity the position is not moved. Otherwise, explain transformer insulation property is undesirable.

 

3, coil connects detect:

 

Block avometer park R&TImes;1, in the test, if the resistance of a certain winding is infinity, explain this winding has trouble of open circuit sex.

 

4, at the beginning of differentiate, secondary coil:

 

Power source transformer is primary bring foot and sub citing a base is to part commonly from two side derivative, and primary winding much mark has 220V model of written characters, sub winding criterion rated voltage is worth line out, wait like 15V, 24V, 35V. Undertake discriminating according to these mark again.

 

5, carry electricity for nothing detect:

 

A, direct measure a way will sub all winding is all open circuit, block avometer park alternating current (500mA, string together primary winding. When the outlet of primary winding inserts report of 220V communication town, what avometer place indicates is to carry electric current to be worth for nothing.

 

The 10% ～ that this value should not be more than transformer to be fully loaded with electric current 20% . The normal sky of transformer of power source of facility of general and common electron carries electric current to should be controlled in 100mA. If exceed too much, explain transformer has trouble of short circuit sex.

 

B, indirect method of measurement establishs ties in the primary winding of transformer the resistor of a 10/5W, sub still carry for nothing entirely. Dial avometer to alternating voltage to block. After appending report, with two watches the pen measures the voltage drop U that gives two end of resistor R, hold voltaic I air with sky of Ohm’s law cipher out next, namely I empty =U/R. F? Carry voltage for nothing detect.

 

power source transformer primary receive 220V town report, receive with avometer alternating voltage ordinal the sky that measures each winding carries voltage to be worth (U21, U22, U23, U24) should accord with a requirement to be worth, allow error limits to be commonly: High-pressured winding ≤±10% , low-pressure winding ≤±5% , the voltage of two groups of symmetrical winding that take central take a percentage of a deal is poor should ≤±2% .

 

6, detect the temperature limits of power source transformer:

 

Transformer of general small-power power source allows temperature rise to be 40 ℃ ～ 50 ℃ , if place is better with insulating material quality, allow temperature rise to still can rise.

 

7, detect differentiate the homonymic end of each winding:

 

When transformer of use power source, the sub voltage that needs to get place sometimes, but will two or series connection of many sub winding rises use. When using series connection law to use power source transformer, the homonymic end of each winding that attends series connection must join correctly, cannot make a mistake. Otherwise, transformer cannot work normally.

 

8, of breakdown of sex of short circuit of power source transformer detect integratedly differentiate:

 

Power source transformer short-circuits the main symptom after sexual breakdown is calorific and serious output voltage with sub winding wrong. Normally, coil interior circles the dot jumps over a short circuit much, short-circuit current is bigger, and transformer is calorific more serious. Detect the simple method that judges power source transformer to whether have trouble of short circuit sex is to measure carry electricity for nothing.

 

Put in the transformer of short circuit breakdown, its carry electricity for nothing the value will be ambitious 10% at be fully loaded with electric current. When short circuit is serious, transformer is in carry for nothing add electric hind a few seconds in can give out heat quickly, core of the feeling that use a hand can have the feeling of very hot hand. Need not measure right now carry electric current to be able to conclude transformer has short circuit to nod existence for nothing.