1. Principle of Isolation Transformer
Isolation transformer belongs to safe power supply, which is generally used for machine maintenance and maintenance, and plays the role of protection, lightning protection and filtering. Isolation transformer is a 1:1 transformer. Primary single-phase 220V, secondary single-phase 220V. Or primary three-phase 380V, secondary three-phase 380V.
Isolation transformer principle refers to the transformer whose input winding and output winding are separated from each other electrically, so as to avoid the danger of accidentally touching the electrified body (or metal parts that may be electrified due to insulation damage) and the ground at the same time. Its principle is the same as that of ordinary dry transformer. It also uses the principle of electromagnetic induction to isolate the primary power circuit and the secondary circuit from the ground. To ensure the safety of electricity use.
This paper illustrates the principle of single-phase and double-winding transformer by taking it as an example. As shown in the figure, when a voltage is added to the primary winding, the current flowing through 1 generates alternating flux in the core. 1. These flux are called main flux. Under its action, the two winding groups feel potential 1 and 2 respectively, and the formula of feeling potential is as follows
E = 4.44fN?
In the formula: E - EMF RMS
F -- Frequency
M--Maximum Main Flux
Due to the difference of turns between secondary winding and primary winding, the magnitudes of potential E1 and E2 are also different. When the voltage drop of internal impedance is omitted, the magnitudes of voltage 1 and 2 are also different.
When the secondary side of the transformer is unloaded, the primary side only flows through the main flux current (0), which is called excitation current. When the secondary side load flows through the load current 2, it also generates flux in the core, trying to change the main flux, but when the primary voltage is stable, the main flux is stable. The primary side will flow through two parts of the current, one part is the exciting current 0, the other part is used to balance 2. This part of the current changes with the change of 2. When the current is multiplied by turns, the magnetic potential.
The main function of isolation transformer is to make the primary side and the secondary side completely insulated, and also to isolate the circuit. In addition, the high frequency loss of the iron core is used to suppress the high frequency clutter into the control loop. The isolation transformer is used to suspend the secondary power to the ground. It can only be used in situations where the power supply range is small and the line is short. At this time, the capacitive current of the system to the ground is not small enough to cause personal injury. Another important role is to protect personal safety! Isolate dangerous voltage.
2. Principle-Characteristic of Isolation Transformer
Isolation transformer belongs to safe power supply, which is generally used for machine maintenance and maintenance. It plays the role of protection, lightning protection and filtering. The output end of isolation transformer is completely "open circuit" isolated from the input end. Isolation transformer can restrain the disturbance caused by lightning, discharge, power grid switching, motor startup and other power grid dryness. The output-input capacitance coupling is small, so it is also called power source noise suppressor by industry people. This also shows that isolation transformer has a protective effect on equipment.
Isolation transformer has the following two characteristics:
(1) Voltage conversion function
(2) Anti-jamming function of filtering - the original and secondary windings are concentrically placed, but electrostatic shielding is added between the windings to obtain high anti-jamming characteristics.