Resonant transformer principle: 1 structural characteristics: resonant transformer core can be made into two different structures: shell and heart type. The core type transformer is not as good as a shell core transformer in terms of a series of main indexes, and its weight and size are relatively large, and the transmission mechanism for adjusting the air gap is relatively complicated. For this reason, the test device we developed uses a shell-type structure with the resonant transformer windings set outside the movable center column. 2 Characteristic curve: The characteristic curve of resonant transformer is shown as in Fig. 2. As can be seen from FIG. 2 , under different air gap lengths δ, the volt-ampere characteristic of the resonant transformer has a good linear relationship, and its inductance L has nothing to do with the voltage value on the transformer. Therefore, when used in an AC resonant test, this resonant transformer can be first tuned under low voltage conditions (by changing the length of the air gap between the moving iron core and the lower yoke core via a transmission mechanism). When tuning to resonance, the resonant transformer is raised again. Voltage, system tuning is very convenient. 3 The relationship between the loop inductance L and the core air gap length δ: The air gap tunable resonant transformer, whether series or parallel, adjusts the core air gap length and changes the loop inductance L to make the resonant transformer resonate. This is the mechanism by which the resonant transformer resonates by changing the length of the core air gap for a device under test that has a certain capacitance to ground. However, it should be noted that the length of the air gap should not be too large, and that the established resonance conditions will be destroyed if it exceeds the General Assembly. 4 Tuning principle: (1) Series tuning: The equivalent circuit of the series resonant transformer is shown in Figure 3. When a US$220V, f=50Hz power frequency voltage is applied to the resonant transformer, the series resonance occurs in the loop when manually or automatically adjusting so that ωL=1/ωC is XL=XC, where the loop current IS is large = Us/ (RL+RC) Because of RC >> RL, there is Is≈US/Rc (1) The voltage UC on the test object and the voltage UL on the tuning reactor are: Uc = (1/ωc)Is = XcIs UL = ωLIs = XLIs When Tuning to Resonance Uc = UL = ω0LIs = (ω0L/Rc)Us (2) The ratio ω0L/Rc = (square root of L/C)/Rc = Q (2) 3) ω0 is the resonance angle frequency Q called the quality factor of the series resonant circuit. Because (root L/C is the second power)>> RC, so Q>>1. The power supply capacity Ps=UsIs=(Uc/Q)Is=Pc/Q is obtained. (4) It can be seen from Equation (4) that when the resonant transformer is tuned to resonance, both the power supply voltage and the capacity are the corresponding voltages and capacities of the sample. 1/Q. Therefore, compared with the general test transformer, the resonant transformer has the advantages of light weight and small size. (2) The equivalent circuit of the parallel-tuned parallel resonant transformer is shown in Fig. 4. When RL ≤ ωL and Rc ≤ 1/ωc, the resonance frequency fo of the parallel resonance is: the quality factor Q of the parallel circuit is: Q=(ω0L)/(RL+Rc)=1(RL+Rc)ω0C (6) RL, RC—inductance and capacitance equivalent series resistance (Ω) L—tuning reactor inductance (H) C—sample capacitance to ground (F) when applying 50Hz AC voltage to parallel resonant transformer As the voltage increases, forced oscillations will occur in the loop. When the loop oscillation frequency is equal to the applied power frequency, the impedance of the loop is large (and purely resistive), so the loop current is small, but the currents IL and IC on L and C are Q times the loop current I, that is, IL =IC=QI. Split Pins, Split Cotter Pins, Spring Cotter Pin Ningbo Brightfast Machinery Industry Trade Co.,Ltd , http://www.brightfastener.com