CN201533158U - Overvoltage restraining and inrush current limiting circuit - Google Patents

Abstract

The utility model discloses an overvoltage restraining and inrush current limiting circuit, which comprises a voltage transformer, a non-linear resistor and an intelligent switch. After being in parallel connection, the non-linear resistor and the intelligent switch are connected between a neutral point of a high-voltage winding of the voltage transformer and the ground. When the circuit is in normal operation, the non-linear resistor is in short circuit via the intelligent switch, when single-phase grounding fault of a system is eliminated, the intelligent switch is switched on, and then the non-linear resistor is put into service. The overvoltage restraining and inrush current limiting circuit has the advantages that 1, an original circuit which is connected into a loop regardless of any work conditions affects an original system, but the circuit which is not put into service when in a normal state and put into service when needed does not affect the original system, and 2, the non-linear resistor utilizes a large-capacity non-linear resistor, is high in capacity and has better overvoltage restraining and inrush current limiting effects.

Description

Overvoltage suppresses and the restricting circuits of shoving

[technical field]

The utility model is about a kind of Power Electronic Circuit, is meant that especially a kind of overvoltage suppresses and the restricting circuits of shoving.

[background technology]

In the prior art, as shown in Figure 1, employing inserts an enough big earth resistance R0 and plays damping and metering function between voltage transformer (PT) high pressure winding neutral point and ground, when single phase ground fault disappears, saturated each electric current of low frequency enters the earth through after the resistance R 0, because most of pressure drop is added on the resistance R 0, thereby suppressed the low frequency saturation current, make the voltage transformer high voltage fuse be difficult for fusing, simultaneously because this resistance R 0 of residual voltage loop series connection, make the saturated superpotential most of voltage drop of voltage transformer on resistance R 0, thereby avoided core sataration, the saturated superpotential generation of deboost instrument transformer.

If but the selected value of resistance R 0 is too little; restriction is little; if resistance R 0 is chosen too big, then when single-phase earthing occurring, most of voltage drop is on R0; can make residual voltage too low; influence the protective device regular event, make the R0 string for a long time in grounded circuit, under the various operating modes of system (resonance, arc grounding); owing to self finite capacity, respective resistances will be damaged because of overheated.

[summary of the invention]

Technical problem to be solved in the utility model is to provide a kind of overvoltage to suppress and the restriction effect of shoving is good and overvoltage capacious suppresses and the restricting circuits of shoving.

The utility model solves the problems of the technologies described above by the following technical programs: a kind of overvoltage suppresses and the restricting circuits of shoving, comprise voltage transformer, a nonlinear resistance and an intelligent switch, described nonlinear resistance and intelligent switch parallel connection are connected on later between the neutral point and ground of high pressure winding of voltage transformer.

The utility model overvoltage suppresses and the advantage of the restricting circuits of shoving is:

1, no matter whether any operating mode exists original circuit, and R0 is connected on back in the network, influences original system, and existing circuit can be realized automatic switching, and normal operation does not drop into, and drops into when fault needs again, and does not influence original system;

2, PTR adopts jumbo nonlinear resistor, and capacity is big, to the better effects if of the overvoltage inhibition and the restriction of shoving.

[description of drawings]

The utility model will be further described in conjunction with the embodiments with reference to the accompanying drawings.

Fig. 1 is the principle schematic of the existing overvoltage inhibition and the restricting circuits of shoving.

Fig. 2 is the principle schematic of the utility model overvoltage inhibition and the restricting circuits of shoving.

[embodiment]

See also shown in Figure 2, the utility model overvoltage suppresses and the restricting circuits of shoving comprises voltage transformer (PT), a nonlinear resistance PTR and an intelligent switch PTK, and described nonlinear resistance PTR and intelligent switch PTK parallel connection are connected on later between the neutral point and ground of high pressure winding of voltage transformer.

During normal operation circuit, there is not the problem of nonlinear resistance PTR heating to nonlinear resistance PTR short circuit in intelligent switch PTK, does not influence the sensitivity problem of system synthesis protective circuit yet; When the single phase ground fault disappearance appearred in system, intelligent switch PTK opened, and nonlinear resistance PTR comes into operation, and shoves thereby limited, and has avoided core sataration, has limited saturated superpotential generation.PTK can realize automatic switching.

In the utility model, nonlinear resistance PTR adopts jumbo nonlinear resistance.

Claims (1)

1. an overvoltage suppresses and the restricting circuits of shoving, comprise voltage transformer, it is characterized in that: also comprise a nonlinear resistance and an intelligent switch, described nonlinear resistance and intelligent switch parallel connection are connected on later between the neutral point and ground of high pressure winding of voltage transformer.

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