SU1078483A1 - High-speed a.c.circuit breaker - Google Patents

Abstract

ACCELERATED ACCURATE HYBRID SWITCH, containing in each pole power contacts, shunted by a thyristor key, and a common control unit, including switching speeds of the accelerated disconnection, which can be used by the trigger switch, which can be processed by the switch for fast operation of the rapid switch-off key, which can be used for the speed of the disconnection by means of a quick disconnection, which can be acted by a switchgear switchgear. oppositely connected windings, a thyristor bridge, a forced-switching unit and a current direction sensor, the indicated saturation throttles are connected in series with the power contacts in the circuit, a thyristor shunted key, a thyristor bridge is connected parallel to the thyristor key, the forced switching unit is included in the diagonal of the thyristor bridge, the current direction sensor is connected to the power contacts circuit. One of the poles is connected to the control unit, the forced switching unit being two parallel circuits, into one of which included the connected inductance coil, precharged capacitor and diode | and in the other there are series-connected inductors, a precharged capacitor, and a thyristor.

Description

The invention relates to low-voltage switching devices protecting electrical installations from short-circuit currents — a hybrid three-phase rfepsMeHHoro current switch, in which the load current conducting and interrupting functions are distributed respectively between contact and shunt contactless elements.

Known high-speed switch AC Cl3.

However, with relative simplicity and low cost, this switch is characterized by low speed, due to the features characteristic of contact systems (inertia of moving mechanisms and arc-welding processes). The consequence of this is degraded current-limiting properties.

Also known is a thyristor switch with artificial capacitor switching, which has effective current-limiting characteristics C2.

The disadvantage of this switch is the increased energy losses in the on state (due to the imperfection of the key properties of the thyristor) and, as a consequence, degraded weight and size parameters.

The closest to the proposed technical essence and achieved, the result is a hybrid switch that contains the main contacts, bridged with a semiconductor key (counter-parallel connected thyristors) 31

To improve speed, the switch can be equipped with an accelerated tripping drive (mainly, induction-dynamic).

However, the principle used for the natural switching of thyristors (switching off the load current when changing polarity) limits the scope of application of the known switch due to low speed (the turn-off time is longer than the half-period of the mains voltage fluctuations) and the absence of current-limiting properties.

The purpose of the invention is to increase the speed of the switch.

This goal is achieved by the fact that, in a fast-acting hybrid AC switch, containing at each pole power contacts, a shunted thyristor key, and a common control unit, including a fast deactivation drive, an accelerated switch-off speed switch, two saturation thrusters with back-turned windings, a thyristor bridge, a forced switching unit and a current direction sensor, indicated saturation throttles are connected in series with power

the thyristor bridge is connected parallel to the thyristor key, the forced switching unit is connected to the diaristor bridge, the current direction sensor is connected to the power circuit of one of the poles and connected to the control unit, with the forced switching unit made in ( A view of two parallel circuits, in one of which are connected in series a coil inductance, a precharged capacitor and a diode, and in the other 5 in series Inductance coil, pre-charged capacitor and thyristor.

Figure 1 is a diagram of the pole of the switch; Fig. 2 is a circuit diagram of a switch in which the thyristor bridge performs the functions of a key; in fig. 3 and 4 is a diagram of the forced switching units for the switches shown in FIGS. 1 and 2, respectively; FIGS. 5 and 6 show timing charts, and their operation is explained.

The switch contains main contacts 1, a thyristor bridge containing thyristors 2-5, a block b of forced capacitor switching, throttles 7 and 8. saturation, current sensor 9, control unit 10 with a tripping drive, a thyristor key containing thyristors 11 and 12, inductors 13–15, precharged capacitors 16–18, diode 19 and thyristor 20.

In FIGS. 5 and 6 OE, it indicates the switch-off setpoint current, H 2 currents in the circuit of block 6, IKJ switchable short-circuit current

(tkz.),

- current in the circuit of contacts

1, IT is the current in the thyristor circuit 11 and 12; Uf. , and, the voltage on the capacitors, corresponding to the currents i, it, ii in block 6, (J is the initial voltage on the capacitors.

The operating principle of the switch shown in FIG. 1, is to be followed.

In steady-state mode, the chokes 7 and 8 are magnetized by the load current, respectively, of positive and negative polarity. In the event of an accident in the load and increasing TK. up to the value of the current setpoint J ,, control unit 10 —. affects the contacts 1, leading to the opening of the latter.

At the moment, j, at the same time, the control unit generates a pulse control signal for thyristors 2, 5 and 11 (for the indicated direction of the TK). In this case, the capacitor 16 in the circuit of the diode 19 (Fig. 3 and 5 is discharged through the still closed contacts 1 to the throttles 7 and 8 is saturated. As a result, the magnetic wire of the throttle 7 is re-magnetized (during the time of the magnetization reversal the current if. The donor drops) and the resistance The circuit with the main contacts increases for the current IKS while the latter goes into the thyristor-11 circuit, so that the opening of the contacts 1 takes place in a de-energized state. In the switching interval, an arc-free contact failure and restoration of the electrical strength of the intercontact state occur. At the moment tctj, a pulse is fed to the thyristor 20, whereby the thyristor 11 is forcibly locked for a time The presence of saturation throttles in the main contacts circuit and this construction of the arc-free switching system allows to increase the speed of the switch shown in FIG. the practical elimination of a short arc at contactors and a decrease in the stage of existence of messslichesky bridges for opening contacts. The switching is carried out in the same way, i. negative polarity, the difference lies in the fact that thyristors 3, 4 and 12 are controlled and the choke is inverted by an 8 V switch, shown in Fig. 2, the functions of the contactless key and the forced switching unit are combined. This is achieved due to the fact that the conductive state of thyristors 2-5 in the opposite direction is provided by the discharge current of the capacitor. Thus, in the process of magnetization re-saturation of the saturation (About FIG. 6), the control of bridge 2-5 occurs similarly to the considered one (the thyristors 2 and 5 are turned on for the indicated direction). In this case, the discharge current of the capacitor 18 (Fig. 4) flows along a contour, indicated by a solid line in Fig. 2. After remagging the throttles 7 (), control is applied to all the thyristors of the bridge 2-5, and the capacitor begins to discharge in the circuits indicated by the dotted line in Fig. 2, ensuring that the thyristors 2-5 are conducting in the reverse direction if (interval). Taking into account the increased resistance of the circuit with the elements (after reversal of the throttles 7) and the reduced resistance of the thyristor bridge (as a result of the flow of discharge current in the thyristor circuit), tk. goes completely into the thyristor circuit at the moment. As a result, the contact break also occurs without an arc in the interval. At this interval, the electrical resistance of the contact gap is also restored. In this case, the condition i- / Vi t, i in the switch shown in Fig. 2 must be fulfilled, the use of block b, made according to Fig. 3, is possible. With this implementation, an increase in the time of exceeding the total discharge current of the capacitor 2 magnitude kc, i.e. of time. provided by block 6 for restoring the electrical strength of the inter-tact gap. In this case, the turning on of the thyristor 20 occurs during the time of action In the case of the use of a discharge current. an accelerated disconnecting drive with power from an accumulative capacitor (for example, an induction-dynamic) can be used as the inductance 15 (FIG. 4) of the control coils of this drive. In this case, the capacitor of the unit 6 serves simultaneously to control the drive and the forced switching of the thyristors of the bridge, thereby achieving a reduction in the dimensions (mass) of the apparatus. The switch shown in Fig. 2 is characterized by a higher speed, which is caused by the absence of an additional key deactivation stage after the restoration of the electrical strength of the contact gap. Thus, due to the installation of saturation throttles in the circuit with main contacts, the use of selective arc-free switching (depending on the polarity of the switched current), as well as the adopted scheme of the implementation of the forced capacitor switching unit, the conditions for arc-free opening of the AC contacts and, , increase the speed of the hybrid switch and improve its weight and size parameters.

. 2

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Claims (1)

A high-speed AC HYBRID CIRCUIT BREAKER, comprising power contacts shunted by a thyristor key in each pole, and a common control unit, which includes a fast-acting accelerated shutdown drive, characterized in that, in order to increase the speed, two saturation chokes are introduced into each pole windings included, thyristor bridge, block for forced switching and current direction sensor, these saturation chokes are connected in series with power contacts in the circuit, doped with a thyristor key, the thyristor bridge is connected parallel to the thyristor key, the forced switching unit is included in the diagonal of the thyristor bridge, the current direction sensor is included in the power contact circuit of one of the poles and connected to the control unit, 'and the forced switching unit is made in the form of two parallel circuits, one of which includes a pre-connected inductance coil, a pre-charged capacitor and a diode, and the other includes a series-connected inductor, etc. digestible capacitor and thyristor. m 00 CO