SU875482A1 - Adjustable transformer change-over switch - Google Patents

Description

(54) SWITCHED REGULATED TRANSFORMER

I The invention relates to a transformer industry and can be used for transformers with stepwise voltage regulation under load. In switching devices of transformers with an on-load tap-changer, the switching current consists of load current and current 1 (circulation. In modern 1x transformers with stepwise voltage regulation under load, active or reactive current-limiting resistances are used to limit the circulating currents. The value of the circulating current depends on the stage EMF control and current limiting resistance. A known switching circuit under load from the applied current-limiting reactor, in which a two-arm reactor is connected in stationary mode using two movable contacts to one tap of transformer transformers The disadvantage of this scheme is the presence of permanent losses in the reactor and high switching current and restoring voltage leading to increased electrical contact of the switch. It is also known a switching device for transformers with stepwise voltage regulation under load, containing a current-limiting resistor, a contactor with a contact in {, - included in the bridge circuit, in one of which diagonals include 1 mobile contacts voters. In this switching device, the current-limiting size is included in one diagonal of the bridge, and in the other diagonal the current interrupter G23 is included. A disadvantage of the known switch is the insufficient resource of moving contacts. The closest to the proposed technical entity is a switch of a transformer that is adjustable under load, containing a recirculation winding, fixed and moving contacts, two current-limiting resistors, three sources of alternating current EMF connected between the moving contacts and their common connection point, and a lead-in conductor H3D.

The disadvantage of the known device is its relative complexity due to the presence of a triple moving contact in its circuit.

The purpose of the invention is to simplify, reduce losses and increase resource by reducing the electrical wear of switch contacts.

The goal is achieved by the fact that in the switching device containing the I adjusting winding from the adjustment steps there are fixed contacts located around the circumference, two insulating contacts 1x from each other moving contacts, 6 as a current limiting device using. A current transformer, the secondary winding of which is connected between the opposite contacts of the opposite control winding, is connected to an alternating current source with an adjustable voltage frequency, and the current lead is connected to the moving contact, and the secondary winding of the current-limiting transformer is attached to the unit. has an emf equal to the control stage ZDS.

The secondary winding of the current-limiting transformer can be made of a low-impedance conductor material, in series with which a resistor is additionally connected. As an alternating current source of the primary winding can be used as an external source, and the secondary and part of the control winding adjustable transformer.

FIG. Figure 1 shows schematically, in a single-phase version, the adjustable side of the transformer and the interconnection of the switching device with it in the conventional mode and in the process of transferring from one tap to another, in FIG. 2 is a diagram of an adjustable transformer with a switch.

The controller contains an irregular part of the winding I, an adjusting winding 2., fixed contacts 3 of the switch, moving contacts 4, a current-limiting transformer 5, a lead-through wire 6, and also the dots indicate the polarity of the windings. It should be emphasized that in the stationary mode one moving contact is closed with a tap of the transformer through a fixed contact, and the other is in the open state.

With the secondary winding of the current-limiting transformer, a resistor 7 is connected in series.

The switch works as follows.

In the stationary mode (Fig. 1 a-d), the lead wire 6 is connected via the right movable 4 and the stationary. - 3 contacts directly to the transformer; The left movable contact is not closed with a transformer tap, therefore on the secondary

in the winding of the current-limiting transformer, the load current does not flow and there is no additional loss. In the process of switching on (Fig. 1b), when the left moving contact closes with a fixed contact, the CMB current is zero. At this moment, a circulating current I will flow in the resulting circuit, which is directed oppositely in the right moving contact, and in the left hand side the load current C and which will be limited either by the secondary resistance of the secondary winding, as it is made of a high-resistance material (Fig. 1) , or cyNwapHbiM resist. the winding and resistor (figure 2). It should be noted, that in this position a part of the load current flows through the bottom contact many times smaller than the top contact. This is due to the inclusion of the internal resistance of the secondary winding of the current-limiting transformer in this branch. When the right contact is opened (fig.1c), its switching current 1 is equal to the difference between the load current and the current of circulator i,

It

f.e. less nomination c h vjt

national load current

When the right contact is closed with the next tap (figure 1 g), the circulating current will not flow in the resulting circuit, since the total emf of the circuit is zero.

In this case, a small fraction of the load current flows along the left contact compared to the right contact.

Claims (3)

When the left contact opens (bringing the circuit to stationary mode at the next tap,) its switching current is much less than the load current. .-... ;; ;;: fe When switching back from position d to position o, only the sequence of current switching by moving contacts will change. In the process of switching contacts, the maximum potential difference between them, i.e. magnitude: regenerative voltage, can only reach the magnitude of the emf of the control stage. Thus, in the process of switching, none of the two moving contacts commutates a current exceeding the nominal value of the load current, and in none of them does the magnitude of the restoring voltage exceed the magnitude of the emf of the control step. These circumstances lead to a significant reduction in electrical wear of the contacts. The proposed switch is rather simple compared to the known Contact Contact switch with a current-limiting transformer reduced by almost an order of magnitude compared to switching devices (reactive and resistive) "KMeter" passive current-limiting with pro-transmission. Claim 1. Adjustable transformer switch, interlock adjustment winding with tap-offs from control steps, fixed contacts, two isolated moving contacts, current lead, characterized in that, in order to simplify, reduce losses and increase resource reducing the electrical wear of the contacts of the switch, a current-limiting transformer is installed in the switch, a secondary winding of the current collector is switched between the moving contacts of the control winding ichivayuschego transformer having an emf equal EMF control stage, wherein the primary winding tokoogranichivakidego transformer connected to AC power with a frequency controlled voltage, and the collector is connected to the conductive movable contact. 2. The non-switch according to claim I, which is annoying, is that which is secondary. The winding of the current-limiting transformer is made of a conductive material, in series with which a resistor is connected. Sources of information taken into account by the ppk examination 1. Petrov T.N. Electric cars . M., Energie, 1974, vol. 1, p. 112 2. Avtorskay certificate of the USSR 418138, cl. I Sh f 29/04, 1978. 3.Avtorg certificate of the USSR No. 754494, cl. “O1 F 29/04, 1978, .one