SU1134984A2 - Device for open-phase protection of electric installation - Google Patents

Abstract

DEVICE FOR PROTECTION OF ELECTRICAL INSTALLATION FROM CLUTCH OF PHASES according to aut. St. No. 862306, characterized in that, with an increased sensitivity circuit, two capacitors and a second resistor are added to it, and the saturating transformer is provided with an additional winding connected oppositely from the main and connected through a second resistor to the full-wave rectifier output, the first condisser connected in parallel an additional winding of the satyamtsegos transformer, and the second capacitor - parallel to the first ballast resistor ..

Description

The invention relates to electrical engineering, in particular, to protection devices of three-phase power consumers from the disappearance of the phases of the supply voltage. According to the main author. No. 862306, there is a known device for protecting an electrical installation from phase failure, containing a half-wave rectifier connected to the phases of a protected electrical receiver, loaded through a ballast resistor by a saturable transformer, the secondary winding of which is connected through a rectifier and integrating an RC chain connected to a reacting organ performed on a transistor, the collector circuit of which is connected to a relay, connected by an actuating disconnecting contact to the control circuit of the Cl3 electrical installation. The disadvantage of this device is low sensitivity, since the transformer operates in particular cycles of magnetization reversal. Induction, therefore, varies from residual to nascentin. A small amount of change in induction causes the induction of a small EMF of the secondary winding. In addition to low sensitivity for such a mode of operation of the transformer, low utilization of the steel of the magnetic core is also characteristic. The aim of the invention is to increase the sensitivity of the device to protect against the disappearance of the phases of the supply voltage. The goal is achieved by the fact that two capacitors and a second resistor are additionally introduced into the device of an electrical installation against phase failure, and the saturating transformer is provided with an additional winding connected in opposite to the main and connected through a second resistor to a half-wave rectifier in parallel additional winding of the transformer, and the second capacitor is parallel to the first ballast resistor. FIG. Figure 1 shows the principle of the electrical circuit of the device to protect the electrical installation from phase failure; in fig. 2 - time diagrams illustrating the principle of operation / device. The device is connected to the terminals of the electric receiver 1 and contains a rectifier 2, loaded by the primary winding of a disconnected transformer 4 connected through the first resistor 3, to the secondary winding of it through the rectifier 5 and the integrating circuit 6 the reacting element 7 is connected. Executive contact To its relay is on; in c, control unit actuator 9. Transformer 4 is equipped with an additional winding 10, shunted by the first capacitor 11 and connected through the second resistor 12 with output of the miter 2. In addition, parallel to the resistor 3 is connected the second capacitor 13. In the diagrams (Fig. 2 and 6) shows the output voltage 14 of rectifier 2 and the magnetomotive force 15 of transformer 4, the magnitude of the saturation threshold 16 of transformer 4, the magnetizing force 17 from the current of the auxiliary winding 10, with FIG. 2a corresponds to the normal mode, and FIG. 26 to phase cut mode. In FIG. 2b, g, and and e show voltages 18 on the secondary winding of the transformer 4, voltage 19 at the output of the rectifier 5, voltage 20 on the integrating circuit 6 and output voltage 21 of the reacting element 7 in the phase failure mode. The device works as follows. The symmetric voltage of the power supply of the protected electrical receiver 1 corresponds to the pulsating thermal voltage 14 shown in Fig. Under the action of this voltage, through the RC-chain 3-13 and the primary winding of the transformer, a current flows, creating a part of the magnetizing force (HC). The current of the additional newly introduced winding 10 creates an almost unchanged magnitude magnetomotive force 17 (MDS) of opposite sign (for this, the additional winding 10 turns on the opposite main). The total MDS 15 of the transformer 4 is shown in FIG. 2a Since the value of MDS 15 in any time interval exceeds the threshold of Natsyena 16 (as can be seen from diagram 2c (), the magnetic core of the transformer 4 is in deep saturation and its secondary voltage is almost zero. At the same time, the output voltage of the integrating circuit 6 also has zero value. The transistor of the reacting body 7 and its actuating relay are, therefore, de-energized. The contact 8 in the control circuit of the protected recipient remains closed.

If, as a result of damage to any element of the supply chain, one of the phases in the rectified voltage curve 14 disappears, dips appear (Fig. 25). At intervals of zero value of the output voltage of the rectifier 2, the primary current of the transformer 4 also decreases to zero. At the point of decreasing the voltage 14 to zero uBvnn the current of the transformer primary winding is not equal to zero, but has a negative value. This is due, firstly, to the presence of a capacitor 13 in the primary winding circuit, while in the initial part of the voltage failure, when the voltage 14 is equal to zero | capacitor 13 charged (negative potential on its top plate). discharged along the circuit: main winding of transformer 4 — additional winding 10 of the same transformer — resistor 12 (another part of the discharge current passes through resistor 3, and in winding 10 it branches into a branch of capacitor 11). From FIG. 1 it is visible that the VAT of the main and additional windings of the transformer 4 at the same time

are summed up (while the currents generated by rectifier 2 in the same windings create dissimilar magnetizing seeps). The resulting NA curve of a transformer has the form shown in FIG. 25 It can be seen from the diagram that, in the incomplete phase p & kim, the MDS 15 passes the entire range from the positive to the negative value of the saturation threshold 16 of the transformer. This mode of the magnetic circuit corresponds to a change in induction from -Vd to Bj, i.e. Lv 2 bg. In this case, therefore, the whole range of possible induction changes is used. The voltage 18 of the secondary winding of the transformer at the same time has a maximum value (FIG. 26). This signal, after rectifying 19, is applied to the integrating circuit 6. The capacitor of the latter is charged from the pulse to and the pulse is charged and after a few periods unlocks the transistor of the reacting organ 7, causing a dangling of the executive relay. Its contact, in turn, opens the supply circuit of the actuator coil. The protected electrical receiver is disconnected from the network in which the phase disappeared.

The proposed device, which has a high sensitivity, can find a wide application for the protection of electrical installations.

Q

sixteen

ABOUT

11 16

one

Claims (1)

THE DEVICE FOR PROTECTING THE ELECTRICAL INSTALLATION FROM THE CLIP OF PHASES by ed. St. No. 862306, characterized in that, in order to increase sensitivity, two capacitors and a second resistor are additionally introduced into it, and the saturable transformer is equipped with an additional winding connected in opposite to the main one and connected through the second resistor to the output of a half-wave rectifier, the first capacitor connected in parallel with the additional saturable transformer winding, and the second capacitor parallel to the first ballast resistor .. SU ..,. 1134984