RU64816U1 - PULSE PROTECTION RELAY - Google Patents

Abstract

A pulse protection relay is proposed for protecting DC networks with a stepwise increase in load current, in particular for protecting traction networks. An impulse protection relay based on an RDSH relay or an inductive shunt circuit breaker containing a current path with two branches, a magnetic system with an armature and an inductive shunt in the form of a magnetic circuit worn on one of the current path branches, the magnetic inductance shunt magnetic circuit containing a non-magnetic gap located along the current conducting branch with a magnetic circuit, characterized in the design of the magnetic circuit of an inductive shunt. The magnetic circuit is divided into sections, and the sections are located relative to the current path so that the air gaps of the sections are in opposite sides relative to each other. Between sections, an adjustable additional air gap is possible, allowing you to adjust the protective characteristic of the relay. The relay automatically adjusts to the characteristics of the current flowing through the relay, so that at low currents preceding the current increment, the dynamic setpoint decreases, and at high currents preceding the current increment, the dynamic setpoint, on the contrary, increases. Due to this, false alarms of the relay are reduced and the sensitivity and speed of the relay are increased.

Description

The utility model relates to relay protection devices, in particular, to pulse DC relays, can be used for feeders of traction DC from short-circuit currents.

A protection relay is known, containing a current lead with two branches, a magnetic system with an armature, the latter being a reed switch A.S. USSR No. 8243300 H01H 51/28. It is designed to work in high current circuits, but does not have an impulse response to a change in current.

Known pulse protection relays, which include switches with an inductive shunt, containing a current path with two branches, a magnetic system with an armature and a magnetic circuit on one of the branches (inductive shunt) - book by V. Kharikov. "Protection of the DC contact network from short circuits" 1987, M .: Transport, p. 17 and relay RDSH - book Harikova V.F. "Protection of the DC contact network from short circuits" 1987, M .: Transport, p.23, the latter is taken as a prototype. This relay, as well as the indicated switch, contains a current lead with two branches, a magnetic system with an armature and an inductive shunt on one of the branches. An inductive shunt is a magnetic circuit, dressed on one of the branches of the relay conductor, and the gap of the magnetic conductor is located along the branch of the current conductor with the magnetic circuit (across the midline of the cross section of the magnetic circuit). The branch for the inductive shunt is selected with a smaller cross section so that the relay reduces its setting for the current increment, and not for its reset. An inductive shunt manifests itself with an increase in current, displacing the change in current from its branch to the branch without an inductive shunt, which ensures the reaction of the relay to the current increment. This is favorable for protection against short-circuit currents. in traction networks,

in which the increase in load current occurs in separate steps. Therefore, even with the commensurability of the magnitude of the load current and the short-circuit current, the increment of the load current is less than the increment of the short-circuit current, which makes the use of pulse relays effective for protecting traction networks. The magnitude of the current rise rate in pulse relays used to protect traction networks affects the relay response much less than the current increment itself, because the time constant of pulse relays is much larger than the rise time constant of the short circuit and load increments.

The disadvantage of a pulse relay with an inductive shunt is the appearance of false positives during increments of load currents, if they were preceded by some initial (steady-state) current. The reason for this is a linear decrease in the relay setpoint according to the current increment (dynamic setpoint) with an increase in the initial current, due to the summation of the magnetic flux from the initial current and the current increment in the relay magnetic system. Therefore, the relay begins to respond to the increment of the load current, although they are smaller in magnitude than the increment of the short-circuit current. In practice, in order to prevent false alarms from incrementing load currents, the static relay set point (the set point when the current increases slowly, the current pulse is absent) is forced to increase, which leads to a decrease in the sensitivity and speed of the pulse relay, see the book by V. Kharikov. "Protection of the DC contact network from short circuits" 1987, M .: Transport, pp. 27-28.

The technical result of the claimed utility model is to increase the sensitivity of the relay and its speed.

The essence of the utility model consists in the fact that in a pulse protection relay containing a conductive circuit with two branches, a magnetic system with an armature and an inductive shunt in the form of a magnetic circuit mounted on one of the branches of the electrical circuit, the magnetic circuit of the inductive shunt contains non-magnetic gaps located across the midline of the transverse sections of the magnetic circuit of an inductive shunt, magnetic circuit

the inductive shunt is divided into sections, and the sections are located relative to the current path so that the air gaps of the sections are located on opposite sides relative to each other.

Figure 1 shows the pulse relay, figure 2 shows the magnetic circuit of the inductive shunt, figure 3 shows the protective characteristics of the utility model, the relay prototype.

In the figures, the numbers mean:

1 - branch of the current lead without a magnetic circuit;

2 - a branch of a current lead with a magnetic circuit (inductive shunt);

3 - magnetic circuit of an inductive shunt;

4 - magnetic relay system with an anchor;

5 - the gap of the magnetic circuit;

6 - sections of the magnetic circuit;

7 - air gap between sections of the magnetic circuit;

8 - characteristic relay according to the prototype;

9 - characteristic of the maximum current relay (analog);

10 - characteristic of the proposed relay;

11 - "optimal protective characteristic."

The relay conductor consists of branch 1 and branch 2, the last one is equipped with magnetic circuit 3, as a result of which branch 2 forms an inductive shunt. A magnetic system with an armature 4 leads to the displacement of the movable contact of the pulse relay. The magnetic circuit 3 of the inductive shunt is divided into sections 6 and is dressed on branch 2. The air gaps 5 of the magnetic circuit are located along the branch 2, with the gap of the left section in the figure located below the branch 2, the gap of the right section in the figure is located on the top of branch 2. The magnetic circuit 3 can have an air gap 7 between sections.

In Fig. 3, the initial current I _{0 is} plotted along the horizontal ordinate axis, and the current increments ΔI are plotted along the vertical ordinate axis. The characteristic of the relay according to the prototype is shown by straight line 8, with small previous currents it lies below straight line 9, which is

overcurrent relay characteristic. Due to this, the sensitivity to short-circuit current increases. However, this also leads to false positives from increments of the load current ΔIн, which occur at nonzero previous currents. To avoid this, the static relay setpoint according to the prototype Iust8 is increased, fulfilling it more than the setpoint of the maximum current relay Iust9. The characteristic of the utility model 10 in the medium and large precurrent currents is close to characteristic 9, which provides greater sensitivity than the prototype, and in the region of small preceding currents it is close to characteristic 8, which provides a response to the current increment. The right side of figure 3 shows a comparison of the characteristics of the utility model 10 with the "optimal protective characteristic" 11 described in the book of V. Harikov on page 29.

The utility model for small prior currents has an increased sensitivity to current increments, and for large previous currents it is reduced due to a change in the design of the magnetic circuit of the inductive relay shunt. With a small current through the relay, the magnetic flux in the magnetic circuit of the inductive shunt flows differently than the prototype. Most of it passes from one section to another, bypassing the air gap. The inductance of the magnetic circuit, and hence the inductive shunt, increases, which provides a greater displacement of the current from the branch with the inductive shunt into the working branch of the pulse relay current lead compared to the prototype, which contributes to a decrease in the dynamic setpoint and thereby increase the sensitivity of the relay. This is important in the event of short circuits just in the absence of current through a pulse relay or in small values of the previous current, when the detection of the short-circuit mode most difficult. Performance increases due to the fact that the operation occurs at lower currents than the prototype.

With the growth of the preceding current through the relay, the magnetic flux in the magnetic circuit of the inductive shunt increases. As a result of this on

saturation regions appear at the boundary of the sections of the magnetic circuit, the magnetic flux begins to pass through the air gaps of the sections, as in the prototype. The inductance of the inductive shunt decreases and the response of the relay to a change in current decreases. The saturation regions at the boundary of the sections of the magnetic circuit increase, which leads to a decrease in the effective cross section of the magnetic circuit and thereby to a decrease in the inductance of the inductive shunt. At large preceding currents, the relay reaction approaches the overcurrent relay. This reduces false positives from load currents. Therefore, the need to increase the static setting of the relay for detuning from load conditions, as in the prototype, disappears. This increases the sensitivity and speed of the relay, compared with the prototype and in the case when the current increment was preceded by the initial (steady-state) current. Relay properties automatically adjust to the characteristics of the current flowing through the relay.

Characteristic 10 obtained experimentally. It belongs to one relay, it is easier to implement than the implementation of characteristic 11. The latter is composite, consists of two direct and requires two independent relays.

With an increase in the gap between the sections of the magnetic circuit, the currents increase at which the regions of the sections of the magnetic circuit become saturated, thereby increasing the boundary current at which the relay reaction approaches the maximum current relay. A shift of this boundary current to a smaller side is possible if the air gap between the sections decreases to zero and the number of sections increases, while maintaining their previous total length.

Sources of information taken into account when compiling a description of a utility model:

1. A.S. USSR No. 8243300 H01H 51/28.

2. Harikov V.F. "Protection of the DC contact network from short circuits" 1987, M .: Transport, p.23 (prototype).

Claims (2)

1. An impulse protection relay comprising a conductive circuit with two branches, a magnetic system with an armature and an inductive shunt in the form of a magnetic circuit mounted on one of the branches of the electrical circuit, the magnetic circuit of the inductive shunt containing a non-magnetic gap located along the branch of the electrical circuit with the magnetic circuit, characterized in that the magnetic circuit divided into sections, and the sections are located relative to the conductor so that the air gaps of the sections are in opposite directions relative to each other. 2. The pulse relay according to claim 1, characterized in that the inductive shunt is placed on the branch of the current lead with the possibility of regulating the gap between the sections.