SU36516A1 - Electrodynamic Power Directional Relay - Google Patents

Description

Dynamometer energy direction relays, used as directional elements in various protection schemes of overhead and cable lines, possess valuable properties of fast action and sensitivity compared to the directional induction principle relay (ferraris), in which the disk is braked in a strong field of the coil and self-propelled induced currents; dynamometer relays give the best results on these solutions, they are indicators.

However, experience has shown that if the speed of operation of a dynamometer-type direction relay is sufficient, their sensitivity is not constant and decreases with an increase in the current in the serial coils.

A good sensitivity determines the minimum length of the dead zone (zone of failure of the relay or non-selective shutdown) for three-pole short circuits, especially likely for cables. In this case, in order to obtain a minimum of the dead zone, it is desirable that the sensitivity does not change at all values of the short circuit current: small multiples (1.5-5) are possible with night short circuits and large (.order 20) - ; damage under normal conditions.

(377)

The described dynamometer of the direction of energy is aimed at maintaining the sensitivity of the relay constant within the practical limits of the multiplicity of short-circuit currents 20-25, which achieves the minimum length of the dead zone, i.e., increasing the reliability of protection of the black lines. For this purpose, in this device, the value of the capacitor capacitively connected to the voltage circuit of the directional relay coils is commensurate so that the self-induction of the latter, together with the capacitance, compensates the current-free component of the current coil when the latter are rotated in the field. current coils. The invention also provides for the use of a reactive coil connected in series with the capacitor, as well as an auxiliary current transformer connected between the capacitor and the voltage coil circuit.

In FIG. 1 depicts the circuit of one pole (phase) of a conventional e.dynamic relay; FIG. 2 and 3 is a diagram of the proposed relay.

Under normal conditions, the magnetic flux FD of the serial coils (coils tsk) 1 PS penetrates frame 2, so

kak- she is being held by an electric neutral, she is arrested by the first freighter. fio, when the relay is operated and the frame is deflected at any CTopGiiy angle a (depending on the cause of accidents) of the first energy), it induces / beats it with a key F force E.

Under the influence of the next nodal in the frame, the current /, flows. It was driven by the total shunt value resistivity, including the design transformer. However, the low-resistance sound can be disregarded as being practically negligible: for three-pole short circuits, when the high-voltage winding is short-circuited, the resistance of the transformer 5 brought to the IV and winding is several ohms. Therefore, the value of / is determined only by the frame resistance and its additional resistance. The current flux / with respect to the voltage E is determined by the ratio of inductive resistance X of frame 2, its ohmic resistance D and additional resistance 3, from the equality tg ": -.-, - t.-,

where R is the value of pre-sparse coped 3.

The magnitude of the false moment of the moment is proportional, therefore, to the product of F I sin o, and its direction will be such that it will seek to return the frame to a neutral position. It is easy to verify that the magnitude of the spurious moment is proportional to the square of the current in the current coil and its action is equivalent to an increase in the arrester's standard, which leads to an increase in the power of the relay to start operating at high currents in the coils 1.

In addition to this reason, in a dynamometer with iron, a decrease in sensitivity, with significant currents, is determined by the saturation of iron. True, it can be minimized and its effect on sensitivity is much less than the influence of a false current.

The idea of the proposed device consists in direct or indirect connection of the capacitor into the circuit of shunt coils.

to neutralize the harmful effects of the inductive resistance of the framework and to compensate for the iron saturation of the current coil system. Indeed, if capacitance C is chosen so that it neutralizes the inductive resistance of the x-frame with an excess, then the excess of the effect of the capacitance, as opposed to the effect of self-induction, will produce a moment in the direction of deviation of the frame, i.e. compensate for the effect of saturation of the iron. Due to this, the sensitivity of the relay can be made constant within practically. occurring current multiplicities.

However, the practical implementation of the inclusion of a container along with the frame has some inconveniences, since at a relatively small value of the reactive counter-frame (on the order of ten ohms) the value of the capacitance is significant. Therefore, the circuits of FIG. 2 and 3 do not provide for various inclusions of capacity, almost, approximately equivalent; in Fig. 2, the capacitance is turned on indirectly on the nanowire coil's minute, but to reduce the capacitance value, the reactance of the coil 2 circuit is artificially increased by turning on a small reactive coil with iron; in fig. 3, the switching of the capacitance is provided by means of a low power transformer 7. This adjustment is possible by changing the air gap of the reactive coil, as well as by changing the leakage current; w or the magnetizing current of the transformer 7.

For the practical implementation of this device, normal 110V radio capacitors (with a capacity of about 2 a /) can be used; The additional device may be placed in a separate casing for joint connection with the relay during installation. The cost of such an additional device is negligible.

The subject matter of the invention.

Claims (3)

1. Electrodynamic power direction relay with capacitor applied in series in nepi voltage coils, is different in that for the purpose of increasing The sensitivity of the relay capacitor capacitance and self-induction of the coil circuit are commensurate so as to compensate for the non-atom component of the current induced in the moving system of the voltage coils when this system is rotated in the field of the stationary current coils. 2. When the relay of claim 1 is used, the coil is connected in series with the capacitor. 3. At the device according to PP, .1 and 2 the use of an auxiliary current transformer ,. included between the capacitor and, the coil circuit eg HiSHMfl. Fig Fig 2 / g