SU792415A1 - Current relay - Google Patents

Description

The invention relates to a relay with a sloping dependent characteristic, the principle of which is based on a change in the constant charging time of the master circuit time depending on the amplitude of the input value and can be used in relay protection circuits.

Known induction current relay type RT-90. The relay consists of an electromagnet with short-circuited coils, a disk with a screw, a toothed segment, a moving frame, a contact system and provides a family of gentle dependent characteristics. The time setting of the relay is adjustable from 0.5 to 4 s 1.

The main drawbacks of the relay are: the complexity of the mechanical part, the impossibility of obtaining long time delays, the considerable power consumption and the large gaba- rits.

It is known a T-306 type relay from commercially available Logic-T elements, based on the principle of reducing a constant time, the time of a master circuit with an increase in the input signal.

The relay contains a starting organ, a timing circuit consisting of two potentiometers, three charging resistors with diodes connected in series with them, and a capacitance reacting organ 2J. ,

The relay allows to obtain a family of dependent characteristics with a large slope, since the value of the charge resistor 10 decreases the time of the driving circuit with increasing input signal.

The aim of the invention is to increase the stability of the time of operation of the relay by obtaining a smooth, sloping, dependent response time characteristic of the relay on the input current.

The goal is achieved

20 in that the current relay containing the starting element, the time of the master circuit consisting of two parallel-connected variable resistors, in series with. one of which is included

25 diode, and capacitance, in parallel with the latter, a reacting organ, a potentiometer connected to the input voltage, are additionally inserted a transistor, the base of which is connected

thirty

to the potentiometer slider, the emitter to the positive output of the power source, the collector to the junction point of the iodine anode, the driver circuit and one of the resistor terminals in the ranzistor collector circuit, another resistor terminal connected to the negative terminal of the power source.

The drawing is a schematic diagram of the proposed current relay.

The current relay contains the starting body 1 with the opening contact 2, potentiometer 3, transistor 4, resistor 5, diode b, variable resistors 7, 8, capacitor 9, reactive body 10.

The relay is tuned to a given characteristic by adjusting the values of the variable resistors 7, 8, as well as by changing the output characteristic of transistor 4 with potentiometer 3.

Adjusting the resistance of the charging circuit with variable resistors 7 and 8 makes it possible to get only a family of gentle dependent characteristics with the same slope, and adjusting the output characteristics of transistor 4 by potentiometer 3 allows you to change the slope of each of the characteristics separately.

Current relay operates as follows.

When triggering device 1 triggers, its contact 2 opens, shunt capacitor 9, the time of the master circuit in normal mode, as a result of which the charging of capacitor 9 begins through a charging circuit formed by variable resistors 7, 8 and a diode. When the voltage on the capacitor 9 reaches the value of the response voltage of the reacting body 10, the latter comes into action and the relay is activated.

Improving the stability of the relay response time by obtaining a smooth, flat dependent response time characteristic of the relay from the input current values is based on an increase in the charge resistance and, consequently, a constant time reference circuit time as the input signal rises due to the control element entered into the relay circuit transistor 4 diode 6. The state of iodine 6, and, accordingly, its resistance depends on both the magnitude and the polarity of the voltage applied to it, the magnitude of which is determined by the voltage difference between the collector output of the transistor 4 and the capacitor plate 9. The voltage at the output of the collector is inversely related to the magnitude of the input voltage, and the voltage on the capacitor 9 plates during charging varies with the response voltage of the response organ -ten .

With a small input current and provided that the response voltage of the reacting organ 10 is less than or equal to the voltage at the collector terminal, the resistance of the charging circuit will be caused mainly by two parallel variable resistors 7, 8, since the resistance of diode 6 is little known. for its open state almost for the entire duration of the charge of the capacitor 9. In this case, the total resistance of the charging circuit will be minimal.

When a large current is applied to the relay input, the diode 6 remains closed for almost the entire charge time of the capacitor 9 due to the small voltage on the collector terminal compared to the response voltage of the response element 10. The resistance of the charging circuit will be maximum.

With average input current values, the diode b during the charging process of the capacitor 9 is equal in time to the open and closed states.

The above shows that the value of the charge resistance of the time of the master circuit depends on the open and closed state of diode b in the process of charging the capacitor 9 and gradually increases with increasing input current.

The proposed current relay can be used in electrical networks to improve the selectivity of the effect of maximum current currents.

Claims (2)

1. Chernobrovov N.V. Relena protection, M., Energie, 1971, p. 56-57. 2. Journal of Electrical stations I 3, 1971, p. 59-65.