SU694930A1 - Minimum voltage protection arrangement - Google Patents

Description

one

The invention relates to electrical engineering, in particular, to undervoltage protection devices. Devices are known that protect electrical installations from undervoltage. Combined current and voltage sources can be used to power these devices.

Of the known devices, the minimum voltage protection device comprising the unit for measuring the voltage value of the protected circuit, the minimum voltage relay, the actuator and the combined power supply unit from the current and voltage of the protected circuit with a summing circuit is the closest to the proposed technical essence and the achieved effect. a three-core transformer, on the middle core of which the current and voltage input windings and the output winding are located.

In this device, special measuring voltage transformers or voltage dividers with damping resistors are used as a unit for measuring the voltage value of the protected circuit, which complicates the circuit.

The aim of the invention is to simplify the device by eliminating the voltage measuring transducer. The goal is achieved by the fact that in the undervoltage protection device containing an actuator connected to the output of the undervoltage relay and a combined power supply unit with a three-rod summing transformer, the input current of which is connected to the current of the protected circuit, the input winding is connected to

the voltage of the protected circuit, and the output winding is connected to the control current of the undervoltage relay and actuator, in a three-rod summing transformer of the combined power supply unit, the input current winding is located on one of the outermost rods, the input winding and the output winding on the middle rod, and on the other extreme rod is one

the part of the newly introduced winding is connected in series with the other part of this winding located on the middle rod, the output of which is connected to the undervoltage relay, and the ratio of the numbers of turns of the parts of the newly introduced winding is inversely proportional to the magnetic flux created by the input current winding in the rods on which are located parts of the above winding.

Claims (2)

The drawing shows the functional circuit of the undervoltage protection device. The device contains minimum voltage 1, actuator 2, combined power supply unit 3, containing a three-pole summing transformer 4, an input current winding 5 located on the outermost rod, an input winding of voltage 6 and an output winding 7 located on the middle rod, and an additional the coil consists of two parts, one of which 8 is located on the middle rod, and the second 9 is at the extreme. The voltage from the output winding 7 is supplied to the control current of the relay 1 and the executive body 2. Parts 8 and 9 of the auxiliary winding, interconnected counter-sequentially, are connected to the input of the minimum voltage relay 1. Generated by the input current winding 5 in the outermost rod, the magnetic flux F (/) splits into two streams: F (/) 1 , passing through the second extreme rod, and Ф (/) 2, passing through the middle rod. The magnetic flux Φ generated by the input winding of voltage 6 in the middle rod (and} is also divided into two streams: 0 (f /) i and Φ (/) 2 passing through the outermost rods of the magnetic circuit. Fluxes F (| C /) and F (/) 2 induces an emf in the output winding 7 proportional to the sum of these currents, as a result of which the voltage removed from this winding is proportional to the sum of the input signals from the current and voltage of the circuit to be protected. This voltage is used to power the device. 9 additional windings are connected oppositely, resulting in EMF, Nav The currents O (/) i and Ф (/) 2 are directed oppositely. The number of turns of parts 8 and 9 is chosen inversely proportional to the flows W, F (/) 1 W F (/) 2 passing through them, as a result of which the total emf of the additional winding from the flux Φ (/) 1 and Φ (/) 2 is zero, i.e. the voltage at the output of the additional winding does not depend on the current. Caused in parts 8 and 9 by the magnetic flux Φ (U) and Φ (/) 1 EMFs are added up. The voltage on the additional winding is proportional to the voltage of the protected circuit, resulting in a given decrease in the voltage of the protected circuit le 1 gives the signal to the actuator 2 for disconnecting switch 10. Connecting auxiliary winding of the summing transformer to the input minimum voltage relay instead of special measuring transformers or voltage dividers resistors simplifies the apparatus construction. Claims An undervoltage protection device containing an actuator connected to the output of the undervoltage relay and a combined power supply unit with a three-pole summing transformer, the input current of which is connected to the protected circuit, the input voltage is connected to the voltage of the circuit to be protected, and the output winding is connected to the control current circuit of the undervoltage relay and the actuator, characterized in that, in order to simplify the design of devices by eliminating the measuring voltage converter, in the three-rod summing transformer of the combined power supply unit, the input current winding is located on one of the extreme rods, the input voltage winding and the output winding are on the middle rod, and on the other extreme rod one part of the additionally inserted winding is connected in series - at the opposite with the other part of this winding located on the middle core, to the output of which the minimum voltage relay is connected, and pieces of additional winding turns is inversely proportional magnetic flux generated by the input current in the winding rods, on which the part of the additional winding.