SU1001281A2 - Device for differential protection of electric installation - Google Patents

Description

The invention relates to electrical engineering and can be used for the differential protection of electrical demand-t.

According to the main author. St. No. 902138. a device is known which contains current sensors whose output windings are connected to the input terminals of a multi-lumen rectifying bridge, and three resistors connected by a triangle and two reactors of the organs are connected to the output of the latter, with the outputs of the latter through the NAND element and the time delay element associated with the exit authority.

A disadvantage of the known device is its low level of accuracy due to the lack of monitoring of the operability of the output windings of current sensors.

The purpose of the invention is to increase the reliability of the device for the differential protection of electrical installations.

The goal is achieved by additionally introducing a control unit, limiting resistance, test current source, pushbutton switch, multi-pole switch, and signaling organ, with the limiting resistance parallel to the control unit, the first output of which is connected to one of the output of the source of the executive current, and the second output - with the terminal of the multi-pole switch, the remaining contacts to torogo connected to the input terminals of the bridge rectifying unit, another output of the test current source terminal is connected to the common point of the windings of the current sensor output, and outputs a control organ ielementa time delay connected to the body of the alarm inputs.

The drawing shows the scheme of the proposed protection device.

The device contains current sensors supplying 1 and powered 2 connections, a multi-shoulder rectifying bridge 3, the output of which is connected to three resistors 4-6, connected by a triangle, and two reactors 7 and 8, connected through the logical block I-HE 9 to the element 10 time limits and the output body 11, the body 12 of the control, the body 13 of the alarm, the source 14 of the test current, the push-button switch 15, the limiting resistance 16 and the multi-pole switch 07.

As an information signal for the logical part of the protection - block 9 - the influencing regulators 7 and 8 use the voltages removed from the resistors B and 5, respectively.

In the load or external mode, the closures at the outputs of the reacting authorities 7 and 8 are equal. The unit that disables the signal at the output of block 9 is not.

In the internal short circuit mode, every half-period, the signals at the output of the sensor are always equal to one and O, or O and one, that 6 causes the device to trip.

The health of the output current windings is monitored as follows.

When pressing the -button switch 15, the test current from the source 14 flows through the closing contacts of the specified switch, the limiting resistance 16, the contacts of the multi-pole switch 17 and the winding of the current sensor being tested, if there is no break in it. Sufficiently high resistances of 4-6 (.10-40 kΩ) are shunted by the low resistance of the windings of the current sensor being tested (40-100 ohms), and the reactors 7 and 8 do not work when the test current flows. If there is no short circuit in the tested winding, then. on it and on the limiting resistance of 16 1, also in the order of 40 ohms, almost the same voltage drops are detected. The control unit 12, the setting of which is close to the value at the outputs of the source 14, also does not work: t. So, if there is no break or short circuit in the tested winding, the signaling organ does not Ctja6a. When the winding breaks, one of the reacting bodies 7 and 8 is triggered, and during a short circuit in the winding, control body 12 is triggered. The latter act on the signaling body 13, which alarms the winding of the sensor and locks the protection. Note that in order for the output body 11 when triggered

one of the reacting bodies 7 and 8 (which corresponds to the internal short circuit mode) did not work, it is necessary to disconnect its input from the output of the time delay element 10 when the button switch 15 is pressed (for this, a second disconnecting pair of the last contact can be used). The position of the common contact of the multipole switch 17 indicates which of the tested sensors is defective. As the test current source 14, it is advisable to use the power supply unit of the protection device.

The introduction of additional units into the device allows for monitoring the operability of the output windings of the sensors and connecting wires between Npmi and thereby increase the reliability of protection against short-circuit currents.

The most appropriate offer. use my device with; magneto-dielectric current sensors (core of magnetodielectric) to protect autonomous electric power systems.

Claims (1)

Invention Formula Device for differential protection of electrical installations, according to author. No. 902138, in order to ensure reliability, a control body, a limiting resistance, a test current source, a push-button switch, a multi-pole switch and an alarm body are added, the limiting resistance is connected in parallel with the control body, the first output of which is connected to one of the output terminals of the test current source through the closing contacts of the BUTTONFLY switch, and the second output - to the common contact of the multi-pole switch, the rest the contacts of which are connected to the input terminals of the multi-shoulder rectifying bridge, the other output terminal of the test current source is connected to the common point of the output windings of the current sensors, and the outputs of the control unit and the time-delay element are connected to the input of the alarm unit.