SU614489A2 - Arrangement for protection of humans from electric shock in ac distributing station - Google Patents

Description

Three differential current transformers 1–3 are installed in a distribution power cabinet or another distribution distribution device similar to it. The supply network to the distribution electrical installation is supplied through the first part of the primary winding 4. The feeder lines of each phase, coming from the distribution electrical installation, through the differential current transformers, form the second part of the primary winding 5, which is opposite to the first winding part 4.

As an output element 13, a differential leakage relay of the RUD-04 type and a remote electromagnetic release of the circuit breaker can be used, the trigger signal of which is supplied from the RUD-04. With the same differential relay, a power source of alternating current can be used to power the amplifier-conversion unit 9.

During normal operation of the distribution electrical installation, the sum of the currents in each phase of the primary windings in the differential current transformers 1–3 is zero.

If there is a fault in any lb of nz differential current transformers 1-3, the currents in the corresponding secondary windings of the current transformers are equal in accordance with a Vits EMF. Such a violation occurs all the time when the current of damage (leakage) inside the distribution electrical installation, for example, due to the contact of the Human with current-carrying parts with different potentials. As a result, the signal will be amplified by one or two blocks 9 And only by the variable component will be transmitted to the input of the output organ 13 through the winding 12. of the transformer 10.

So, if a touch penetrates between one phase of phase and a grounded metal structure, in the primary winding of the corresponding differential current transformer alone there is a violation of the currents. Owing to this in his magnetic circuit, according to Wits MDS. from which n the EMF will be excited in the secondary winding of this current transformer. Further, the signal will be amplified in the usual way, the output body 13 will operate from it.

When a person touches two phases, for example, phases B and C, in the secondary windings of current transformers 2 and 3, AC is used. To the input of the corresponding obonh amplifiers 9, the voltage of the emf will be given the same in magnitude and phase. Therefore, both amplifier 9 will simultaneously amplify the same signals. Owing to this, the output transformer 10 magnetic conductor will be excited from two primary windings I1 operating in parallel and with its secondary winding 12 a signal will be transmitted to the operation of the output protection element 13.

When a current appears in the distribution box, damage between the phases A and B will lead to the excitation of the magnetic current 1 n 2 magnetic circuits. The secondary windings also appear in their secondary windings. However, the voltage from these windings under the influence of capacitor 6 and resistor 7 will be shifted by an angle of 90 ° (actually, this angle is less than 90 °).

Therefore, in the secondary winding 12 of the output transformer 10, the EMF will be excited by the resulting MDS, the value of which is equal to the geometric sum of the MDS of the two primary windings II, included in the channels of phases A and B.

A similar protection triggering effect can be obtained if instead of a shunt resistor 7, an inductance coil is installed and the secondary winding of the differential current transformer 2 is connected to the same group of connections to which the windings of current transformers 1 and 3 are connected.

Thus, the proposed protection device ensures reliable operation

circuit elements in the event of a dangerous situation in the distribution of electrical installation prn any current path through the human body. At the same time, the current setpoint, depending on the current path, is not damaged by more than 50%. In addition, in comparison with the known protection, the proposed design has a significantly simplified design by reducing the number of power supplies for semiconductor amplifiers. Due to this, at the same time, the level of reliability is significantly increased and the costs are reduced during the production of protection.

Testing of the prototype model of differential protection for electrical safety in distribution electrical installations

It was confirmed that the efficiency of the passage through the body of the injured person in any situation, touching the current carrying parts to the current carrying parts And the ground, ensured that the passage of the dangerous amount of current through the body. This current setting, on which the differential leakage relay is set, does not change in the direction of coarsening of the protection.

; B. The preparation of a scientific and technical document is being completed for transmission to interested institutions with a view to further developing prototypes and organizing the serial production of power distribution cabinets with a device to protect people from electric shock at the distribution point

current.

Claims (1)

Invention Formula A device for protecting a person from electric shock at a distribution center of alternating current in auth. St. No. 536559, characterized in that, in order to increase the sensitivity, it is additionally equipped with two resistors and a capacitor that shunts the secondary winding of one current transformers, and resistors shunt the secondary windings of the other two current transformers. Sources of information taken into account in the examination: I. Application No. 208;} 432/07. And 02 And 5/12. 1975. I 7 --R "/ Gl sS-L bo3S --bofe. --Cad .. „l