RU2269191C1 - Asymmetric-running protective gear for three-phase loads - Google Patents

Abstract

FIELD: electrical engineering; asymmetric-running protection of three-phase loads.

SUBSTANCE: proposed protective gear has electromagnetic starter one of whose coil leads is connected to neutral conductor of supply mains and other one, to supply mains phase lead through STOP button and triac; gate electrode of triac is connected through current-limiting resistor and diode to center tap of capacitor and resistor series-connected to inductance coil and connected to other phase leads of supply mains. START button is connected in parallel with triac cathode and anode.

EFFECT: enhanced electric safety in handling of protective gear; simplified design.

1 cl, 1 dwg

Description

The invention relates to electrical engineering and can be used to protect three-phase consumers from asymmetric operating modes.

A device / 1 / is known that contains a negative sequence voltage filter, with its input connected between the power contacts of the controlled switching device and the input terminals of the consumer, the electromagnetic relay is connected to its output, which breaks the power supply circuit of the switching device with its contact in the event of a phase failure or voltage unbalance.

The disadvantage of this device is the presence of a contact in the control circuit of the switching device, which reduces the reliability of its operation and limits its use in rooms with aggressive and explosive atmospheres.

При этом кнопка "Пуск" механически соединена с силовыми контактами электромагнитного пускателя.There is also known a device for protecting three-phase consumers / 2 /, adopted as a prototype, containing an electromagnetic starter, the coil of which is connected to the first phase of the network via the opening contact of the Stop button between the power contacts and the power source, and the second terminal is additionally connected to the common point between the capacitor and the resistor with an inductive coil connected in series, connected between the power contacts of the electromagnetic starter and the consumer. The ratio of the resistances of the capacitor and inductive coil is 2: 1, and between the resistances of the resistor and inductive coil is

In this case, the "Start" button is mechanically connected to the power contacts of the electromagnetic starter.

The disadvantages of this device include insufficient electrical safety during the work of personnel with powerful electromagnetic starters and a limited selection of electromagnetic starters with a mechanical “Start” button that acts on the armature of the electromagnetic starter.

The purpose of the invention is to increase electrical safety when working with a protection device while simplifying it.

The specified technical result is achieved by the fact that a triac is additionally introduced into the device for protecting three-phase consumers from asymmetric operating modes between the phase of the network and the coil of the electromagnetic starter, the control electrode of which is connected through an additionally inserted diode and a current-limiting resistor to a common point between the capacitor and the inductor coil connected in series connected between the power contacts of the electromagnetic starter and the consumer, the capacitor is not connected bschim to output the lagging phase, and a resistor connected to the terminal uncommon advanced phase relative to the phase network, which is connected to a first terminal of the coil of the electromagnetic contactor through the "Stop" button, and a power circuit of the triac, parallel to the cathode and anode of the triac connects button "Start".

The drawing shows a diagram of the inventive device. The device for protecting three-phase consumers from asymmetric operating modes contains a Stop button 1, through the Start button 2, inserted into the power supply circuit of the coil 3 of the electromagnetic starter, the second output of which is connected to the neutral working conductor of the network, in addition to the Start button 2, a triac 4, the control electrode of which is connected through a current-limiting resistor 5 and a diode 6 between a capacitor 7 and a resistor 8 with an inductive coil 9, the capacitor being connected by a non-common output to the lagging phase, and the resistor li ne uncommon terminal to the network advanced phase relative to the phase to which is connected a first terminal of the coil of the electromagnetic contactor 2 through the "Stop" button 1 and the triac power circuit 4, the power contacts of the electromagnetic contactor 10 which commute phase consumer 11.

The proposed device operates as follows.

When the Start button 2 is initially turned on, the supply voltage is supplied to the coil 3 of the electromagnetic starter, the power contacts of the electromagnetic starter 10 are closed, and a linear voltage system is supplied to the three-phase consumer 11. With a symmetrical mode of operation of the network through the control electrode of the triac 4, a rectified current flows enough to open it. The power contacts of the electromagnetic starter 10 are self-retaining by the electromagnetic force of the coil 3 and feed the three-phase consumer 11.

When the phase failure in the network or the occurrence of significant asymmetry, the current in the circuit of the control electrode of the triac 4 decreases. A decrease in current causes the triac 4 to close and the electromagnetic coil of the electromagnetic starter 3 to be de-energized, while the power contacts of the electromagnetic starter 10 are opened. To manually turn off the consumer, the Stop button 1 is provided in the control circuit.

Thus, the protection of three-phase consumers 11, for example, asynchronous motors, is more electrically safe with high reliability under asymmetric operating modes.

Information sources

1. Kokovin V.E. Filters for symmetrical components in relay protection. - M .: Energy, 1968, p.12.

2. RF patent №2218645, class. H 02 H 7/085, 2003 - prototype.

Claims (1)

A device for protecting three-phase consumers from asymmetric operating modes, containing the Start and Stop buttons, an electromagnetic starter, the coil of which is connected to the zero working conductor of the network by the first output, a capacitor, the first terminal of which is connected to the first phase of the network between the power contacts of the electromagnetic starter and the consumer , a resistor, the first terminal of which is connected to the third leading phase of the network between the power contacts of the electromagnetic starter and the consumer, the second terminal is connected to one of the terminals in the inductive coil, the second output of which is connected to the second output of the capacitor, characterized in that the second output of the coil of the electromagnetic starter is connected to the cathode of an additional triac, the anode of which is connected via the Stop button to the second lagging phase of the network between the power contacts of the electromagnetic starter and the power source , the control electrode of the triac through a current-limiting resistance is connected to the cathode of the additionally introduced diode, the anode of which is connected to the midpoint between the capacitor and an inductive coil, parallel to the cathode and anode of the triac connects button "Start".