SU792441A1 - Device for single-phase earthing protection in mains with neutral wire - Google Patents

Description

connected to another additional input of the main element AND, while the second input of the second element OR the output of the newly entered second element is NOT connected, the input of which is connected to the output of the newly introduced element LIMITED MEMORY connected to the second input of the additional element AND, and the output of the element LIMITED HAt -lfiTb is connected to the output of the MEMORY element,

The drawing shows the block diagram of the device for protection.

The device contains a zero-sequence voltage transformer 1 (TNIP), a starting body 2 (SW), a power direction organ 3 (OHM), a zero-sequence current transformer 4 (TNTP), an alternating current amplifier 5, a threshold element b (PE), an actuator 7 (BUT), coil 8 disconnect, element MEMORY 9, elements OR 10 - AND, elements AND 12-14, elements NOT .7, - elements LIMITED MEMORY 18 and 19, time delay organ (HBV) and block pin 21 switch.

The elements AND 14, LIMITED to MEMORY 19 and NOT 17, together with OVV 20, play the role of a pulse shaper, the elements NOT 15 and LIMITED MEMORY 18 — the role of the switch for OHM 3,

The device works following dim sum.

In the normal mode of the network, software 2, OHM 3, PE 6, IO 7, the elements of MEMORY 9 LIMITED MEMORY 18, 19 AND OVV 20 are in the initial state, the KOKHTiKT 21 block is open.

When a single-phase ground fault occurs at the protected connection, PO2 and PE 6 are activated. As a result, the output of the element 13 and the input of the element MEMORY 9, respectively, signals appear and the EUT 7 is triggered, turning on the disconnecting coil 8 at a direct voltage. Under the action of this voltage, the coil 8 begins to flow around the current, growing exponentially. Simultaneously, an OVV 20 is triggered, with a time delay, which in magnitude assumes a shorter actuator time for the switch and a longer time for interference to the inputs of the device. After a predetermined setpoint, OVV 20 triggers and sends a signal to the input element NOT 16 and erasing the input element MEMORY 9, As a result, the signal at the output of element 9 disappears and, in addition, erasures the alarmed information (memory). The EUT 7 returns to its original state, and from the disconnecting coil 8 is removed. voltage, and the signal at the input of the element is NOT 16 and the erase input

the element MEMORY 9 acts briefly, in the form of a pulse formed by the elements 14, LIMITED MEMORY 19 and NOT 17.

The amount of time for which the signal is memorized by the element LIMITED MEMORY 19 is selected from the condition of detuning from the switch off time. This ensures a one-time occurrence of the signal at the output of the logic element 14,

The actuator 7 (and, accordingly, the coil 8) will be triggered only if software 2, PE b, OHM 3 are in the activated state, and a signal is present at the output of the element 12. The latter will occur when signals are applied to the device, not due to interference, but by the process of single-phase ground fault,

When the device acts on interference signals with a duration not exceeding the time delay of the OVV 20, the re-activation of the EUT 7 and the disconnecting coil 8 will not occur, as software 2, OHM 3 and PE b will be in an inoperative state.

An introduction to a device for protection against single-phase earth faults of a short-term single pulse shaper, time-delaying organs and power directions, as well as elements of LIMITED MEMORY AND, OR, and does NOT allow to obtain more selective protection against earth faults, and this in turn increases reliability of power supply and electrical safety of electrical installation services.

Claims (1)

Invention Formula A device for protection against a single-phase earth fault in a network with an insulated neutral, containing a zero-sequence voltage transformer, to the secondary winding of which is connected a starting element a zero-sequence current transformer connected through an amplifier to a threshold element, an executive element connected through the MEMORY element and the main element And to the mentioned triggering organ and the threshold element, that is so that, in order to ensure selectivity, the impulse impulse A time delayed organ whose input is connected to the MEMORY output and the output through the first element is NOT connected to the first additional input of the AND element and through the first input of the newly introduced first OR element. to the erase input of the mentioned element MEMORY, the output of which