RU207004U1 - Relays for voltage and control of residual current devices - Google Patents

Abstract

The proposed utility model relates to relays that are triggered when electrical indicators deviate from normal values. The technical result consists in preventing false operation of the protection associated with the transmission of erroneous signals to shutdown due to the automatic prevention of ground faults. The specified technical result is achieved due to the fact that the device is equipped with an additional timer with a closing contact drive mechanism, moreover, an additional timer is connected to the terminals of the phase and neutral conductors, and different sides of the auxiliary load circuit, opening and closing contacts are connected to the terminals of the phase and protective conductors. 4 c.p. f-ly, 7 ill.

Description

The proposed utility model relates to relays that are triggered when electrical indicators deviate from normal values. In this subclass, protective relays are well known, which are triggered by a voltage drop and overvoltage [GOST 3699-82, GOST 17523-85, GOST EN 50550-2016, IEC 63052-2019], they are widely used to protect electrical lines, circuits, machines and appliances for industrial, household and similar purposes. It is also known that overvoltage and undervoltage relays are effectively used for remote or direct control of differential current devices [RU 198896 U1, 05.05.2020], [RU 198910 U1, 27.05.2020], [RU 2737951 C1, 03.06.2020], which provides electrical safety, prevention of accidents and fires in electrical installations.

As a rule, to solve control problems, a voltage relay must have a threshold element (detector), a time delay module (timer), usually built into the threshold element, as well as closing and opening contacts, the drive mechanism of which is part of the timer. The listed structural components are provided in the following analogs: [RU 55218 U1, September 26, 2005], [RU 2457596 C2, 02/13/2007], [RU 2478238 C1, 07/20/2011], including as part of "Overvoltage protection devices" [ US 2020/0321777 A1, Okt. 8, 2020], which is selected as the closest analogue. In this device, the closing and opening contacts are connected to each other in a series circuit containing an auxiliary load (for example, a resistor), and the threshold element is connected to the contacts by an actuator so that, depending on the monitored voltage, it provides simultaneous closing or opening of the corresponding contacts.

The operation of such voltage relays in conjunction with differential current devices revealed a drawback, which is associated with the initial state when the power is turned on (the relay itself and the electrical receiver). Even when the supply voltage is within acceptable limits, the residual current device receives a trip signal from the voltage relay because an earth fault occurs. As a result, a false (erroneous) protection operation occurs. In fact, switching on has to be done manually, for example, by disconnecting the control line until the moment when the contacts are in the working position.

The proposed utility model makes it possible to overcome the technical problem associated with the transmission of erroneous tripping signals due to the automatic prevention of ground faults.

The specified technical result is achieved due to the fact that the device is equipped with an additional timer with a drive mechanism of closing contacts, and the additional timer is connected to the terminals of the phase and neutral conductors, and different sides of the auxiliary load circuit, opening and closing contacts are connected to the terminals of the phase and protective conductors.

In addition, the device can be equipped with a green indicator lamp connected between the terminals of the phase and neutral conductors, and a red indicator lamp connected through a current limiter between the terminals of the neutral and protective conductors, and the auxiliary load can consist of a resistor and a capacitor connected in series. Alternatively, the auxiliary load circuit and the break contacts will be duplicated, and the duplicate circuit will be connected from different sides with the make contacts and the neutral conductor terminal. Another option is to provide the device with a temperature sensor with normally open contacts, which are connected on the one side to the phase conductor and on the other side to the connection of the auxiliary load and the open contacts. Also, for a polyphase network, it is proposed to add leads for connecting the threshold device with current sensors and branching the circuit of closing contacts into identical circuits with auxiliary loads and opening contacts for each phase.

The proposed design of the device and its principle of operation correspond to the diagrams in FIG. 1-7. Including FIG. 1 shows the diagram and state before energizing, FIG. 2, 3 - at the moment of energization and in working condition, respectively, in Fig. 4 - the state in the event of an accident, in Fig. 5-7 - additional embodiments of the device.

On all these diagrams, the following designations are adopted: 1 - housing, 2 - threshold element, which has a timer with an opening contact drive mechanism, 3 - an additional timer with a closing contact drive mechanism, 4 - electrical receiver, 5 - electrical panel, L (L ₁ , L ₂ , L ₃ ), N, Pe - respectively phase, neutral and protective conductors, as well as the terminals of these conductors, QFD - a residual current device, for example, a residual current circuit breaker with built-in overcurrent protection, K - electrical consumer switch, K ₁ , K ₃ - open contacts, K ₂ - close contacts, R ₁ , R ₂ - auxiliary load resistors, C ₁ , C ₂ - auxiliary load capacitors, t ° C - temperature sensor with closing contacts; I ₁ , I ₂ , I ₃ - terminals for connection with current sensors, R _H - conditional resistance of the electric receiver; U, U _min , U _max - respectively the voltage between the phase and neutral conductors, its permissible minimum and maximum values, T - current time, T ₀ - the moment of voltage supply, ΔТ ₀ - time delay until the contacts K _{2 are} closed when voltage is applied, T ₁ - the moment of the onset of the accident, ΔТ ₁ - time delay until the contacts K ₂ open when the voltage is disconnected, I _T - earth fault current.

Details of the voltage relay and control of differential current devices (Fig. 1) are placed in the housing 1, which has outputs of phase (L), zero (N) and protective (Pe) conductors. In case 1 there is a threshold element 2, connected to the terminals of the phase (L) and neutral (N) conductors, as well as closing contacts K ₂ , connected in series in a circuit with an auxiliary load R ₁ and opening contacts K ₁ , and the threshold element 2 has its own threshold element timer with opening contact actuator K ₁ . The design in case 1 is also equipped with an additional timer 3 with a closing contact actuator K ₂ , an additional timer 3 is connected to the terminals of the phase (L) and neutral (N) conductors, with different sides of the auxiliary load circuit R ₁ , opening K ₁ and closing K ₂ contacts are connected to the terminals of the phase (L) and protective (Pe) conductors.

Under normal conditions, when the voltage U is within the specified limits [U _min , U _max ], the device operates as follows. At the initial moment of time T ₀ (Fig. 2) after switching on the differential current device QFD and the switch K, the voltage is supplied through the power supply line of the electric receiver 4. Then, according to the scheme, power is simultaneously supplied to the threshold element 2 and additional timer 3. An additional timer is set as follows: that the signal to close the contacts K ₂ is transmitted after the delay ΔT ₀ , which is longer than the delay time of the threshold device timer. Therefore, during the time T [T ₀ <T <T ₀ + ΔT ₀ ], the contacts K ₁ open, and the contacts K ₂ remain open. Closing of contacts K ₂ is performed at time T ₀ + ΔT ₀ (Fig. 3). This corresponds to the operating state, therefore the contacts K ₁ and K ₂ ensure the continuity of the break of the auxiliary load circuit R ₁ , no earth fault occurs, the fault current is zero (I _T = 0), the QFD differential current device remains in the closed position, and the proposed device further monitors the power supply status of the electrical receiver 4.

Turning off the electrical receiver using the switch K returns the proposed device to its original position (Fig. 1), while the absence of voltage at terminal (L) excludes the appearance of a ground fault current and the QFD device remains in a closed position.

An accident at the moment of time T ₁ , at which the voltage goes beyond the set limits (Fig. 4), leads to the operation of the threshold device 2 and to the closure of the contacts K ₁ . An additional timer for this case is set so that the time delay ΔT ₁ before the opening of contacts K _{2 is} greater than the time of closing contacts K ₁ . Therefore, from the moment the contacts K _{1 are} closed until the contacts K _{2 are} opened, an earth fault current I _T occurs in the auxiliary load circuit R ₁ . The magnitude of this current is limited by the auxiliary load resistance, which is selected so that the current I _{T is} greater than the rated residual breaking current of the QFD. Thus, the operation of the differential current device is ensured for various reasons. For example, if the neutral conductor shown in FIG. 4, the voltage U will be less than the minimum value U _min and, perhaps, even equal to zero, but the proposed device _{transmits a shutdown signal during the time ΔT 1} , and the electrical receiver 4 will be safe. Similarly, the protection will operate when significant transition resistances appear (U <Umin), as well as when overvoltage (U> U _max ).

It is possible to connect the proposed device to the power supply line of the electric receiver anywhere, including through a conventional socket with a grounding contact, however, correct operation for the first version of the circuit is ensured if the order of connection of the terminals is observed. In this regard, the variant in figure 5 is supplemented with indicator lamps C2 and C5. If the leads are connected correctly, the C5 light will be green, and the C2 indicator will not turn on. If there is a connection error due to the connection of the L pin to the neutral conductor, and the N pin to the phase conductor, the red light will turn on - C2. In addition, the auxiliary load in the event of erroneous switching is selected consisting of a resistor R ₁ and a capacitor C ₁ . These additions simplify the operation of the device 1. The following option solves the same problem (Fig. 6). Due to the symmetry with respect to the terminal of the protective conductor Pe, the circuits K ₁ -C ₁ -R ₁ -K ₂ and K ₃ -C ₂ -R ₂ -K ₂ replace each other at any connection of the terminals L and N, and regardless of this, the protection design is fully preserved from erroneous shutdown signals.

The use of the proposed device in multiphase (three-phase) electrical installations (Fig. 7) is achieved by branching the circuit of closing contacts into identical circuits with auxiliary loads and opening contacts for each phase. In addition, the addition of leads for connecting the threshold device with current sensors will expand the list of monitored electrical indicators, and supplying the device with a temperature sensor with closing contacts (t ° C) will also allow monitoring non-electrical indicators. At the same time, the constructive solution remains unchanged, which prevents the transmission of erroneous shutdown signals.

The performance test of the proposed device was carried out in single-phase and three-phase electrical installations (230 and 400 V, 50 Hz), where differential current devices were used for ground-fault protection, having rated residual current of 30 mA and 100 mA, and the auxiliary load parameters were selected from values for 30 mA: R ₁ = 130 Ohm, 3.9 kOhm, (R ₁ = 27 Ohm, C1 = 1 μF); and for 100 mA: R ₁ = 130 Ohm, 1.5 kOhm, (R ₁ = 27 Ohm, C ₁ = 3.3 μF). The timer of the threshold device 2 had the setting of the time delay for opening the contacts K ₁ - 2 sec at normal voltage, closing the contacts K ₁ - 0.1 sec for overvoltage and 2 sec for the voltage drop. Additional time 3 was adjusted so that the setting of the time delay for closing the contacts of K2 was 3 seconds (ΔT ₀ ), and the setting for the time delay for opening the contacts of K2 was also 3 seconds (ΔT ₁ ).

The tests were carried out when simulating power failures of an electrical receiver by changing the voltage U, adding a conditional transition resistance of 10 Ohm to the circuit of the neutral and phase conductors, breaking the neutral conductor, and also igniting the arc at the point where the conductors are broken using a Yablochkov candle. The heat protection test is carried out with a temperature sensor at 60 ° C.

In all of the above emergency situations, the operation of the residual current device has been confirmed. On the contrary, under normal (non-emergency) conditions, the absence of false trip signals in the form of ground faults is shown when the device or electrical receivers are powered on.

Claims (5)

1. Relay of voltage and control of differential current devices, containing a case with terminals of the phase, neutral and protective conductors, a threshold element connected to the terminals of the phase and neutral conductors, closing contacts connected in series in a circuit with an auxiliary load and opening contacts, a threshold element timer with with an opening contact drive mechanism, characterized in that it is equipped with an additional timer with a closing contact drive mechanism, and an additional timer is connected to the terminals of the phase and neutral conductors, and different sides of the auxiliary load circuit, opening and closing contacts are connected to the terminals of the phase and protective conductors. 2. The device according to claim 1, characterized in that it is equipped with a green indicator lamp connected between the terminals of the phase and neutral conductors, and a red indicator lamp connected through a current limiter between the terminals of the neutral and protective conductors, and the auxiliary load consists of series-connected resistor and capacitor. 3. The device according to claim. 1, characterized in that the circuit of the auxiliary load and the breaking contacts is duplicated, and the redundant circuit is connected from different sides with the closing contacts and the output of the neutral conductor. 4. The device according to claim 1, characterized in that it is equipped with a temperature sensor with closing contacts, which on the one hand are connected to the phase conductor, and on the other hand - to the connection of the auxiliary load and the opening contacts. 5. The device according to claim 1, characterized in that it is provided with leads for connecting the threshold device with current sensors and branching the circuit of closing contacts into identical circuits with auxiliary loads and opening contacts for each phase of the polyphase network.

Images