CN206945869U - A kind of low-voltage load side neutral line break warning device - Google Patents

Abstract

The utility model provides an alarm device for disconnection of the zero line on the low-voltage load side, which is used to solve the problem in the prior art that it is difficult to judge and check when the zero line on the low-voltage load side is broken, resulting in excessive load voltage and burning out user appliances. It includes: the secondary winding of the three-phase transformer is an open delta winding, the two ends of the open delta winding are connected to the coil of the overvoltage relay, the two ends of the first winding are connected to the detection and alarm unit, and the detection and alarm unit includes the first branch of the working switch to control the parallel connection and The second branch; the first branch includes the normally open contact of the overvoltage relay and the delay closing normally open contact of the time relay in parallel, and then the coil of the time relay and the reset switch are connected in series; the second branch includes the normally open contact of the time relay and the alarm is connected in series light. The beneficial effects include: when load imbalance occurs on the load side and the neutral point voltage deviation exceeds the set threshold, it can be judged whether the neutral point voltage deviation is caused by the disconnection of the neutral line of the electrical equipment, and an alarm is issued to remind that the neutral point voltage deviation has occurred. Line disconnection fault.

Description

A low-voltage load side zero line disconnection alarm device

Technical field:

The utility model relates to the technical field of electric power, in particular to an alarm device for disconnection of zero line on the low-voltage load side.

Background technique:

The zero line of 380V low-voltage users is disconnected. When the load is seriously unbalanced, the neutral point voltage shifts, and the voltage deviates from the normal value, which makes the load voltage too high and burns out the electrical appliances. . Since the user's room has been decorated and the wires are installed in the dark, it is difficult to judge and check. The workload of the electricity inspection staff is heavy, and it is impossible to observe and judge when the load is symmetrical.

Invention content:

The utility model provides an alarm device for disconnection of the zero line on the low-voltage load side, which is used to solve the problem in the prior art that it is difficult to judge and check when the zero line on the low-voltage load side is broken, resulting in excessive load voltage and burning out user appliances.

The utility model provides a low-voltage load side zero line break alarm device, comprising: the secondary winding of a three-phase transformer is an open triangle winding, the two ends of the open triangle winding are connected to the coil of an overvoltage relay, and the two ends of the first winding are connected to a detection alarm Unit, the detection alarm unit includes the first branch and the second branch of the parallel connection of the working switch control; the first branch includes the normally open contact of the overvoltage relay and the delay closing normally open contact of the time relay in parallel, and then the coil of the time relay is connected in series. Reset switch; the second branch includes the normally open contact of the time relay connected in series with the alarm indicator light.

Preferably, it also includes: a phase line disconnection alarm module; the phase line disconnection alarm module includes a relay connected between each phase line and neutral line of the primary winding of the three-phase transformer, which are respectively the first relay, the second relay and the neutral line. The third relay; the normally closed node of the first relay is connected in series with the first signal light to form the third branch, the normally closed node of the second relay is connected in series with the second signal light to form the fourth branch, and the normally closed node of the third relay is connected to the third branch. The signal lights are connected in series to form the fifth branch, and the third branch, the fourth branch and the fifth branch are connected in parallel to both ends of the first winding; the normally open node of the first relay, the normally open node of the second relay and the third The normally open nodes of the relays are connected in series to the main road in front of each branch.

Preferably, when the voltage across the coil of the overvoltage relay exceeds a set value, the normally open contact of the overvoltage relay closes, and the set value is set to exceed 10% to 15% of the rated voltage.

Preferably, after the time delay of the time relay, the time delay closing normally open contact of the time relay is closed, and the delay action time is set between 5 seconds and 10 seconds.

Preferably, the reset switch is pressed after the alarm indicator light gives an indication to restore the initial state of the zero line disconnection alarm device on the low-voltage load side.

The beneficial effects of the utility model include: when the load on the load side is unbalanced and the neutral point voltage shift exceeds the set threshold, it can be judged whether the neutral point voltage shift is caused by the disconnection of the zero line of the electrical equipment, and an alarm is issued. Remind the staff that there is a zero line disconnection fault; moreover, it also has a phase line disconnection alarm function, which can also promptly remind the staff which phase line is disconnected when the phase line is disconnected.

Description of drawings:

Accompanying drawing 1 is a schematic diagram of the circuit structure of a low-voltage load-side zero line disconnection alarm device in a preferred embodiment. Accompanying drawing 2 is a schematic diagram of the circuit structure of a low-voltage load-side zero line disconnection alarm device with a phase line alarm function in a preferred embodiment.

detailed description:

In order to give a real-time alarm reminder when the zero line is broken to avoid burning out electrical appliances when the load voltage is too high, the utility model provides a zero line break alarm device on the low-voltage load side. Novel preferred embodiments are described.

Referring to Fig. 1, the utility model provides a low-voltage load-side zero line disconnection alarm device, including: the secondary winding of the three-phase transformer T is an open delta winding, and the two ends a and z of the open delta winding are connected to the overvoltage relay YJ The two ends a and x of the first winding are connected to the detection and alarm unit, and the detection and alarm unit includes the first branch and the second branch of the parallel connection controlled by the working switch K; the first branch includes the normally open contact YJ of the overvoltage relay YJ ₁ is connected in parallel with the delay closing normally open contact SJ ₁ of the time relay SJ and then connected in series with the coil of the time relay SJ and the reset switch TA; the second branch includes the normally open contact SJ ₂ of the time relay SJ connected in series with the alarm indicator light BD.

Specifically, the voltage sampling and working power supply of the low-voltage load-side zero line disconnection alarm device is a three-phase transformer T, the overvoltage relay YJ is connected to both ends of the open delta winding a and z as the measurement terminal, and the normally open contact of the time relay SJ The second branch connected in series between SJ ₂ and the alarm indicator light BD is the alarm indication branch.

When the load is asymmetrical, the two ends of the open delta winding of the three-phase transformer, that is, the two ends of a and z, generate zero-sequence voltage. After the voltage at both ends of the coil of the overvoltage relay YJ exceeds the set value, the normally open contact YJ of the overvoltage relay YJ ₁ closed, wherein, the setting value is set between 10% and 15% of the rated voltage, and the rated voltage of the secondary side is 100/3V. At this time, the coil of the time relay SJ is energized, and the normal The open contact SJ ₂ is closed, the alarm indicator light BD is on, after the delay of the time relay SJ, the time delay of the time relay SJ is closed and the normally open contact SJ ₁ is closed, and the delay action time is set between 5 seconds and 10 seconds. After confirming that the two ends of the overvoltage relay YJ still exceed the set value under the delay of the time relay SJ, the time relay SJ is in a self-holding state by closing the normally open contact SJ ₁ through the delay, and will not be caused by the two coils of the overvoltage relay YJ. When the instantaneous voltage at the terminal does not exceed the set value, disconnecting the normally open contact YJ ₁ will cause the alarm prompt to be interrupted. Even if the three-phase load is restored to balance in this design, the alarm prompt will not reset. The zero line disconnection alarm device on the low-voltage load side returns to the initial state.

Referring to Fig. 2, the low-voltage load side zero line disconnection alarm device in the utility model also includes: a phase line disconnection alarm module; Relays are connected between A, B, C and the neutral line N, respectively the first relay YJ _a , the second relay YJ _b and the third relay YJ _c ; the normally closed node YJ _a2 of the first relay YJ _a is connected in series with the first signal lamp L1 It is the third branch, the normally closed node YJ _b2 of the second relay YJ _b is connected in series with the second signal lamp L2 to form the fourth branch, and the normally closed node YJ _c2 of the third relay YJ _c is connected in series with the third signal lamp L3 to form the fifth branch The third branch, the fourth branch and the fifth branch are connected in parallel and connected to both ends a and x of the first winding; the normally open node YJ _a1 of the first relay YJ _a and the normally open node of the second relay YJ _b YJ _b1 and the normally open node YJ _c1 of the third relay YJ _c are connected in series to the main road before each branch; when any phase line is disconnected, the zero line disconnection alarm circuit is blocked.

Specifically, the phase wire disconnection alarm module sends a phase wire disconnection signal when any phase wire is disconnected. When the phase line is disconnected, any phase of the first relay YJ _a , the second relay YJ _b and the third relay YJ _c loses power, the normally open node YJ _a1 of the first relay YJ _a and the normally open node of the second relay YJ _b As long as one node of YJ _b1 and the normally open node YJ _c1 of the third relay YJ _c changes from the closed state to the open state, the zero line break alarm signal circuit will be blocked, and at the same time the normally closed node YJ _a2 of the first relay YJ _a , the second The normally closed node YJ _b2 of the relay YJ _b and the normally closed node YJ _c2 of the third relay YJ _c change from the corresponding open state to the closed state, and the indicator light corresponding to the broken phase line lights up to inform the maintenance personnel which is the broken line phase line.

Claims (5)

1. A low-voltage load side zero line disconnection alarm device is characterized in that it includes: the secondary winding of the three-phase transformer is an open delta winding, the two ends of the open delta winding are connected to the coil of the overvoltage relay, and the two ends of the first winding are connected The detection and alarm unit includes the first branch and the second branch connected in parallel by the working switch control; the first branch includes the normally open contact of the overvoltage relay and the delay closing normally open contact of the time relay connected in parallel and then connected in series with the time relay A coil and a reset switch; the second branch includes a normally open contact of the time relay connected in series with an alarm indicator light. 2. The low-voltage load side neutral line breakage alarm device as claimed in claim 1, further comprising: a phase line breakage alarm module; the phase line breakage alarm module is included in each of the primary windings of the three-phase transformer The relays connected between the phase line and the neutral line are respectively the first relay, the second relay and the third relay; the normally closed node of the first relay is connected in series with the first signal light to form the third branch, and the normally closed node of the second relay is connected to the third branch. Two signal lamps are connected in series to form the fourth branch and the normally closed node of the third relay is connected in series with the third signal lamp to form the fifth branch. The third branch, the fourth branch and the fifth branch are connected in parallel and connected to both ends of the first winding. ; The normally open node of the first relay, the normally open node of the second relay and the normally open node of the third relay are connected in series to the main road before each branch. 3. The low-voltage load side zero line disconnection alarm device as claimed in claim 1, characterized in that, after the voltage across the coil of the overvoltage relay exceeds a set value, the normally open contact of the overvoltage relay is closed, and the set value is set It is between 10% and 15% over the rated voltage. 4. The low-voltage load side zero line disconnection alarm device as claimed in claim 1, characterized in that, after the delay of the time relay, the delay closing normally open contact of the time relay is closed, and the delay action time is set to 5 seconds to 10 seconds. 5. The low-voltage load-side zero-line disconnection alarm device according to claim 1, wherein the reset switch is pressed after the alarm indicator light gives an indication to restore the initial state of the low-voltage load-side zero-line disconnection alarm device .