JPH066673Y2 - AA leakage breaker with neutral phase protection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial application field) The present invention relates to an improvement of an earth leakage breaker with open-phase protection used for a single-phase three-wire type distribution line.

(Prior Art) A conventional leakage breaker with AA neutral line open-phase protection includes an energization detection circuit and an abnormal voltage detection circuit, and the leakage detection circuit detects an abnormal current due to a grounding fault of a line, and the like. The abnormal voltage detection circuit detects an abnormal voltage due to an open phase accident of the neutral line and inputs a control signal to the switch circuit to trip the coil to energize the coil to open the main circuit contact to open the neutral line. The signal extraction circuit to be connected is provided with a terminal for external connection, and is connected to the abnormal voltage detection circuit through internal wiring.

(Problems to be solved by the invention) However, the signal take-out circuit connected to the neutral line may be connected in a positive connection or in a reverse connection depending on how the breaker is applied to the distribution line system. Since it must be possible to connect the upstream side of the main circuit contact, that is, the power supply side, or the downstream side, that is, either side of the load side, when the signal extraction circuit is connected to the power supply side,
Even if the main circuit contact of the breaker is open, the signal extraction circuit is still connected to the power source side, so it is necessary to test or measure the insulation resistance between the main circuit contact and the load side line downstream from the ground. Since it is in conduction with the neutral line grounding circuit on the power supply side when it is installed, the accuracy of the insulation resistance test or measurement will be low. Remove the connected lead wire circuit at the lead wire terminal or the other end provided on the breaker each time,
The work that had to be reattached was necessary.

In addition, another aspect, that is, when configuring a distribution line network that combines the breaker and various loads, reverse connection of the breaker, in order to improve load safety and reliability of the distribution system,
That is, the load is connected to the power supply side terminal of the breaker, and the method / system of connecting the power supply line to the load side terminal is also frequently adopted, but when this reverse connection system is adopted, the leakage detection circuit of the breaker, Since the control system composed of the abnormal voltage detection circuit, the switch circuit, the trip coil, etc. is connected to the power supply side upstream from the main contact of the breaker, it will not turn off even if the main contact is in the open state, Since the control system is in an operable state, if the test push button of the breaker is pressed, the control system operates for the test, and therefore, if the test push button is continuously pressed, the control system is incorporated in the control system. A test resistor, or
The trip coil and the like continue to be energized, resulting in noise, vibration, burnout, and other malfunctions.

(Means for Solving Problems) Therefore, the present invention solves the above-mentioned drawbacks by the following configuration. In other words, an electronic AA medium type that is used for a single-phase three-wire type power distribution line and that energizes a trip coil to open a main circuit contact by an abnormality detection signal from an earth leakage detection circuit and an abnormal voltage detection circuit. In the earth leakage breaker with open-circuit protection, a single-pole interlocking with the main circuit contact is provided in the test push-button circuit that is provided to confirm whether the breaker is in a proper operating state in the event of a ground fault. An auxiliary contact for the double throw control circuit is provided, and when the main circuit contact is closed, it is closed on the external neutral wire lead wire terminal side to form a neutral wire open phase monitoring circuit, and when the main circuit contact is open, it is tested. When a test push button is pressed, the test operation detection circuit outputs a test operation signal to the abnormal voltage detection circuit to excite the trip coil from the abnormal voltage detection circuit. Is a single 3 neutral phase loss With circuit breaker, characterized in that allowed to stop the output of the energized causing abnormal signal.

(Operation) To describe the operation of the above configuration, the earth leakage detection circuit provided in the breaker uses a distribution line composed of two voltage lines and one neutral line as a primary coil and a ground fault zero-phase current. Is detected as an abnormal current signal by an output from a zero-phase current transformer ZCT having a secondary coil as a sensor, and a leakage current is detected, which is tripped to a switch circuit to energize the coil and output a signal for opening a main circuit contact. The abnormal voltage detection circuit extracts the line voltage from each of the two voltage lines and one neutral line as a signal, detects the imbalance of the line voltage due to the open phase of the neutral line as an abnormal signal, and switches it. The trip coil is energized to the circuit to output a signal that opens the main circuit contact. The test pushbutton circuit is a pseudo-leakage circuit composed of a test resistor and a pushbutton contact between a voltage line and a neutral line, and a part of the circuit is a part of the constituent elements of the primary coil of the zero-phase current transformer ZCT. As a ground fault zero-phase current flowing in the primary coil, a pseudo leakage current generated by crossing the secondary coil and pressing the test push button induces a secondary current in the sensor, which is the secondary coil, as an abnormal current signal. The leakage detection circuit outputs a signal to the switch circuit to energize the coil to open the main circuit contact, and the series of operations in which the main circuit is in the open state can be tested. The above is the basic operation as an earth leakage breaker with AA neutral line open-phase protection. Three signal circuits input to the abnormal voltage detection circuit, that is, two voltage lines and one neutral line. The signal circuit from the neutral wire, out of the three, is connected to the abnormal voltage detection circuit only when the main circuit contact is closed via the single-pole double-throw auxiliary contact that works with the main circuit contact of the breaker. To be done. Therefore, when measuring the insulation resistance to ground of the load side circuit by opening the main circuit contact, even if the signal circuit from the neutral line is connected to the power supply line upstream from the main circuit contact of the breaker, the main circuit contact Since it opens together with it, an accurate measured value can be obtained without being affected by the grounding of the neutral wire on the power supply side. Also, when the main circuit contact is open, one end of the test push button circuit is connected to the test operation detection circuit through the other contact of the single pole double throw auxiliary contact, and the breaker is used in the reverse connection method. If
When the test push button is pressed, the operation is detected and a test operation signal is input from the test operation detection circuit to the abnormal voltage detection circuit so that the abnormal voltage detection circuit trips the switch circuit to energize the coil. Block the output of the signal. Therefore, when the main circuit contact is open, even if the test push button is pressed, it is possible to prevent unnecessary electric conduction to the trip coil.

(Embodiment) The configuration of an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit block diagram of a leakage breaker with an AA neutral line open-phase protection to which an auxiliary contact is added according to the present invention. The main circuit is composed of two voltage lines L1 and L2 and one neutral line N. It is equipped with power source side terminals 1, 2 and 3 and load side terminals 4, 5 and 6, respectively, and three poles in the middle are interlocked at the same time so that they can be opened and closed by manual operation, and the trip coil TC is energized and excited by electromagnetic waves. A main circuit contact 7 is provided which can be closed by being biased by force. The control circuit uses three main circuits L1, L2, N and one test circuit LT as primary coils, and two leakage current sensors.
Leakage detection circuit 10 combined with a zero-phase current transformer ZCT as a secondary coil, the main circuits L1 and L2, and a main circuit contact 7
It is closed when the main circuit contact 7 of the single-pole double-throw auxiliary contact 11 that is interlocked with is closed. That is, the contact terminal 12 is closed when energized.
An abnormal voltage detection circuit 13 for extracting voltage information from three points of the neutral line N outside the breaker and the main circuit L.
A switch circuit 14 for energizing and controlling a trip coil TC for opening the main circuit contact 7 by electromagnetic force when the main circuit contacts 7 and 1, L2 are closed, and a zero phase through the test resistor RT using the main circuits L1 and N as power sources. A part of the primary coil LT of the current transformer ZCT is provided and is connected to a test circuit that is energized by a test with a test push button 15, and via a contact terminal 16 of an auxiliary contact 11 that is closed when the main circuit contact 7 is open. And a test circuit connected to the test operation detection circuit 17.

Next, the operation of the above configuration will be described with reference to the electric circuit diagram of FIG. In the control system of the breaker, AC power is supplied to the main circuits L1 and L2, half-wave rectification is performed at D1, and the current is smoothed by the resistor R1 and the capacitor C1 and distributed to each circuit. The leakage detection circuit 10 includes main circuits L1, L2, N and a test circuit L.
Push button 15 for test when testing the primary coil made of T
A zero-phase current transformer configured to take out, as a signal current, a secondary current induced in a secondary coil by a ground-fault zero-phase current that flows in an abnormal state, including a pseudo-leakage current that flows in the test circuit LT when is pressed. ZCT, resistor R6, capacitor C3
Connected with a bypass circuit consisting of, and when a signal current of a set value or more is input, it is considered that a leakage has occurred in the distribution line, and the switch circuit 14 is tripped to output a command signal for energizing the coil TC. 14 is a thyristor S
The CR is ignited, and the trip coil TC is energized and excited to open the main circuit contact 7 to protect the load and human life. The abnormal voltage detection circuit 13 obtains the signal voltage from the load side neutral line N and the main circuits L1 and L2 by the lead line from the contact terminal 12 of the auxiliary contact 11 which is closed when energized together with the main circuit contact 7. The current from the load-side neutral wire N via the lead wire is diode D
Alternately rectified by 1, D2, main circuit L1, N and N, L2
The above two line voltages are applied to the resistors R2 and R3 for each half wave, and are divided and input to the IC of the abnormal voltage detection circuit 13. FIG. 3 is a voltage waveform diagram across the resistor R3 in a normal state. FIG. 4 is a voltage waveform diagram of an abnormal state in which the line voltage between the main circuits L1 and N and the line voltage between N and L2 is unbalanced due to a failure such as open phase in the neutral line electric circuit. That is, when the trip level with the trip coil TC is reached, the abnormal voltage detection circuit outputs a command signal for energizing the trip coil TC to the switch circuit 14, and the switch circuit 14 fires the thyristor SCR to trip the trip coil. The main circuit contact 7 is opened by energizing and exciting TC to protect the load from abnormal voltage. Regarding the test operation detection circuit 17, when the test push button 15 is pressed, a test current, that is, a pseudo leakage current, from the main circuit L1 via the test resistor RT, passes through the contact terminal 12 of the auxiliary contact 11, and the load side neutral line N. However, since a part LT of this circuit tolerances the secondary coil of the zero-phase current transformer ZCT on the way, a signal current is induced in the secondary coil by this pseudo leakage current, and the leakage detection circuit 10 that receives this signal A command signal for energizing the trip coil TC is output to the switch circuit 14, and the switch circuit 14 fires the thyristor SCR to energize and energize the trip coil to open the main circuit contact 7 and disconnect the load from the power supply. However, when the breaker is connected to the power distribution line by the reverse connection method, when the test push button 15 is pressed, the resistors R2 and R3 are connected to the resistors R2 and R3. A voltage shown in FIG. 5 is applied, the main circuit contact 7 is opened according to the test sequence, and the auxiliary contact 11 interlocked with the main circuit contact 7 is also switched at the same time, so that the test current is cut off, but the power supply of the control circuit of the breaker is the main circuit. The control circuit is on the upstream side of the contact 7 and is always active. When the test push button 15 is pressed, the voltage of the main circuit L1 is input to the abnormal voltage detection circuit 13 via the test resistor RT. As shown in FIG. 5, the main circuit L1,
The line voltage of N is OV, and the line voltage of L2 and N is in an abnormal voltage generation state that is twice the rated value. On the other hand, the auxiliary contact 11 has already been switched to the contact terminal 18 side. This abnormal voltage is applied to each base of the transistor Q1 of the test operation detecting circuit 17 by dividing the voltage by the resistors R4 and R5 and applying every half wave. The transistor Q1 is synchronized with the waveform shown in FIG. When the switch is turned on, the operation of the abnormal voltage detection circuit 13 is stopped and the switch circuit 14 is prevented from energizing the trip coil TC to prevent the trip coil from being burned.

(Effect of the Invention) As described above, by adding a single-pole double-throw auxiliary contact interlocking with the main circuit contact and a circuit for detecting the operation of pressing the test push button to the leakage breaker with AA open circuit protection, Even if is connected to the distribution line by the reverse connection method, if the main circuit contact is open, the neutral wire lead-out circuit will also be open, and when measuring or testing the insulation resistance between the load side circuit and the ground,
It is not necessary to consider the influence of the neutral wire grounding of the power supply at all, the work of attaching and detaching the lead wire is not required, the work efficiency is improved, and the manual work is unnecessary. The deterioration of the quality of the distribution line is eliminated, and the reliability and safety of maintenance and inspection are further improved. It is also possible to check the disconnection of the leader line circuit by pressing the test push button. On the other hand, even when the test push button is pressed, after the main circuit contact 7 is opened, the auxiliary contact forms the circuit of the test operation detection circuit 1 and the abnormal voltage detection circuit outputs the unnecessary energization command to the trip coil. In order to prevent this, it is possible to prevent noise and vibration that excite the trip coil, or burnout due to energization for a long time. Further, since the operation of the above two items, that is, the opening / closing of the neutral wire drawing circuit and the prevention of unnecessary energization of the trip coil are possible with one single-pole / double-throw auxiliary contact, the breaker box can be downsized. effective.

[Brief description of drawings]

FIG. 1 is a block diagram of a leakage breaker with AA neutral line open-phase protection to which an auxiliary contact and a test operation detection circuit according to the present invention are added, and FIG. 2 is a simplified electric circuit diagram for explaining the operation of the breaker. FIG. 3 is a waveform diagram of the signal voltage in the control circuit of the breaker in a normal state, FIG. 4 is a waveform diagram in the same abnormal state, and FIG. 5 is a waveform diagram of the signal voltage when the test push button is pressed, FIG. 6 is an explanatory diagram showing a relationship between a power source, a load and a lead wire when the breaker is used in a positive connection system and in a reverse connection system, and FIG. 7 is a simplified electric circuit diagram of a conventional technique. 10 ... Leakage detection circuit 11 ... Auxiliary contact 13 ... Abnormal voltage detection circuit 14 ... Switch circuit 15 ... Test push button 17 ... Test operation detection circuit R2, R3, R4, R5 ... Resistors D1, D2 ... … Diode Q1 …… Transistor

Claims (1)

[Scope of utility model registration request] 1. An abnormality detection signal from a leakage detection circuit and an abnormal voltage detection circuit used for a single-phase three-wire type distribution line,
In an electronic leakage breaker with AA neutral line open phase protection that energizes the trip coil to open the main circuit contact, check whether the breaker is in a proper operating state in the event of a ground fault. The test push button circuit provided for confirmation is provided with auxiliary contacts for the control circuit of the single-pole double-throw that interlocks with the main circuit contact, and when the main circuit contact is closed, it is on the lead wire terminal side for the external neutral wire. When the main circuit contact is open, the neutral line open-phase monitoring circuit is formed, and when the main circuit contact is open, the circuit side that connects to the test operation detection circuit is closed and the test operation detection circuit detects the abnormal voltage when the test push button is pressed. A leakage breaker with an AA neutral line open-circuit protection, which outputs a test operation signal to the circuit to stop the output of the abnormal signal that trips the abnormal voltage detection circuit and energizes the coil.