JP3334008B2 - Neutral line open phase detector for single-phase three-wire wiring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a neutral phase loss in a single-phase three-wire system.

[0002]

2. Description of the Related Art Single-phase three-wire wiring is a relatively large-capacity power distribution system.
As shown in FIG. 4, for example,
Power supply terminal L of power supply 30 composed of a single-phase transformer with a neutral point
₁, L _TwoFrom the neutral terminal N via the breaker 31
Powered. Power supply terminal L₁And L _TwoThe voltage between
200V, power supply terminal L₁And L_TwoAnd the neutral terminal N
Is between 100 V and the power supply terminal L₁And L_TwoBetween 2
00V device 33 is connected to power terminal L₁And L_TwoAnd neutral point
100 V equipment 3 between neutral wire n connected to terminal N
2 are connected.

In this single-phase three-wire system, if a phase loss occurs in the neutral line n, the neutral line n becomes a floating form, and the 100 V equipment is determined by the impedance of the load, for example, 150.
An overvoltage of ~ 180V is applied, and there is a risk that these devices may be damaged. For this purpose, as shown in FIG. 5, the two power supply terminals L ₁ , L ₂ and the neutral wire n of the single-phase three-wire system are connected to the two power supply input terminals I ₁ , I ₂ and the neutral wire input terminal I, respectively.
A neutral line open phase detecting device 34 to which _n is connected is provided. When the open phase of the neutral line n is detected, a detection signal is output from its signal output terminals P ₁ and P ₂ , and the circuit breaker 31 is tripped. To protect. The connection of the neutral input terminal I _n the neutral line n, when so connected to the load side terminal of the neutral line n as shown in FIG. 4, phase loss of all points of the neutral line n Can be detected.

FIG. 6 is a circuit diagram showing a conventional example of such a neutral line open phase detecting device. In FIG. 6, the neutral line open phase detecting device includes a rectifier circuit 1 having an AC terminal connected to both power input terminals I ₁ and I ₂ , a negative DC terminal of the rectifier circuit 1 and a neutral line input terminal I 2. _n , a voltage _dividing resistor 2 and 3 connected in series, a capacitor 9 connected in parallel to the voltage _dividing resistor 3, and a Zener diode 4 connected in series to the voltage _dividing resistor 3 respectively. A resistor 8 and a resistor 11 connected in series between a positive DC terminal and a negative DC terminal of the rectifier circuit 1;
A transistor 6 having its collector connected to the connection point of the resistors 8 and 11, its emitter to the negative DC terminal of the rectifier circuit 1, its base connected to the connection point of the Zener diode 4 and the resistor 5 via the resistor 7, A resistor 14 and a capacitor 15 are connected in series between the positive DC terminal and the negative DC terminal of the circuit 1, and the collector of the resistor 14 and the capacitor 15 are connected via the resistor 13.
The transistor 12 has its emitter connected to the negative DC terminal of the rectifier circuit 1, its base connected to the connection point of the resistors 8 and 11, and its transistor connected in series to the capacitor 15 in parallel. Zener diode 16, resistors 17 and 18, and the anode of which is connected to the rectifier circuit 1 via the anode and cathode of diode 20.
And a thyristor 19 whose cathode is connected to the negative DC terminal of the rectifier circuit 1 and whose gate is connected to the connection point between the resistors 17 and 18, respectively. terminals P ₁ and P ₂ is pulled out.

The operation of the neutral point open phase detecting device is as follows. First, in a normal state where no phase loss occurs in the neutral wire n, the voltage between the power supply terminal L ₁ and the neutral wire n and the voltage between the power supply terminal L ₂ and the neutral wire n are divided by the voltage dividing resistor 2. And 3 are alternately applied to the series circuit for each half-wave, and a voltage drop is generated in the voltage dividing resistor 3 by dividing the voltage by the voltage dividing resistors 2 and 3. Now cause open phase neutral line n, since the voltage of the neutral line n move to a voltage determined by the load impedance, the power supply terminal L ₁
And between the neutral line n or one of the voltage between the power supply terminal L ₂ and the neutral line n increases, the voltage drop of the voltage dividing resistor 3 increases. This voltage drop is smoothed by the capacitor 9 and applied to a series circuit composed of the Zener diode 4 and the resistor 5. When the voltage value exceeds the voltage of the Zener diode 4 as a set voltage, the transistor 6 is turned on.
When the transistor 6 is turned on, the transistor 12 is turned off, and the capacitor 15 is charged with a charging time constant determined by the capacitance of the capacitor 15 and the resistance value of the resistor 14. When the voltage between both terminals of the capacitor 15 exceeds the voltage of the Zener diode 16, the thyristor 19 is turned on, and a DC voltage is output from the output terminals P ₁ and P ₂ as a detection signal.
The detection signal trips, for example, a breaker to protect the circuit. The resistor 13 is a current limiting resistor for the discharge current of the capacitor 15, and the diode 20 is a diode for preventing a surge voltage generated when the trip coil of the breaker is turned off.

[0006]

[SUMMARY OF THE INVENTION In neutral wire open-phase detector described above, the voltage between the power supply terminal L ₁ and the neutral line n as shown in FIG. 6, the power supply terminal L ₂ and neutral n is taken out as the voltage drop of the voltage dividing resistor 3,
This voltage drop is smoothed by the capacitor 9 and input to the Zener diode 4 to detect the phase loss of the neutral line. However, since the capacitor 9 smoothes this voltage drop, a delay occurs in the detection operation. There's a problem. Further, in the neutral wire open-phase detection device, and forget to connect the neutral input terminal I _n the neutral line n of single-phase three-wire wiring, since the transistor 6 is not operated device is inoperative However, there is a problem that cannot be identified from outside.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the delay of the detection operation and to provide a neutral line disconnection provided with a protection means in the case where the neutral line input terminal is forgotten to be connected to the neutral line of the single-phase three-wire system. An object of the present invention is to provide a phase detection device.

In order to achieve the above object, the present invention provides a dual power input terminal and a neutral input terminal connected to a dual power terminal and a neutral wire of a single-phase three-wire wiring, respectively, and a dual power input terminal. A rectifier circuit having the AC terminal connected thereto, a voltage dividing resistor connected between the negative DC terminal of the rectifying circuit and the neutral input terminal, and a Zener connected in parallel with the voltage dividing resistor. A series circuit including a diode and a resistor; a first transistor that is turned on when a voltage drop of the voltage dividing resistor exceeds a voltage of the Zener diode as a set voltage value; and a first transistor that is turned off by turning on the first transistor. And a transistor for detecting an open phase of a neutral line by turning off the second transistor, wherein the voltage of the neutral line input terminal is equal to the voltage of the negative DC terminal of the rectifier circuit. When it becomes Ku, a protective means for turning off the second transistor. Alternatively, the resistor comprises a resistor connected between the neutral line input terminal and the positive DC terminal of the rectifier circuit, and when the neutral line input terminal is open, the voltage dividing resistor is connected to the neutral line input terminal through the resistor. Protective means for causing a voltage drop equal to or higher than the set voltage value is provided.

[0009]

In the neutral line open phase detecting device according to the first aspect of the present invention, the connection between the neutral line input terminal and the negative DC terminal of the rectifier circuit is prevented from being connected to the neutral line n. If the neutral input terminal is forgotten to be connected to the neutral wire of the single-phase three-wire system, the voltage of the neutral input terminal and the voltage of the negative DC terminal of the rectifier circuit become equal if the neutral input terminal is forgotten. This is utilized to perform an open phase detection operation. As a result of the detection operation of the open phase, a DC voltage is output from the output terminals P ₁ and P ₂ as a detection signal.

[0010]

Alternatively, according to the second aspect of the present invention, the neutral line input terminal is open, comprising a resistor connected between the neutral line input terminal and the positive DC terminal of the rectifier circuit. At this time, since a protection means for causing a voltage drop of a set voltage value or more to be generated in the voltage dividing resistor through this resistor is provided, if one forgets to connect the neutral line input terminal to the neutral line of the single-phase three-wire system, A voltage equal to or higher than the set voltage value is induced in the voltage dividing resistor, and an open phase detection operation is performed. As a result of the detection operation of the open phase, a DC voltage is output from the output terminals P ₁ and P ₂ as a detection signal.

[0012]

FIG. 1 is a circuit diagram showing an embodiment of a neutral line open phase detecting apparatus according to the present invention. The neutral-phase-loss detecting apparatus of the present invention shown in FIG. 1 eliminates the delay of the detecting operation. The capacitor 9 in the conventional neutral-phase-loss detecting apparatus shown in FIG. A capacitor 31 connected between a negative DC terminal of the rectifier circuit 1, a resistor 32 connected between the connection point and the collector of the transistor 6, and a connection point between the connection point and the resistor 11. And an off-operation holding means 30 for the transistor 12 comprising a resistor 33 connected between the first and second transistors.

The operation of the neutral-phase-loss detection device is as follows. When a phase loss occurs in the neutral line n, the voltage drop of the voltage dividing resistor 3 increases as in the conventional example of FIG. In this case, since this voltage drop does not include the capacitor 9 as compared with the conventional example of FIG. 6, it becomes a pulsating voltage without delay corresponding to the power supply frequency. The value of the pulsating voltage is the voltage of the Zener diode 4,
That is, when the voltage exceeds the set voltage value, the transistor 6 is turned on. When the transistor 6 is turned on, the voltage between both terminals of the capacitor 31 becomes zero, and the transistor 12 is turned off. Next, when the value of the pulsating voltage falls below the Zener diode voltage, the transistor 6 is turned off. However, the rise of the base voltage of the transistor 12 is suppressed by the capacitor 31, and the transistor 12 is kept off. This off state is continued until the transistor 6 is turned off again in the next power cycle. Thus, when the voltage drop of the voltage dividing resistor 3 exceeds the set voltage value,
The transistor 6 is turned on without delay, and the transistor 6
Turns on, the transistor 12 is turned off, so that the delay of the detection operation is reduced. When the transistor 12 is turned off, even if the transistor 6 is turned off, the transistor 12 is kept off until the next power supply cycle, so that there is no problem in the detection operation. Other operations are the same as those in FIG.

FIG. 2 is a circuit diagram showing a different embodiment of the present invention.
It is. The neutral line open phase detecting device of the present invention shown in FIG.
Sex input terminal I_nIf you forget to connect to the neutral wire n
A neutral line open phase detecting device shown in FIG.
The difference is that the neutral input terminal I _nAnd the negative DC of the rectifier circuit 1
A resistor 41 and a resistor 41 connected in series between the
Capacitor 42 and its collector are rectified via resistor 45
The emitter of the rectifier circuit 1 is connected to the positive DC terminal of the circuit 1
The base of the negative DC terminal is connected to a resistor 41 via a resistor 43.
And the transistor 4 connected to the connection point of the capacitor 42
4 and its collector to the collector of transistor 6
Is connected to the negative DC terminal of the rectifier circuit 1 and its base
Is a transistor connected to the collector of the transistor 44.
This is the point that the protection means 40 including the data 46 is provided.

The operation of the neutral line open phase detecting device is as follows. If the user forgets to connect the neutral line input terminal In to the neutral line n, the voltage of the neutral line input terminal In becomes equal to the voltage of the negative DC terminal of the rectifier circuit 1, and the resistance 41 and the capacitor 4
Since the voltage applied to the series circuit consisting of 2 becomes zero, the transistor 44 is turned off. When the transistor 44 is turned off, the transistor 46 is turned on. When the transistor 46 is turned on, the transistor 12 is turned off.
An open phase detection operation is performed. By this open phase detection operation,
DC voltage is output from the output terminals P ₁ and P ₂ as a detection signal.
It is. Other operations are the same as those in FIG. Also,
This protection means can of course be used in the conventional neutral line open phase detecting device shown in FIG.

FIG. 3 is a circuit diagram showing still another embodiment of the present invention. Neutral wire open-phase detection device of the present invention shown in Figure 3, in which a protective means forgotten to connect the same neutral input I _n and 2 in the neutral line n, 1 different from the neutral wire open-phase detecting device shown is that a protective means 50 comprising a resistor connected 51 between the neutral input terminal I _n and the positive-side DC terminal of the rectifier circuit 1.

The operation of the neutral line open phase detecting device is as follows. If the neutral line input terminal In is forgotten to be connected to the neutral line n, the voltage dividing resistor 3 supplies the voltage between the positive and negative DC terminals of the rectifier circuit 1 (the full-wave rectified voltage of the voltage between the power supply terminals L1 and L2). ) Causes a voltage drop divided by the resistor 51 and the voltage dividing resistors 2 and 3. Here, by determining the resistance value of the resistor 51 so that the voltage drop becomes larger than the voltage of the Zener diode 4, that is, the set voltage value, an open phase detection operation is performed. By this open phase detection operation,
DC voltage is output from the output terminals P ₁ and P ₂ as a detection signal.
It is. Other operations are the same as those in FIG. Also,
This protection means can of course be used in the conventional neutral line open phase detecting device shown in FIG.

The transistor 6 is called a first transistor, and the transistor 12 is called a second transistor.

[0019]

As described above, the single-phase three-wire type open-phase detecting apparatus of the present invention has high performance, high reliability and high practical effect because the delay of the detecting operation is small.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a neutral-phase-loss detecting apparatus for single-phase three-wire wiring according to the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the neutral-phase open-phase detecting device of the single-phase three-wire system according to the present invention.

FIG. 3 is a circuit diagram showing still another embodiment of the neutral line open phase detecting device of the single-phase three-wire system according to the present invention.

FIG. 4 is a circuit diagram for explaining single-phase three-wire wiring;

FIG. 5 is a circuit diagram for explaining a neutral-phase open-phase protection system for a single-phase three-wire system.

FIG. 6 is a circuit diagram showing an example of a conventional neutral line open phase detection device of a single-phase three-wire system.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 rectifier circuit 2 voltage dividing resistor 3 voltage dividing resistor 6 transistor (first) 12 transistor (second) 30 off-operation holding means 40 protection means 50 protection means

Claims (2)

(57) [Claims] A power supply terminal and a neutral line input terminal connected to a power supply terminal and a neutral line of a single-phase three-wire system, respectively, and a rectifier having an AC terminal connected to the power supply terminals. Circuit, a voltage dividing resistor connected between the negative DC terminal of the rectifier circuit and the neutral input terminal, a series circuit including a Zener diode and a resistor connected in parallel to the voltage dividing resistor, A first transistor that is turned on when a voltage drop of the voltage dividing resistor exceeds a voltage of the Zener diode as a set voltage value, and a second transistor that is turned off by turning on the first transistor;
In detecting the open phase of the neutral line by turning off the second transistor, when the voltage of the neutral line input terminal is equal to the voltage of the negative DC terminal of the rectifier circuit,
A neutral-phase-loss detection device for single-phase three-wire wiring, comprising a protection means for turning off the second transistor. 2. A two-phase power supply terminal and a neutral line input terminal respectively connected to a two-phase power supply terminal and a neutral line of a single-phase three-wire type wiring, and a rectifier having an AC terminal connected to the two power supply input terminals. Circuit, a voltage dividing resistor connected between the negative DC terminal of the rectifier circuit and the neutral input terminal, a series circuit including a Zener diode and a resistor connected in parallel to the voltage dividing resistor, A first transistor that is turned on when a voltage drop of the voltage dividing resistor exceeds a voltage of the Zener diode as a set voltage value, and a second transistor that is turned off by turning on the first transistor;
In detecting an open phase of a neutral line by turning off the second transistor, the neutral transistor includes a resistor connected between the neutral line input terminal and a positive DC terminal of the rectifier circuit,
A single-phase three-wire wiring, comprising: a protection means for causing a voltage drop of not less than the set voltage value to occur at the voltage dividing resistor through the resistor when the neutral input terminal is opened. Neutral line open phase detector.