JPS62201015A - Three-phase missing neutral line detecting breaker - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an AA neutral line open phase detection and cutoff device that detects open phase of the neutral phase of a single-phase three-wire power source and shuts off the power supply.

[Background Art J] This type of open-phase detection circuit breaker in the United States drives a tripping relay in the following manner when an open phase occurs in the neutral phase. In other words, as shown in Fig. 3, there is a method in which a series circuit of the trip relay drive coil 3 and the thyristor 7 is inserted between the neutral phase N and the power supply phase L1 or L2, and as shown in Fig. 4. There was a method of inserting it between power supply phases L1 and L2.

However, in the former case, when an open phase X occurs in the neutral phase N, one load 1b is connected in series to the above series circuit, so the impedance of the load is limited. For example, if the load 1b happens to be not in use, The power supply voltage is not applied to the series circuit of the trip relay drive coil 3 and the thyristor 7, and even if the open phase detection section A detects an open phase, the current i as shown does not flow and the thyristor 7 does not operate. As a result, there was a problem that it could not fulfill its role as a circuit breaker. Note that 2 is an opening/closing contact.

In the latter case, the potential difference between the phase-opening detection section A and the trigger pulse that is applied to the thyristor 7 based on the detection signal of the phase-opening detection section A is large (as shown in the figure, there is a large potential difference between the circuit TG and the thyristor 7). However, insulating means such as an insulating pulse transformer must be used, which has the disadvantage of increasing costs.

On the other hand, there are two possible methods for detecting abnormal voltage. One is the two-phase voltage V1. There is a method of detecting the voltage difference of V2 and a method of detecting the voltage of Vl and V2 respectively.1For example, in the case of a 100/200V single-phase three-wire system, the voltages set as abnormal voltages are 150■ and 50■. When doing so, one is to detect a difference of 100V between 150■ and 50■ as abnormal voltage, and the other is to ignore 50V and set it as 1.
When only 50■ is detected, this is regarded as an abnormal voltage. By the way, when the power supply voltage of 200■ changes to 220■ for some reason, with the former method, for example, 16
0■ and 60V, in the latter method, for example, 150V
The method detects an abnormal voltage when the voltage is 70 V. Considering the protection of the load equipment, the latter method that can maintain the load within the maximum voltage is considered to be more appropriate and desirable, so the present invention uses the latter method. method is adopted.

[Object of the Invention] The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a system that can be manufactured at low cost without requiring any insulating means, and that can detect phase loss according to the magnitude of the power supply voltage. The purpose of the present invention is to provide an AA neutral wire open phase detection circuit breaker.

[Disclosure of the Invention] The AA neutral wire open-phase detection circuit breaker of the present invention includes a full-wave bridge rectifier that rectifies the AC voltage between both power supply phases of a single-phase three-wire system, and a rectified output voltage of the full-wave bridge rectifier. A resistor that steps down the voltage,
A current mirror that uses the DC obtained from the step-down rectified output as a power source, flows the pulsating current from the positive output of a full-wave bridge rectifier as a reference current, and obtains an output current according to the difference between the current flowing from the detection input terminal and the current flowing from the detection input terminal. a circuit, an open phase detecting section detecting an open phase using a current obtained by adding the current from the positive output of the full-wave bridge rectifier to the output current of the current mirror circuit; is connected to the negative output of the full-wave pre-7 rectifier, and the 7 node is connected to one of the output ends of the full-wave pre-7 rectifier.The thyristor is connected in series to the energizing circuit of the thyristor. The open-phase detection section is equipped with means for discriminating the potential difference between the detection input terminal connected to the neutral phase and the cursor point of the thyristor.

The present invention will be explained with reference to the following embodiments. 6 Embodiments FIG. A tripping relay drive coil 3 is inserted between the phase L1 and the single power lamp of the full-wave bridge rectifier DB, and a constant voltage element is connected between the output terminals of the full-wave bridge rectifier DB via a resistor 4 for stepping down the power supply. 5. At the same time as connecting the smoothing capacitor 6, the open-phase detecting section A having a tri-circuit is connected. The reverse blocking three-terminal type thyristor 7, which is triggered by the detection output of the open phase detection section A, connects 7 nodes to the power supply phase L1 via the drive coil 3, and connects the cathode to the negative electrode side of the full-wave bridge rectifier DB. Connect to one output light. The neutral phase N is connected to the detection input in of the open phase detection section A.

The open phase detection section A is composed of current mirror circuits CMI and 0M2, an integrating circuit, and a humpator COM, and is further provided with a tri-four circuit for the thyristor 7. The current mirror circuit CMI allows current 11 to flow from the positive side of the full-wave bridge rectifier DB through resistor R1 to transistor Q1, and current I2 to flow from the detection power Hkn to transistor Q2 through resistor R2, so that there is no phase loss. Current I at normal time -2 1. The values of I2 are set to be equal. Further, a resistor R5 is arranged so that a current I4 from the positive output terminal of the full-wave bridge rectifier DB flows into the capacitor C1.

In such a configuration, when a 100V/200V single-phase three-wire power supply is used, a voltage of 100V is applied to each load 1a and lb if there is no open phase in the neutral phase N. That will happen.

If an open phase occurs in the neutral phase N, each load 1a.

1b, different voltages Vl and V2 are applied to both ends of each except when they are equal, and an abnormality occurs in the applied voltages. During this phase loss, the open voltage V (not shown) between the detection input terminal n of the phase loss detection section A and the negative electrode side of the full-wave bridge rectifier DB, that is, the cathode point of the thyristor 7, is Vl and V2 every half wave. This results in a pulsating voltage proportional to . In this way, when an abnormal voltage V is generated due to the unbalance of the impedance of the loads 1a and lb during an open phase, the current generator 2 shown in FIG. 2(b) will generate the current shown in FIG. 2(a) every half wave. (2) It becomes a value higher than 1, and as a result, the current mirror circuit CMI outputs a current value 3 corresponding to the difference.

This current wire 3 is connected to the capacitor C1 via the guide D1.
flows into. On the other hand, a circuit that connects directly from the positive terminal side of the full-wave bridge rectifier WDB to the capacitor C1 via the resistor R5 generates a voltage proportional to the magnitude of the power supply voltage, as shown in the solid line waveform (a) in Fig. 2(e). The sum of the current 4 and the current I3 flows into the capacitor C1 and is integrated by the transistors Q3 and Q4 of the current mirror circuit CM2.

Here, the broken line in FIG. 2(e) indicates the electric current worker 4 during the period c+7). The integral value of the current is trunk
．． When the output voltage becomes larger than the integral value of the set constant current value of the current mirror circuit CM2 configured by Q4, the output voltage ■3 becomes
It rises as shown in FIG. 2 (cl). Comparator C
The OM compares this output voltage 3 with the threshold value Vth, and when the output voltage v3 exceeds the threshold value Vth, turns on the transistor Q5, and creates a voltage 2 across the resistors R3 and R4 as shown in FIG. 2(e). 4 to trigger the thyristor 2 and turn it on. Here, the output voltage ■3 is Ll
Since the current I4, which is proportional to the power supply voltage between L2 and L2, is obtained by flowing through the capacitor C1, the difference voltage detected by the comparator COM is proportional to the voltage between the power supply phases to be detected. Can be set small.

In this way, the circuit shown in Figure 1 converts the normal power supply voltage into a current without setting a constant reference potential, and this current
and the current I2 obtained by converting the voltage at the detection input terminal n connected to the neutral phase N, and detect an open phase by integrating and discriminating only the difference current, It can drive a trip relay.

Note that an integrating circuit may be constructed by connecting a resistor instead of the current mirror circuit CM2, or the operation of the comparator COM may have hysteresis.

[Effects of the Invention 1] The AA neutral wire open phase detection circuit breaker of the present invention includes a full-wave bridge rectifier that rectifies a single-phase three-wire AC voltage with both power supply phases open, and a rectifier of the full-wave pre-γ) rectifier. a resistor that steps down the output voltage;
Using the DC obtained from the step-down rectified output as a power source, the pulsating current from the positive output of the full-wave pre-7 rectifier is passed as a reference current, and the output current is obtained according to the difference with the current flowing from the detection input terminal. an open phase detection section that includes a current mirror circuit and detects an open phase by adding the current from the positive output of the full-wave bridge rectifier to the output current of the current mirror circuit; A reverse-blocking three-terminal thyristor whose cathode is connected to the negative output of a full-wave bridge rectifier and whose 7 nodes are connected to one of the output ends of the full-wave bridge rectifier is inserted in series into the current-carrying circuit of the thyristor. and a drive coil for a tripping relay, and the open phase detection section is equipped with means for discriminating the potential difference between the detection input terminal connected to the neutral phase and the cursor point of the thyristor.
Since it is an I command, it is possible to share the power supply of the open phase detection part and the power supply of the thyristor, and there is no need to provide expensive insulation means like the 7 Oto coupler, so it can be manufactured at low cost, and it is possible to use Since the current proportional to the power supply voltage from the positive output is detected in addition to the output current of the mirror circuit, the detection difference voltage can be set to decrease as the power supply voltage increases. This has the effect that phase loss can be detected in accordance with the magnitude of the power supply voltage.

[Brief explanation of drawings]

Fig. 1 is a specific circuit diagram of the AA neutral wire open phase detection circuit breaker of the present invention, Fig. 2 is a waveform diagram for explaining the operation of the same as above, Fig. 3 is a basic circuit diagram of a conventional example, and Fig. 4 is This is a basic circuit diagram of another conventional example, where 3 is a drive coil, 7 is a thyristor, DB is a full-wave bridge rectifier, 4 is a resistor, CMI, CM2 are current mirror circuits, Ll, L2 are power phases, N is neutral phase, n is a detection input terminal, 11, I2, 13, and I4 are currents. Agent Patent Attorney Ishi 1) Chief Figure 7 2

Claims (1)

[Claims] (1) A full-wave bridge rectifier that rectifies the AC voltage between both power supply phases of a single-phase three-wire system, a resistor that steps down the rectified output voltage of the full-wave bridge rectifier, and a DC obtained from the stepped-down rectified output as a power source. , is provided with a current mirror circuit that flows a pulsating current from the positive output of the full-wave bridge rectifier as a reference current and obtains an output current according to the difference between the current flowing from the detection input terminal, and the positive output of the full-wave bridge rectifier. an open phase detection section that detects an open phase using a current added to the output current of the current mirror circuit, and a cathode connected to the negative output of the full-wave bridge rectifier triggered by the output of the open phase detection section; It consists of a reverse blocking three-terminal type thyristor whose anode is connected to one of the output ends of a full-wave bridge rectifier, and a drive coil of a trip relay inserted in series with the energizing circuit of the thyristor. 1. An AA neutral line open phase detection circuit breaker comprising means for discriminating a potential difference between a detection input terminal connected to a neutral phase and a cursor point of a thyristor.