JPH0315223A - Single-phase three-wired power supply system switch - Google Patents

Abstract

PURPOSE:To prevent application of a voltage of rated value or more to a load by opening a single-phase 3-wired 3-interlocking switch when the fact that, when the switch is ON, no current flows to a neutral line is detected. CONSTITUTION:3-interlocking switch 26 is connected to voltage lines 24a, 24c and a neutral line 24b extending from a power distribution transformer 21, and loads 27, 28 adapted for a power source voltage Vo are connected to the output side. A potential difference detector 32 is connected to the input/output terminals of a neutral line switch 26b to detect the presence or absence of the current of the line 24b. If a current normally flows, the output of the detector 32 is zero, but if there is a malfunction, it generates a potential difference, outputs from terminals X, Y, thereby opening the contact of a relay 34. A coil 35 energized by the power lines 24a, 24c is deenergized, and the switch 26 is opened by a spring, not shown. Thus, even if the loads 27, 28 are unbalanced, a voltage more than rated value is not applied to the loads 27, 28 to prevent the loads from burning.

Description

Detailed Description of the Invention (Summary) The present invention relates to a single-phase three-wire power supply system switch, and particularly a single-phase three-wire power supply system switch that controls current supplied to a load in a single-phase three-wire system using a three-interlock switch. Regarding this, the purpose is to provide a single-phase three-wire power supply system switch that can protect the load when current is being supplied to the load, and in the single-phase three-wire power supply system switch as described above, a three-interlock switch is a detection means for detecting that no current flows between the contacts of the neutral line switch of a triple-interlock switch connected to the neutral line when current is being supplied to the load in the on state, and emitting a signal; A switch opening means is provided to open the connection between each contact of the triple interlocking switch based on the signal.

[Industrial application field]

The present invention relates to a single-phase three-wire power supply system switch, and more particularly to a single-phase three-wire power supply system switch in which current is supplied to a load in a single-phase three-wire system and is controlled by a three-interlock switch.

[Prior Art] As a conventional single-phase three-wire power supply system switch, for example, the one shown in FIG. 4 is known.

In Fig. 4, 11 is a distribution transformer on the power supply side.
The coil 12 and the coil 13 are connected in series, voltage lines 14a and 14c are drawn out from both sides thereof, and a neutral line 14b is drawn out from the connection point, thereby supplying current to the load side in a single-phase three-wire system. Single-phase three-wire power supply system switch 16
consists of voltage line switches 16a, 16c connected to each voltage line 14a, 14c, respectively, and a neutral line switch 16b connected to a neutral line 14b, and each switch 16a, 1
6b and 16c are designed to work together. On the load side, a load l7 with impedance ZA and a load l8 with impedance Za are connected to voltage line switch 16a and switch 1.
6c, and the connection point is switch 1.
It is connected to 6b.

In the circuit configured as described above, when the single-phase three-wire power supply system switch 16 is closed and turned on, the coil 12
and the voltage at both ends of the coil 13. Close, load 1
The voltages VA and VB applied to 7.18, respectively, are as follows: VA = VB = Vo.

(Problem to be Solved by the Invention) However, in such a conventional single-phase three-wire power supply system switch, current is normally supplied to the load 17, 18 when the single-phase three-wire power supply system switch 16 is in the on state. When the neutral wire switch 16b connected to the neutral wire 14b has a contact failure or the like and current no longer flows between the contacts, the load 17 on the load side and the load There is a problem in that a voltage imbalance occurs between the two loads, and a voltage higher than the rated voltage is applied to one load, which may cause damage or destruction to that load.

That is, assume that a contact failure occurs between the contacts of the neutral line switch 16b in the conventional circuit shown in FIG. 4, and current no longer flows between the contacts. At this time, the voltages VA and VB applied to the loads 17.18, respectively, are as follows, and a voltage equal to the impedance ratio is applied to each of the loads 17.18. Therefore, if the impedance of both loads is the same value, the above problem will not occur, but if the impedance of one load is larger than the impedance of the other, a voltage higher than the rated voltage will be applied to the load with larger impedance. Become.

SUMMARY OF THE INVENTION Therefore, the present invention provides a single-phase three-wire power supply system switch that can protect a load even if current does not flow between the contacts of a neutral line switch when current is being supplied to the load. With the goal.

(Means for solving the problems) In the present invention, the means for solving the above problems are as follows:
As shown in Fig. 1, in a single-phase three-wire power supply system switch that is controlled by a three-interlock switch 2, in which current is supplied to a load l in a single-phase three-wire system, the current is supplied to the load 1 when the three-interlock switch 2 is on. A detection stage 5 detects that no current flows between the contacts of the neutral line switch 4 of the three-interlock switch 2 connected to the neutral line 3 and issues a signal when the neutral line 3 is being supplied; A switch opening means 6 is provided for opening the contacts of the triple interlocking switch 2 based on a signal.

[Effect]

According to the present invention, when the triple interlock switch 2 is in the on state, the load 1
If current does not flow between the contacts of the neutral line switch 4 when current is being supplied to the neutral line switch 4, the detection means 5 detects this.
detects and issues a signal.

The switch opening stage 6 opens the three-linked switch 2 in response to a signal from the detection means 5, and can stop the current supply to the load 1.

〔Example〕

Embodiments of the single-phase three-wire power supply system switch according to the present invention will be described below with reference to the accompanying drawings.

As shown in FIG.
, 24c and the neutral wire 24b, and controls the current supply from the distribution transformer 21 to the loads 27, 28. It is composed of a triple interlock switch 26, a potential difference detection device 32, and a trip device 33. It has been pierced.

The triple interlock switch 26 includes voltage line switches 26a and 26c connected to each voltage line 24a and 24c, respectively, and a neutral line 2
4b, and a neutral line switch 16b connected to the neutral line switch 16b.
Each switch is interlocked and always urged in the opening direction by a spring (not shown).

The potential difference detection device 32 is provided in the neutral line switch 26b of the triple-linked switch 26, and detects that no current flows between the contacts of the neutral line switch 26b based on the potential difference between the contacts, and issues a signal. The precepts are shown in Figure 3. In the same figure, 41 is a rectifier that pulls out an electric wire from between the contacts of the neutral line switch 26b and rectifies the AC potential difference therebetween to produce a DC voltage, and 42 inputs the DC voltage value to the positive input terminal and also to the negative input terminal. A comparator inputs the trip operating voltage value predetermined by the trip operating voltage determining power supply 46 and compares the two, and 45 is an SSR drive power supply that applies a drive voltage to a solid state relay (hereinafter referred to as SSR) to be described later. It is. Further, the comparator 42 is
Power is taken in from the voltage lines 24a and 24b, and the rectifier 41
When the DC voltage value output from the trip activation voltage value is larger than the trip activation voltage value, a constant current is output to the light emitting diode 43. When the light emitting diode 43 emits light, the phototransistor 44 detects the light and becomes conductive, so that the SSR drive power source 45 applies a drive voltage to the SSR 34.

The trip device 33 receives the signal from the potential difference detection device 32 and opens the three-linked switch 26, that is, switches 26a,
26b and 26c at the same time, and the second
As shown in the figure, it is composed of an SSR 34 and a switching coil 35.

The SSR 34 maintains an on state when a drive voltage as an input signal is not applied from the potential difference detection device 32, and shifts to an off state when a drive voltage is applied. Furthermore, the switching coil 35 is connected to the voltage line 24a and the SSR3.
A current is supplied from the voltage line 24c via 4,
When the SSR 34 is on, the three-interlock switch 26 is attracted by electromagnetic force to maintain its on state.

In the single-phase three-wire power supply system switch 30 configured as described above, first the three-interlock switch 26 is turned on, and the neutral line switch 26b is connected normally to the load 27 from the distribution transformer 21 without any abnormality such as poor contact. It is assumed that a current is supplied to each of 28.

, At that time, the potential difference between the contacts of the neutral line switch 28b is
It does not occur approximately equal to 0 [V]. Therefore, the DC voltage value output by the rectifier 41 in the potential difference detection device 32 is approximately 0 [V], which is smaller than the trip activation voltage value, so that the comparator 42 does not output current to the light emitting diode 43. Since no current flows through the light emitting diode 43, it does not emit light, and the phototransistor 44 also does not conduct.

As a result, no drive voltage is applied to the SSR 34 from the SSR drive power supply 45.

In the switch opening device 33, the SSR 34 maintains an on state without applying a driving voltage. When the SSR 34 is in the on state, current is supplied from the voltage line 24a and the voltage line 24b, so the switching coil 35 attracts the triple interlock switch 26 by electromagnetic force, and reliably maintains the on state of the triple interlock switch 26. do.

On the other hand, when the triple interlock switch 26 is on, the load 27.28
Assume that when current is being supplied to the neutral line switch 26b, current no longer flows between the contacts of the neutral line switch 26b due to a fault such as a contact failure in the neutral line switch 26b.

At this time, the potential of the contact point of the neutral line switch 26b on the distribution transformer 21 side is 0 [v1 because the neutral line 26b is grounded, whereas the potential of the contact point of the neutral line switch 26b on the load side is 0[v1].
Since the potential at the contact point 6b is equal to the potential at the 'vc connection point between the loads 27 and 28, a potential difference occurs between the contacts of the neutral line switch 26b. Therefore, the rectifier 41 in the potential difference detection device 32 converts the potential difference into a DC voltage, and inputs the DC voltage value to the positive input terminal of the converter 42 . Since this DC voltage value is larger than the trip activation voltage value, the comparator 42 is caused to output a current. Then, a current flows and the light emitting diode 43 emits light, and the phototransistor 44 detects the light and becomes conductive, causing the SSR drive power source 45 to output light from the SSR 3.
Driving power is supplied to 4.

Then, since the drive current is supplied to the switch opening device 33, the SSR 34 shifts from the on state to the off state. Then, the VC connection between the voltage line 24c and the switching coil 35 is opened, and the current supply to the switching coil 35 is stopped.

Since the electromagnetic force generated in the switching coil 35 disappears and the attractive force is lost, the three-linked switch 26 is operated in the opening direction by the repulsive force of the spring and is turned off. As a result, the loads 27 and 28 are disconnected from the distribution transformer 21, and a voltage higher than the rated voltage is not applied to the loads 27 and 28, thereby protecting the loads 27 and 28 from damage.

Therefore, according to this embodiment, since the potential difference detection device 32 and the switch opening device 33 are provided, the three-interlock switch 26
When the neutral wire switch 26b is in the on state and current is being supplied to the load 27, 28, if current no longer flows between the contacts due to poor contact of the neutral line switch 26b, the potential difference detection device 32 detects this and outputs a signal. When the switch opening device 33 receives the signal, it opens the three-linked switch and turns off the other switches 26a and 26b, so that the load 27.2
8 and the distribution transformer 21 on the power supply side is cut off, a voltage higher than the rated voltage will not be applied to the load 27.28, and the load 27.28 can be protected from damage.

In the above embodiment, the repulsive force of the spring of the switch and the electromagnetic force of the switching coil were used as the switch opening device, but the switch opening means of the present invention is not limited to that of this embodiment. Any device that can open the contacts between the interlocking switches may be used.

(Effects of the Invention) As explained above, according to the single-phase three-wire power supply system switch according to the present invention, when the three-interlock switch 26 is in the on state and current is being supplied to the load, the contact points of the neutral wire switch a detection means for detecting that no current flows through and emitting a signal;
A switch opening means is provided to open the contacts of the three-interlock switch in response to a signal from the detection means, so if current stops flowing between the contacts of the neutral line switch while current is being supplied to the load, the switch can be opened. The detection means detects this, and the switch opening means opens the contacts of the triple interlocking switch.
A voltage higher than the rated voltage will not be applied to the load, and the load can be protected from damage.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of the present invention, Fig. 2 is a circuit diagram showing a single-phase three-wire power supply system switch according to an embodiment of the present invention, and Fig. 3 is a detailed configuration diagram of the potential difference detection device of this embodiment. , FIG. 4 is a circuit diagram showing a conventional single-phase three-wire power supply system switch. 1... Load 2... Triple interlock switch 3... Neutral line 4... Neutral line switch 5... Detection means 6... Switch opening means

Claims (1)

[Scope of Claims] A single-phase three-wire power supply system switch in which a three-interlock switch (2) controls current supplied to a load (1) in a single-phase three-wire system, wherein the three-interlock switch (2) is in an on state and the load When current is being supplied to (1), it detects that no current flows between the contacts of the neutral line switch (4) of the triple interlock switch (2) connected to the neutral line (3), and outputs a signal. Based on the signal from the detection means (5) and the detection means (5), the three-interlock switch (
2) Switch opening means (
6) A single-phase three-wire power supply system switch.