JPH02241322A - Breaker - Google Patents

Abstract

PURPOSE:To improve safety by detecting reverse phases from a capacitor, a resistance, and a relay, which are individually connected on the extension lines from each conductor connecting a three-phase AC power source with an overload relay, so as to actuate a second breaking part. CONSTITUTION:A first breaking part 2a, which breaks switches S1-S3 at overload, are provided between each phase R-T on the input side and each phase R-T on the load side. Moreover, the switches S1-S3 are also broken by the inputs from terminals a and b. Furthermore, a resistance 5a, a capacitor 4a, and a coil 7 are individually connected to respective conductor of each phase so as to form a reverse phase detection circuit 3a. If reverse phases are detected, large currents flow to the coil 7 and the contact of a relay 6a is closed, and the coil L5 of a second breaking part 9 is energized, which breaks the switches S1-S3. Hereby, it is protected from overcurrents and reverse phases, and safety improves.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a circuit breaker for a three-phase AC power supply, and particularly to a circuit breaker that can detect an opposite phase and shut off the circuit, even if the three-phase AC power supply is incorrectly connected. The purpose of this circuit breaker is to provide a circuit breaker that can prevent damage, etc., and is installed between a three-phase AC power source and a device driven by the power supplied from the power source, so that the power supplied to the device is controlled at a specified level. In a circuit breaker equipped with a first cutoff circuit that cuts off the three-phase AC conductor when the load exceeds the load, a capacitor, a resistor, and a relay are provided on each of the three lead-out conductors drawn out from each conductor, The configuration includes an anti-phase detection section that detects an anti-phase of the conductor based on a change in the current flowing through the relay, and a second cut-off section that interrupts the three-phase AC conductor based on the detection output of the anti-phase detection section.

[Industrial application field]

TECHNICAL FIELD The present invention relates to a circuit breaker for a three-phase AC power supply, and particularly to a circuit breaker that can detect an opposite phase and shut off the circuit.

In recent years, No Fuse Breakers (hereinafter referred to as NFB), which supply power to devices such as computers, have come to cut off the power supply when the load increases due to short circuits, etc., or when a cutoff command signal is received from an external source. However, with three-phase AC power supplies in particular, phase connection errors are likely to occur during electrical work such as adding on equipment or rearranging equipment, so the phase is checked each time using a phase rotation needle that checks the direction of rotation. However, if the wiring is branched and multiple NFBs are installed, there is a possibility of omission of confirmation, which may result in equipment damage or fire, so for safety reasons, it is necessary to detect the opposite phase. A method of cutting off the power is desired.

[Conventional technology]

Figure 3 is a circuit diagram illustrating an NFB installed in a three-phase AC power supply. In the figure, R, S on the NFB 10 input side,
The T phase is connected to the power supply, and the R, S, and T phases on the load side are connected to devices such as computers.

The cut-off part 2a shown surrounded by a dashed line is a coiled part 1 to L4.
．． It is composed of switches 51 to S3 that open and close in conjunction with each other.

With this configuration, under normal load conditions, the current flowing through the coils 1 to L3 is small, and the current flowing through the switches 31 to S3 is small.
3 is in the connected state, and if a current exceeding the set value flows into the coil due to a short circuit on the load side and flows through 1 to L3, the switches Sl to S
3 blocks it.

Moreover, if a voltage is applied to a and b from the outside and a current is caused to flow through the coil L4, the switches 31 to S3 can be shut off.

This kind of NFB 1 is installed in multiple stages by branching the wiring, and when there is a new installation or connection change due to electrical work due to equipment expansion or rearrangement, each time a phase with a motor is installed. The correctness of the phase is confirmed by the direction of rotation using a rotation direction meter or the like.

[Problem to be solved by the invention]

According to the above conventional method, when a new NFB is installed or changed due to electrical work, etc., the correctness of the phase is checked each time. There is a problem that if the power is turned on as it is, the device may be damaged or catch fire.

Although the NFB has a function of shutting off when overloaded or by inputting a shutoff instruction from the outside, it does not have a function of detecting an opposite phase, so a method to solve this problem is desired.

An object of the present invention is to provide a circuit breaker that can prevent damage to the device even if a three-phase AC power source is incorrectly connected.

[Means to solve the problem]

FIG. 1 is a block diagram of the principle of the present invention.

In the figure, 2 indicates when the power supplied to the device exceeds the predetermined load,
A first interrupting part 3 interrupts the three-phase alternating current conductor;
．． Resistor 5. and a relay 6, each of which detects the opposite phase of the conductor based on a change in the current flowing through the relay 6; 9 cuts off the three-phase AC conductor based on the detection output of the reverse phase detector 3; This is the second blocking section.

Therefore, the phase of the input voltage three phases and the capacitor 4. Utilizing the fact that the current changes due to the phase delay or lead of the resistor 5° and the relay 60, the reverse phase detection unit 3 detects the reverse phase, and the second
The power supply is cut off by a cut-off section 9.

[Effect]

When power is supplied to the device, if the phase connections of the three-phase AC conductors are normal, the current flowing to the relay 6 of the anti-phase detector 3 will be small, and the relay 6 will not operate and the contacts will be open. , the second cutoff section 9 normally supplies power to the load side.

When the phase connection is reversed, the current flowing through the relay 6 increases, the relay 6 operates, the contact portion closes, and the second cutoff portion 9 cuts off the power source.

Also, when the power supplied to the device exceeds the specified load,
It is blocked by the first blocking section 2.

As shown in step 2, not only can the power be shut off in the event of an overload, but the power can also be shut off by detecting whether the phase connection is correct or not, which prevents equipment damage and fire.
Safety can be increased.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The same reference numerals refer to the same objects throughout the design.

FIG. 2 shows NFBla in which the present invention is applied to NFB1 described in the conventional example.

In the figure, an anti-phase detection circuit 3a surrounded by a dashed line
is composed of a capacitor 4a, a resistor 5a, and a relay 6a shown by a broken line. Also, 7 is an inductance, 8 is a contact, and L5 is a coil.

The capacitor 4a, the resistor 5a+, and the lead wire on one side of the relay 6a are connected, and the contact 8 of the relay 6a is connected to the coil L5.
When the current flowing through inductance 7 is small and relay 68 does not operate, contact 8 is open.
Contact 8 is designed to close when relay 6a is activated.

Further, the cutoff section 9a shown surrounded by a two-dot chain line is composed of a coil L5 and switches 81 to S3.

In FIG. 2, the cutoff section 2a19al and the anti-phase detection circuit 3a are the same as the first cutoff section 2.1 in FIG. Second blocking section 9. and anti-phase detection section 3, respectively.

With this configuration, when power is supplied to the device, the reverse phase detection circuit 3a uses the capacitor 4a.

The inductance 7 of the resistor 5a and the relay 6a detects whether the phase of the three-phase AC power supply is correct or not. That is, since the current changes depending on the phase of the three input terminal phases and the phase delay or lead of the capacitor 4a, resistor 5a, and inductance 7 of the relay 6a, this is used to detect whether the phase is correct or not.

First, when the connection is normal, the current flowing through the inductance 7 is smaller than when the phase is reversed, and the relay 6a does not operate, so the contact 8 opens and no current flows through the coil L5, and the switches 31 to S3 remain connected. , supplies power to the load side.

If there is an error in the phase connection, the current flowing through the inductance 7 increases, the relay 6a operates, the contact 8 closes, a current flows through the coil L5, and the connections of the switches 31 to S3 are opened to cut off the power supply.

For example, capacitor 4a = 0.068μF, resistor 5a = 43Ω, inductance of relay 6a 7 = 81.7H, input voltage = 200V, frequency = 50) lZ, when the phase connection is normal, the current #3mA3mA connection is reversed. The current L at the time is 11 mA. Therefore relay 6
The operating characteristic of a is set so that it does not operate at 3 mA but operates at 11 mA, and the opposite phase is detected.

In addition, under normal load conditions, the current flowing through the coils 1 to L3 is small, and the switches 31 to S3 are in the connected state, and due to a short circuit on the load side, a current exceeding the set value flows through the coils 1 to L3.
When the current flows to , the switches 31 to S3 are cut off.

Alternatively, the switches 31 to S3 can be shut off by applying a voltage to a and b from the outside to cause current to flow through the coil L4.

In this way, it is possible to not only cut off the power in the event of an overload or in response to a cut-off instruction signal from the outside, but also to detect whether the phase connection is correct or not, and to cut off the power in the event of an incorrect connection. It is possible to automatically prevent equipment damage and fire caused by

〔Effect of the invention〕

As explained above, according to the present invention, there is an anti-phase detection unit that includes a capacitor, a resistor, and a relay each on a lead-out conductor from each conductor of a three-phase AC power supply, and a second anti-phase detector that cuts off the power supply upon detection thereof. The cut-off section can automatically cut off the power when the three-phase AC power supply is in reverse phase, which protects the equipment from overload and prevents equipment damage or fire due to reverse phase, improving safety. It has the effect of increasing

[Brief explanation of drawings]

Fig. 1 is a principle block diagram of the present invention, Fig. 2 is a circuit diagram showing an embodiment of the present invention, and Fig. 3 is a NFB
FIG. 2 is a circuit diagram showing a conventional example. In the figure, 2 is a first cut-off part, 2a and 9a are cut-off parts, 3 is an anti-phase detection part, 3a is an anti-phase detection circuit, 4 is a capacitor,
4a is a capacitor, 5.5a is a resistor,
6 is the relay, 6a is the relay, 9 is the second
The cut-off part is shown.

Claims (1)

[Claims] Provided between a three-phase AC power source and a device driven by the power supplied from the power source, when the power supplied to the device exceeds a predetermined load, the three-phase AC In the circuit breaker equipped with a first interrupting part (2) that interrupts the conductor wires, a capacitor (
4), one resistor (5) and one relay (6) are provided,
an anti-phase detection section (3) that detects an anti-phase of the conductor based on a change in the current flowing through the relay (6);
A circuit breaker characterized by comprising: a second interrupting section (9) that interrupts the three-phase alternating current conductor based on the detection output of step 3).