JPH0589769A - Circuit breaker - Google Patents

Abstract

PURPOSE:To allow a user to conduct a proper treatment correspondingly when an open phase is generated. CONSTITUTION:A load current detecting circuit 6 for detecting a load current value running in main circuits 3a, 3b, 3c is provided. A tripping device 10 for opening and closing contacts 4a, 4b, 4c in the main circuits 3a, 3b, 3c when the detected current value of the load current detecting circuit 6 exceeds an allowable value, is provided. Further, an open phase detecting means 13 for judging the presence of an open phase by the output signal of the load current detecting circuit 6 and outputting an open phase signal S4 when the open phase is generated, is provided, and a notifying means 12 for performing notifying operation when the open phase signal S4 is outputted from the open phase detecting means 13, is also provided. In this case, the tripping device 11 is never operated except for an excess current flowing even if the open phase is generated, and the current is successively carried to the load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit breaker having a function of detecting a phase loss when it occurs.

[0002]

2. Description of the Related Art Generally, a circuit breaker is provided with an opening / closing contact in a main circuit, and when an overcurrent such as a short-circuit current flows in the main circuit, it is detected to instantly open / close the opening / closing contact by a trip device. It is designed to be opened. In such a circuit breaker, in recent years, an open phase detection circuit has been provided to detect a phase loss due to a power line disconnection accident, etc. There is a device in which a disconnecting device is operated to shut off the main circuit.

[0003]

By the way, with the recent office automation (OA), so-called OA such as a personal computer and a word processor is provided on the load side of the circuit breaker in addition to a drive source such as a motor. Devices are also often connected. in this case,
If the main circuit is immediately shut off when a phase loss occurs, as in the above-mentioned conventional example, the data stored in the RAM (volatile memory) of the OA device will be erased, and the subsequent business processing will be hindered. I had to come.

The present invention has been made in view of the above circumstances, and therefore an object thereof is to provide a circuit breaker which allows a user to take appropriate measures in response to the occurrence of a phase loss. To provide.

[0005]

The circuit breaker of the present invention comprises:
A switching contact interposed in the main circuit, a load current detection circuit that detects the load current value flowing in the main circuit, and the switching contact is opened when the detection current value of this load current detection circuit exceeds the allowable value. And a tripping device for enabling the open phase detecting means for determining the presence or absence of the open phase by the output signal of the load current detecting circuit and outputting the open phase signal when the open phase occurs, and the open phase detecting means. And an informing means for performing an informing operation when the open phase signal is output from the.

[0006]

When a phase loss occurs, the phase loss detecting means detects the phase loss and outputs a phase loss signal to activate the notifying means to notify the user of "occurrence of phase loss". At this time, if the detected current value of the load current detection circuit is within the allowable value, the trip device does not operate even if a phase loss occurs, and the load is continuously energized. Therefore, even when the phase loss occurs (when the notification means is activated), unless the overcurrent flows, the user continues to supply the load, and the user can take appropriate measures (for example, OA device) against the load (for example, OA device). It is possible to manually shut off the main circuit after saving the stored data etc.).

If an overcurrent flows in the main circuit during the occurrence of a phase loss (during the reporting operation of the reporting means), the detected current value of the load current detection circuit exceeds the allowable value. The disconnecting device also operates to shut off the main circuit and protect the load from overcurrent.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. For example, the terminals 1a, 1b, 1c of the three-phase AC power source and the load side terminals 2a, 2b, 2c are connected by main circuits 3a, 3b, 3c, respectively, and the main circuits 3a, 3b, 3c are respectively connected.
Switching contacts 4a, 4b, 4c are respectively provided in c. The main circuits 3a, 3b, 3c are provided with current transformers 5a, 5b, 5c, respectively.
b and 5c are connected to the load current detection circuit 6. The load current detection circuit 6 detects the load current value flowing through the main circuits 3a, 3b, 3c based on the output current values of the current transformers 5a, 5b, 5c, and a detection signal of a level corresponding to the detected current value. Output S1.

The detection signal S1 is input to both the overcurrent detection circuit 7 and the open phase detection circuit 8. The overcurrent detection circuit 7 outputs a trip signal S2 to the gate of the thyristor 9 when the detected current value (S1) of the load current detection circuit 6 exceeds the allowable value, that is, when the overcurrent is detected. Turn this on. This thyristor 9 is connected in series with the trip device 10, and when the thyristor 9 is turned on, the trip device 10 is turned on.
When the tripping device 10 is energized, the trip device 10 is turned on and off.
b and 4c are opened and the main circuits 3a, 3b and 3c are cut off.

On the other hand, the open-phase detection circuit 8 determines whether or not the signal S1 is input for all three phases based on the load current detection signal S1 for each phase input from the load current detection circuit 6. If the signal S1 is not input even in one phase, it is determined that the phase is open and the detection signal S is output to the open phase signal output circuit 11.
3 is output, and the open phase signal S4 is output from the open phase signal output circuit 11 to the notification means 12. The phase loss detection circuit 8 and the phase loss signal output circuit 11 constitute phase loss detection means 13.

The informing means 12 is composed of, for example, a display, an alarm lamp, a buzzer, etc., and informs the user of "occurrence of an open phase" by a display or an alarm sound when the open phase signal S4 is inputted. The notification means 12 may be provided in the main body case (not shown) of the circuit breaker, but the notification means 12 may be provided in a place away from the main body case of the circuit breaker (for example, a place where the user can easily see). It may be arranged.

The overcurrent detection circuit 7, the open phase detection circuit 8 and the open phase signal output circuit 11 are all supplied with the DC voltage Vcc from the power supply circuit 14. The power supply circuit 14 is configured to generate a DC voltage Vcc by converting the voltage supplied from the inside of the load current detection circuit 6 into a constant voltage.

Next, the operation of the above configuration will be described.
By closing the switching contacts 4a, 4b, 4c, the main circuits 3a, 3b,
When a load current is flowing through 3c, the load current value is detected by the load current detection circuit 6 by the output current value of each of the current transformers 5a, 5b, 5c. Then, the load current detection circuit 6 outputs a detection signal S1 having a level corresponding to the detected load current value to both the overcurrent detection circuit 7 and the open phase detection circuit 8. At this time, the detected current value of the load current detection circuit 6 (S
If 1) is within the allowable value, the overcurrent does not flow in the main circuits 3a, 3b, 3c, so the trip signal S2 is not output from the overcurrent detection circuit 7, and the main circuits 3a, 3b, 3c Maintain a closed state.

Further, the load current detection signal S1 of each phase output from the load current detection circuit 6 is also input to the open phase detection circuit 8, and the open phase detection circuit 8 outputs the signal S1 for all three phases.
It is determined whether or not is input. If there is no open phase, the open phase detection circuit 8 maintains the state in which the signal S1 is input for all three phases. Therefore, the open phase signal output circuit 11
The open-phase signal S4 is not output from the device and the notification means 12 does not operate.

After that, if a phase loss occurs due to a disconnection of the transmission line or the like, the signal S1 of a part of the phase is not input from the load current detection circuit 6 to the phase loss detection circuit 8. At this time, the open phase detection circuit 8 determines that there is a open phase and outputs the detection signal S3 to the open phase signal output circuit 11, and outputs the open phase signal S4 from the open phase signal output circuit 11 to the notification means 12. To do.
As a result, the notification means 12 notifies the user of "occurrence of phase loss" by means of a display, an alarm lamp, a buzzer, etc. By this notification, the user can be surely informed of "occurrence of phase loss".

Even when such a phase loss occurs, the main circuits 3a, 3a
If the load current flowing in b, 3c does not exceed the allowable value, the trip signal S2 is not output from the overcurrent detection circuit 7 as described above, so that the main circuits 3a, 3b, 3c continue to be closed. Therefore, even when the phase loss occurs (when the notification means 12 is activated), unless the overcurrent flows, the user continues to apply the current to the load, and the user takes appropriate measures against the load (for example, OA equipment) ( The main circuits 3a, 3b, 3c can be manually shut off after the stored data is stored, for example. Therefore, it is possible to solve the conventional problem that the data stored in the RAM (volatile memory) of the OA device disappears due to the occurrence of the phase loss.

On the other hand, when an overcurrent flows through the main circuits 3a, 3b, 3c during the occurrence of a phase loss (during the reporting operation of the reporting means 12), the detected current value (S1) of the load current detection circuit 6 is an allowable value. In this case, the trip signal S2 is immediately sent from the overcurrent detection circuit 7 to the gate of the thyristor 9 at the time when the detected current value (S1) exceeds the allowable value, that is, when the overcurrent is detected. Output and turn it on. As a result, the trip device 10 is energized, and the trip device 1
0 opens the switching contacts 4a, 4b, 4c to open the main circuit 3a,
3b and 3c are cut off to protect the load from overcurrent.

If an overcurrent flows through the main circuits 3a, 3b, 3c even when the phase loss has not occurred, the trip signal S2 is output from the overcurrent detection circuit 7 in the same manner as described above. The circuits 3a, 3b and 3c are cut off.

The present invention is not limited to the above embodiment, and for example, the open-phase signal output circuit 11 and the notification means 1 are provided.
If 2 is driven by an external power source of a system different from that of the main circuits 3a, 3b, 3c, the open phase signal S4 can be held even after the main circuits 3a, 3b, 3c are cut off, and the notification means 12 performs the notification operation. Can be continued and the past phase loss occurrence status can be known.

[0020]

As apparent from the above description, according to the present invention, when a missing phase occurs, the missing phase detecting means detects it and causes the informing means to perform the informing operation. The user can be surely notified that “a phase has occurred”. In this case, if the overcurrent does not flow even if the phase loss occurs, the trip device will not operate and the load will continue to be energized. Therefore, when the phase loss occurs (when the alarm means operates).
However, as long as no overcurrent flows, the user should operate the main circuit manually with the load (for example, OA equipment) taking appropriate measures (for example, storing data) while the load is still energized. Thus, it is possible to solve the conventional problem that the data stored in the RAM (volatile memory) of the OA device is lost due to the occurrence of the phase loss.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

[Explanation of symbols]

3a, 3b and 3c are main circuits, 4a, 4b and 4c are switching contacts, 6 is a load current detection circuit, 7 is an overcurrent detection circuit,
Reference numeral 8 is a phase loss detection circuit, 10 is a trip device, 11 is a phase loss signal output circuit, 12 is a notification means, and 13 is a phase loss detection means.

Claims (1)

[Claims] 1. A switching contact interposed in a main circuit, a load current detection circuit for detecting a load current value flowing in the main circuit, and a detection current value of the load current detection circuit exceeding an allowable value. In a circuit breaker having a trip device for opening the switching contact, an open-phase detecting means for determining the presence / absence of open phase by an output signal of a load current detection circuit and outputting an open phase signal when the open phase occurs A circuit breaker comprising: and an informing unit that performs an informing operation when the open phase signal is output from the open phase detecting unit.