JPH09308083A - Phase interruption detection circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain easy repairing service by providing a signal processing circuit which discriminates between the phase interruption and negative phase of a three-phase power supply from a two-phase pulse outputted from a phase interruption detection part, and recognizing and displaying a phase which has a phase interruption. SOLUTION: A pulse generating circuit 5 into which respective line voltages of a three-phase power supply are inputted from a connecting terminal 2 generates two- phase pulses E0, E1 synchronized with the interphase voltage of a power supply between a plurality of phases. A signal processing circuit 6 detects an ordinary condition, a negative phase condition, and respective conditions of phase interruption of phase-A, phase-B and phase-C according to an order for changing the output conditions of two-phase pulses E0, E1 which the pulse generating circuit 5 outputs, and outputs no circuit closing signals to a switch 3 so as not to operate a motor 4 in case of some failure condition such as when the phase order for connecting the three-phase power supply 1 to the connecting terminal 2 is opposite, or a three-phase electric line is not connected. Any of the negative phase condition, and respective conditions of phase interruption of phase-A, phase-B and phase-C is displayed on a display means 9 and its display signal is outputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an open phase detection circuit.

[0002]

2. Description of the Related Art A conventional open phase detecting circuit is disclosed in Japanese Patent Publication No. 7-67.
As described in Japanese Patent Publication No. 224 and JP-B-7-67225, a full-wave bridge circuit and a reverse blocking three-terminal type thyristor are provided, and the voltage charged in the capacitor by the voltage that continues in the cycle of the power supply is used to make a defect. Had detected a phase.

[0003]

The prior art not only cuts off the relay to which a specific circuit is connected when a phase loss is detected, but also has no means for detecting which phase is broken. However, since it does not have the display means, no consideration has been given to the fact that a great amount of time and labor is spent in repairing the device at the time of maintenance service.

It is an object of the present invention to provide means for detecting which phase has a wire breakage and means for displaying the wire breakage, and displaying the wire breakage phase when a missing phase is detected and providing a means for easily repairing it. It is in.

[0005]

In order to achieve the above object, the present invention inputs the line voltage of each of the three-phase power supplies to the open phase detection circuit and synchronizes with the interphase voltage of the power supplies between a plurality of phases. It is equipped with a pulse generation circuit that generates a two-phase pulse and a signal processing circuit that determines the open phase and the reverse phase of the three-phase power supply from the two-phase pulse output from the open phase detection unit. A means for recognizing and displaying is provided.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail.

FIG. 1 is a block diagram showing an embodiment of the present invention. In this embodiment, a three-phase power source 1, a connection terminal 2, and an electric motor 4 which is operated / stopped by a switch 3 connected thereto.
A phase loss detection circuit 8 including a pulse generation circuit 5 and a signal processing circuit 6, a power supply circuit 7 for supplying power to the phase loss detection circuit 8, and a display means 9 driven by the phase loss detection circuit 8. It

A three-phase power source 1 consisting of three AC voltages, Euv, Evw, and Ewu, which are electrically different in phase by 120 degrees,
The electric motor 4 is operated / stopped by the switch 3 connected to the connection terminal 2 and connected thereto. A pulse generation circuit 5 to which each line voltage of the three-phase power supply is input from the connection terminal 2
Is a two-phase pulse E0, E1 that is synchronized with the interphase voltage of the power supply between a plurality of phases among the three-phase voltage Euv, Evw, Ewu.
Occurs. The signal processing circuit 6 outputs the two-phase pulse output from the pulse generation circuit 5, the order in which the output states of E0 and E1 change, that is, the normal state, the anti-phase state, the A state according to the state transition.
Detects each state of open phase, open phase B, open phase C,
In the normal state, a closing signal is output to the switch 3 to drive the electric motor 4. However, when the phase sequence in which the three-phase power supply 1 is connected to the connection terminal 2 is reversed, or when there is an abnormal state such as when three-phase electric wires are not connected, a closing signal is not output to the switch 3, The motor 4 is not operated, and a display signal is output to the display means 9 for each of the reverse phase state, the A phase open phase, the B phase open phase, and the C phase open phase. The display means 9 may express each display state in each of the reversed phase state, the A-phase open phase, the B-phase open phase, and the C-phase open phase. Therefore, for example, the number of times the LED blinks and digital display is possible. Various abnormal states are expressed by a method such as LED or LCD.

FIG. 2 is a circuit diagram for explaining the pulse generating circuit 5 in detail. R1, R2, R depending on the interphase voltage of three phases
A current is supplied to the photocouplers PQ1 and PQ2 through 3 and each photocoupler outputs output signals E0 and E1.
Further, R4, R5, D1, and D2 are photocouplers PQ1 and
A protection circuit that protects when a reverse breakdown voltage is applied to the primary side of PQ2 is configured.

FIG. 3 shows the output signals E0 and E1 of the photocoupler.
The pulse signals E0 and E1 synchronized with the two-phase power source among the three phases can be expressed as the binarized signals E0 (BIN) and E1 (BIN), respectively. 16 evolution signal E (HEX) is 2, 1, 3, 2,
It changes in the order of 1, 3 ,.

FIG. 4 shows the output signals E0 and E1 of the photocoupler.
5 is a pulse waveform when the phase is reversed, and FIG. 5 is a pulse waveform when the output signals E0 and E1 of the photocoupler are out of phase with C. 16-evolution signal E (HEX) of pulse waveforms E0 and E1 in reverse phase
Is a 16-evolution signal E of the pulse waveforms E0 and E1 at the time of the reversed phase at the C-phase open phase in the order of 2, 3, 1, 2, 3, 1 ,.
(HEX) changes in the order of 2, 3, 3, 2, 3, 3, ....

FIG. 6 is a diagram showing various transitions of the hexadecimal output signal E (HEX). From this, normal state, reverse phase state, A
The order in which E (HEX) changes differs depending on the states of the open phase, the B open phase, and the C open phase. Therefore, the change order of E (HEX) can be detected by the flowchart shown in FIG. For example, normal state, reverse phase state, A phase open phase,
It is possible to detect each of the B-phase open phase and the C-phase open phase.

[0013]

According to the present invention, a pulse generator circuit for inputting each line voltage of a three-phase power supply to a phase loss detection circuit and for generating a two-phase pulse synchronized with the interphase voltage of the power supply between a plurality of phases. , The signal processing circuit for determining the open phase and the reverse phase of the three-phase power supply from the two-phase pulse output from the open-phase detector is provided, and the means for recognizing and displaying the open phase at the open phase is provided. The equipment can be easily repaired during maintenance service.

[Brief description of drawings]

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

FIG. 2 is a pulse generation circuit diagram.

FIG. 3 is a pulse waveform diagram in a normal state.

FIG. 4 is a pulse waveform diagram in the reverse phase.

FIG. 5 is a pulse waveform diagram at the time of C-phase open phase.

FIG. 6 is a transition diagram of an output signal E (HEX).

FIG. 7 is a flowchart of a signal processing circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Three-phase power supply, 2 ... Connection terminal, 3 ... Switch, 4 ... Electric motor, 5 ... Pulse generation circuit, 6 ... Signal processing circuit, 7 ... Power supply circuit, 8 ... Open phase detection circuit, 9 ... Display means.

Claims (2)

[Claims] 1. A three-phase power source, an electric motor operated by the three-phase power source, a switch for energizing / interrupting the three-phase power source and the electric motor, and a connection for connecting the three-phase power source and the switch. A motor drive circuit composed of a terminal, a pulse generation circuit for inputting the line voltage of each of the three-phase power supplies, and generating a two-phase pulse synchronized with the interphase voltage of the power supply between a plurality of phases, and an open phase detector From the two-phase pulse output from the three-phase power supply, the open-phase detection circuit of the three-phase power supply equipped with a signal processing circuit for determining the open-phase and reverse phase of the three-phase power supply recognizes the open-phase at the open-phase. A phase loss detection circuit, characterized in that means for displaying is provided. 2. The signal processing circuit, which receives the two-phase pulse output from the open-phase detector, inputs the sequence of each phase of the two-phase pulse synchronized with the power supply cycle input within a predetermined time. The open-phase detection circuit according to claim 1, further comprising a signal processing circuit that counts the number and determines from the two-phase pulse whether the three-phase power supply has open phase, reverse phase, or disconnection.