JPH0143914B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reverse phase and phase loss detection circuit that detects a reversal of phase rotation and a phase loss in a three-phase circuit, and reverses the output relay to the non-operating side in either case. In this case, the reverse phase and open phase detection circuits connected to each phase of RST are connected to a first rectifier circuit via a photocoupler, the first rectifier circuit is connected to a first judgment circuit, and each phase of ST is connected to A second rectifier circuit connected via impedance is connected directly and via a constant voltage circuit to a second determination circuit, and the first and second determination circuits are connected to a relay drive circuit, A negative phase/open phase detection circuit that reverses the output relay to the non-operating side when a phase occurs, and turns on a compensation circuit having the same resistance as the output relay when the output relay is off. The present invention relates to a reverse phase and open phase detection circuit characterized by the following.

An object of the present invention is to eliminate voltage instability and operate stably with a simple power supply.

Conventional negative-phase and open-phase detection circuits rectify and smooth the line voltage of the ST phase, and supply the voltage to the relay drive circuit via a constant voltage circuit. Therefore, since the constant voltage circuit supplies voltage to the determination circuit and other electronic circuits as well as to the output relay, it is necessary to increase the capacity of the power supply circuit.

The present invention has been made in view of this point, and will be explained in detail below with reference to Examples.

In Fig. 1, 1 is a reverse phase, open phase detection circuit,
RST is connected to each phase and detects that the voltage is lower than normal in the case of reverse phase and R phase open phase.
Connect to. 4 is a first determination circuit connected to the first rectifier circuit 3; 5 is a second rectifier circuit, which is connected to each phase of the ST via an impedance 6, and the output thereof is divided by resistors R ₇ and R ₈ and sent directly or via a constant voltage circuit 7 to the second judgment circuit. Connect to 8.
The first determination circuit 4 and the second determination circuit 8 are connected to a relay drive circuit 9. Relay drive circuit 9 applies the output voltage of second rectifier circuit 5. 10 is a compensation circuit, which is a resistor with the same resistance value as output relay 11.
It has _R14 and turns on when the output relay 11 is off.

Figure 2 is a specific circuit diagram of the first embodiment, with a resistor
R ₁ , R ₁ ′, R ₂ and capacitor C constitute a negative phase, R phase loss detection circuit, which is Y-connected to the three-phase AC, and the voltage across the resistor R ₁ ′ is positive phase and loss detection circuit. In the case of no phase, the line voltage of the RS phase is determined by resistors R ₁ , R ₁ ′, R ₃
It is almost equal to the partial pressure divided by . However, when the phase is reversed, the voltage decreases to approximately 1/3 of this voltage, and when the R phase is open, it becomes approximately 0. As mentioned above, the voltage across the resistor R ₁ ' decreases in abnormal conditions, so if the Zener voltage of the Zener diode ZD ₁ and the ratio of the resistors R ₁ and R ₁ ' are appropriately selected, the light emitting element of the photocoupler 2 can be A current can be passed through 2a, and the current can be stopped in the event of an abnormality. The diode _D1 is for reverse breakdown voltage protection of the light emitting element 2a. The voltage across the resistor R ₃ connected to the light receiving element 2b of the photocoupler 2 is connected to the diode D ₂ , the capacitor C ₂ ,
A comparator that performs rectification and smoothing with a first rectifier circuit 3 configured with a resistor _R4 , and configures a first judgment circuit 4.
Applied to the non-inverting input of COMP ₁ . Here, if the inverted input voltage of comparator COMP ₁ is determined appropriately using resistors R ₅ and R ₆ , the comparator
COMP ₁ can be turned off and turned on in case of abnormality. Note that the comparator COMP ₁ is the output of the opacity collector. Further, the resistor _R4 is a resistor for discharging the electric charge of the capacitor _C2 , and is used to turn on the comparator _COMP1 after a certain operating time when the input changes from normal to abnormal. The line voltage of the S-T phase is stepped down by its own current consumption through an impedance 6 consisting of a resistor, capacitor, reactance, or any combination of these, and is composed of a diode bridge DB and a capacitor _C3 . The input voltage is applied to the second rectifier circuit 5, where it is rectified and smoothed, converted into a DC voltage approximately proportional to the input voltage, divided by resistors R ₇ and R ₈ , and then connected to a comparator.
It is input to the second judgment circuit 8 formed by COMP ₂ . The second judgment circuit 8 receives this input and the DC voltage stabilized by the constant voltage circuit 7 through resistors R ₉ and R _{10 .}
The voltage is compared with the divided reference voltage and a judgment output is output. That is, the comparator COMP ₂ is turned off when normal, and turned on when abnormal. Here, the comparator
Even if the input state is such that the output of COMP ₁ is turned off, if the comparator COMP ₂ is turned on, the output is prioritized to be turned on, and is transmitted to the relay drive circuit 9, which turns off the transistor _Q1 and turns off the output relay 11. In addition, even if the input state is such that the output of comparator COMP ₂ turns off, comparator COMP ₁
If it is on, the output relay 11 is turned off.

In the above-mentioned reverse phase/open phase detection circuit, the present invention applies power to the relay drive circuit 9 from the output voltage V _D of the second rectifier circuit 5, and when the output relay 11 is not operating, the transistor of the compensation circuit 10 is applied. Turn on Q ₂ and set the same resistance as the resistance of output relay 11.
The circuit current i is always kept constant through _R14 . In the absence of the compensation circuit 10, the output voltage V _D of the second rectifier circuit 5 is as follows when the output relay 11 is turned on.
The voltage drop due to impedance 6 increases by the increase in current consumption of output relay 11, and decreases by this voltage drop. However, this voltage drop is equivalent to a drop in the S-T phase line voltage,
Output relay 11 is on during normal operation, output voltage V _D decreases,
This causes abnormality detection and malfunction of output relay 11 off, resulting in abnormal operation of output relay 11. Therefore, when the output relay 11 is turned on, the transistor
Q ₂ is turned off, and conversely, when the output relay 11 is turned off, transistor Q ₂ is turned on and the circuit current i is always maintained.
If it is kept constant, the voltage drop due to the impedance 6 will be constant, and the above-mentioned malfunction can be prevented.

As mentioned above, in the present invention, when the output relay is off, a compensation circuit having the same resistance as the output relay is turned on, so that voltage instability can be prevented with a simple power supply, malfunction can be prevented, and stability can be achieved. This has the effect that it can be operated.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram of an embodiment of the present invention.
FIG. 2 is a specific circuit diagram of the same as above. DESCRIPTION OF SYMBOLS 1... Reverse phase, open phase detection circuit, 2... Photocoupler, 3... First rectifier circuit, 4... First determination circuit, 5... Second rectifier circuit, 6... Impedance, 7... ... constant voltage circuit, 8 ... second judgment circuit,
9... Relay drive circuit, 10... Compensation circuit, 11
...Output relay, _R14 ...Resistor.

Claims (1)

[Claims] 1 Connect the reverse phase and open phase detection circuits connected to each RST phase to the first rectifier circuit via a photocoupler,
connecting the first rectifier circuit to a first determination circuit;
A second terminal connected to each phase of ST via impedance.
of the rectifier circuit directly and through the constant voltage circuit.
and the first and second determination circuits are connected to a relay drive circuit, and the output relay is reversed to the non-operating side when a reverse phase or an open phase occurs. What is claimed is: 1. A negative phase and open phase detection circuit, which turns on a compensation circuit having the same resistance as the output relay when the output relay is off.