JPS58156863A - Detecting circuit for opposite phase and open phase - Google Patents

Abstract

PURPOSE:To detect an opposite phase and phase absence stably at low cost by a small-sized constitution while improving the precision of the detection, by turning off an output relay once the opposite phase or open phase state occurs. CONSTITUTION:A voltage detecting circuit 1 for opposite phase and open phase in R-phase is connected in respective phases R, S, and T and detects a voltage dropping below a normal voltage in case of the occurrence of an opposite phase or open phase state; and it is connected to the 1st voltage level deciding circuit 3 while insulated by a photocoupler 2. An S and T open phase voltage detecting circuit 4 is connected to the phases S and T respectively and detects a voltage dropping below the normal voltage in case of open of the phases S and T; and it is connected to the 2nd voltage level detecting circuit 5. A relay driving circuit 6 turns off the output relay 7 when an opposite phase or open phase occurs. Consequently, the precision of the opposite phase and open phase detection is improved, the detection is carried out stably, and a small-sized, inexpensive constitution is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a reverse phase and phase loss detection circuit that detects reversal of phase rotation and phase loss of one phase in a three-phase circuit, and reverses the output to the non-operating side in either case. Regarding R, S, T
The reverse phase and R phase open phase voltage detection circuits connected to each phase are connected to the first voltage level determination circuit via a photocoupler, and S1
The S and T phase open phase voltage detection circuits connected to each phase of T are connected to a second voltage level determination circuit, and the first voltage level determination circuit and the second voltage level determination circuit are connected to a relay drive circuit. Connect and output when reverse phase or phase loss occurs.
This relates to a negative phase/open phase detection circuit characterized in that it is configured by inverting the phase difference to the non-operating side.

An object of the present invention is to improve the accuracy of detecting reversed phase and open phase, to enable stable detection, and to make the detection compact and inexpensive.

Conventionally, detection of reverse phase and open phase has been operated by independent detection circuits, and there is a system that uses an AC relay as a voltage detector to detect both reverse phase and open phase as an abnormality. However, with this type, it is difficult to guarantee the characteristics because it depends largely on the operating voltage characteristics of the AC sushi.The disadvantages are that it is large and expensive because it requires two AC relays. It had

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

In Figure 1, the tlFi reverse phase and R phase open phase voltage detection circuit is connected to the R, S, and T phases, and is used to detect that the voltage is lower than normal when there is a reverse phase and R phase open phase. to do,
It is insulated with a photovoltaic tube (2) and connected to the first voltage level determination circuit (3). (4) is the S and T phase open phase voltage detection circuit, which is connected to each S1T phase and detects that the voltage is lower than normal when each S and T phase is open.
Connected to the second voltage level determination circuit (5). (6) is a relay drive circuit which inverts the output relay (7) to the non-operating side when the phase is reversed or one phase is open. (8)
is a power supply circuit that supplies power to each circuit.

FIG. 2 is a specific circuit diagram of the embodiment shown in FIG.
Connected to 1T phase. Also, the first voltage is the bell! l#
1 constant circuit (3) and second voltage level determination circuit (5)
Cossiparators COMP, COMP2, and COMP2 are used, respectively, and these cossiparators are outputs from an aperture collector. Further, instead of output sushi (7), ra-zu, zuza, etc. may be used.

Next, the operation will be explained with reference to FIGS. 1 and 2. The resistors R1, R1, R2 and ]'Jjishiri CI in Fig. 2 are Y-connected to the three-phase AC, and are a well-known negative phase detection circuit, so that the voltage across the resistor island is in positive phase and there is no open phase. in case of,
It is approximately equal to the line voltage of the R-8 phase divided by the resistors R1 and RI%R2. 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. In addition, in the case of a voltage open phase circuit, it is often connected to a three-phase induction motor, but in this case, even if the R phase is open due to the generated voltage from the motor, it does not become O, and the R-8 phase voltage It is natural that the voltage will be proportional to . Now, as mentioned above, the voltage across the resistor R8 decreases in abnormal conditions, so if the ratio of the Zener voltage of the Zener diode ZD and the resistor R1 is appropriately selected, the photoforce (2) can be reduced under normal conditions. It is possible to cause current to flow through the light emitting element (2a), but not to flow the current in the event of an abnormality. Diode D is for reverse breakdown voltage protection of the light emitting element (2a). The voltage across the resistive island connected to the light receiving element (2b) of the photocoupler (2) is as shown in FIGS. 3(a) to (c) depending on the input conditions. FIG. 3(a) shows the normal state, FIG. 3(b) shows the state of reverse phase or complete phase loss, and FIG. 3(c) shows the state of incomplete phase loss. Next, the diode D2, the diode IjC2,
When passed through a peak value rectifier circuit consisting of a resistor island, the voltage across the resistor R3, ie, the non-inverting input voltage of the cosciparator COMPi, becomes as shown in FIGS. 4(a) to 4(e). Figure 4 (a) shows the normal state, Figure 4 (6) shows the reverse phase or complete phase loss, and the third
Figure (c) shows the state of incomplete phase loss. Therefore, the voltage across the resistor during normal operation becomes a DC voltage as shown in FIG. 5(b). Therefore, by appropriately determining the inverted input voltage of the resistor & COMP, it is possible to turn off the cosiparator COMP in normal conditions and turn it off in abnormal conditions. Here, the resistor R3 is a resistor for discharging the electric charge of the cosciparator C2, and turns on the cosciparator COMP after a certain operating time when the input changes from normal to abnormal. Cossiparator COMPI is off,
When cosiparator COMP2 is also off, transistor Q1
becomes the oscillator, and the output sushi (7) is driven. If the cossiparator COMP becomes the oscillator, the cossiparator COMP
Even if the input state is such that P2 is turned off]
Since the outputs of MP, , COMP2 are connected, the output is turned on, transistor Q is turned off, and output (7) is released. As described above, the output relay (7) is turned off when the phase is reversed and the R phase is missing.

Next, the case of S phase or T phase open phase will be explained.

The line voltage of the ST phase is a resistance island, a diode ridge DB
% It is converted into a DC voltage that is approximately proportional to the input voltage by the rectifier and smoothing circuit using the cosidesizer C3.

Here, the resistance R,l-! Since it lowers the two-power voltage, ko'J5! It may be a jig or intertaftasis. As mentioned above, the voltage across C, is not stabilized, and is proportional to the voltage between the S and T phase lines by about 11, so this is the voltage across the resistor island, which is divided by a resistor island. The voltage is, of course, a direct current voltage, such as an ST phase line phase line pressure voltage. Since some ripple voltage occurs in the voltage across the voltage sensor C3, the voltage difference +Jc4 is smoothed to reduce this voltage. It's Siri. The voltage across the terminal C8 is a constant voltage circuit made up of resistors R, o, Zener diode ZD2, and terminal C5, and is a stable DC voltage V within a certain range of the S-T phase line voltage. It becomes 0. This can be similarly achieved with transistors and other constant voltage circuits.

The non-inverting input of the cosciparator COMP2 has a cosciparator c.
A voltage of 4 is applied across the terminal, and a voltage of V is applied to the inverting input. 0 as resistance R
A reference voltage divided by 11RI2 is applied. Therefore, if there is a voltage between the ST phase line and the voltage drops below the level, the cossiparator COMP2 turns on, and if it rises above a certain level, the cossiparator COMP2 turns off.

An open phase in the S phase or the T phase is detected by such an operation, and the output sushi (7) is released. In addition, the cosiparator COMP
Even if the input of , is a condition for turning off the cosciparator COMP, if the cosparator COMP2 is turned on, the output sushi-(7) is turned off preferentially.

To summarize the above, if the phase is positive and there is no open phase in RX, sXT, then the output is output (7). The output relay (7) is turned off. Note that the above operation can be easily reversed by adding an inverting circuit formed by a transistor to the front stage of the relay drive circuit (6).

As described above, the present invention detects the negative phase and R phase open phase voltage detection circuits connected to each phase of the R15XT through a photoelectric force.
The S and T phase open phase voltage detection circuits connected to the S and T phases are connected to the voltage level judgment circuit of the second voltage level judgment circuit, and the S and T phase open phase voltage detection circuits connected to the S and T phases are connected to the second voltage level judgment circuit. The voltage level determination circuit is connected to the sushi drive circuit, and the output sushi is inverted to the non-operating side when a reverse phase or an open phase occurs.This improves the detection accuracy of reverse phase or open phase. It has the advantage of being able to detect stably, and being small and inexpensive.

[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 the above, and Fig. 3 (a) to (c) shows resistors connected in series with the photovoltaic force as shown above. Voltage waveform diagrams under the conditions, Figure 4 (a) to (c) are the same heat value rectification r
T! FIG. 4 is an output voltage waveform diagram under various conditions of the circuit. fil...Reverse phase, R phase open phase voltage detection circuit, (2)...
・Photocoupler, (3)...first voltage level determination circuit, (4)...s1T phase open phase voltage detection circuit, (5)・
...Second voltage level determination circuit, (6)...Relay drive circuit, (7)...Output relay. Agent Patent Attorney Ishi 1) Long Shichigan Figure 3 (0) (b) (C) Figure 4 (0) (b) (C)

Claims (1)

[Claims] (11R% 8% The negative phase and R phase open phase voltage detection circuits connected to each phase of T) are connected to the first voltage level determination circuit via an odocoupler, and the SXT phase open phase voltage detection circuits are connected to the SX% phase. The circuit is connected to the second 'magnetic pressure level pre-judgment circuit, and the above-mentioned 4! The j1 voltage output bell 4#4J constant circuit and the second voltage output bell judgment circuit are connected to the relay drive circuit, and when a reverse phase or an open phase occurs, the output relay is reversed to the non-operating side pressure. Features reverse phase and open phase detection circuit.