JPH0636628B2 - Current type control circuit in remote monitoring equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an operation monitoring circuit and a logic in a remote monitoring device for remotely controlling a power load such as a general-purpose motor and displaying the operation state to monitor the load. Control circuit connected to a load control circuit such as a circuit and transmitting an input signal from the load control circuit, such as the operating state of the load, to the operation circuit and receiving a control command from the operation monitoring circuit and outputting the control command to the load control circuit Is.

[Conventional technology]

Such a distant monitoring device is for centrally monitoring and controlling electric equipment for air conditioning and water supply / drainage of buildings which are often installed in a distributed manner, and as a remote control system thereof, a multiplex transmission control system is mainly used. The simple and economical single-track control system is often adopted. Among this single line control system,
The AC power supply type single line control system is widely used for remote monitoring control of a power load such as a lighting device because of the economic efficiency of the power supply and the simplicity of the operation monitoring circuit. As a conventional example of the control circuit of the remote monitoring device of the AC power source type single line control system, there is, for example, the one shown in the third diagram. In FIG. 3, reference numeral 2 denotes a control circuit, which is a keep relay 8 including a load contact 3 connected to a load, an electromagnetic coil 4 for operating the load contact 3 and a switching auxiliary contact 7 interlocking with the load contact 3. It has two diodes 5 and 6, and the two diodes 5 and 6 are connected in parallel between the electromagnetic coil 4 and the switching terminal of the switching auxiliary contact 7 with opposite polarities. Reference numeral 1 is a control power supply transformer, one end of the secondary side of which is connected to the electromagnetic coil 4 of the control circuit, and the other end of which is a common communication line 9.
Control circuit 2 via operation monitoring circuit 10 and signal communication line 17
Is connected to the common terminal of the switching auxiliary contact 7. The operation monitoring circuit 10 includes a display circuit in which light emitting diodes 13 and 14 are connected in parallel to each other in opposite polarities and a resistor 16 is connected to one end thereof, and diodes 11 and 12 are connected in parallel to each other in opposite polarities and a three-point selector switch is connected to one end thereof. An operation circuit to which 15 is connected is connected in parallel between the common communication line 9 and the signal communication line 17 to the display circuit and the operation circuit.

However, when the selector switch 15 of the operation monitoring circuit 10 is tilted toward the diode 12 side from the intermediate position, the selector switch 1
A closed circuit of 5-diode 12-transformer 1-electromagnetic coil 4-diode 5-switching auxiliary contact 7-switching switch 15 is formed, and the current I ₁ flows in the direction of the arrow in this circuit, and the electromagnetic coil 4 is excited. The load contact 3 is closed and a load such as a motor is activated, and the switching auxiliary contact 7 is switched to the diode 6 side in conjunction with the load contact 3. And with this, the current I
₁ is blocked, the switching auxiliary contact 7- diode 6- electromagnetic coil 4 transformer 1-emitting diode 13 resistor 16 switched closed circuit is formed of the auxiliary contact 7 current _{I 2} in this circuit
Flows in the direction of the arrow, the light-emitting diode 13 lights up, and the load of the load contact 3 is closed. The current I _{2 at} this time is the electromagnetic coil 4
Since the resistor 16 is connected in series, the operating current of the keep relay 8 is smaller, and the electromagnetic coil 4 is not excited by this.

Next, when the changeover switch 15 of the operation monitoring circuit 10 is changed over to the diode 11 side, the diode 11-the changeover switch 15-the changeover auxiliary contact 7-the diode 6-the electromagnetic coil 4-
Closed circuit of the transformer 1 diode 11 is formed, since the resistor 16 to the electromagnetic coil 4 to the current I _{2 (in} this case current I ₂ in this circuit is not connected in series, the keep relay 8
Flow in the direction of the arrow, the electromagnetic coil is excited, the load contact 3 opens, and the load such as the motor stops, and the switching auxiliary contact 7 is switched to the diode 5 side in conjunction with the load contact 3. And with this, the current I ₂ is cut off,
Diode 5- switching auxiliary contact 7 resistor 16 light-emitting diodes 14 transformer 1 closed circuit of the electromagnetic coil 4 diode 5 is formed a current _{I 1} to the circuit (current _{I 1} in this case is to the electromagnetic coil 4 Since the resistor 16 is connected in series, a current smaller than the operating current of the keep relay 8 flows, the light emitting diode 14 lights up, and the load contact 3 is opened, so that it is indicated that the load such as the motor is stopped. .

[Problems to be solved by the invention]

However, the control circuit in this conventional remote monitoring device is intended to control the load by giving directionality to the operating current flowing in the electromagnetic coil by the switching connection of the switching auxiliary contacts for the two diodes connected in parallel with opposite polarities. Therefore, there is an inconvenience that the operation switch in the operation monitoring circuit has to be a two-way closing type. Further, it is possible to connect the operation monitoring circuits in parallel via one common communication line and the signal communication line, but in this case, if the ON command and the OFF command are simultaneously issued from a plurality of operation monitoring circuits, the keep relay will be released. There was a problem that a flapping phenomenon that repeatedly turns on and off occurred. Further, since the load control circuit and the control circuit that sends a control signal to the load control circuit are connected by a keep relay, the control operation may lack stability and reliability due to lack of insulating property against noise, and the load control circuit may not be logical. Since it cannot be an electronic circuit by a circuit, it has a drawback that it cannot be used for power control that requires fault monitoring such as general-purpose motor control.

An object of the present invention is to solve the problems of the conventional technique.

[Means for solving problems]

In order to achieve the above object, the present invention is connected to a load control circuit such as an operation monitoring circuit and a logic circuit, transmits an input signal such as an operating state of a load from the load control circuit to the operation monitoring circuit, and the operation monitoring circuit. In a control circuit in a remote monitoring device that receives a control command from the controller and outputs it to a load control circuit, a current control transistor and a threshold current detection transistor, a reception current control resistor and a threshold current detection resistor, and a transmission photocoupler And a receiving photocoupler, between the collector and base of the current control transistor, in order to transmit the input signal such as the operating state of the load input to the control circuit to the operation monitoring circuit by identifying the presence or absence of the current flowing in the control circuit. Connect the output end of the transmission photocoupler via the reception current control resistor to the control command from the operation monitoring circuit In order to output to the load control circuit such as a logic circuit by distinguishing the magnitude of the current flowing through the control circuit based on the threshold current set by the current detection resistor, the emitter of the current control transistor connected to the threshold current detection resistor It is characterized in that the input end of the receiving photocoupler is connected to the emitter of the threshold current detection transistor connected to the base.

[Action]

When the input signal 1 of the operating state of the load is input to the transmission photocoupler of the control circuit, a current flows to the base of the current control transistor through the reception current control resistor, the current control transistor becomes conductive, and the threshold current A current flows through the control circuit through the detection resistor, and the monitoring light emitting diode of the operation monitoring circuit lights up to display the operating state of the load based on the input signal 1. In this case, the current flowing in the control circuit is small because it is limited by the monitoring current limiting resistance connected in series to the monitoring light emitting diode of the operation monitoring circuit, so the threshold current detection transistor does not conduct and the receiving photocoupler does not operate. . When the operation push button of the operation monitoring circuit is pressed in this state, the monitoring current control resistor is short-circuited, so a large current flows in the control circuit, and the threshold current detection transistor conducts, limiting the base current of the current control transistor. The current flowing through the control circuit becomes a constant current, that is, the threshold current I ₁ set by the threshold current detecting resistor, and the current I ₂ limited by the receiving current controlling resistor flows on the light emitting side of the receiving photocoupler. The received signal becomes 1 and the receiving photocoupler operates to output a control command to a load control circuit such as a logic circuit to control the load. When the control command is output from the receiving photocoupler, the input signal to the transmitting photocoupler becomes O as an answerback, the current control transistor becomes non-conductive accordingly, and the monitoring light emitting diode is turned off to control the load. Is displayed. However, the operation push button of the operation monitoring circuit is turned off by the lever state to prepare for the next control command.

As described above, the operation signal of the load input to the transmission photocoupler is transmitted to the operation monitoring circuit by detecting the input signal as the presence or absence of the current flowing in the control circuit via the current control transistor, and the operation monitoring circuit The control signal is output from the receiving photocoupler by detecting the control signal as the magnitude of the current flowing in the control circuit through the threshold current detection transistor, that is, the threshold current.

The current flowing through the control circuit when a control command is issued from the operation monitoring circuit is a constant current set by the threshold current detection resistor, that is, the threshold current.

〔Example〕

Next, an embodiment of the present invention will be described with reference to FIGS.

Reference numeral 20 denotes a control circuit, which is connected in series with the operation monitoring circuit 21 via a DC power source E. Control circuit 2
0 has a current control transistor Q ₁ and a threshold current detection transistor Q ₂ , a threshold current detection resistor R ₁ and a reception current control resistor R ₂ , a transmission photocoupler P ₁ and a reception photocoupler P _2. is doing. The output end of the transmission photocoupler P ₁ is connected between the collector and the base of the current control transistor Q ₁ via the reception current control resistor R ₂ . The emitter of the current control transistor Q ₁ is connected to the threshold current detection resistor R ₁ and the base of the threshold current detection transistor Q ₂ . The collector of the threshold current detection transistor Q ₂ is connected to the base of the current control transistor Q ₁ and the output terminal of the transmission photocoupler P ₁ . The emitter of the threshold current detection transistor Q ₂ is connected to the other end of the threshold current detection resistor R ₁ via the input end of the reception photocoupler P ₂ . Operation monitoring circuit 21
Has an operation push button switch PB, a monitor current control resistor R, and a monitor light emitting diode LED. The operation push button switch PB and the monitor current control resistor R are connected in parallel, and one end of this parallel circuit is a monitor light emitting diode LED. Connected to the anode side of. In the figure, a is a current input terminal, b is a current output terminal, c is a transmission (input) signal terminal, and d is a reception (control).
The control circuit 20 is a signal output terminal, and the signal input terminal c,
It is connected to a load control circuit such as a logic circuit via d.

FIG. 2 is a time chart between the current flowing in the control circuit of the control circuit in the remote monitoring apparatus according to the above embodiment, the operation push button switch, and the input / output signals of the transmission / reception photocouplers P ₁ and P ₂ .

In the figure, the state of the time chart T ₁ shows the case where the input signal 1 of the operating state of the load is input to the transmission photocoupler P ₁ from the load control circuit such as the logic circuit. When a current flows to the light emitting side of the photocoupler P _1, the light receiving transistor becomes conductive, and the current control transistor Q ₁ passes through the reception current control resistor R _2.
Base current flows to the, the transistor Q ₁ is turned on.
Along with this, a current flows through the monitoring light emitting diode LED through the threshold current detection resistor R ₁ and the monitoring current control resistor R of the operation monitoring circuit 21, and the LED is turned on to display the operating state of the load. At this time, the current flowing through the control circuit is limited by the monitoring current control resistor R, so that the potential appearing across the threshold current detection resistor R ₁ causes a current to flow to the base of the threshold current detection transistor Q _2. It is sufficiently smaller than the electric potential. That this potential threshold current detecting base of the transistor Q ₂ - for those sufficiently smaller than the sum of the voltage and the light emitting side forward voltage of the reception photocoupler P ₂ between the emitters, transistor Q ₂ is not conducting, Therefore, no current flows on the light emitting side of the receiving photocoupler P _2, the received signal is O, and the receiving photocoupler P ₂ does not operate.

In the time chart T ₂ , the operation push button switch PB of the operation monitoring circuit is pressed from the above state to issue the control command. In this case, the operation push button switch PB is turned on.
As a result, the monitoring current control resistor R is short-circuited, so that a larger current flows through the threshold current detection resistor R ₁ than at the time of transmitting the input signal, and the potential appearing at both ends thereof becomes large. a current flows through the _second base conductive transistor Q ₂ is, current control transistors Q ₁
The base current is restricted and the current flowing through the resistor R ₁ becomes a constant current, that is, the threshold current I ₁ set by the resistor R ₁ . Then, on the light emitting side of the reception photocoupler P ₂ , a current I ₂ limited by the reception current control resistor R ₂ flows through the transistor Q ₂ , a control command is received (reception signal 1), and the reception signal output terminal is used. A control signal is output to a load control circuit such as a logic circuit to control the load. The time chart T ₃ shows the case where the load is controlled based on the control command and the input signal to the transmission photocoupler P ₁ becomes O as an answer back. In this case, the light emission side current of the transmission photocoupler P ₁ becomes O. Therefore, the light-receiving side transistor becomes non-conductive, the base current of the current control transistor Q ₁ is cut off, the transistor Q ₁ becomes non-conductive, and the current flowing to the monitoring light-emitting diode LED becomes O and the LED becomes
Turns off, which indicates that the load is controlled based on the control command from the operation monitoring circuit.

From this state, the operation push button switch can be turned off, and the next input signal of the operating state of the load can be transmitted and the control command from the operation monitoring circuit can be received.

〔The invention's effect〕

As described above, the present invention transmits the input signal to the operation monitoring circuit by detecting the presence or absence of the input current based on the input signal of the operation state of the load to the transmission photocoupler by the current control transistor and displays the display. In addition, the threshold value of the current flowing in the control circuit is identified by the threshold current detection transistor, and the control command from the operation monitoring circuit is larger than the current when the input signal is transmitted and is set by the threshold current detection resistor. Since the current is detected and received as a value current, and the control signal is output to the load control circuit such as a logic circuit via the receiving photocoupler, the above-mentioned drawbacks of the conventional technique are eliminated and the following effects are produced. .

That is, the control current does not need to be directional, and thus the operation switch of the operation monitoring circuit does not need to be a bidirectional closing type, and a single-direction push button switch can be formed. The configuration can be made simpler than the conventional one, and the operation is also simple. Further, since the photocoupler is used for the control circuit, the insulation between the load control circuit and the control circuit of the monitoring device is good, so that the load control circuit can be an electronic circuit by a logic circuit. Furthermore, since the control command is received and output by detecting a constant current (threshold current) set by the threshold current detection resistor, the fluctuation allowance of the DC power supply voltage can be wide, and the noise margin is strong. The load control circuit can be electronically coupled with high stability and reliability, and the failure state of the load can be monitored.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a current type control circuit in a remote monitoring device according to an example of the present invention, FIG. 2 is a time chart of the same, and FIG. 3 is a circuit diagram of a conventional control circuit. 20 ...... control circuit, 21 ...... operation monitoring circuit Q 1 _...... current control transistor Q 2 _...... threshold current detector transistor R 1 _...... threshold current detection resistor R 2 _...... reception current control resistor P ₁ ... … Sending photocoupler P ₂ …… Receiving photocoupler PB …… Operation pushbutton switch R …… Monitor current control resistance LED …… Monitor light emitting diode

Claims (1)

[Claims] 1. An operation monitoring circuit and a load control circuit such as a logic circuit are connected to transmit an input signal from the load control circuit, such as an operating state of a load, to the operation circuit and receive a control command from the operation monitoring circuit. A control circuit in a remote monitoring device for outputting to a load control circuit includes a current control transistor and a threshold current detection transistor, a reception current control resistor and a threshold current detection resistor, a transmission photocoupler and a reception photocoupler. In order to transmit the input signal such as the operating condition of the load input to the control circuit to the operation monitoring circuit by identifying the presence / absence of current flowing in the control circuit, via the reception current control resistor between the collector and base of the current control transistor. The output terminal of the transmission photocoupler is connected, and the control command from the operation monitoring circuit is set by the threshold current detection resistor. Threshold current detection in which the base is connected to the emitter of the current control transistor connected to the threshold current detection resistor in order to output to the load control circuit such as a logic circuit by discriminating the magnitude of the current flowing in the control circuit based on the value current A current type control circuit in a remote monitoring device characterized in that an input end of a receiving photocoupler is connected to an emitter of a transistor.