JPH0359701A - Fail-safe circuit - Google Patents

Abstract

PURPOSE:To turn on all lighting loads only when abnormality is generated in a transmission line by allowing latching relay charge accumulated from the transmission line to flow into the ON winding of a latching relay only when both of a load power supply and transmission line abnormality detecting output exist. CONSTITUTION:Driving power for turning on/off the latching relay is obtained from the transmission line 2 and a transmission line abnormality detecting part 6 and a load power supply detecting part 8 are included in a terminal equipment. Only when both the load power supply detecting output and transmis sion line abnormality detecting output exist, latching relay driving charge accu mulated from the transmission line 2 is allowed to flow into the ON winding 72 of the latching relay. Consequently, all the lighting loads can be turned on by fail safe control only when transmission abnormality such as transmission line disconnection and short-circuit is generated without executing the fail safe control at the time of service interruption.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a control terminal connected to a two-wire transmission line and receiving transmission signals from a central processing unit to remotely monitor and control a lighting load. Regarding fail-safe circuits.

[Prior Art] Conventionally, a system is known in which one or more lighting loads connected to each of a plurality of terminal devices are centrally controlled on/off based on a transmission signal from a central processing unit.

FIG. 3 shows the configuration of a load control system that is a conventional example and is also an example to which the present invention is applied, as will be described later. In the figure, 1 is a central processing unit, 2 is a two-wire transmission line, and 31 is a control terminal that receives transmission signals sent from the central processing unit 1 to the transmission line 2 and controls the lighting load 33 on/off. It is.

The control terminal 31 turns on/off an internal control latching relay (not shown) based on a transmission signal sent from the central processing unit 1, and the lighting load 33 turns on/off as the latching relay turns on/off. Turned on/off.

[Problem i to be solved by the invention] By the way, such a system is provided with a fail-safe circuit, which detects an abnormality in the transmission line 2 and turns on all lighting loads 33 in the event of an abnormality. .

However, according to such conventional fail-safe circuits, all lighting loads turn on when the power is restored from a power outage, and in order to return to the control state immediately before the power outage, an operation must be performed to return to the original control state. There was a problem that it was necessary.

In particular, in the event of a so-called instantaneous power outage, all lighting loads, including lighting loads that had been turned off, will be turned on instantly, causing discomfort to those in the room.

In view of the problems with the conventional type described above, the present invention maintains the original control state without performing fail-safe control in the event of a power outage, and performs fail-safe control only when a transmission line abnormality such as a disconnection or short circuit occurs in the transmission line. The purpose of this invention is to provide a fail-safe circuit for a lighting control system that lights up the entire lighting load.

[Means and effects for solving the problem] In order to achieve the above object, the present invention provides a system that is connected to a two-wire transmission line and receives a transmission signal sent from a central processing unit via this transmission line. , a fail-safe circuit for a control terminal device that controls on/off a predetermined lighting load by turning on/off a control latching relay based on this transmission signal. The power source for driving is obtained from the transmission line, and a transmission line abnormality detection part and a load 7TF source detection part are installed in the terminal, and only when there is a load power supply detection output and a transmission line abnormality detection output, transmission is performed. The electric charge accumulated through the wire for driving the latching relay is made to flow into the on-winding of the latching relay.

As a result, the fail-safe control is activated only when the load power supply is present and an abnormality in the transmission line is detected. Conversely, even if an abnormality in the transmission line is detected, if the load power supply is lost (for example, due to a power outage), the failsafe control will not work and the lighting load will remain on or off. Therefore, the entire lighting load will not be lit.

Furthermore, the power supply for driving the latching relay is not obtained from the transmission line, but from the load power supply side of the lighting load, and the abnormality detection output of the transmission line is configured to be supplied to the on-winding drive circuit of the latching relay. You can also do it.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block circuit diagram showing a schematic configuration of a control terminal equipped with a fail-safe circuit according to an embodiment of the present invention. The control terminal device configured as shown in the figure is connected to the third
An example used as the terminal device 31 shown in the figure will be described below.

In FIG. 1, 2 is a two-wire transmission line connected to the central processing unit, 3 is a transmission interface, 4 is a power supply circuit for obtaining electricity from the transmission line 2 via the transmission interface 3, and 5 is a power supply circuit for obtaining electric power from the transmission line 2 via the transmission interface 3. This is a signal processing device for controlling the lighting device 6; 1 on/off by analyzing the transmission signal on the transmission line 2 and controlling the latching relay on/off based on the transmission signal. Further, 6 is a transmission abnormality detection circuit for detecting an abnormality such as a disconnection or short circuit in the transmission line 2, 8 is a load power supply detection circuit for detecting the presence or absence of a load power supply, and 9
is an AND circuit, and 10 is an OR circuit. 71 is an off winding of the latching relay, 72 is an on winding, and 73 is a relay contact, which constitute a latching relay. 74 is a switching transistor for turning off the latching relay, and 75 is a switching transistor for turning on the latching relay.

In the above configuration, when the transmission signal on the transmission line 2 indicates ON control, the signal processing device 5 inputs this transmission signal via the transmission interface 3, and sends the ON signal to one input terminal of the OR circuit 0. Output towards the target. This ON signal is applied via the OR circuit 10 to the base terminal of a switching transistor 75 for driving the ON winding 72. This turns on transistor 75 and turns on winding 7
2 is supplied with current, and the relay contact 73 is turned on. As a result, power is supplied to the predetermined lighting load and the lighting load is turned on.

On the other hand, when a transmission signal indicating off control is sent to the transmission line 2, the signal processing device 5 sends an off signal to the base terminal of the switching transistor 74 for driving the off winding 71. As a result, the transistor 74 turns on and current is supplied to the off winding 7I, and the relay contact 73
turns off. Therefore, power is not supplied to the connected lighting load and the lighting load is turned off.

Next, the operation of the amount generated during a power outage and the amount normally generated by a transmission line will be explained.

Table 1 below shows the output of each block in the event of a power outage or a transmission line abnormality such as a transmission line disconnection.

The ON signal output of the signal processing device 5 in Table 1 (■) is a signal that is output to one of the input terminals of the OR circuit 10, and the output is This is the low health signal L (Low). As the output of the transmission abnormality detection circuit 6 in (2), a high level signal H (High) is outputted because an abnormality in the transmission line 2 is detected in both cases of power failure (2), 1, and transmission line abnormality. Since the output of the load power supply detection circuit 8 in (2) is the same as when there is a load power supply and there is no H1, L is output during a power outage, and the transmission line 54J
If one episode occurs, H is output.

Here, since the AND circuit 9 has two inputs, the output of the transmission abnormality detection circuit 6 (■) and the output of the load power supply detection circuit 8 (■), the output of the AND circuit 9 becomes H because the negative angle power supply is This is a case where an abnormality is detected in the transmission line. At this time, the output H of the AND circuit 9 turns on the switching transistor 75 via the OR circuit 10, thereby supplying current to the on winding 72. Therefore, the relay contact 73 is turned on, and 1((bright load is lit.) If a transmission abnormality is detected in this way, fail-safe control can be performed to light all the lighting loads.

On the other hand, according to Table 1 above, when the power supply from the load power supply is lost due to a power outage, etc., the load power supply detection circuit 8
Since the output of the AND circuit 9 is L, the output of the AND circuit 9 is L.

Therefore, the fail-safe control does not work and the relay contacts are maintained as they were at the time of power outage, so there is no change in the control state of the lighting negative G even if the power is restored from a power outage or the like.

FIG. 2 is a block circuit diagram showing an example of a fail-safe circuit in which power for a latching relay is obtained from a load power supply. In this figure, members or blocks common to those in FIG. 1 are denoted by the same numbering.

In Fig. 2, 11 is a transformer for obtaining power for driving the latching relay from the load power supply, 12 is a rectifier circuit, and 1
3.14 is a transistor, 15 is a capacitor, and 16 is a diode. In the circuit shown in FIG. 2, unlike the circuit shown in FIG.

In the above configuration, normal on/off control of the lighting load is performed by the signal processing device sending out an off signal or an on signal based on the transmission signal of the transmission line. That is, when the signal processing device 5 inputs an off signal to the base terminal of the switching transistor 74 for driving the off winding 71, the transistor 74 is turned on and the off winding 71 is turned on.
Current is supplied to the relay contact 73 to turn it off. Thereby, the predetermined lighting load is controlled to be turned off. Further, when the signal processing device 5 outputs an on signal to the OR circuit 10,
The ON signal is inputted to the base terminal of the switching transistor 75 for driving the ON winding 72 via this OR circuit IO, and current is supplied to the ON winding 72. This results in
Relay contact 73 is turned on, and lighting of the lighting load is controlled.

In the above control, 1, power for the off winding 71 and the on winding 72 is supplied from the load power supply. That is, the voltage from the load power source is stepped down to an appropriate voltage by a transformer 11, rectified by a rectifier circuit 12, smoothed by a capacitor 15, and this voltage is transferred to an OFF winding 71 and an ON winding 7.
2.

When power is being supplied from the load power source, the transistor 13 is turned on, and the transistor 14 is thereby turned off.

Here, suppose that the power supply from the load power supply is lost, for example, due to a power outage. At this time, the transistor 13 is turned off, and the charge stored in the capacitor 15 turns on the transistor 14, so that the charge stored in the capacitor 5 immediately becomes zero.

Therefore, from this point on, the off winding 71 and the on winding 7
2 is not supplied with power and the relay contact 73 does not operate. That is, in the event of a power outage, the failsafe control does not work, and the relay contact 73 remains in the state immediately before the power outage. Therefore, when the power is restored from the power outage, the lighting load will be turned on or off again in the original control state.

On the other hand, if a transmission line abnormality is detected when the load power source is supplied with power, the output of the transmission abnormality detection circuit 6, that is, the human power of one of the OR circuits 10 becomes a signal H, so that the signal for driving the ON winding 72 is A signal H is applied to the base terminal of the switching transistor 75, and this transistor 75 is turned on. Since the load power supply is in the ON state, current is supplied to the ON winding 72 at this time and the relay contact 73 is turned ON.

In this way, fail-safe control is achieved in the event of a transmission line abnormality.

[Effects of the Invention] As explained above, according to the present invention, fail-safe control is not performed in the event of a power outage, and all lighting loads are turned on by fail-safe control only in the case of a transmission line abnormality such as a transmission line disconnection or short circuit. be able to. Therefore, when the lighting load recovers from the power outage state, the lighting load remains in its original on or off state, and there is no need for the user to perform control to return to the original state. In addition, there is an advantage that momentary turning off at 0 o'clock and turning on of the entire lighting load are prevented, and no discomfort is caused.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing a schematic configuration of a control terminal equipped with a fail-safe circuit according to an embodiment of the present invention. FIG. FIG. 3 is a block circuit diagram showing a schematic configuration of a control terminal using a safe circuit, and is a configuration diagram of a load control system which is a conventional example and is also an example to which the present invention is applied. 1; Central processing unit, 2; Transmission line, 3; Transmission interface, 5; Signal processing device, 6; Transmission entry detection circuit, 8; Load power supply detection circuit, 9; AND circuit, 1
0; OR circuit, 71; Off winding, 72; On winding,
73; Relay contact, 13.14, 74, 75, h transistor.

Claims (2)

[Claims] (1) Connected to a two-wire transmission line, receives a transmission signal sent from the central processing unit via the transmission line, and turns on/off the control latching relay based on the transmission signal to perform a predetermined control. A fail-safe circuit for a control terminal that controls on/off of a lighting load, comprising: power supply means for obtaining power for the latching relay from the transmission line; and transmission line abnormality detection means for detecting an abnormality in the transmission line. and a load power source detection means for detecting the presence or absence of power source power supplied to the lighting load, and only when the load power source is present and the transmission line abnormality detection output is present, the latching relay is used for the latching relay accumulated from the transmission line. 1. A fail-safe circuit comprising: control means for causing electric charge to flow to an on-winding of a latching relay. (2) Connected to a two-wire transmission line, receives a transmission signal sent from the central processing unit via the transmission line, and turns on/off the control latching relay based on the transmission signal to perform a predetermined operation. A fail-safe circuit for a control terminal device that controls on/off of a lighting load, comprising a power source means for obtaining power for the latching relay from a load power source for the lighting load, and detecting an abnormality in the transmission line. A fail-safe circuit comprising: transmission line abnormality detection means; and control means for driving the on-winding of the latching relay when there is a transmission line abnormality detection output.