Emergency supervisory system

• US 4,752,698 A
• Filed: 07/21/1986
• Issued: 06/21/1988
• Est. Priority Date: 07/19/1985
• Status: Expired due to Term

• Current Assignee: Hochiki Kabushiki Kaisha
• Original Assignee: Hochiki Corporation
• Inventors: Kojima, Yoshinori, Fournier, Louis, Yuchi, Sadataka, Tsuru, Hiroaki, Furuyama, Akira, Kurimoto, Mitsuhiro, Matsuoka, Naoya
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Ip, Paul
• Application Number:
  US06/887,237
• Time in Patent Office: 701 Days
• Field of Search: 307/34, 307/35, 307/37, 307/38, 307/39, 307/40, 307/41, 307/116, 307/115, 370/53, 370/55, 370/57, 370/58, 370/67, 370/89, 370/86, 370/88, 370/87, 370/85, 340/825.06, 340/504, 340/825.05, 340/507, 340/825.13, 340/508, 340/825.12, 340/825.18, 340/310 A, 340/310 R, 364/492, 364/493, 361/41, 361/93, 361/90, 361/92
• US Class Current: 307/116
• CPC Class Codes: G08B 25/045 with sensing devices and central station in a closed loop, e.g. McCullough loop

Abstract

The present invention relates to an emergency supervisory system which comprises a plurality of supervisory apparatus provided for respective supervisory regions and connected in parallel with each other to signal lines derived from a central signal station; and switching devices which are provided at positions for separate the supervisory apparatus from each other and adapted to be closed normally and opened upon detection of short-circuiting to separate the supervisory apparatus adjacent thereto from the lines, thereby to supervise an emergency such as a fire through one or both of the signal lines.

Claims

1. An emergency supervisory system comprising:

a central signal station and a pair of power lines connected thereto in a loop for receiving therefrom a supply voltage and call signals corresponding to individual addresses;

a plurality of individual supervisory means each having a respective address and connected in parallel to said lines for receiving therefrom said supply voltage and a respective call signal corresponding to the respective address thereof;

each supervisory means comprising detector means disposed in a corresponding supervisory region for monitoring physical variables for emergency conditions, and trunk means for receiving data acquired by said detector means relating to the physical variables being monitored;

such trunk means further receiving the corresponding call signals as instructions to transmit the acquired supervisory data to the central signal station;

a plurality of switching means respectively connecting said plurality of supervisory means to said power lines in parallel;

each switching means comprising detection circuitry connected to one power line for electrically detecting the presence and absence of fault conditions on a corresponding load side thereof, a switch connected to said one power line, and switching control circuitry for actuating said switch to an open state for effectively disconnecting the corresponding supervisory means from said one power line to thereby electrically isolate it from the system when a fault condition is detected and for actuating the switch to a closed state maintaining connection of the corresponding supervisory means to the power line when the absence of a fault condition is detected; and

means in the central signal station for receiving the supervisory data transmitted by the supervisory means and for effecting transmission of said call signals and said supervisory data to an opposite end of the power line loop other than the end thereof in use preceding the detection of a fault condition when any of said switching means determines a fault condition and has disconnected a supervisor means;

said switching means detection circuitry comprising;

a first short-circuit detecting circuit for detecting a short circuit between the power lines when the line voltage at the connection of said switch to said one power line is lower than a first predetermined voltage which is lower than the line voltage following such connection; and

a second short-circuit detecting circuit for detecting a short circuit between the power lines when the line voltage at such connection is lower than a second predetermined voltage which exceeds the line voltage following such connection;

said switching control circuitry comprising a switching control circuit responsive to outputs of the first and second short-circuit detecting circuits.

2. An emergency supervisory system according to claim 1, in which the switching control circuit comprises means for generating a first control output for activating the switch to an open state when a fault condition is detected and means for generating a second control output for activating the switch to a closed state when the absence of a fault condition is detected.

3. An emergency supervisory system according to claim 2, in which said switching means comprises inhibiting means to inhibit a change of state of said switch, thereby to effect a lag in changes of state of the switch.

4. An emergency supervisory system accirding to claim 3, in which said inhibiting means to inhibit a change of state of said switch is a mono-stable multi-vibrator.

5. An emergency supervisory system according to claim 1, further comprising inhibiting means receptive of the short-circuit detecting circuit outputs as a trigger for developing an inhibit signal output applied to said switching control circuit to delay the switching control circuit actuation of the switch for a delay period set to allow time for reset time for devices on a load side of the switching means.

6. An emergency supervisory system according to claim 1, including a resistor connected in said one power line shunting said switch to provide reduced power voltage to said one line on a load side of the switching means while normal power voltage is applied and the switch is in an open state, the resistance of the resistor having a predetermined value to keep the voltage on said one line below normal until the switch assumes a closed state.

7. An emergency supervisory system according to claim 1, in which each said switching means comprises means for developing a selected constant voltage lower than normal line voltage and for appling said constant voltage to said one power line on said load side of said switching means when said switch is an open state, said constant voltage having a preselected level for maintaining a voltage on said one power line effective to keep microcomputers on said line from erratic operations when the power line is open for a predetermined time.