Centralized control system for controlling loads such as an electric motor

• US 4,835,706 A
• Filed: 07/09/1987
• Issued: 05/30/1989
• Est. Priority Date: 07/16/1986
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Asahi, Shigeo
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Trans, V. N.
• Application Number:
  US07/071,736
• Time in Patent Office: 691 Days
• Field of Search: 364/492, 364/132, 364/200, 364/900, 340/825.05, 340/825.06
• US Class Current: 700/293
• CPC Class Codes: H02J 13/00017 using optical fiber
• CPC Class Codes: H02J 13/00019 using optical means
• CPC Class Codes: H02J 13/00034 the elements or equipment being or involving an electric power substation
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 40/124 using wired telecommunication networks or data transmission busses

Abstract

A centralized control system for controlling loads includes local or slave control stations, the number of which corresponds with the number of electric motors as loads, the local control stations each executing control of the making and breaking of each motor main circuit, a start compensating operation, and overload and phase-loss protection operations; a key or master control station for transmitting signals for making and breaking each motor main circuit, data signals associated with a soft starting period, and tripping conditions to each local control station, to thereby control the local control stations in a centralized manner; and optical fiber cables connecting between the key control station and the local control stations for data transmission so that a line of loop signal transmission path is formed. When optical signals are supplied to each local control station from the key control station, the optical signals are converted to electrical signals at each local control station. The local control stations fetch the electrical signals directed to the individual local control stations. The electrical signals directed to the other local control stations are converted to optical signals again and are transferred to the next local control station through the optical fiber cable.

Claims

1. A centralized control system for controlling a group of electric motors, comprising:

a single key control station;

a number of local control stations connected in series to the key control station through optical fiber cables so that a line of closed loop signal transmission path is formed between a signal delivering a signal receiving end of the key control station, said local control stations corresponding to a number of motors;

semi-conductive switching elements having gates provided so as to close and open electrical power supply circuits of the motors;

and a programmable controller for supplying each local control station with an on-off operation command for turning each semi-conductive switching element on and off to control each motor so that each motor is driven and stopped in accordance with a predetermined program, each of the local control stations comprising;

(a) a current transformer for measuring a load current flowing through a power supply circuit of the motor;

(b) an overload detector for detecting an output current of the current transformer to determine whether or not the motor is in the overload condition, thereby producing a detection signal, said overload detector executing a motor protection operation, of tripping the motor by turning off the semi-conductive switching element, in accordance with the detection signal;

(c) a first optical connector for converting optical signals to corresponding electrical signals, said first optical connector being connected to the optical fiber cable through which data is transmitted from other local control stations;

(d) a second optical connector for converting electrical signals to corresponding optical signals, said second optical connector being connected to the optical fiber cable through which data is transmitted to other local control stations;

(e) a signal receiving controller for sequentially receiving electrical signals corresponding to data supplied from the first optical connector;

(f) gate control means for controlling the gate of the semi-conductive switching element in accordance with data supplied from said signal receiving controller; and

(g) a signal delivering controller for sequentially delivering to the second optical connector detection data produced by the overload detector and output data produced by the current transformer so that both data are transmitted to the key control station, said signal receiving controller transmitting to the signal delivering controller data supplied from the first optical connector to be directed to other local control stations so that data supplied from the first optical connector to be directed to the other local control stations is transmitted through the second optical connector to the optical fiber cable;

the key control station comprising;

(a) soft starting period setting means for producing data associated with the soft starting of each motor in accordance with which each semi-conductive switching element is controlled so that the input voltage of each motor is gradually increased at the time of the starting of each motor;

(b) tripping condition setting means for producing data associated with the tripping of each motor to determine the time at which the overload detector starts the motor protection operation;

(c) a reference number selecting switch for providing reference numbers so that inherent reference numbers are given to the respective local control stations in order to direct data thereto;

(d) a first memory for storing the on-off commands produced by said programmable controller for each local control station;

(e) a second memory for storing data supplied from said soft starting period setting means by manually operating the same, the data being stored in the second memory for each local control station in a manner so that the data is discriminated by reference numbers of the local control stations;

(f) a third memory for storing data supplied from said tripping condition setting means by manually operating the same, the data being stored in the third memory for each local control station in a manner so that the data is discriminated by reference numbers of the local control stations;

(g) a signal delivering controller for converting data of on-off commands stored in the first memory and data stored in the second and third memories to serial electrical signals so that the data is transmitted to the respective local control stations;

(h) a first optical connector, connected to the optical fiber cable connected to the first local control station, the optical fiber connector converting the serial electrical signals supplied from the signal delivering controller to corresponding optical signals, thereby supplying the optical signals to the optical fiber cable;

(i) a second optical connector, connected to the optical fiber cable extending from the last local control station, the second optical connector for converting the optical signals to corresponding electrical signals;

(j) a fourth memory for storing data concerning the load current and data concerning overload detection, both supplied from each local control station through said second optical connector for each local control station; and

(k) a display means for displaying the data stored in the fourth memory.

2. A centralized control system for controlling a group of electric motors, comprising:

a single key control station;

a number of local control stations connected in series to the key control station through optical fiber cables so that a line of closed loop signal transmission path is formed between a signal delivering and a signal receiving end of the key control station, said local control stations corresponding to a number of motors;

semi-conductive switching elements having gates provided so as to close and open electrical power supply circuits of the motors; and

a programmable controller for supplying each local control station with an on-off operation command for turning each semi-conductive switching element on and off to control each motor so that each motor is driven and stopped in accordance with a predetermined program,

each of the local control stations comprising;

(a) a current transformer for measuring a load current flowing through the power supply circuit of the motor;

(b) an overload and phase-loss detector for detecting an output current of the current transformer to determine whether or not the motor is in the overload or phase-loss condition, thereby producing a detection signal, said overload and phase-loss detector executing a motor protection operation, of tripping the motor by turning off the semi-conductive switching element, in accordance with the detection signal;

(c) a first optical connector for converting optical signals to corresponding electrical signals, said first optical connector being connected to the optical fiber cable through which data is transmitted from other local control stations;

(d) a second optical connector for converting electrical signals to corresponding optical signals, said second optical connector being connected to the optical fiber cable through which data is transmitted to other local control stations;

(e) a signal receiving controller for sequentially receiving electrical signals corresponding to data supplied from the first optical connector;

(f) an on-off switch supplying an on-off operation command to turn the semi-conductive switching element on and off, thereby controlling the motor so that the motor is driven and stopped;

(g) soft starting period setting means for producing data associated with the soft starting of the motor in accordance with which each semi-conductive switching element is controlled so that the input voltage of the motor is gradually increased at the time of the starting of the motor;

(h) tripping condition setting means for producing data associated with the tripping of the motor to determine the time at which the overload and phase-loss detector starts the motor protection operation;

(i) a first data selector alternatively selecting a command from the on-off switch or from the signal receiving controller;

(j) a second data selector alternatively selecting data from the soft starting period setting means or from the signal receiving controller;

(k) a third data selector alternatively selecting data from the tripping condition setting means or from the signal receiving controller;

(l) a REMOTE/LOCAL mode selecting switch for supplying each of said first, second and third data selectors with a selection signal for the selection;

(m) controller means for controlling the gate of the semi-conductive switching element in accordance with data supplied from the first to third data selectors;

(n) a signal delivering controller for converting detection data from the overload and phase-loss detector, output data from the current transformer, and data supplied from each of the first to third data selectors into serial electrical signals so that the data is transmitted to the second optical connector to thereby supply the key control station with the serial signals, said signal receiving controller transmitting data directed to its own local control station to each of the data selectors and transmitting data directed to other local control stations to the signal delivering controller so that data directed to other local control stations is supplied to the optical fiber cable through the second optical connector;

said key control station comprising;

(a) soft starting period setting means for producing data associated with the soft starting of each motor in accordance with which each semi-conductive switching element is controlled so that the input voltage of each motor is gradually increased at the time of the starting of each motor;

(b) tripping condition setting means for producing data associated with the tripping of the motor to determine the time at which the overload and phase-loss detector starts the motor protection operation;

(c) a reference number selecting switch for providing reference numbers of the local control stations so that inherent reference numbers are given to the respective local control stations in order to direct data thereto;

(d) a first memory for storing the on-off commands produced by said programmable controller for each local control station;

(e) a second memory for storing data supplied from said soft starting period setting means by manually operating the same, the data being stored in the second memory in the order of the local control stations in a manner so that said data is discriminated by the reference numbers of the local control stations;

(f) a third memory for storing data supplied from said tripping condition setting means by manually operating the same, the data being stored in the third memory for each local control station in a manner so that the data is discriminated by reference numbers of the local control stations;

(g) a signal delivering controller for converting data of on-off commands stored in the first memory and data stored in the second and third memories to serial electrical signals so that the data is transmitted to each local control station;

(h) a first optical connector, connected to the optical fiber cable extending from the first local control station, the optical connector converting the serial electrical signals supplied from said signal delivering controller to optical signals, thereby transmitting the optical signals to the optical fiber cable;

(i) a second optical connector, connected to the optical fiber cable extending from the last local control station, the second optical connector for converting the optical signals to corresponding electrical signals;

(j) fourth to seventh memories for storing data concerning soft starting, tripping, load current, overload, and phase-loss supplied from each local control station for each local control station, respectively; and

(k) a display means for displaying the data stored in the fourth to seventh memories.