摘要:
An electrical switch with overcurrent protection communicates as a slave with a remote master station by sending return messages to the remote master station only in response to messages addressed to it. A portable unit plugs into the electrical switch and disables communications between the electrical switch and the remote master station. The portable unit then establishes communications with the electrical switch by sending a global message to the electrical switch requesting the unique address at successive baud rates until a return message containing the electrical switches' address is received. A communications module in the electrical switch transfers to a master mode in response to the global message in order to send the return message containing its unique address. It then reverts to the slave mode for response to subsequent messages from the portable unit containing the unique address. Either the remote master station or the portable unit can test the circuit breaker by sending a message containing a digital test current to the circuit breaker.
摘要:
A PC computer monitors the energy consumed at a plurality of local stations placed behind the electrical meter of the utility company for individual billing of the local users, a bidirectional communication line being used therebetween. A command from the PC computer causes at each station the totalized energy to be stored, and thereafter the PC computer derives individually the results for separate estimations and central billing.
摘要:
A PC computer monitors the energy, power, voltage, and current consumed at a plurality of local stations placed behind the electrical meter of the utility company for individual billing of the local users, a bidirectional communication line being used therebetween. A command from the PC computer causes at each station the power, voltage, current and totalized energy to be stored, and thereafter the PC computer derives individually the results for separate estimations and central billing.
摘要:
A distributed processing unit (DPU) or drop which performs process control and data acquisition functions in a distributed processing control system having a data highway linking a plurality of such units. A DPU functional processor accesses the local process I/O interface thereby continually receiving plant information for storage in digital form and subsequent use in the functional processor or for transmission along the data highway. DPU control programs use process values in a transparent fashion, that is without regard to whether these values were obtained through local process I/O interface or via the data highway. The DPU software structure is made up of execution software and support software. The execution software is a collection of data acquisition and process control programs which are developed at an engineer's console drop using a DPU programming language which operates in text and CRT graphic display modes, the latter programming modes allowing system documentation via hard copy graphic display printout. These programs are initiated, performed consecutively, and repeated at specified intervals. The support software initiates process loop execution. Control programs which have been presented to the DPU as representations of ladder diagrams for sequential control or process flow diagrams for continuous process control are executed in the DPU functional processor to achieve the required process control operation.
摘要:
A network protector relay for a circuit breaker includes a microcontroller routine which provides a positive sequence network voltage from polyphase network voltages on a network bus. Another microcontroller routine provides a positive sequence phasing voltage from the polyphase network voltages on the network bus and polyphase feeder voltages on a feeder bus. A recloser circuit automatically recloses the circuit breaker connected between the polyphase feeder bus and the polyphase network bus in response to a function of a plurality of setpoints and the positive sequence phasing voltage which indicates a first flow of power from the polyphase feeder bus to the polyphase network bus. A receiver receives a remote close command. Another routine temporarily changes at least one of the setpoints in response to the received close command, in order to conditionally close the circuit breaker for a second flow of power from the polyphase feeder bus to the polyphase network bus, with the second flow of power being less than the first flow of power.
摘要:
A personal computer (PC) system determines a demand usage value at a predetermined time for a load powered by an electric power system. The computer system includes a database for storing energy usage values and time values; a PC software logging routine for acquiring the values of energy consumed from the electric power system by the load, for determining corresponding time values for times at which the energy was consumed by the load, and for storing the energy usage values and time values in the database; and a PC software calculation routine for retrieving a predetermined count plus one of pairs of those values from the database, with one of the time values corresponding thereto being about equal to the predetermined time. The calculation routine determines a first demand value from a pair of the energy usage values and a pair of the time values corresponding thereto, and also determines at least one second demand value from at least another pair of the energy usage values and at least another pair of the time values corresponding thereto. The calculation routine averages the first demand value with the at least one second demand value to determine the demand usage value which is determined over a time interval about equal to the predetermined count times a predetermined time interval.
摘要:
The trip curves of circuit protection devices in an electric power distribution system are individually adjusted and coordinated in a hierarchy of protection devices by graphical manipulation, such as by dragging with a mouse, segments of the trip curves presented on a display device. The existing parameter settings can be provided to the display device and the adjusted parameter settings returned to the protection devices manually, but preferably, a communications network provides automatic transfer of the settings in both directions.