1. Field of the Invention
This invention pertains generally to electrical switching apparatus and, more particularly, to such apparatus including a number of accessories. The invention also relates to methods of communicating between a number of accessories and an electrical switching apparatus.
2. Background Information
Electrical switching apparatus, such as circuit breakers, are widely used in industrial, commercial and residential applications for protecting electrical conductors and apparatus. Circuit breakers, for example, are used to protect electrical distribution systems from damage due to an overcurrent condition, such as an overload condition or a relatively high level short circuit or fault condition. In small circuit breakers, commonly referred to as miniature circuit breakers, used for residential and light commercial applications, such protection is typically provided by a thermal-magnetic trip device. This trip device includes a bimetal, which heats and bends in response to a persistent overcurrent condition. The bimetal, in turn, unlatches a spring powered operating mechanism, which opens the separable contacts of the circuit breaker to interrupt current flow in the protected power system.
Some circuit breakers include a trip unit, which senses overcurrent conditions in an automatic mode of operation. Upon sensing an overcurrent condition, the trip unit trips the operating mechanism to a trip state, which moves the separable contacts to their open position. It is well known to employ trip units to detect various types of overcurrent trip conditions and to provide various protection functions, such as, for example, a long delay trip, a short delay trip, an instantaneous trip, and/or a ground fault trip. The earliest electronic trip unit circuit designs utilized discrete components such as transistors, resistors and capacitors. More recently, designs, such as disclosed in U.S. Pat. Nos. 4,428,022; and 5,525,985, have included microprocessors, which provide improved performance and flexibility. These digital systems sample the current waveforms periodically to generate a digital representation of the current. The microprocessor uses the samples to execute algorithms, which implement one or more current protection curves.
Electrical switching apparatus, such as circuit breakers, as well as transfer switches, network protectors and the like, are often equipped with accessories such as, for example and without limitation, auxiliary contacts, bell alarms, open/close pushbuttons, shunt trip devices, and under voltage release (UVR) devices.
Auxiliary contacts and bell alarms provide signals indicating certain conditions within the apparatus. For example, auxiliary contacts (e.g., without limitation, normally open; normally closed) of an auxiliary switch signal, for example, the open or closed state of separable contacts of the apparatus. Bell alarm contacts signal, for example, the trip state of the apparatus. These mechanical status indicating accessories are often mounted within the apparatus casings and are used by external monitoring and control equipment.
Open/close pushbuttons provide a remote mechanism to open or close the separable contacts without standing directly in front of the circuit breaker. For example, two normally open switches (one for open and the other for close) can be used for this purpose. If one and only one switch is closed, then the circuit breaker performs the corresponding requested action (open or close the circuit breaker separable contacts). If both switches are either opened or closed, then no action is taken.
Shunt trip and UVR devices can be employed in a variety of ways to initiate a change in status of the apparatus such as, for example, to trip open the separable contacts of the apparatus in response to an electrical fault condition (e.g., without limitation, current overload; short circuit; under voltage) or other external condition. The connection between the apparatus and the various accessory devices is conventionally accomplished in parallel using two wires per accessory device. The installation of these wires is costly and time consuming.
U.S. Pat. No. 6,175,780 discloses an electronic trip unit that communicates with plural remote, accessory devices over a two wire communication bus.
The installation of the above wires is both costly and time consuming.
There is, therefore, room for improvement in electrical switching apparatus and corresponding accessories.
There is also room for improvement in methods of communication between electrical switching apparatus and corresponding accessories.
These needs and others are met by embodiments of the invention, which provide wireless communication between an electrical switching apparatus and a number of accessories thereof.
In accordance with one aspect of the invention, an electrical switching apparatus comprises: an electrical switching apparatus housing; separable contacts; an operating mechanism structured to open and close the separable contacts; a first processor cooperating with the operating mechanism to determine an open or closed state of the separable contacts; a number of accessories, each of the number of accessories comprising a wireless receiver, a second processor and a number of outputs; and a wireless transmitter structured to wirelessly transmit the open or closed state of the separable contacts from the first processor to the wireless receiver of the number of accessories, wherein the wireless receiver is structured to wirelessly receive the open or closed state of the separable contacts from the wireless transmitter, wherein the second processor is structured to receive the open or closed state of the separable contacts from the wireless receiver and to output the open or closed state of the separable contacts to the number of outputs, and wherein the number of accessories are located on or internal to the electrical switching apparatus housing.
As another aspect of the invention, an electrical switching apparatus comprises: separable contacts; an operating mechanism structured to open and close the separable contacts; a first processor cooperating with the operating mechanism to open and close the separable contacts; a wireless receiver structured to wirelessly receive a signal; and a number of accessories, each of the number of accessories comprising a wireless transmitter, a second processor and a circuit structured to generate the signal for the second processor or communicate the signal to the second processor, the second processor being structured to output the signal to the wireless transmitter, the wireless transmitter being structured to wirelessly transmit the signal to the wireless receiver, wherein the first processor is structured to receive the signal from the wireless receiver and to responsively cause the operating mechanism to open or close the separable contacts.
As another aspect of the invention, an electrical switching apparatus comprises: separable contacts; an operating mechanism structured to open and close the separable contacts; a first processor cooperating with the operating mechanism to determine an open or closed state of the separable contacts and to open and close the separable contacts; a wireless transceiver cooperating with the first processor and being structured to wirelessly transmit the open or closed state of the separable contacts from the first processor and to wirelessly receive a signal; a plurality of accessories, a first one of the accessories comprising a wireless receiver, a second processor and a number of outputs, and a second one of the accessories comprising a wireless transmitter, a third processor and a circuit structured to generate the signal for the third processor or communicate the signal to the third processor, the third processor being structured to output the signal to the wireless transmitter, the wireless transmitter being structured to wirelessly transmit the signal to the wireless transceiver, wherein the first processor is structured to receive the signal from the wireless transceiver and to responsively cause the operating mechanism to open or close the separable contacts, wherein the wireless receiver is structured to wirelessly receive the open or closed state of the separable contacts from the wireless transceiver, and wherein the second processor is structured to receive the open or closed state of the separable contacts from the wireless receiver and to output the open or closed state of the separable contacts to the number of outputs.
As another aspect of the invention, a method of wirelessly communicating between a number of accessory nodes and an electrical switching apparatus including separable contacts, comprises: wirelessly connecting the electrical switching apparatus and the number of accessory nodes to a wireless communication network; wirelessly communicating over the wireless communication network: (a) an open or closed state of the separable contacts from the electrical switching apparatus to one of the number of accessory nodes, and responsively outputting the open or closed state from the one of the number of accessory nodes, or (b) a signal from one of the number of accessory nodes to the electrical switching apparatus, and responsively opening or closing the separable contacts responsive to the signal; employing the electrical switching apparatus including an electrical switching apparatus housing; and locating the number of accessory nodes on or internal to the housing.
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
As employed herein, the term “number” shall mean one or an integer greater than one (i.e., a plurality).
As employed herein, the term “processor” means a programmable analog and/or digital device that can store, retrieve, and process data; a computer; a workstation; a personal computer; a microprocessor; a microcontroller; a microcomputer; a central processing unit; a mainframe computer; a mini-computer; a server; a networked processor; or any suitable processing device or apparatus.
As employed herein, the term “wireless” shall expressly include, but not be limited by, radio frequency (RF), light or visible light or infrared light not using optical fibers, ultrasound, wireless area networks, such as, but not limited to, IEEE 802.11 and all its variants (e.g., without limitation, 802.11a; 802.11b; 802.11g), IEEE 802.15 and all its variants (e.g., without limitation, 802.15.1; 802.15.3, 802.15.4), IEEE 802.16 and all its variants, other wireless communication standards (e.g., without limitation, ZigBee™ Alliance standard), HyperLan, DECT, PWT, pager, PCS, Wi-Fi, Bluetooth™, and cellular.
As employed herein, the term “wireless communication network” means a communication network employing wireless communications.
As employed herein, the term “network coordinator” (NC) means a communicating device, which operates as the central controller in an ad-hoc communication network or a wireless communication network.
As employed herein, the term “network device” (ND) means a communicating device, which participates in a wireless communication network, and which is not a network coordinator.
As employed herein, the term “node” includes a ND, a NC or other node, which participates in an ad-hoc communication network or a wireless communication network.
The invention is described in association with a circuit breaker, although the invention is applicable to a wide range of electrical switching apparatus.
Referring to
The A/D converter 84 samples analog voltages and currents, for example, at sampling instances determined by interrupts generated by the processor 46 in a manner more particularly described in U.S. Pat. No. 5,600,527, and the patents referenced therein. The processor 46 utilizes the data generated by the digital samples to provide voltage based protection functions, for example, under/over voltage protection for the electrical system 12, and also uses the samples for waveform capture and harmonic analysis for metering and display purposes.
In implementing the overcurrent protection functions, the second processor 24 operates in a protection mode to generate a trip signal when any one of the current/time characteristics of a delayed trip protection function is exceeded. This trip signal is passed to a trip mechanism, such as trip circuit 32, which opens separable contacts 34A,34B,34C in the respective three phase conductors 14A,14B,14C of the electrical system 12. The trip circuit 32 is typically a mechanically latched electronically released mechanism. Although typically not provided in the United States, additional separable contacts can be included to also interrupt current in the neutral conductor 14N. The processors 24 and 46 can also communicate with one another through, for example, a suitable serial peripheral interface (SPI) link 42.
The processor 24 provides the overcurrent protection and communicates with the trip circuit 32 to implement an overcurrent instantaneous trip requirement. The processor 46 also monitors the state of the separable contacts 34A,34B,34C or the operating mechanism (not shown) of the circuit breaker 11 through a breaker status circuit 26 to indicate the breaker's open/closed state. The processor 24 communicates through a wireless transceiver 40 (e.g., without limitation, IEEE 802.15.4; ZigBee) to a wireless communication network 48 (e.g., without limitation, IEEE 802.15.4; ZigBee).
The electronic trip unit 10 advantageously employs wireless communication between (i.e., to and/or from) the trip unit 10 and a number of wireless accessories 47 (e.g., without limitation, accessory nodes) associated with that particular electronic trip unit 10 through the wireless communication network 48 that is also shown in
Referring to
In this example, the circuit breaker 100 includes a circuit breaker housing 116, and a number of the accessories 108 are located on or internal to (as shown in
Referring to
In this example, the circuit breaker 100′ includes a circuit breaker housing 116′, and a number of the accessories 120 are located on or internal to the housing 116′.
Referring to
Although the wireless communication network 48 of
Although the invention is applicable to one or more wireless accessory nodes (e.g., as shown in
As contrasted with the circuit breakers 100 of FIG. 7 and 100′ of
Referring to
Otherwise, if the accessory 160 is used as an auxiliary switch, the normally open/normally closed contacts preferably track (e.g., without limitation, the normally open contact is closed for the contacts closed state; the normally open contact is open for the contacts open state) the open or closed state of the circuit breaker separable contacts (e.g., the separable contacts 102 of
As shown in
Referring to
Similarly, the shunt trip accessory 152 of
As shown in
As shown in
The electronic trip unit 10 of
As an alternative to Example 17, a peer-to-peer structure may be employed. In this example, the electronic trip unit 10 and the various wireless accessory nodes 150, 152, 154, 156 and 158 are peer nodes of the wireless communication network 48.
The wireless messages, such as 157,159,182,204,206, preferably convey the information to and from the remote wireless accessory nodes 47 from and to the master trip unit 10 as fast as possible.
In Example 17, the master node 10 may employ, for example, one message type (e.g., 204;206) to send a digital output (e.g., an auxiliary switch signal; a bell alarm signal) to one of the slave nodes 47 and another message type (e.g., 157;159;182) to request a digital input (e.g., a shunt trip signal; a UVR trip signal; an open signal; a close signal) from one of the slave nodes 47 for the master/slave approach.
In the peer-to-peer approach of Example 18, the various nodes 10,47 preferably employ messages that indicate that the sending node has some thing for the receiving node, in order to preferably wirelessly communicate the information between the respective wirelessly communicating nodes in the quickest manner possible.
Referring to
In this example, the wireless signal 212 from the node 208 to the UVR 156 is relayed to the trip unit 10 as signal 157′ by the UVR 156. Also, the signal 157″ from the trip unit 10 to the UVR 156 is relayed to the node 210 as signal 214 by the UVR 156.
Although separable contacts 34A,34B,34C,102 are disclosed, suitable solid state separable contacts may be employed. For example, the disclosed circuit breakers 100,100′,100″, 100′″ include a suitable circuit interrupter mechanism, such as the separable contacts 102 that are opened and closed by the operating mechanism 104, although the invention is applicable to a wide range of circuit interruption mechanisms (e.g., without limitation, solid state or FET switches; contactor contacts) and/or solid state based control/protection devices (e.g., without limitation, drives; soft-starters).
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.