Circuit Breaker Control Device

It is well recognized that electrical energy consumption tends to peak during the heat of the day. Because these peak energy demands exist during only a portion of the day this energy is generally supplied by smaller capacity power-plants. The obvious result is higher cost per kilowatt-hour than energy consumed during non-peak periods. This cost is of course passed on to the consumer. Considerable cost savings would result, both to the consumer and the electrical utility, in addition to conservation of natural resources, if consumers of electrical energy could be persuaded to redistribute their demands to a more uniform level throughout the day.

While economic reasons have been found effective in causing industrial consumers of electrical energy to disperse their demands away from peak demand periods, residential peak loads have thus far proven substantially unmanageable. Most pleas to "turn down the thermostat" and the like appear to be ineffectual. Therefore, utilities in general are seeking ways of controlling customer demands directly to redistribute demand throughout the day. This redistribution is generally referred to as "peak-shaving."

Most existing "peak shaving" systems involve some form of communications, such as ripple signals superimposed on the power system, radio, power line carrier, or combinations of these types of equipment. Unfortunately, each of the above systems tends to be economically unjustifiable because of costly installation of the controlled devices between the customer's appliances and the circuit breaker housing. In addition to the cost of installation, the utility is put in an unfavorable position if damage to the customer's appliances should occur.

Thus, there has been a need for an economical device that can be installed at low costs for redistributing energy demand away from peak demand periods with minimal risk to a customer's appliances.

The present invention accomplishes the above objects by use of a control device responsive to either an external or internal, to the load center, command signal to cause a circuit breaker to open, thereby disconnecting the associated, energy-consuming apparatus until the command signal permits the circuit breaker to reclose. If an internal control signal is used, the signal may for example be a ripple signal supplied by a central generating station and carried on the line current itself. Typically, the circuit breaker control device is installed to control only 220 volt circuits, since these circuits usually control high energy devices such as electric clothes dryers and the like. In this manner, the demand for energy may be reduced independently of the consumer, without causing power losses to conventional 110 volt circuits which power clocks and other appliances requiring a constant or emergency power supply.

The control device of the present invention also avoids many of the installation problems of prior art devices. The device may be configured to fit within existing circuit breaker dimensions, and in fact may be packaged as an exact replacement for existing circuit breakers. Thus, installation costs are substantially reduced. Further, since the device is inside the Load Center Panel, it is less subject to tampering than a switching device mounted near or within the appliance to be controlled.

The control device of the present invention is also advantageous in that it controls the energy-consuming circuit in an entirely conventional manner, by simply opening a circuit breaker. Since such power losses are foreseeable, household appliances are designed to sustain them without injury.

It is one object of the present invention to provide an improved controlled circuit breaker.

It is another object of the present invention to provide a cost effective residential load management system.

It is a further object of the present invention to provide an improved load management device for distributing energy demands away from peak periods.

It is another object of the present invention to provide an energy efficient controlled circuit breaker.

It is a further object of the present invention to provide a residential load management system which is not injurious to the appliances of customers.

It is yet another object of the present invention to provide a controlled circuit breaker which does not require constant energization.

Other and further advantages of the present invention will be apparent from the following detailed description.

FIG. 1 is a schematic diagram of a first embodiment of the invention.

FIG. 2 is a schematic diagram of a second embodiment of the invention.

FIG. 3 is a schematic diagram of an embodiment suitable for use with existing circuit breakers.

Referring now to FIG. 1, there is shown therein a first embodiment of the load management device of the present invention. In this embodiment the control device is integrated into the circuit breaker package itself, yielding a single unit which accomplishes both purposes. Since the unitary package will outwardly appear to be a conventional circuit breaker, the package has not been illustrated.

A controller 100, such as a ripple receiver, time clock, or other suitable device, provides a signal which operates a switch 150. The switch 150 is of the momentary contact type and controls an impulse relay coil 152, causing the impulse relay contacts 154 to open or close depending upon the previous state of the contacts. More specifically, power (typically from a 220 v source) is applied through conventional magnetic and thermal trip elements 155 and 156, together with their associated trip contact 158, to the anode of a retifier diode 160. The anode of the diode 160 is connected to a resistor 162, the remote terminal of which is connected to one terminal of a capacitor 164, one terminal of a second resistor 166, and one leg of the switch 150. The remaining terminals of the resistor 166 and the capacitor 164 are connected to the neutral bus 168 of the 220 v source. The neutral bus 168 is also connected to the coil 152, the remote terminal of which is connected to the remaining leg of the switch 150.

The impulse relay 152 is operated in the following manner. The resistors 162 and 166 form a voltage divider through which the capacitor 164 is charged. The relative values of the resistors are adjusted to provide the voltage necessary to energize the impulse relay 152, for example 30 volts.

Once the capacitor 164 is suitably charged, momentary closure of the swtich 150 causes the impulse relay coil 152 to energize from the charge stored on the capacitor 164. Assuming the contacts 154 were previously open, energization of the coil 152 causes the contacts 154 to close and mechanically lock closed, a feature which is characteristic of the impulse relays described herein. With the contacts 154 closed, the appliances connected to the outputs of the device will operate in an entirely conventional manner. The impulse relay 152 is typically maintained in this state, with the contacts 154 closed, during non-peak periods of energy demand.

If demand for electrical energy should rise to a level that load management is required, the impulse relay contacts 154 may be caused to open by momentary closure of the switch 150 by a signal from the controller 100 or otherwise. This momentary closure will cause the coil to energize by the circuit through the capacitor 164, which will have recharged when the switch 150 returns to the open position. When the coil 152 energizes, the mechanical lock of the relay 152 is released and the contacts 154 open, disconnecting that leg of the circuit from the power source. Thus, an effective means for externally controlling residential demands for electrical energy is disclosed.

At some point, the demand for electrical energy will have reduced sufficiently to permit appliance to be reconnected, by closing the contacts 154 of the impulse relay 152. This is again caused by a momentary closure of the switch 150 by a signal from the controller 100 or other suitable means. The capacitor 164, again being charged, causes the coil of the impulse relay 152 to energize, closing and locking the contacts 154. It should be noted that the embodiment shown in FIG. 1 requires energization of the control circuitry only during switching, and thus provides an economical and energy-efficient controlled circuit breaker.

Because the controlled circuit breaker of FIG. 1 may be packaged as an exact replacement for existing circuit breakers, the present invention may be installed in conventional circuit breaker panels (not shown). This permits the controlled circuit breaker of the present invention to be covered to inhibit the consumer from disconnecting or otherwise tampering with the controlled device. The result is that demand for electrical energy can be controlled independently of the consumer, so that these demands may be shifted away from periods of peak energy use.

The controller 100, as previously described, typically comprises a ripple receiver, time clock or other suitable device. Depending upon application, a single controller may be employed to control a plurality of devices, or a number of controllers may be employed to manage different circuits at different times during the day. Likewise, a different controller may be employed for each controlled circuit.

Turning now to FIG. 2, there is shown therein a second embodiment of the present invention. As with the device shown in FIG. 1, line current, typically 220 volts is supplied across the lines 200 and 202, with the line 204 being neutral. Conventional magnetic trip elements 155, thermal trip elements 156 and associated contacts 158 are provided in each of the lines 200 and 202. A pair of resistors 206 and 208 form a voltage divider, the junction of which is connected to a rectifying diode 210. The anode of the diode 210 is connected to one terminal of a capacitor 212, the anode of a zener diode 214 and a coil 216 of an impulse relay 218. The values of the resistors 206 and 208 are adjusted to suitably charge the capacitor 212 through the rectifying diode 210, while the zener diode 214 is provided to prevent damage to the capacitor 212 by line surges.

The coil 216 of the impulse relay 218 is associated with a pair of contacts 220. A photo-optical device 222, such as an LED, may be connected with the contacts 220 to provide an indication of the status of the contacts. A resistor 224 may also be provided for current limiting.

The remaining terminal of the coil 216 is connected to a controller such as the control device 100 in combination with the momentary switch 150 shown in FIG. 1. Thus, when energy demand is such that the load is to be disconnected from the source at lines 200 and 202, the controller 100 signals the switching element 150 and causes the coil 216 to energize, thereby opening the contacts 220. Similarly, when the energy demand is low enough that the appliances or other loading devices connected to the lines 226 and 228 are are permitted to be used, the coil 216 is again energized to change the state of the contacts 220, thereby connecting the lines 200 and 202 to the lines 226 and 228. The control signals may also be supplied via telephone lines connected to the external control lines 230 and 232.

The purpose of the LED 222 associated with the impulse relay contacts 220 is to provide an indication of status of the contacts 220. For this purpose, the LED 222 is optically coupled with a photodetector 234, and provides an output status signal on a line 236. In the event that an isolated status signal is preferred, the status signal may be taken from the lines 236 and 232.

For at least some applications, it is preferable that the control circuitry be integrated with the circuit breaker itself. However, in some other instances this may not be preferable. For such applications, the embodiments shown in FIG. 3 may be preferred. As can be appreciated from a comparison of FIG. 2 and FIG. 3, the control circuitry therein is substantially similar and parts having like function have been given like numbers. The device shown in FIG. 3 is suitable for connection between a source and load independently of a circuit breaker. However, the control and status ports are provided in the same manner as for FIG. 2.

From the above it can be appreciated that a new and effective circuit breaker control device, useful for managing residential demands for electrical energy in an energy efficient manner, has been disclosed. Having fully described the invention, it is to be understood that the embodiments disclosed herein are exemplary only. Many equivalents and alternatives will be apparent to those skilled in the art, based on the teachings herein, and it is intended that the equivalents and alternatives be included within the scope of the invention.