Abstract: Embodiments of voltage monitoring are disclosed.

Abstract: A load shedding system and method for controlling imbalances in a power system includes a signal generator adapted to generate a signal representative of a local system, and a modifying circuit adapted to adjust set frequencies. The system also includes a processing circuit adapted to process data received from the signal generator and modifying circuit and set load shedding priorities for the local system based on the processed data.

Abstract: A method of drying clothes in a clothes dryer comprising a clothes chamber for receiving clothes, an air supply system for directing air through the clothes chamber, and a heater for heating the air supplied by the air supply system. The method comprises cycling the heater between an ON state by energizing the heater until a heater trip condition is met and an OFF state by deenergizing the heater until a heater reset condition is met, determining a heater off time by determining the time between the heater trip condition and the heater reset condition, and determining a drying time based on the heater off time.

Abstract: In a power system stabilization system for stabilizing a small-scale electric power system to which electric power generated by a rotating power generator is supplied, an electric water heater receives electric power from the electric power system and heats water, a system frequency measuring device measures system frequency of the electric power system, and a hot water controller increases the power consumption of the electric water heater when the system frequency exceeds a reference frequency, and decreases the power consumption of the electric water heater when the system frequency is less than the reference frequency.

Abstract: A system and method for adaptive control of power among a plurality of loads based on a categorization of the loads as either delayable or non-delayable, wherein the non-delayable loads are preferably supplied power over the delayable loads. In one aspect, the system may be used to allocate limited power from a backup power source.

Abstract: A multi-output DC-DC converter is advantageous over the conventional multi-output DC-DC converter in terms of increased power efficiency and power density. The inventive multi-output DC-DC converter is characterized by that the rectifying circuit located at the output stage of the DC-DC converter is implemented by a pair of self-driven synchronous rectifier transistors that can prevent a reverse current from flowing through the switch elements of the DC-DC converter. Also, a plurality of post voltage regulators are tapped to a secondary winding of the DC-DC converter, in which each post voltage regulator includes a voltage level shifter circuit for allowing gate drivers to impose a small amount of dead time on the control pulse signals for driving the internal transistor switches to minimize the dead time loss occurred during power conversion operation.

Abstract: Electrical appliance energy consumption control methods and electrical energy consumption systems are described. In one aspect, an electrical appliance energy consumption control method includes providing an electrical appliance coupled with a power distribution system, receiving electrical energy within the appliance from the power distribution system, consuming the received electrical energy using a plurality of loads of the appliance, monitoring electrical energy of the power distribution system, and adjusting an amount of consumption of the received electrical energy via one of the loads of the appliance from an initial level of consumption to an other level of consumption different than the initial level of consumption responsive to the monitoring.

Abstract: A signal transmission circuit having four lanes includes a constant voltage circuit to generate a constant voltage, a current supply circuit, and differential driver circuits respectively placed for the lanes. The current supply circuit receives a constant voltage from the constant voltage circuit and generates four currents having a value corresponding to a prescribed voltage-current conversion ratio and outputs them in parallel. The differential driver circuits respectively receive the currents output from the current supply circuit and output a voltage having an amplitude corresponding to the prescribed voltage-current conversion ratio. The current supply circuit includes a voltage divider circuit and an analog selector, which form a current supply control circuit capable of changing the voltage-current conversion ratio.

Abstract: In a method for regulating the power supply of a plurality of field devices S1, S2, S3, A1, A2, connected to a data bus DBL and supplied with electrical current over the data bus DBL, the electrical current requirements of the individual field devices S1, S2, S3, A1, A2 are determined, and the electrical current consumptions of the field devices S1, S2, S3, A1, A2 are adjusted by means of corresponding control signals. In this way, the electrical current consumption of individual field devices S1, S2, S3, A1, A2 can be centrally adjusted and therewith the process conditions matched.

Abstract: A method for controlling multiple voltages in a power supply includes providing a plurality of DC to DC power converters. Each power converter includes a pulse width modulator controller having a control pin. The method also includes when a voltage supply to the power controllers reads a particular level. After the particular level is met, the method includes providing a respective rising ramp control signal to each respective control pin of the pulse width modulator controller such that each respective power converter generates desired voltage level over time characteristics.

Abstract: A device for inhibiting power supply voltage fluctuation that is caused by fluctuation of a load current generated by a load circuit. The device includes a current consumption circuit, a data generation circuit, and a D/A converter. The current consumption circuit is connected to a power supply and the load circuit to generate a consumption current that flows parallel to the load current of the load circuit. The data generation circuit controls the consumption current of the current consumption circuit in order to inhibit fluctuation of an output current of the power supply, which is the sum of the load current and the consumption current, when the load current rises and when the consumption current falls. The D/A converter converts the digital signal to an analog signal and provides the analog signal to the current consumption circuit.

Abstract: It is intended to be possible to use a respective setting apparatus (E1, E2) to set the color and the brightness of an illumination device separately. Light sources having three different colors are operated for this purpose. Only one first power supply (CON, PWM1) is provided for two colors, whereas the third color is supplied by a second power supply (CON, PWM2). The brightness can be set by altering the power output of the first (CON, PWM1) and the second (CON, PWM2) power supplies at the same time. The color can be set by altering the power output of the second (CON, PWM2) power supply.

Abstract: A method and system for providing power to a wireline logging system includes a rectifier section operable to receive an AC input signal and generate a first DC power signal as an output. A converter section cascadedly coupled to the rectifier section converts the first DC power signal to a second DC power signal. An inverter section cascadedly coupled to the converter section is operable to generate an output power signal providing power to a system in response to receiving the second DC power signal. A control section is coupled to the rectifier section, the converter section, the inverter section and a communications link. The communications link is operable to receive information describing waveforms for the output power signal. The control section is operable to receive the information and control a corresponding section to generate the waveforms in response to receiving the information.

Abstract: A real-time thermal management and power conservation apparatus and method for computers employs a monitor to determine whether a CPU may rest based upon a real-time sampling of temperature and CPU activity levels and activates a hardware selector to carry out the monitor's determination. If the monitor determines the CPU may rest, the hardware selector reduces or stops CPU clock time; if the CPU is to be active, the hardware selector returns the CPU to its previous high speed clock level. Switching back into full operation from its rest state occurs without a user having to request it and without any delay in the operation of the computer while waiting for the computer to return to a “ready” state. Furthermore, the monitor adjusts the performance level of the computer to manage power conservation and thermal management in response to the real-time sampling of temperature and CPU activity levels.

Abstract: A system and method are provided to power a plurality of magnetrons devices. The system may include a power supply device to power a first magnetron device, a second magnetron device and a third magnetron device. A control device may control (or apportion) an amount of current to each of the second and third magnetron devices.

Abstract: A device for supplying energy by means of a first DC voltage source e.g. in the form of a DC voltage bus, a drive system comprising several electric motors is connected to said DC voltage bus. The electric motors are comprised e.g. in a number of yarn feeding devices co-acting with a weft insertion system in a shuttleless weaving machine for producing a woven fabric having a multi-colour pattern. The electric motors operate with energy consumption function phases (start and acceleration) and with energy generating function phases (deceleration or braking). The first DC voltage source is associated with at least one second DC voltage source via a variable voltage converter.

Abstract: A voltage-regulation, protection and filtering assembly (20) is connected between a power-supply input and an energy output in order to deliver the same security-protected operating voltage to a number of elements (12a, 12b, 12b, 12c, 14, 16) via an energy bus (26) linked to the energy output. The assembly (20) further includes an information input for connection to a first information bus (24), an information output for connection to an information bus (26) specific to the elements, and a monitoring circuit for transferring, on the specific information bus, the information relating to the said elements flowing on the first information bus, and visa versa.

Abstract: Consumer use of 240 VAC power can be reduced automatically by a power utility. A switch, remotely controllable by the power utility, can break the normal T1-P1 and T2-P2 power connections, and instead allow T1 to float, and coupled P1 and P2 together and via a current limiter to T2. The result is that in-phase 120 VAC is available from P1 or P2, but no 240 VAC is provided, thus eliminating power consumption by 240 VAC appliances. When the need to reduce 240 VAC power consumption has passed, the switch is reconfigured to again connect T1-P1 and T2-P2. The switch may be disposed on a power utility pole, or at a consumer's premises, before, after, or indeed within the consumer's power meter.

Abstract: The invention is an apparatus and a method for connecting loads to a polyphase power distribution system in such a way that the loads on the individual phases of the system are balanced. The apparatus includes an equipment rack having multiple electrical equipment mounting positions and multiple electrical outlets wherein contiguous groups of mounting positions are adjacent to groups of outlets connected to different phases. The apparatus also provides for other groups of outlets adjacent to the mounting positions to be connected to different power sources for increased reliability when the equipment has redundant power supplies.

Abstract: In a method for controlling a plurality of electrical loads operated at the same time by a current source using a clocked or pulsed operating current, the instant and/or duration of pulse driving for the operating current of at least one load are synchronized to the operation of the other loads in such a way, and are matched to one another such, that the sum of the currents flowing to supply the loads assumes as constant a value as possible, and both the fluctuations and the rates of change in the sum of the currents flowing to supply the loads are minimized. The clocking or pulsing of the operating current of the electrical loads sets a partial load state for the load, or the load is operated from a power supply having a higher voltage than the rated operating voltage of the load.

Abstract: The invention provides a new hybrid 4-in-1 power controller chip for a PC mainboard which integrates a synchronous buck switching regulator to supply the CPU core voltage, a standard buck switching regulator for I/O circuits, a linear controller for the GTL bus, and a linear regulator with built-in pass transistor for a clock generator. On this basis, a hybrid power system for a PC mainboard is constructed. As compared with the conventional separate power systems on a PC mainboard, the hybrid power system of the present invention can save board area and reduce cost. Test results show this system has high precision and its synchronous switching regulator meets the specifications of Intel's VRM8.4 design guidelines for Pentium III CPUs.

Abstract: A multiple output power supply with a constant volt-second clamp circuit is provided. The multiple output power supply includes a transformer having a primary winding electrically connected to a supply voltage and at least two secondary windings for providing multiple output voltages, and a constant volt-second clamp circuit electrically connected to the primary winding for achieving a constant volt-second product clamp over a varying input voltage at the primary winding where the constant volt-second product clamp over the varying input voltage at the primary winding is independent of a load effect of the secondary windings.

Abstract: A system and method are provided to power two magnetrons devices. The system may include a power supply device to power a first magnetron device and a second magnetron device. A control device may control an amount of current reaching at least the first magnetron device.

Abstract: A switch remoting system for extending the function of an existing wired switch in a residence or other building, so that, in its extended function, the switch controls AC power available at one or more additional AC outlets. The basic system comprises two plug-in modules including a control unit and a remote switching unit. The control unit is plugged into an AC outlet controlled by the switch whose function is being extended. When that switch is actuated, the AC power transition and the resulting "on" or "off" power state is sensed and corresponding encoded switching control signals are generated and relayed to the remote switching unit. There, the switching control signals are decoded, and actuate an internal AC switch that controls AC power to an integral AC outlet receptacle in the remote switching unit. A lamp or other device plugged into the AC receptacle of the remote switching unit is thereby switch controlled by action of the switch whose function is being extended.

Abstract: A managed electrical outlet includes a plurality of electrical receptacles, a current sensor, logic circuitry, a switch driver, and one or more switches. The electrical current provided to the managed electrical outlet is measured by the current sensor, which in turn sends an electrical signal to the logic circuit, representative of the amount of electrical current flowing through the outlet. The logic circuit compares the level of current flowing through the outlet with a reference current level to determine whether an over-current state exists. If the logic circuit determines the presence of an over-current state, the logic circuit sends a signal to the switch driver, causing the switch driver to trigger the switch into an open-circuit condition. In a two-receptacle outlet, one of the two receptacles is coupled to the switch while the other receptacle is unmanaged.

Abstract: An electrical power transmitting system (50) in accordance with the invention includes an alternating current electrical power generator (12) for producing alternating current on an output having a specified maximum; at least one electrical load (22) which is coupled to a point of regulation (16) in the electrical transmitting system; a feeder (14) having a specified maximum voltage drop, a length extending between the output and the point of regulation for transmitting the alternating current to the point of regulation, an inductance having an inductive reactance at a fundamental frequency of the alternating current, a capacitance (54, 66, 80 and 100) in series with the inductance having a capacitive reactance at the fundamental of the frequency of the alternating current which cancels at least part of the inductive reactance at the fundamental frequency of the alternating current to provide a reduced impedance in the feeder at the fundamental frequency of the alternating current to produce a reduced voltage

Abstract: An electrical circuit has a power source line from a battery. The power source line is divided into a primary side and a secondary side by a device, such as, for example, a diode. A high current load circuit is connected to the primary side and a lower current device, such as, for example, a display-related circuit and a capacitor are connected to the secondary side. The display-related circuit continues to receive adequate power when the battery voltage drops due to operation of the high current load circuit. In addition, a voltage detector is connected to the secondary side, where the voltage fluctuates less than on the primary side. The voltage detector controls operation of the high current load circuit. As a result, the high current load circuit can be efficiently driven.

Abstract: A method of employing add/shed routines to individual load controllers in a system for a building or plant that has more than one load. It allows for cooperative adjustments of energy usage in accord with prearranged exigency information agree between the utility provider and the building user. Duty cycle time is also adjustable in accord with tier level signal information provided by the utility.

Abstract: A humidity control device includes a microcontroller, a variable impedance humidity sensing circuit and a zero crossing detector circuit. The humidity sensing circuit and zero crossing circuit are provided with an AC line voltage and both have outputs which are provided to the microcontroller. The humidity control device also includes a semiconductor switch circuit which switches the AC line voltage to an external electrical device, such as a dehumidifier or heater, at the zero crossing.

Abstract: Disclosed is an AC power module for controlling the level of power to multiple electrical devices such as lights and household appliances according to control signals supplied from a processor unit. The apparatus utilizes low voltage control signals which are synchronous with the standard AC power supply to control several solid state relay which in turn regulate the AC power supplied to the devices. Each relay is optically isolated from the module. The module incorporates additional terminals through which back-up switching or control of additional relays (with different power ratings) may be provided.The module may be constructed on a single printed circuit board (PCB) to facilitate installation and removal. According to this embodiment, the PCB has pins which matably attach to a corresponding number of L-shaped tabs provided on a standard electrical box.

Abstract: An apparatus using a battery as a power source requires a battery having an extended life time. A burden upon a battery can be reduced by operating the inner circuit at a low voltage and current. The present invention aims at providing a compact and low power consuming apparatus. A battery used as a power source drives a circuit for a low voltage circuit system and a switching circuit which switches power supply when the battery voltage becomes a preset voltage. A circuit for a high voltage circuit is directly driven by the battery when the battery voltage is high, and the circuit is powered from the output (for example, 1.5 volts) of a step-up circuit when the battery voltage is low. Switching of power sources is made in such a manner, resulting in low power consumption. Extension of life time of battery, and reduction in size of battery and apparatus can be achieved.

Abstract: A scheme for maintaining current balance within a plurality of semiconductor devices, particularly thyristors and gate turn-off thyristors, which plurality is connected between two electrical power sources which devices are configured to be simultaneously conductive to share the current between the two sources, employs the scheme for maintaining the current within the several devices of the plurality equal. The scheme provides for the generation of individual current signals which represent the individual current magnitudes within the several devices. Further generated is an average current signal representing the average current within the plurality. A difference signal is generated with respect to each of the individual current signals which represents the difference between the average and the individual current signal.

Abstract: A tapped inductor slave regulating circuit provides a second slave output voltage derived from a tapped connection to the filter storage inductor of a first output voltage of a switching power supply converter. In the converter, an unregulated voltage is provided through a switching circuit to a storage inductor to develop a first output. The switching circuit is turned off and a synchronous rectifier is turned on to freewheel the current through the storage inductor and the load. The storage inductor is center-tapped and coupled to a switching circuit to provide a second slaved output. The location of the center tap is chosen to provide the proper voltage of the second output. In one embodiment, the switching circuit for the slaved output is turned on during the freewheel portion of each cycle to provide a proper voltage level for the second output. In another embodiment, a separate local feedback circuit is provided to further regulate the second output voltage level.

Abstract: Method and apparatus for monitoring the operation of a plurality of electrical loads in an automotive vehicle with a single current sensor. The current sensor detects the change in the total output current associated with the electrical loads and generates an output signal based on the current change. The apparatus also includes a controller which activates each electrical load at a given time to obtain a like plurality of timing signals so that each electrical load receives a portion of the output current. The controller processes the output signal and the timing signals to obtain a diagnostic signal related to an operating condition of at least one of the electrical loads. Finally, the controller controls an operating state of the at least one of the electrical loads based on the diagnostic signal.

Abstract: A system and method for controlling plural load with high reliability, comprising plural control devices for respectively controlling the plural electric loads, plural switches for respectively giving ordering signals to the control devices to control the respective loads, and a monitor circuit for detecting an out of order control device and generating ordering signals for selecting another control device which is not out of order based on the superiority of the other electric load and the ordering signals from the switches which correspond to the other control device to change from the control device which is out of order to the other control device.

Abstract: In an appliance having a relatively low voltage control section controlling one or more AC power loads through switch devices such as triacs, the triacs are gated sequentially within each half cycle such that the peak load on the low voltage control circuitry caused by gating the plural triacs is equal to the load created by gating only a single triac. Distribution of the gating of plural triacs is accomplished through the use of a timing circuit or microprocessor, or RC timing circuits having differing time constants.

Abstract: Disclosed is an electrical control circuit (10) for controlling current through a plurality of resistive loads (14(1), 14(2) . . . 14(N)). The control circuit includes a plurality of current control stages (12(1), 12(2), . . . 12(N)), a comparator circuit (18), and a plurality of diodes D.sub.1, D.sub.2. . . D.sub.N-1 in serial connection with the current control stages. The comparator circuit controls the current that is drawn collectively through the loads. The diodes ensure that all preceding current control stages in the series are conducting a predetermined level of current before the next current control stage begins to source current through its respective load. Each current control stage includes an operational amplifier (30), a pass transistor (34), a sense resistor (R.sub.s), and a feedback resistor (R.sub.f). The operational amplifiers are a pre-drive to the pass transistors to allow smaller sense resistors to be used, thereby providing greater efficiency. The feedback resistors (R.sub.

Abstract: Electric power uses or loads in a premises are controlled or managed depending upon whether the use is for heating, hot water, heat pump, air conditioning, lights, appliances, pumps, etc., according to programs that are controlled by the electric Power Company, for the purposes of spreading power uses at the premises over a day or other time interval, to avoid peak load periods encountered by the Power Company, while still providing the normal comfort levels required by the subscriber from the various power uses. Power levels of several uses at the subscriber's premises are sensed and the power for each use is controlled according to a program that includes a schedule of power level and/or the time of day that is inserted in the program or controlled in the program by the Power Company to accomplish the spreading. In a particular embodiment, a programmed computer unit is provided at the premises that is monitored by the Power Company via the subscribers telephone line.

Abstract: High efficiency, post regulation of auxiliary outputs in multiple output-power supplied is provided by connecting a regulating switching device in parallel with a filter inductor connected in the current path from the rectifiers to the output terminal. For minimum output power for that auxiliary output, the switching device is held off at all times. When increased power is required, the switching device is turned on for a short period during each cycle of the inductor voltage. The switching system may be configured to conduct current from the output end of the inductor to the input end of the inductor or vice versa or either one selectively, in accordance with the particular regulation scheme chosen. Efficiency is maximized since current flows in the switching device for only a small portion of each cycle of the inductor voltage.

Abstract: Reducing the power consumption of loads fed by one or more power supplies is achieved by the use of apparatus which determines the power supply output and, upon the occurrence of a predetermined condition, generates a signal to the power-consuming loads. In response to this signal, the loads alter their mode of operation so as to reduce the overall demand on the power supply. Several implementations of this load-shedding technique, which is particularly suitable for use in a communications system, are disclosed.

Abstract: An operating system for a dual fuel heating system having first and second heat pump stages, first and second gas furnace stages, an executive controller for tracking time increments and call control strategies at appropriate levels, a demand control for calculating the amount of time each heat pump can be on during a predetermined time window, a data storage apparatus, a thermostat, a first predicting module for predicting non-heat pump electrical load based on a moving average, a second predicting module for predicting heat load based on a moving average, and a limiting module for setting demand limits for off-peak, mid-peak and peak periods. The executive controller is operated to initiate operation of the foregoing routines to determine, based on historical building profile information including non-heat pump electric power information the availability of heat pump power with no increase in demand charges during any given incremental interval.

Abstract: The invention concerns the distribution of electric power to several functional units (10, 11, 12) with variable power consumption. A preset limit value (Pmax) of the total power supply which is lower than the sum of the highest possible individual powers (P10, P11, P12) is maintained. By evaluating the total power consumption (I) or the operating voltage (U) of all functional units (10, 11, 12), an increase in the supply current or a drop in operating voltage (U) is used to reduce the supply current (I3) of functional units(12) of a lower importance is favor of the supply current of functional units (11) of a higher importance. This invention is used especially in electrical telephone subscriber's stations that are supplied over the subscriber's line.

Abstract: An electronic controller, connected to a digital communication network, is responsive to commands from a master controller to control solenoid operated circuit breakers. The electronic controller also determines the status of all circuit breakers and reports back to the master controller to verify that the command from the master controller was executed and to provide historical data regarding the status of the circuit breakers. The electronic controller is synchronized to the same alternating current (AC) power source as the circuit breakers to control the operation of the respective circuit breakers to minimize electromagnetic interference (EMI) caused by the switching of the circuit breakers. The electronic controller further controls the operation of the circuit breakers to reduce the duty cycle of the power supply for the circuit breaker solenoids.

Abstract: In an automatic vending machine having a heater for boiling water, and a motor-driven compressor for refrigeration, a flow of current to the heater is stopped when the compressor is started. On the other hand, while the compressor is being operated stably, the current flowing in the heater is controlled in phase such that the sum of an effective current flowing in the compressor and an effective current flowing in the heater does not exceed a predetermined value.

Abstract: A modular power supply system in which a plurality of power supply modules connected in parallel to a load contribute equal currents, even if one or more of the power supply modules fails. A first order fault tolerant modular power supply system includes three power supply modules (38, 40 and 42) connected in parallel to a load (32). The output current from each of the power supply modules is separately compared to the output current from one of the other power supply modules in a loop arrangement, using three control circuits (64, 66 and 68). A signal indicative of the current contributed by each pair of the power supply modules is input to the control circuit, producing a differential output signal used as a reference to control the output current from each of the power supply modules.

Abstract: A control system is provided in which a plurality of independent control elements are each capable of generating a random value and determining a time delay as a function of that random value. Each of the control elements accesses the magnitude of a sensed parameter and responds to that magnitude. When correction of the sensed parameter is required, each independent control element senses the need for a correction and delays by an amount of time determined randomly and independent from all other control elements. After the randomly determined time delay has elapsed for each control element, that control element again accesses the magnitude of the sensed parameter and, if correction is still required, changes the connection status of an associated switch. In a preferred embodiment of the present invention, the control element interrogates the status of its associated switch to determine if actuation would benefit the correction of the magnitude of the sensed parameter.

Abstract: A power interrupt switching device for independently controlling normal and remote loads from a single control switch. The device includes an edge detector, an energy storage element, and a latch. When power is applied to the switching device, the edge detector detects the power transition and generates an output pulse for a predetermined time. The storage element charges and generates an output after a second predetermined time greater than the first. Consequently, both outputs are not present simultaneously upon the first application of power. If power is interrupted momentarily and then reapplied, the edge detector again generates an output while the storage element maintains its output during the interruption. With both outputs present, the latch is triggered to deliver power through the switching device to a remote load. The latch remains closed until power is removed.

Abstract: A multi-phase switched reluctance motor is driven from a tow-point d.v. supply (11) in which capacitors (12) and (13) are provided across the supply with their common point (14) constituting a third power supply point. The load windings W.sub.1, W.sub.3, W.sub.5 and W.sub.2, W.sub.4, W.sub.6 are connected in two different load circuits connected across the different capacitors. In order to prevent the voltage of the third point wandering because the currents in the the two load circuits are not the same, control means (21) can control the distribution of current between the various load windings by appropriate control of semi-conductor switches in the various load circuits.

Abstract: A circuit is disclosed which provides power isolation between the initializing and driven circuit, allowing the logic of a wide pulse width signal to be effectively transmitted across pulse transformers and faithfully reproduced.

Abstract: A power control circuit for a color encoder of a video camera having a camera head portion, a signal processing circuit for generating a luminance signal and a chrominance signal, a color encoder supplied with the luminance signal and the chrominance signal and for generating a composite video signal, and an external output terminal at which the composite video signal is obtained includes a power switch for controlling the power supply to the color encoder, a comparator connected to the external output terminal and for comparing the level of a synchronizing signal at the external output terminal with a reference level and a control circuit supplied with the output of the comparator and for controlling the power switch such that the power switch is turned on when the external output terminal is terminated.