摘要:
An electrical device includes a first terminal structured to electrically connect to a power source; a second terminal structured to electrically connect to a load; a voltage sensor electrically connected to a point between the first and second terminals and being structured to sense a voltage at the point between the first and second terminals; a switch electrically connected between the first terminal and the second terminal; and a control unit structured to detect a power quality event in the power flowing between the first and second terminals based on the sensed voltage and to control a state of the switch based on the detected power quality event.
摘要:
The invention relates to a detection device (100) for detecting an arc (104a-i; 909) occurring between a first current-carrying element (103; 903a) and at least one conductive element (103b, 108; 903b, 907), comprising at least one measuring device (101; 901, 902), which is designed to measure a current (I) flowing through the first current-carrying element (103a; 903a), and an analysis device (102) which is designed to determine a frequency spectrum of the measured current (I) and to detect the arc (104a-i; 909) occurring between the first current-carrying element (103a; 903a) and the at least one conductive element (103b, 108; 903b, 907) on the basis of a high-frequency range of the determined frequency spectrum.
摘要:
An electrical device includes a first terminal structured to electrically connect to a power source; a second terminal structured to electrically connect to a load; a voltage sensor electrically connected to a point between the first and second terminals and being structured to sense a voltage at the point between the first and second terminals; a switch electrically connected between the first terminal and the second terminal; and a control unit structured to detect a power quality event in the power flowing between the first and second terminals based on the sensed voltage and to control a state of the switch based on the detected power quality event.
摘要:
An electrical device includes a first terminal structured to electrically connect to a power source; a second terminal structured to electrically connect to a load; a voltage sensor electrically connected to a point between the first and second terminals and being structured to sense a voltage at the point between the first and second terminals; a switch electrically connected between the first terminal and the second terminal; and a control unit structured to detect a power quality event in the power flowing between the first and second terminals based on the sensed voltage and to control a state of the switch based on the detected power quality event.
摘要:
An electrical circuit to interrupt a DC current includes a bypass switch and an AC high voltage breaker which includes interrupters that are rated for carrying a current having a value of the DC current for a period of time less than or equal to continuous duty. The first interrupter is electrically coupled in parallel with the bypass switch. A making switch causes a cancellation current to flow from an energy source through the second interrupter, and through the first interrupter, in addition to the DC current. The AC high voltage breaker is adapted to a DC service as the DC current in addition to the cancellation current causes an arc quench which allows the AC high voltage breaker to cause the interruption of the DC current in the electrical circuit. A method for interrupting a DC current flowing in an AC high voltage circuit breaker is also described.
摘要:
A power status monitor for an electronic system includes a charge/discharge model of the system power supply. The charge/discharge model contains an estimate of the amount of time during which energy-storage devices in a system DC power supply are capable of maintaining system operation following loss of AC power. The power status monitor monitors the frequency and an amplitude of the voltage of the AC power source for signs indicating imminent failure of the AC power source. In the event that such signs are detected, the estimate in the charge/discharge model is decremented at a rate corresponding to the rate at which charge is consumed. A trip value, applied to the charge/discharge model, determines the time at which a signal is generated enabling an orderly shutdown of the system load. If acceptable AC power is resumed before the trip value is reached, the charge/discharge model increases its estimate of the time available at a rate corresponding to the charge accumulation in the DC power supply.
摘要:
An armature of an electric motor for an elevator car is controllably driven by a three-phase source through a semiconductor converter controlled with a difference between a command and an actual car speed signal. A relay for sensing a ripple current from the converter is serially connected to a tuned filter across the armature. When a break occurs anywhere in a circuit with the motor armature, the sensor relay is deenergized and connects an emergency braking circuit across the armature. Alternatively the sensor relay may be connected via the filter to a reactor connected to the converter.
摘要:
A circuit for protecting speakers connected to the output of an audio amplifier. The output of the amplifier is connected to a filter which blocks normal audio frequency signals but passes both high and low frequency signals outside the normal audio range. The positive and negative filter output signals are connected respectively to the inverting and non-inverting inputs of an operational amplifier whose output is connected via a turn-on delay circuit to a speaker relay, which, when closed, connects the speaker to the amplifier. The turn-on delay circuit prevents speaker relay closure until turn-on transients have ended. If a DC voltage or a high frequency signal is present at the amplifier output, the operational amplifier generates a signal to open the relay thereby disconnecting the speaker from the amplifier output. The speaker relay quickly opens when power is turned off so that amplifier turn-off transients are not connected to the speaker either.
摘要:
In an amplification system comprising an amplifier, a loudspeaker, normally open contacts connected in series between the amplifier and the speaker, and a power supply for the amplifier having relatively long buildup and decay times of its output voltage in response respectively to the connection and disconnection of the power supply to and from the a.c. line, means are provided responsive to the connection of the power supply to the a.c. line for delaying the closing of the normally open contacts until after the power supply voltage has built up to its full operating potential for eliminating the transient audio signals from the amplifier associated with power supply voltage buildup from being reproduced by the loudspeaker. Means are also provided for opening the contacts quickly after the power supply is disconnected from the a.c. line for eliminating the distorted audio signals from the amplifier associated with power supply decay from being reproduced by the loudspeaker. Additionally, if the amplifier is of the balanced type which exhibits a zero d.c. output potential during normal operation, means are provided for quickly opening the contacts upon the occurrence of a high d.c. amplifier output potential of either polarity for protecting the loudspeaker.
摘要:
A protecting device for a semiconductor memory which protects the plural semiconductor memory elements from damage due to an abnormal pulse being received from the driving circuits. The output signals from the precharge and chip select signal drivers in a MOS-RAM are sampled and time-delayed. The sampled signals are compared with the time delayed signals in gating circuits. If the sampled signals exceed a predetermined pulse width, sensing means are actuated to activate the alarm and terminate the source voltage to prevent damage to the memory elements.