Abstract: A DC grid (100) comprising a plurality of AC/DC converters (105) which are interconnected via DC lines (115) is provided, wherein, in order to limit the effects of a fault in the DC grid, the DC grid is divided into at least two zones (200) by means of at least one current limiter (205) in a manner so that a current limiter is connected in each of the DC line(s) (115z) by which two zones are interconnected. A method of limiting the effects of a fault in a DC grid by dividing the DC grid into at least two zones is also provided.

Abstract: A controller identifies a condition of a hazardous internal short by comparing patterns of series element voltages to the last known balance condition of the series elements. If the loaded or resting voltage of one or more contiguous series elements uniformly drop from the previously known condition by an amount consistent with an over-current condition, an over-current internal short circuit fault is registered. The desired response is to prevent the affected series elements from heating to a hazardous temperature by summoning the maximum heat rejection capability of the system until the short ceases and the affected elements cool, the cooling function is no longer able to operate due to low voltage, or the affected series string has drained all of its energy through the short. Also includes are responses that allow the battery pack to continue to power the cooling system even though it may enter an over-discharged state.

Abstract: A current source regulator for controlling an output device (Mp) of current source, the output device (Mp) providing an output current (Isrc) to a load. The current source regulator comprises a first feedback loop (1) and second feedback loop (2). The first feedback loop (1) includes a first sensing path to provide a first sensing signal (Is1) for comparison with a first reference to generate a first control signal. The second feedback loop (2) comprises a second sensing path to provide a second sensing signal (Is3, Is3?) for comparison with a second reference (Ib5) to generate a charging current signal (Icharge). The charging current signal (Icharge) is applied to the control signal during a transient state of the current source regulator.

Abstract: A protection system for an IT electrical distribution system (EDS) has a floating reference conductor and two electrical conductors in the form of an active conductor and a neutral conductor. System includes two input terminals for electrically connecting to an MEN electrical power source that is upstream of system. Two output terminals are electrically connected to an electrical load in the form of an electrical motor for a compressor of an upright freezer display. Motor is downstream of the system. A protection device, in the form of an MCB, electrically connects terminals to allow a supply of electrical power from source to motor. MCB is responsive to a fault signal at a port for selectively electrically disconnecting at least one of terminals to prevent the supply of electrical power. A sentinel unit selectively generates the fault signal at port in response to the current in conductor being greater than a predetermined threshold.

Abstract: A switching power source apparatus includes a high-side MOSFET 11, a ramp signal generator 18 to generate a ramp signal, an amplitude signal generator 2 to generate an amplitude signal Comp corresponding to an amplitude of the ramp signal, a superposing circuit 3 to generate a superposed signal by superposing a second ramp signal on a first reference voltage, a first feedback controller 1 to control the ON timing and ON width of the high-side MOSFET, an overcurrent detector to detect if a current of an output load is an overcurrent, and an OFF timer 26 to determine a period during which the high-side MOSFET 11 is forcibly turned off and generate a forcible OFF signal. If an overcurrent is detected, the controller 1 turns off the high-side MOSFET, and according to the forcible OFF signal, forcibly turns off the high-side MOSFET 11 for the determined period.

Abstract: Devices, such as mobile devices, may be exposed to short circuit and output overload events. To protect against such events, mobile devices typically include circuitry to limit currents so as not to exceed a pre-programmed current limit. Various embodiments of the present invention include devices and methods for detecting pre-programmed current limits and for limiting currents in response to such detection. In some embodiments, both the current limit detector and the current limit controller circuitry include scaled current switches. The scaling may be substantially similar between the programmed-current limit detector and the current limit controller circuitry.

Abstract: A system and method for limiting in-rush current from a power source to a load includes sensing that a load has been electrically connected to receive electrical power from the power source. A current limiter circuit is configured to at least inhibit electrical current flow from the power source to the load for a predetermined time period. After the predetermined time period, the current limiter circuit is configured to no longer at least inhibit the electrical current flow from the power source to the load. Upon sensing that the load has been electrically disconnected from the power source, the current limiter circuit is reconfigured to at least inhibit electrical current flow from the power source to a load that may be subsequently connected to receive electrical power from the power source.

Abstract: A compressor monitoring system includes current and voltage monitors, current and voltage averaging modules, a control module, and a switch. The current monitor measures a current drawn by a motor of a compressor. The current averaging module generates first and second average current values based on the current measured by the current monitor. The voltage monitor measures a utility power voltage. The voltage averaging module generates first and second average voltage values based on the voltage measured by the voltage monitor. The control module selectively generates a fault signal when a first ratio is greater than a first predetermined threshold and a second ratio is less than a second predetermined threshold. The first ratio is based on the first and second average current values. The second ratio is based on the first and second average voltage values. The switch deactivates the motor when the fault signal is generated.

Abstract: A voltage regulator is capable of continuously and smoothly preventing an inrush current independently of a startup characteristic of a reference voltage circuit. The voltage regulator is provided with an inrush current protection circuit composed of a constant-current circuit, a first transistor having the source thereof connected to the constant-current circuit and the gate thereof controlled by an output voltage detection circuit, a capacitor connected between the first transistor and the gate of an output transistor, a second transistor having the gate thereof connected to the drain of the first transistor and the source thereof connected to a power supply terminal, and a third transistor, which is connected between the second transistor and the output transistor and the gate of which is controlled by the output voltage detection circuit.

Abstract: A power supply device for intrinsically safe power supply of an intrinsically safe load circuit includes a voltage source, a power-limiting circuit including at least two controllable semiconductor devices, a current-limiting circuit including at least one resistor, and a load circuit connector connected to the load circuit. The power-limiting circuit and the current-limiting circuit are active between the voltage source and the load circuit connector. The resistor includes a resistance value that suffices to limit a short circuit current to a current without danger of a spark ignition.

Abstract: Active current surge limiters and methods of use are disclosed. One exemplary system, among others, comprises a current limiter, including an interface configured to be connected between a power supply and a load; a disturbance sensor, configured to monitor the power supply for a disturbance during operation of the load; and an activator, configured to receive a control signal from the disturbance sensor and to activate the current limiter based on the control signal.

Abstract: Active current surge limiters and methods of use are disclosed. One exemplary system, among others, comprises a current limiter, including an interface configured to be connected between a power supply and a load; a disturbance sensor, configured to monitor the power supply for a disturbance during operation of the load; and an activator, configured to receive a control signal from the disturbance sensor and to activate the current limiter based on the control signal.

Abstract: An overcurrent protection apparatus for a secondary battery includes a main relay, an auxiliary relay connected in parallel with the main relay, a current limiting resistor connected in series with the auxiliary relay and a controller for detecting an overcurrent and protect the battery module. The controller turns on the main relay and turns off the auxiliary relay in a normal state where the battery module is recharged by the generator. When the overcurrent is detected, the controller turns on the auxiliary relay and turn off the main relay so that a limited current flows through the current limiting resistor.

Abstract: An in-rush current limiting system has a fast response time so that it can be used with power supplies that turn on and off rapidly. The system dissipates very little power during the normal mode of operation. This is achieved, in various embodiments, by connecting a regulator in series with a load capacitance and in parallel with the system load.

Abstract: A protection and attenuation circuit for sensitive AC loads is described. The circuit provides AC power protection and attenuation utilizing high-efficiency switch-mode techniques to attenuate an AC power signal by incorporating a bidirectional, transistorized switch driven from a pulse width modulation signal, PWM. The circuit monitors characteristics of the AC power signal driving a known load and characteristics of the load or other elements and determines the duty cycle of the pulse width modulated signal, PWM, based upon the duration and amplitude of the over-voltage, over-current, over-limit or other event.

Abstract: An open magnetic circuit coil (6) is arranged on a line connecting a battery (1) to a charger (CH1). Furthermore, a resistor (2) is connected in series with a large-capacitance electrolytic capacitor (7) for smoothing a charger output which is connected to the output of the charger (CH1). This can suppress an abrupt change in current flowing in the connection line between the battery (1) and the charger (CH1) in connection between plugs (3a, 3b).

Abstract: In one embodiment of the present invention, a multiphase electric circuit is disclosed for shutting down a current conducted over respectively one AC power controller. The neutral points of the voltage systems connected to the phases are not connected to each other via a neutral conductor. The AC power controller of each phase is provided with two thyristors. A single series connection is connected parallel to all phases, which series connection comprises a capacitor and a number of parallel-connected quenching switches corresponding to the number of phases. The capacitor can be charged up via a diode bridge and a transformer.

Abstract: A system that detects electrical disconnection of one connector from another connector includes a detection circuitry and a protection circuitry. The detection circuitry detects that a plug connector has been electrically disconnected from a corresponding receptacle connector. In response to the detection, the detection circuitry sends a signal to the protection circuitry. In response to the signal, the protection circuitry lowers or terminates power being supplied to a host device via one of the contacts of the plug connector. This helps to prevent shocks/shorts that may be caused by accidental disconnection of the plug connector.

Abstract: There is provided a protection apparatus for a load circuit, capable of protecting the load circuit by simulating a fuse. A pseudo heat capacity Cth* smaller than a heat capacity of an electric wire used in the load circuit is set, and a temperature of the electric wire is calculated with reference to an arithmetic expression of heat generation amount of the electric wire, an arithmetic expression of heat radiation amount of the electric wire, a time counted by the count unit, and the pseudo heat capacity Cth*. Then, a semiconductor relay S1 is interrupted when the calculated temperature of the electric wire reaches an allowable temperature of the electric wire to protect the load circuit from heat generation.

Abstract: Presented systems and methods can facilitate efficient switching and protection in electronic systems. A system can comprise: an input operable to receive a signal; an adjustable component configurable to operate in a first mode which includes a low resistance and the component configurable to operate in a second mode which includes a current limiting operation in which the second mode enables continued operation in conditions that are unsafe for operation in the first mode; and an output operable to forward a signal. The adjustable component can be configurable to turn off if unsafe to operate in either the first mode or second mode. The first mode can include a relatively large component configuration with a relatively low drain to source on resistance. Utilizing a small component configuration in the second mode can include a relatively increased gate to source voltage compared to a large component configuration in the second mode.

Abstract: In a fault current limiter (FCL) of a saturated core type having at least one coil wound around a high permeability material, a method of suppressing the time derivative of the fault current at the zero current point includes the following step: utilizing an electromagnetic screen or shield around the AC coil to suppress the time derivative current levels during zero current conditions.

Abstract: A system for poling piezoelectric devices comprises a plurality of thin-film components, a plurality of piezoelectric devices, a poling pad for poling the piezoelectric devices, a plurality of traces, and a plurality of current-limiting elements. The thin-film components are separated by dice lanes to form an array, and the piezoelectric devices are formed on the thin-film components. The traces connect the piezoelectric devices across the dice lanes in parallel to the poling pad. Each current-limiting element is connected in series with one of the piezoelectric devices, in order to limit current to individual piezoelectric devices that experience current-related failure.

Abstract: A system and method for a vehicle control system is disclosed herein. The system includes an inverter circuit, a permanent magnet synchronous motor, and a crossover connected between the inverter circuit and the permanent magnet synchronous motor. The system may also include at least one current sensor installed between the inverter circuit and the permanent magnet synchronous motor. A contactor may also be connected between the inverter circuit and the permanent magnet synchronous motor and may pass or shut off electricity between the inverter circuit and the permanent magnet synchronous motor. The system may also include a control unit connected to the contactor and the current sensor. The control unit may detect a current abnormality using information from the current sensor and open the contactor if an abnormality is detected.

Abstract: Provided are an overcurrent protection device and an overcurrent protection system which can provide time differences among the timings for executing the retry operations among a plurality of overcurrent protection devices connected to a common power supply. When a battery voltage (VBA) becomes a value equal to or lower than a threshold voltage after an FET (Q1) of an IC circuit (51-1) is turned on, all FETs (Q1) of the respective IC circuits are turned off, and a time until the battery voltage (VBA) reduces to a value lower than a threshold voltage after the turning-on of the FET (Q1) is clocked. When the time is smaller than 400 ?sec, the count value N is incremented. Further, turning-on of the FETs (Q1) is repeated after the lapse of the standby time (Tp) set randomly. When the count value N reaches 7, the FET (Q1) of the IC circuit 51-1 is held in the turned-off state.

Abstract: There are provided an output inverter for single phase which can detect a current with high precision through a smaller number of components, and an output current detecting method thereof. A first current detector (6) is disposed between a positive electrode P side of a DC power supply and a parallel connector (1) in a first arm (8), a second current detector (7) is disposed between a negative electrode N side of the DC power supply and a parallel connector (4) in a second arm (9), a current in a first convection mode is detected by the first current detector (6), a current in a second convection mode is detected by the second current detector (7), and an output current is detected from signals output from the first current detector (6) and the second current detector (7).

Abstract: Provided is a voltage regulator capable of enabling overcurrent protection in a state in which an output current is large even if an input/output voltage difference is small, without waiting until the output voltage decreases. A sense current that a sense transistor flows is detected by a differential amplifier circuit, and hence, in the state in which the input/output voltage difference is small and the output current is large, the overcurrent protection can be enabled even when the output voltage does not decrease. Further, a good fold-back characteristic can be obtained.

Abstract: A load circuit operates by power supplied from a power supply apparatus. A capacitive element is connected in parallel with the load circuit. A switching element is connected between the power supply apparatus and the load circuit in series with the power supply apparatus and the load circuit. A monitor section monitors voltage of the capacitive element and is connected in parallel with the capacitive element. An inrush current control section changes resistance of the switching element on the basis of the voltage monitored by the monitor section in order to control inrush current that flows at the time of an electronic device being plugged into or unplugged from the power supply apparatus. A breaker circuit prevents electric charges stored by the capacitive element from flowing into the monitor section at the time of the electronic device being unplugged from the power supply apparatus.

Abstract: An assembly is disclosed which may include a serviceable unit and a current limiting device coupled to the serviceable unit. The serviceable unit may include a positive electrical terminal connection, a negative electrical terminal connection, and a plurality of energy storage devices operatively coupled to the positive electrical terminal connection and the negative electrical terminal connection to form an electrical path of the serviceable unit. The current limiting device may include a current limiting component. The current limiting component being included in the electrical path of the serviceable unit.

Abstract: The invention relates to a power transistor for protecting, by limiting current, an electrical power supply, including one or more basic power vertical-junction field-effect transistors (602). Each basic power vertical junction field-effect transistor (602) includes at least one semiconductor depletion region (618, 620) forming a partially buried gate that defines a vertical channel (622) inside a first region (612). Each basic transistor includes a semiconductor depletion region (618, 620) forming an upper surface gate that is not buried, and defining a side channel inside a region (612) vertically adjacent to the first region.

Abstract: The present invention relates to a device and a method for reliably securing an electric line with a controllable switching element, wherein the device and the method can be easily adapted to the properties of an electric line. The device comprises a controllable switching element (110, 610) that is designed to take on at least two states, specifically a first state with a first resistance and a second state with a second resistance that is lower than the first resistance.

Abstract: A short circuit detection device is provided to check a circuit layout. The circuit layout includes electronic components connected in parallel. Any of the electronic components includes two contacts on the circuit layout. The short circuit detection device includes a determination circuit configured to determine whether a short circuit has occurred in the circuit layout, and a detection circuit configured to determine the specific electronic component or components responsible for the short circuit. The determination circuit connects with one contact of any of the electronic components. The detection circuit connects with two contacts of any of the electronic components.

Abstract: The present invention provides a multichannel active sensing and switching device featuring a multiple sensing and switching module configured to respond to operational conditions of different load types and provide load type sensor signals containing information about the operational conditions of the different load types, and also configured to respond to controller signals for controlling the operation of the different load types in two or more different protection configurations; and a controller module configured to respond to the load type sensor signals and provide the controller signals in order to control the operation of the different load types in the two or more different protection configurations. The controller module may be programmable and configured to provide a default circuit breaker configuration and a device specific configuration using active intelligence (AI).

Abstract: A functional element is prevented from breakdown and deterioration because of mounting and demounting of the functional element immediately after cut-off of driving power from a constant-current power supply or during supply of the driving power. An electric circuit is configured to electrically connect a constant-current power supply 1 having a capacitance between an output terminal and a reference potential terminal and a detachable functional element 2 to each other. The electric circuit has an element breakdown prevention circuit 10 having a first circuit terminal connected to an output terminal of the constant-current power supply 1 through the functional element 2, and a second circuit terminal connected to the reference potential terminal of the constant-current power supply 1 through the functional element 2.

Abstract: New techniques for limiting transmission of fault current are disclosed. In one particular exemplary embodiment, the technique may be realized with a new type of apparatus for limiting transmission of fault current. The apparatus may comprise: a first enclosure electrically decoupled from ground, such that the first enclosure is electrically isolated from ground potential; first and second terminals, at least one of which is electrically connected to first one or more current carrying lines; and a first superconducting circuit contained in the first enclosure, the first superconducting circuit electrically connected to the first and second terminals, wherein the first enclosure is maintained at same electrical potential as the first one or more current carrying lines.

Abstract: According to one embodiment, a power supply system includes a switching device operable to be turned on and off for causing power to be delivered to a load. The switching device has a control terminal. Driver circuitry, coupled to the control terminal of the switching device, is operable to drive the switching device. The driver circuitry further operable to detect a fault condition in the power supply system. If the switching device is turned on when the fault condition is detected, the driver circuitry reduces the voltage at the control terminal of the switching device to a level just above the threshold voltage for the switching device, and holds the voltage at the control terminal to the level just above the threshold voltage for a controlled duration, thereby reducing the saturation current flowing through the switching device. The driver circuitry further reduces the voltage at the control terminal of the switching device after the controlled duration, thereby safely turning off the switching device.

Abstract: The load driving device disclosed in the specification includes a controller to generate a first control signal based on an input signal, a first output transistor to supply an output current to a load according to the first control signal, a first dividing circuit to output a first divided voltage by dividing a voltage across a first primary electrode and a second primary electrode of the first output transistor by a first transistor and a second transistor connected in serial, a first voltage generating circuit to output a first reference voltage, and a first comparator to supply a first over current detection signal to the controller based on the first reference voltage and the first divided voltage.

Abstract: A protection circuit to protect from a reverse current, including a current limitation element to connect between an external reference terminal and an internal reference potential to limit the amount of current flowing from the external reference terminal to a power source terminal, when a reversed polarity voltage is applied at the power source terminal; and a conducting element to connect between the power source terminal and the internal reference potential to adjust the internal reference potential to the voltage at the power source terminal, when the reversed polarity voltage is applied.

Abstract: A protection circuit 2 of a first embodiment comprises a resistance-variable switch 10, an overcurrent detection unit 20, a control voltage application unit 30, a capacity unit 40, a control terminal voltage change unit 50, and an outer terminal 11. The resistance-variable switch 10 has a control terminal 10a, a first terminal 10b, and a second terminal 10c. The control terminal voltage change unit 50 includes a switch 51 and a resistor 52 which are provided in series between the control terminal 10a of the resistance-variable switch 10 and a reference potential terminal.

Abstract: Fault Current Limiters (FCL) provide protection for upstream and/or downstream devices in electric power grids. Conventional FCL require the use of expensive conductors and liquid or gas cryogen handling. Disclosed embodiments describe FCL systems and devices that use lower cost superconductors, require no liquid cryogen, and are fast cycling. These improved FCL can sustain many sequential faults and require less time to clear faults while avoiding the use of liquid cryogen. Disclosed embodiments describe a FCL with a superconductor and cladding cooled to cryogenic temperatures; these are connected in parallel with a second resistor across two nodes in a circuit. According to disclosed embodiments, the resistance of the superconducting components and its sheath in the fault mode are sufficiently high to minimize energy deposition within the cryogenic system, minimizing recovery time.

Abstract: An exemplary aspect of the present invention is a current limiting circuit including: an output transistor that controls a current flowing to a load from a power supply; a current sense transistor through which a current dependent on a current flowing through the output transistor flows; a sense resistor connected in series with the current sense transistor; a potential difference detection unit that detects a potential difference generated between both ends of the sense resistor; a constant current generation unit that supplies a constant current to the potential difference detection unit; and a control unit that controls a conduction state of the output transistor based on a control voltage generated based on the potential difference and the constant current, in which the sense resistor is disposed so as to surround the potential difference detection unit.

Abstract: An intelligent power switch (IPS) circuit providing current protection for a power switch, a gate terminal of the power switch being controlled by a first control signal generated by a gate driver. The IPS circuit includes a first circuit to measure a current in the power switch, determine a first difference between a first voltage and a first reference voltage, and reduce the first control signal if the first difference exceeds a first predetermined limit; and a second circuit to measure the current in the power switch and determine a second difference between the first voltage and a second reference voltage, wherein if the second difference exceeds a second predetermined limit the first control signal is set to turn OFF the power switch.

Abstract: A circuit and method protect switching devices from alternating current overload. By protecting the switching devices from AC overload, the reliability of the equipment using the switching devices is improved, cost for repair is decreased and information regarding the cause of the AC overload is available.

Abstract: A load current is limited to a safe level with a current protection logic circuit within a first selected interval after detection of a fault condition. The current protection logic circuit returns the load current to a normal level within a second selected interval after correction of the fault condition, wherein said safe level is less than one half of the normal level. The current protection logic circuit is a feature of a high side driver comprising at least two source drivers, each source driver being configured to switch an electrical load to a common power supply, and comprising a respective current protection logic circuit.

Abstract: A switching mode power supply with a multi-mode controller is provided. The switching mode power supply may include a transformer having a primary winding and a secondary winding to supply power to a load. A feedback circuit may be included to generate a feedback signal that varies in relation to the load on the secondary winding. The multi-mode controller may include a switching circuit, a frequency control circuit and a current limiting circuit. The switching circuit may be coupled to the primary winding to control current flow through the primary winding. The frequency control circuit may control a switching frequency of the switching circuit based on the feedback signal. The current limiting circuit may limit current flow through the primary winding by causing the switching circuit to suspend current flow through the primary winding when the current reaches a peak current limit that is set based on the feedback signal.

Abstract: An intrinsically safe energy limiting circuit for connection between an upstream DC power source and a downstream electrical load powered from the upstream DC power source, wherein the circuit comprises from upstream to downstream an input to be connected to the DC power source, an electronic current limiter configured to limit a current through the circuit to a maximum value if the current reaches this value, a fuse designed to open at a current value greater than the maximum value, a DC-to-DC converter configured to convert a DC input voltage to a lower nominal DC output voltage, a zener barrier having a zener voltage higher than the DC output voltage, and an output for connection to the electrical load.

Abstract: An apparatus for detecting and controlling current. A current detector for generating a first value that represents an amount of current being delivered to a device. A current limit circuit for generating a second value that represents a maximum permitted current level from a current source. A current controller for controlling the amount of current drawn by the device if the first value exceeds the second value.

Abstract: In a typical DC-DC converter, an error amplifier is used to sense and amplify the difference between the feedback voltage and the reference voltage. In the event of current overloading (limit condition), example embodiments of the disclosed systems and methods of over-load protection with voltage fold-back fold back the reference voltage proportional to the current limit. The regulator may continue to regulate in this fold-back voltage reference condition without shutting down the converter, saturating the inductor, or causing a catastrophic failure at the power FETs. The disclosed systems and methods of over-load protection with voltage fold-back resolve consecutive switching cycle current build up in high input voltage DC/DC convertor applications due to the latency of current limit circuitry.

Abstract: A protection apparatus of a load circuit, comprises: a temperature estimation unit configured to estimate a temperature of an electric wire based on a pseudo-temperature arithmetic expression; and a breaking control unit configured to break a switch portion when the temperature estimated by the temperature estimation unit has reached an allowed temperature of the electric wire. The pseudo-temperature arithmetic expression is set in such a manner that, in a temperature arithmetic expression of the electric wire, the temperature arithmetic expression using the elapsed time counted by the timer, the current detected by the current detection unit, and a heat capacity and conductor resistance of the electric wire, a pseudo-heat capacity smaller than the heat capacity of the electric wire is assigned to the heat capacity, and a pseudo-conductor resistance larger than the conductor resistance of the electric wire is assigned to the conductor resistance.

Abstract: A current limiter in one exemplary embodiment of the present disclosure has a protection element that protects a current limiting element from excessive power dissipation. The protection element senses a parameter that is indicative of an amount of power being dissipated by the current limiting element. The protection element controls the current limiting element based on the sensed parameter such that power dissipation for the current limiting element is reduced to a safe level during a fault condition thereby protecting the current limiting element from damage during the fault condition.

Abstract: A brushless fan motor control circuit assembly consists of a high-frequency filter circuit, a rectifier circuit, a power factor enhancing circuit, a current-limit and voltage regulation circuit and a brushless fan motor driving circuit. By means of the high-frequency filter circuit to suppress high frequency noises, the power factor enhancing circuit to enhance the power factor and to save power consumption, the current-limit and voltage regulation circuit to limit the current and to achieve overload protection, the brushless fan motor control circuit assembly controls the operation of a motor of an electric accurately and safely, avoiding fan vibration.