Abstract: A multi-functional hybrid contactor has a motor protection function against an abnormal state in addition to the starting, running and stopping of the motor, the same effect as the case that an electronic motor protection relay (EMPR) is connected in parallel can be obtained with only one multi-functional hybrid contactor. Also, the size of the product is much reduced compared to the case that the electric motor protection relay (EMPR) is connected in parallel, and its cost can be reduced. In addition, since the semiconductor switch is turned on only in the initial stage of starting and stopping, the rated current capacity and size of the semiconductor switch can be considerably reduced compared to the conventional soft starting method in which the semiconductor switch is used for controlling of all of starting, running and stopping.

Abstract: A method for measuring three-phase alternating current using a current sensor and an apparatus therefore, which are capable of not changing an average voltage for a switching period by changing reference voltages for modulating pulse width in a switching period of an inverter and compensating for the changed reference voltages in the same switching period. It is possible to prevent current from being distorted, to detect three-phase output current in all of the switching periods, and to rapidly control instantaneous current by changing the reference voltages of arbitrary two phases in one switching period of an inverter, measuring current of each phase for the switching period using the current sensor, and compensating for the amounts of changes in the changed reference voltages of the two phase in the switching period.

Abstract: In a hybrid DC electromagnetic contactor, by including a power unit for supplying a certain power voltage; a main contact point of a breaking switch for providing a supply path of the power voltage by being switched in accordance with a voltage apply to an operational coil; a switch for providing a supply path of the power voltage according to a gate signal; a snubber circuit for charging voltage at the both ends of the switch in turning off of the switch and being applied-discharged an electric current when the charged voltage is not less than a certain voltage; and a discharge current removing unit for removing the discharge current by providing a discharge current path to a load block in turning off of the switch, it is possible to minimize a size of leakage current when the main contact point and the semiconductor switch are turned off, and accordingly it can be practically used.

Abstract: In an apparatus and a method for measuring a queue length of vehicles, by installing a camera toward a direction same with a proceeding direction of vehicles on the road, photographing images of the road at the rear of vehicles and measuring a queue length of vehicles, it is possible to measure a queue length of vehicles accurately. The apparatus includes a camera for photographing the rear of vehicles on the road; an image converter for converting analog image signals corresponding to images photographed by the camera into digital image signals; and a control unit for extracting characteristics of vehicles from the converted digital images, calculating positions of vehicles on the road on the basis of the extracted characteristics and calculating a queue length of vehicles on the road on the basis of the calculated positions of vehicles.

Abstract: A system for determining a kind of vehicle and a method therefore, including a vehicle detection unit for detecting a vehicle which reaches to a vehicle detection region on a roadway, a wheel shaft number counting unit for counting a number of wheel shafts of the detected vehicle, an image photographing unit for photographing a front or rear image of the detected vehicle and a vehicle kind determination unit for yielding distances and widths of the tires of the detected vehicle on the basis of the photographed image from the image photographing unit and determining the kind of the vehicle on the basis of the number of wheel shafts detected from the wheel shaft counting unit and the yielded distance and width values can precisely determine the kind of vehicle traveling the roadway.

Abstract: A switching mechanism of a circuit breaker for a gas insulated switchgear is able to extinguish arc gas by changing a volume of a compressing chamber without increasing a stroke of a movable cylinder and without increasing required output power of an actuator.

Abstract: A rotation speed search apparatus for an induction motor includes: a voltage control unit for comparing a rated current of a motor and a current detected from the motor and generating an output voltage; and a frequency control unit for comparing a reference excitation current of the motor and an excitation current detected from the motor and generating an output frequency. In case of a big load, an output frequency is reduced. Thus, the slip of the motor is moved to a slip where a maximum torque is generated to enable the induction motor to start. If the speed of the motor in operation is greater than a target frequency, an output frequency is increased, so that the motor can be operated even in the regenerative region of the motor.

Abstract: A simultaneous starting apparatus of a positioning decision module and a method therefore, including an external simultaneous starting input pin for performing simultaneous starting by receiving an external simultaneous starting input signal of a “high” status from the outside under the condition that the external simultaneous starting output signal of a plurality of ASICs composed of logic circuits is a “high-impedance” status can remove time difference among orders for controlling a motor. Therefore, positioning decision processing speed among a plurality of independent positioning decision ASICs can be shortened and accordingly, the positioning decision module can become high-functional.

Abstract: The present invention relates to a communication device using three-step communication buffers which temporarily stores received data or data to be transmitted between a serial communication device and a central processing unit. To prevent an error resulted from that the serial communication device and the central processing unit simultaneously access to the communication buffer, the access to the communication buffer is allowed at different edges of the system clock signal, thereby having a time difference of the access.

Abstract: A motor torque control apparatus and method are disclosed. By adding the value of the compensation voltage which is obtained by proportionally integrating a difference value between the predetermined reference magnetic flux component current value and the actually measured magnetic flux component current value to the q-axis instructing voltage, the magnetic flux component current, that is, the excitation current, can be constantly controlled without excess or shortage. In addition, since the magnetic flux is constantly controlled irrespective of the speed of the motor, a high torque can be generated even at the initial stage of starting of the motor (at the low speed), and thus, the torque of the motor can be smoothly controlled in every operation range from a low speed to a high speed.

Abstract: A sensorless vector control system of an induction motor includes: a magnetic flux and speed controlling unit for receiving a predetermined command value and generating two phase voltages of DC component; a first reference frame converting unit for converting the two phase voltages of DC component into three phase voltages of AC component; an inverter for receiving the three phase voltages of AC component and driving an induction motor; a current detecting unit for receiving the three phase power of AC component flowing between the inverter and the induction motor, and detecting and outputting three phase currents of AC component; a second reference frame converting unit for receiving the three phase currents of AC component, and converting and outputting two phase currents of DC component; a magnetic flux and speed estimating unit for receiving the two phase voltage of DC component and the two phase currents of DC component, estimating a magnetic flux and speed required for a vector control; and a primary re

Abstract: In an air circuit breaker, in order to provide a position indicating apparatus of a draw out type air circuit breaker which is capable of distinguishing a position of a breaker body accurately even a user can not distinguish colors by improving a structure for indicating a position of the breaker body, in a position indicating apparatus of an draw out type air circuit breaker comprising a lead bar rotatably placed at a base frame and moving in a direction opposite to a moving direction of a lead screw by abutting to one wall surface of a cradle and a cam connected to the lead bar and rotating by the linear movement of the lead bar, the position indicating apparatus includes a movable plate connected to the cam and converting the rotation of the cam into the vertical linear motion, an indicating cam connected to the movable plate, converting the vertical linear motion of the movable plate into the rotation motion and having a portion indicating a position of the breaker body according to the rotation, and a fr

Abstract: Disclosed is a circuit for driving a gate of an IGBT (insulated gate bipolar transistor) inverter. The present invention includes a first IGBT of which collector is connected to a DC voltage, a second IGBT of which collector is connected to an emitter of the first IGBT, wherein an output signal is outputted from a connection point between the collector of the second IGBT and the emitter of the first IGBT, and of which emitter is connected to a ground, first and second driving circuits supplying gates and the emitters of the first and second IGBTs with DC driving voltages, respectively, through first and second gate resistors, and first and second noise interruption circuits connected between the gates-emitters of the first and second IGBTs and the first and second driving circuits, respectively, so as to interrupt noises.

Abstract: A sensorless vector control apparatus includes a speed controller for receiving a speed command value from a user and outputting a synchronous speed; a ‘d’ and ‘q’ axis voltage command unit for receiving the synchronous speed and outputting a ‘d’ axis voltage and a ‘q’ axis voltage; a voltage converter for receiving the ‘q’ axis voltage and the ‘d’ axis voltage, and converting the two phase voltages into three phase voltages; and an inverter for receiving the three phase voltages and controlling a speed of an induction motor. Since the vector control may be performed over the whole velocity range without using a speed sensor, the sensorless vector control apparatus may be used with advantage.

Abstract: A vacuum interrupter for a vacuum breaker, by which melting on contact surface caused by are concentration when a large current is broken and the arc can be rapidly extinguished by forming a strong magnetic field in vertical direction same as the arc when electrodes are separated, comprises: a vacuum container; a stationary cylinder electrode fixed on upper part of the vacuum container so as to be sealed; a movable cylinder electrode disposed on lower part of the vacuum container so as to be moved in vertical direction; and a stationary contact assembly and a movable contact assembly respectively connected to the stationary cylinder electrode and to the movable cylinder electrode for inducing electric current to be rotated to one direction and forming a compounded vertical magnetic field.

Abstract: A contact portion switch device of a circuit breaker which is capable of guaranteeing reliable operation by restraining distortion of each construction part in the operation of the circuit breaker and permitting an easy installation of an additional part for performing multifunction is disclosed.