Design Structure
The complete NRRQV series soft start device is a standard motor starting and protection device used to control and protect high-voltage AC motors. The standard NRRQV product mainly consists of the following components: high-voltage thyristor module, thyristor protection component, fiber optic triggering component, vacuum switch component, signal acquisition and protection component, system control and display component.
●Thyristor module：Install thyristors with the same parameters in series and parallel in each phase. According to the peak voltage requirements of the power grid used, the number of thyristors selected in series varies.
●Controllable silicon protection components：It mainly includes an overvoltage absorption network composed of RC network and a voltage equalization protection network composed of voltage equalization units.
●Fiber optic trigger component：Adopting a strong trigger pulse circuit to ensure consistency and reliability of triggering; Reliable high and low voltage isolation using fiber optic triggering.
●Vacuum switch components：After the start-up is completed, the three-phase vacuum bypass contactor automatically closes and the motor is put into operation on the power grid.
●Signal acquisition and protection components：The main circuit voltage and current signals are collected through voltage transformers, current transformers, lightning arresters, and zero sequence current transformers, and controlled and protected by the main CPU.
●System control and display components： 32-bit ARM core microcontroller for central control and LCD/touch screen display, capable of displaying three-phase voltage, current, fault information, operating status, etc.
Overall Structure
The overall structure of the NRRQV series is carefully considered to adapt to various requirements of control cabinet design, ensuring suitability for various usage objects and working environments.
●Structure：The structure adopts the common technical requirements of GB11022-1999-T high-voltage switchgear and control equipment, and sealing treatment is applied in the cabinet to reduce pollution inside the machine, with a reasonable layout. The advanced digital triggering system connects the low-voltage control to the high-voltage section through optical fibers, and the convenient maintenance design allows each phase module to be quickly replaced separately. For operational safety reasons, the high-voltage and low-voltage parts are completely isolated.
●Region： The overall structure of NRRQV is divided into three mutually insulating parts. A high-voltage circuit composed of high-voltage thyristor modules, thyristor protection components, vacuum switch components, etc; A thyristor trigger and signal acquisition and system protection unit composed of fiber optic trigger components and signal acquisition and protection components; A system control and human-computer interaction unit composed of system control and display components; Three units are insulated from each other to achieve reliable isolation between high and low voltage.The power cable can enter from the top or bottom of the cabinet, leaving enough space inside the cabinet for connecting power supply lines. The motor cable can be bent appropriately when entering from the bottom of the cabinet.
●Ground wire：To ensure the reliable operation of NRRQV, the grounding wires of each control unit in the cabinet are connected to the lower grounding copper bar of the cabinet.
●Transportation regulations：The openings and corners on the cabinet can withstand and support the maximum weight of the entire cabinet structure.
Working Principle
The control core of the NRRQV series is the microprocessor CPU. The microprocessor triggers the SCR phase angle to reduce the voltage applied to the motor, and then gradually increases the motor torque by controlling the voltage and current applied to the motor smoothly until the motor accelerates to full speed. This starting method can reduce the starting surge current of the motor and minimize the impact on the power grid and the motor itself. At the same time, it also reduces the mechanical impact on the mechanical load device connected to the motor, extending the service life of the equipment and reducing the time for fault and shutdown detection.
When the motor reaches full speed operation, the motor current drops to the normal full speed operation current value. The NRRQV series soft start device has a bypass output relay, which closes the bypass high-voltage vacuum contactor, allowing the motor current to pass through the bypass contactor, preventing heat loss caused by the pressure drop caused by SCR conduction, and improving work efficiency and reliability.