Application

MVS series soft starters are widely used in electric power, building materials, chemical industry, metallurgical steel and paper industry with rated voltage 3KV-10KV. It is an ideal starting and protecting equipment for medium-voltage motor. It can be used with fans, compressors, crushers, mixers, belt conveyors, water pump, elevator, mill, etc.

Introduction

MVS series of medium voltage solid state soft starting device is a high voltage motor soft starting device designed with the latest concept, which is mainly suitable for the control and protection of squirrel cage asynchronous and synchronous motor starting and stopping. The device is made of a plurality of thyristors connected in series and parallel which can meet different current and voltage requirements.

Principle

1.     The control core of the MVS series is the microprocessor CPU. The microprocessor uses phase angle trigger control on the SCR to reduce the voltage applied to the motor, and then increases the motor torque smoothly by slowly controlling the voltage and current applied to the motor until the motor accelerates to full speed. This starting mode can reduce the starting impulse current of the motor and reduce the impact on the power grid and the motor itself. At the same time, the mechanical impact on the load device connected to the motor is reduced to prolong the service life of the equipment and reduce the time of failure and shutdown detection.

2.     When the motor reaches full speed operation, the motor current drops to the normal full speed operation current value, MVS series soft starting device has a bypass output relay, thus causes the bypass high-voltage vacuum contactor to close, causes the motor current to bypass the contactor. It can prevent the heat loss caused by the voltage drop of SCR, and improve the working efficiency and reliability.

3.     The microcontroller is composed of CPU control board, optical fiber trigger board, power supply board, sample-collecting board and display screen. With MCU processor, it can realize electronic control, voltage and current signal acquisition, communication interface, synchronous signal detection and control, display communication and control, protection function.

4.     Adopt LCD touch screen, built in menu. LCD touch screen can be used 7 inches,10 inches according to different configuration requirements. Parameters can be set and displayed according to customers needs.

5.     The part of pulse amplification is to modulate 24V DC power supply into pulse current. The modulation signal is controlled by micro-controller and transmitted by optical fiber, which realizes the electrical isolation between micro-controller and pulse amplification part.

6.     When the pulse current passes through the pulse transformer, the current can be induced at the secondary side. The induced current is modulated into a pulse trigger signal for thyristor trigger, and the whole thyristor trigger is finally realized. The pulse amplifying part and the energy triggering part are connected by electromagnetic induction, and the electrical isolation is realized.

Technology features

Soft starting device is a standard motor starting, protection device, used to control and protect high-voltage AC motor. Standard MVS products are mainly composed of the following components: High Voltage thyristor modules, thyristor protection components, optical fiber trigger components, vacuum switch components, signal acquisition and protection components, system control and display components.

Thyristor modules: each phase is adopted the same parameters of thyristors which are in series-parallel installation together. The quantities of thyristor series connection is different according to the peak voltage requirement of the power grid.

SCR protection component: mainly consists of RC network composed of overvoltage absorption network, Voltage equalization unit composed of voltage equalization protection network.

Optical fiber trigger: strong trigger pulse circuit is adopted to ensure the consistency and reliability of trigger, and high and low voltage isolation is achieved by using optical fiber trigger.

Vacuum switch components: After starting is completed, the three-phase vacuum bypass contactor is automatically closed and the motor is to start operation with grid.

Signal acquisition and protection components: through voltage transformer, current transformer, lightning arrester, zero sequence current transformer to main circuit voltage, current signal acquisition, main CPU control and corresponding protection.

System control and display components: 32-bit ARM core microcontroller control center, LCD touch screen display, can display three-phase voltage, current, fault information, running state, etc.

Installation is simple: MVS is a complete motor starting control and protection system. Only need to connect the power cord and motor wire for installation, which can be put into operation. Before the high-voltage operation, allowing the use of low-voltage electrical testing of the entire system.

Backup features: The device is equipped with a vacuum contactor which can start the motor directly. If MVS fails, the vacuum contactor can be used to start the motor directly to ensure the continuity of production.

With high-voltage thyristor as the main circuit components, and with voltage-sharing protection and over-voltage protection system.

MVS is installed electromagnetic locking device to prevent it against connecting into the high-voltage device accidentally.

Advanced optical fiber transmission technology, to achieve high-voltage thyristor trigger detection and low-voltage control loop isolation.

Adopt 32-bit ARM core microcontroller to perform central control, which is real-time, high efficient, intuitive display, high reliability and good stability.

Chinese/English LCD touch screen display system, user-friendly interface.

With RS-485 communication interface, which can communicate with upper computer or centralized control center.

Specification