Low voltage soft starters

General characteristics

  • Motor starting in forward and reverse direction of rotation;
  • Rotation direction reverse of the motor;
  • Motor shutdown;
  • Automatic changeover to the shunting switching device (“bypass”) upon start-up completion, and automatic switching from the bypass if controlled braking is required;
  • “Motor Drying” mode.

Starting mode

  • The “invisible” breakaway torque – a soft increase of the motor starting current from a zero, according to a special algorithm, with its subsequent restriction at a given level;
  • Starting current supply with initial inrush and subsequent smooth increase and limitation – for motors with a high starting torque;
  • Setup of a quasi-frequency starting mode with a “frequency converter” effect during starting-up to the speed – for motors with a high starting torque;
  • Linear increase of motor voltage from zero to a full voltage without current limiting.

Shutdown mode

  • Shutdown with instantaneous collecting of current – motor shutdown upon running-down;
  • Shutdown with a soft  decrease in current or voltage – controlled stop for mechanisms not permitting abrupt braking (pumps with possible hydraulic shock);
  • Dynamic braking shutdown with a set constant current or braking voltage – for mechanisms not permitting a sustained braking because of possible high vibrations or because of a requirement to increase cycling mechanisms performance by reducing the shutdown time thereof;
  • Holding the motor in a stalled state by a transition upon dynamic braking completion to a holding current or voltage – for mechanisms with ever-present pulling torque.


  • Local control – via press button commands on the starter panel;
  • Remote control – via contact commands on the drive control dashboard;
  • Remote control – via network interface of Automated Process Control System on the level of workshop, plant, etc.

Control signals

  • Input control signals with variable (programmable) functions – 5 units.
  • Possible functions for programming signals:
    – forward;
    – back;
    – inrush;
    – trigger;
    – stop;
    – dynamic braking;
    – operative shutdown;
    – emergency shutdown;
    – bypass interlock;
    – protections acknowledgement (checkback);
    – other (options).

Input and output signals

  • Input signals parameters
    – received signal type……………………………………….……………………………………………«dry contact»;
    – galvanic isolation type………………………………………………………………………..………..optron;
    – open contact voltage (to ensure reliable contact in the dry contact circuit) ……….110 V;
    – closed contact current …………………………………………………………………………..……..17 mA;
  • Output signals parameters
    • Functions of signals:
    – readiness;
    – bypass switch-on;
    – warning;
    – emergency shutdown.
    • Types of signals:
    – relay;
    – transistor (open collector with a voltage of 24 V).

Parameter settings

  • Parameters are set via a console terminal with a menu in Russian;
  • The self-explanatory menu structure of the console terminal allows to adjust the settings without special training for the staff;
  • The optimal, baseline parameters for configuration of the starter.
    For the majority of designs, it is sufficient to set up 3 parameters:
    – motor rated current;
    – input current requirement;
    – maximum allowed starting time.
  • Easily re-programmable functions of input and output control signals;
  • Further development of starter’s functionality of any complexity by the manufacturer experts as per technical requirements of the Customer.

Protection system

  • overcurrent protection;
  • overvoltage protection;
  • overload protection in accordance with the name plate, time-current characteristic of motor g tolerance;
  • power circuit disconnection protection;
  • open-phase switching-on protection;
  • extended start protection;
  • protection for no conductivity of thyristors in the converter;
  • automatic reclosing upon decrease and/or power outage;
  • no-load protection.


  • The built-in system records and archives the data on parameters and status of the starter and the motor:
    – the number of parameters registered simultaneously – 1 … 16;
    – registration time resolution – 3.3 … 100 ms;
    – recording fragment duration – 1.5 … 30 s;
    – the number of data fragments archived during emergency shutdowns – 4;
    – recording the date and time of archived fragments storing in real-time terms;
    – graphical visualization of archived and current data from the recorder via a special-purpose program and diagnostic system on the basis of a portable computer;
  • electric power meter for energy consumed by the motor – during a start-up and for the set period of operation.

Interfaces (optional)

  • support of network interfaces such as Profibus DP, Modbus, Ethernet, CAN;
  • flexible structure of the control and regulation system, open for monitoring and control from Automated Process Control System via network interfaces;
  • possible integration via serial interfaces with Automated Process Control System and monitoring systems.

Structural design

  • A thyristor converter is made according to a three-phase scheme with two opposite connected thyristors on the arm of two versions -non-reversible and reversible;
  • Air cooling: natural cooling for rated currents of up to and 100A (inclusively), forced cooling for rated currents above 100A;
  • One input for power circuits and auxiliary power supply;
  • Block and cabinet versions;
  • The block version of the product consists of:
    – power unit with a control system;
    – relay (optional): “Ready”, “Accident”, “Bypass”;
    – terminal block for external input / output control signals;
    – сmeans of local control and administration for the block version of design.
  • The cabinet version of the product consist of:
    – power unit with a control system;
    – input circuit breaker;
    – relay switching equipment (optional);
    – terminal block for external input / output control signals.
  • Means of local control and administration for the cabinet version:
    – “Motor current” device;
    – lamps: “Power supply”, “Readiness”, “Warning”, “Accident”;
    – buttons: “Forward (Start)”, “Back”, “Stop”, “Emergency Shutdown”;
    – console terminal;
    – other means of control and management (optional).

Computer Workstation

The supply of soft starters can be completed with an automated workstation – a computerized human-machine interface that can control and monitor an equipment complex.
AWS implements the following functions:

  • monitoring and graphical display of a status and parameters for the starters, motors and other equipment;
  • control of a start-up, shutdown and other modes of equipment operation;
  • duplication of the starter’s console terminal;
  • backlog / protocol of equipment operation modes;
  • maintenance of hourly and daily data archive from the equipment parameters recorder;
  • graphic display of data from parameters recorders embedded into the starter’s controllers.

Structurally, AWS is made, depending on the intended location, in the following versions:

  • cabinet rack with built-in industrial computer – for placement directly in the equipment room;
  • desktop computer in industrial design for the work position of a controller on duty or an operator;
  • industrial computer panel embedded in the panel of an existing equipment control panel.

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