Low voltage frequency converters

General characteristics

• Motor start and speed control;
• Reverse;
• Acceleration, deceleration, shutdown;
• Motor and converter protection;
• Dynamic braking during shutdown;
• “Pick up” in motion;
• Technological parameter PI-control;
• Preset speed parameters;
• Auto-reclosing;
• Linear or S-shaped velocity controller.

The converter consists of:

• Input three-phase current-limiting reactor;
• Radio frequency interference filter (optional);
• Circuit breaker or contactor with fuses (converters for currents from 160 to 630 A);
• Converter power unit;
• Dynamic braking device (converters for currents from 160 to 630 A, optional);
• Rectifier with regeneration mode (only applied in converters for currents from 160 to 630 A, optional);
• Microprocessor control system;
• Console terminal;
• Output filter limiting voltage rise time on motor excitation winding – dU / dt or sinus (optional).

Control system

• Motor control
  U/f control (linear, quadratic, programmable control):
  – permissible tolerance of output voltage with a rated input voltage and change of current at converter output from zero to a rated value is not exceeding ± 3%;
  – permissible tolerance of output voltage frequency from a rated value with the change of current at converter output from zero to a rated value and change of input voltage in specified range – not exceeding ± 1%;
  – converters provide for operation at 1.5 x current overload for 120 sec;
  – output voltage frequency range – from 0 to 200 Hz;
  – efficiency – at least 95% (over 53 kW), at least 93% (below 53 kW);
  – power factor – at least 0,9;
  – operating mode: continuous. Vector with a real-time identification of electric drive parameters. There is a mode of automatic presetting of engine parameters.
• Protection system
  – short-circuit currents protection;
  – prohibited current overload protection;
  – dump or unacceptable decrease in the supply input voltage;
  – unacceptable increase of the supply input voltage;
  – overtemperature of semiconductor power devices;
  – phase failure of the input and output voltages;
  – short circuits to ground protection.
  – engine overheating protection;
• Types of sensors
  – Tachogenerator;
  – Pulse speed and position sensors;
  – Selsin;
  – Temperature sensors;
  – Pressure sensors, etc

• Administration programs
  – Basic program;
  – Main program;
  – Local – remote control;
  – PI-regulation;
  – Control over pumps and fans;
  – Administration according to the requirements of the customer.