Rectifiers for electrolysis, electrotechnology and electrothermics

Main specific features

Functions of rectifiers:

power supply of electrolysis units for electrowinning of non-ferrous metals from melts (aluminum, magnesium) and solutions (zinc, copper, nickel, sodium, cadmium, lead, manganese, water etc.);
power supply of electrolysis units for gas production (chlorine, fluorine);
power supply of electro-graphitization furnaces;
similar loads with necessity of high operating currents.

Main components of rectifier unit:

transformer part;
converter part;
heat exchanger;
DC disconnectors;
current meters;
auxiliaries auto-reclose cabinet;
remote control panel for one or several rectifiers.

Rectifier circuit:

bridge (B);
«Y — reverse Y with paralleling reactor» (N). Control of output current under load — OLTC, thyristor control angle

high power characteristics

high measuring accuracy of heavy current

high installation and commissioning readiness

Centralized control and diagnostics

Benefits:

high power characteristics (efficiency, cos φ) in combination with the possibility of smooth-step current control;
high accuracy of heavy currents measurement up to 0,1%;
centralized control and diagnostics using modern microprocessor systems and industrial computers, automatic generation of reporting documents and protocols;
process control optimization;
high installation and commissioning readiness;
minimal impact on supply network when running several rectifiers due to the use of multi-pulse rectifying circuits and phase-rotation devices and compensation winding built into power transformer.

Application fields:

nonferrous metallurgy;
chemical industry.

CONVERTING PART
CONTROL SYSTEM
Remote control panel (RCP)

Converting part includes:

power converting sections (rectifier units);
control system.

Power converting sections are made with bridge or neutral rectification circuit with an equal number of bridges and transformer secondary windings connected into Y and delta to increase pulse number.

Applied power semiconductors: thermodynamic diodes (thyristors) of TDC type, without plasma emission. Devices are connected into parallel arms, which number is determined by the rectifier output current.

Control system is a two-level software and hardware system:

rectifier control system controllers (control cabinet);
remote control panel for a group of rectifiers (functions of process controller and operator interface);
analog remote control panel (operator interface functions).

Control system functions:

current setup and regulation;
protection and signaling;
current and voltage monitoring;
HV circuit breaker closing/opening;
automatic and manual control of transformer OLTC and NLTC;
processing of information from transformer monitoring cabinet;
control of DC disconnectors;
data reception and transmission from control cabinet to remote control panel.

Remote control panel functions:

generation of commands for the rectifier switching on/off;
current setting for each rectifier;
signals processing and receiving from each rectifier of the group;
alarms, warnings archives creation;
current on load graphs making;
rectifiers current and voltage data array formation;
current and voltage average values archiving;
data transfer to process automatic control system database via any of the following networks: Profibus-DР, Ethernet, Modbus, САN or other;
equipment operation charts and graphs displaying and printing.

Design: