Libratherm offers a ready-to-use Thyristor DC Rectifier ranging from 10A/Single phase to 500A/3 phase. Single Phase/Two Phase rectifiers are built using triggering card model LTC-13, and three-phase rectifier is built using LTC-18 card. The SCR modules are mounted on suitable size aluminium heat sinks with input and output clip-on-type heavy-duty connectors or aluminium /copper bus bars, semiconductor fuses, and thermal cutouts. The entire assembly is fitted inside an MS powder-coated enclosure, which can be easily mounted inside the closed control panel. Libratherm offers a complete, ready-to-use control panel with a suitable PID / Program voltage/current controller and other switch gears as per user specifications and requirements. The DC output voltage from such a single-phase or three-phase rectifier is unfiltered, and the user needs to incorporate an external LC filter to reduce the ripple factor as per the application demand.

Key Features:

• Digital Firing Cards for single-phase/two-phase/three-phase rectifiers – Field-proven for 25+ years.
• Semikron brand SCR Modules—The SKKT Series is used for three-phase AC-to-DC control, and the SKKH series or equivalent is used for single-phase AC-to-DC control.
• Auto-detection of phase sequence and auto-synchronization.
• Heatsinks are mounted with thermistors to protect against overheating and auto cut-off in case of over-temperature.
• Built-in Current Limit and Overcurrent Trip facility to limit the desired current through the DC load.
• Soft start and Soft stop voltage across the load.
• Does not incorporate any LC filter at the output.
• A separate auxiliary supply of 230 VAC with a built-in RFI/EMI filter protects electronics from line voltage fluctuations and RFI/EMI electrical noise.
• Suitable RC snubber and surge suppressors are incorporated to protect SCR Modules.
• High-speed ball bearing type cooling fan – To keep Thyristor cool.
• Built-in safety fuses for the cooling fan and Auxiliary supply.
• Rugged metal enclosure & modular design – easy to install & easy to maintain.

Applications:

Thyristor DC rectifiers have varied applications and can be used for electroplating, ETP/STP water purification, battery charger, induction heating, anodic and cathodic corrosion protection, etc. DC rectifiers built using thyristors have many advantages, such as smooth variable DC voltage and current output from 0 to 100%, soft increase and decrease of DC voltage and current across the load, and DC control through CT or shunt feedback.
For a single-phase rectifier, two SCR / Diode full wave bridge configuration is used, and for a three-phase rectifier, three SCR/SCR full wave bridge configuration is used (As shown in diagram 1).