Continuous casting mold electromagnetic stirring (EMS) as an effective means to improve the quality of continuous casting billet is widely used in modern continuous casting machines. Due to the use of a rotating magnetic field inside the mold, the molten steel rotates horizontally through the steel The liquid rotation separates the lighter oxide inclusions and bubbles from the heavier molten steel and promotes its floating; secondly, the internal quality of the continuous casting is improved, and the molten steel is forced to flow during the solidification process by stirring, and the molten steel is superheated It is extremely important to quickly reduce, thereby expanding the production of high-carbon steels such as heavy rails and harder wires. In the system operation, the magnetic induction intensity begins to appear at 0100103T, and the effect above 0104T is better, but too large will cause negative segregation (white bright band), so the maximum magnetic induction intensity should be controlled below 0108T, and the stirring frequency is generally below 10kHz, usually 2kHz .
The control principle of the electromagnetic stirrer is: after the stirring frequency setting and current setting are calculated by the controller, it is transmitted to the communication module of the converter. The converter has a current regulator and a loopless logic controller. According to the controller ’s Given a signal, the converter output current generates a magnetic field. The current regulator calculates the trigger angle of the inverse cosine. The system has grid voltage adaptation and regulator parameter adaptation, which greatly improves the control performance. The process machine gives the continuous casting PLC the mixing model number. The PLC automatically controls the furnace model number. The logic controller in the converter accepts the PLC's instructions to control the operation of the converter. The stirring current and stirring frequency are manually set on the MMI, and the stirring mode is set by the process machine and MMI, respectively.
We adopt the advanced technology imported from Europe, patented technology, specialized software to optimize the design for33kV cast resin Dry Type Transformer. The core is made of cold-rolled grain-oriented silicon steel sheet which cut in step-lap by GEORG Germany TBA core cutting lines and laminated by the method of fifth-order step-by-step stacking technology, enabling the no-load performance of the core to improve greatly. The epoxy resin from American HUNTSMAN is adopted for the windings which casted in the vacuum resin casting machine imported from HEDRICH, Germany. The winding material ensures good permeability, no bubbles occur, which leads to minimum partial discharge. The HV and LV winding mate with each other tightly, which ensures solid strength of structure and capability to withstand short circuit and vibration. Under normal service condition, the service life of dry type transformer is 30 years. No crack will form on the surface of transformer winding due to temperature variation as long as the transformer runs under normal service condition.
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Hangzhou Qiantang River Electric Group Co., Ltd.(QRE) , https://www.qretransformer.com