1. Power feedback. The dedicated power feedback function reports the power of every controller back to the DCS, making it easy for the customer to allocate power across the plant grid. On this float glass line the tin bath has a total power of 4,485 kW. With power feedback, the actual operating power of each controller is transmitted over the bus to the central control room, helping the power supply room balance the plant load and secure a stable supply. Most controllers on the market lack this function; a separate power feedback instrument costs about 2,000 yuan each, while the SANCH controller integrates it, saving the customer that cost.
2. Automatic phase-angle / zero-cross switching. Silicon carbide (SiC) heating elements with a transformer form an inductive load whose resistance is close to zero at room temperature; direct zero-cross firing at startup would blow the unit and damage the equipment. The tin bath is the most critical thermal facility in float glass production: its space must be filled with protective gas (a nitrogen-hydrogen mixture) kept at slight positive pressure to prevent oxidation of the molten tin, with strict sealing and continuous replenishment of fresh gas. Phase-angle control gives the SiC elements a soft start and soft stop, so the start and stop current ramps up gently. With direct zero-cross firing, the inrush current would strike the elements and greatly shorten their service life. Because of the furnace structure, the SiC elements in a tin bath cannot be replaced; if an element fails, the only temporary remedy is to raise the temperature of other zones to balance the damaged one, and the glass produced under such conditions shows defects and cannot reach high quality. On the other hand, if the controller stayed in phase-angle mode all the time, it would inject strong harmonic interference into the grid and disturb equipment such as PLCs, DCS and monitoring systems. The SANCH controller therefore switches automatically between the two modes: phase-angle control soft-starts the cold SiC elements, and once they have warmed up it changes over to zero-cross control, fully protecting both the elements and the grid.
3. Networked power distribution. When multiple controllers regulate power in parallel, they may all switch on at the same moment. With a conventional simultaneous start on this line, the grid would instantly have to absorb the starting current of the full 4,485 kW rating — a heavy shock that can cause a large transient voltage dip, strong bus fluctuation, transformer or generator noise, and even prevent other equipment from working properly. The "networked power distribution" function solves this. For example, the 38 controllers on the line (4,485 kW in total) can be divided into 10 networked groups started in rotation. Each start then draws only about 450 kW, greatly reducing the impact of a collective start on the grid.
