When power of melting system is over 10,000kW,we adopt power supply with parallel resonance design. For super power situation，parallel resonance design is has a better safety degree compared with series resonance.Our unique power supply with parallel resonance,which is a fully open design, ensure the maximinum power factor,minimum harmonics when the power is over 40% of the rated power.
Our power supply design ensures 100% starting success,Even in large power condition,it makes furnace coil voltage in a reasonable range,guarantees the safety of equipment. Power supply, with parallel resonance design and large power need,connects with one furnace to form the melting system so called “one power supply/one furnace”.it can easily achieve “one power supply/two furnaces” or “two power supply/three furnaces”switch melting system by using external pneumatic switch to choose furnace,so different needs can be achieved.
Multi-pulse rectifier design, with 12 pulses and 24 pulses,can futher decrease harmonics. Unique design of rectifier firing board can balance the input current automatically. Moreover, soft starting to prevent the inrush to the power supply. As an fast electronic switch, shut off the power supply under fault situation.
All of digital signal transferred through optical fiber. Has high anti-noise capability, and a more stable system. Power supply, with paraller tank output design, is enclosed completely in a cabinet.All copper bus bar and copper tube used inside power supply are supplied from recognized vendor with famous brand; Every copper bus bar is made according to standard, and through sand-blasting, inhibiting processes. All the components layout, connections, wiring are designed with much attention, they meet standard, and are easy to access for repair and maintenance.
Power supply equipped with a melt-manager, which is mainly composed of an PLC and HMI. Functions includes: automatic sintering, cold start, fault diagnosis, fault message storage and display, system running data display, and system status display etc.. There is an isolated enclosure located at the top section of front door, with main control board, feedback board, control power supply installed inside，Service personnel can easily observe the signal on MCB. The main power electronics components of the power supply use water for cooling, when the components run,the temperature rise makes no difference to isolated control enclosure, so extra cooling system for the isolated enclosure is not needed. What is more, all of the electronic elements on MCB are selected according to high temperature grade.
Incoming power circuit breaker protection system. Fast reacting circuit breaker is mounted at power supply front face, It is electrically operated to close and open, an 24V under voltage trip solenoid function as interlock protection.when over current occurs,it trips as a result of over current protection,and cuts off incoming power supply. Bridge rectifier converts AC to DC, provide a stable DC platform for inverter section. Capacitors are planted in an enclosure cabinet，which is fabricated by high strength cold rolled sheet steel.
Equipped with both differential current and DC injection leakage detection alarm circuit. It composed of indicator, leakage meter nad detection circuit etc. It continuously monitor during normal running. It shut off power when the following situation occur:
①metal penetrates lining and approaches coil,
②too much moisture exist in lining material,
③some parts has low resistance to ground.
Induction coil is made of Oxygen-free copper tube. Active and cooling sections are wound with continuous single winding, no division between sections.So different current and DC injection leakage detection alarm circuit can protect the whole coil. The different current leak detector is electronic so that it has a fast reaction speed, when the output circuit has a flashover fault to ground, it reacts at the fastest speed. However, the DC injection leakage detector is not electronic, which reacts slow comparatively. But when the power supply cabinet stops running, it can still detect the leakage for the furnace.