提高大功率可控硅等离子切割机暂载率的有效途径

由于大功率可控硅空气等离子面所需空载电压较高，而切割时的电弧电压仅为空载电压的1／2－1／3，导致目前的大功率可控硅等离子切割机均存在暂载率低的现象。其实质因大的移相角，导致功率因素下降。为了保证额定的输出，电路中流过较大的电流，产生大量的无用功，线圈发热严重，暂载率下降。本文通过改变主电路的拓扑结构，在部分初级线圈中串接电容，对无功功率进行补偿，提高功率因素，克服了以往只对网络功率因素补偿，而不对负载功率因素补偿的缺点，减少额定功率输出时流过变压器原边的输入电流，提高了暂载率，使变压器工作在最佳状态，

Improvement of Duty Cycle of Plasma Arc Cutting Machine

Air plasma cutting machine requires high open circuit voltage ,but arc voltage is half or one third of it.So far the duty cycle for the high power SCR arc plasma cutting machine is low,which results from bigger angle of lap,and power factor goes down.To ensure rated power output,more input current is required and the coil is heated heavily.In this paper,the topology is changed and the capacitor bank is connected with primary coil in series.The idle work is also compensated to improve load power factor.Therefore,it can reduce input current of transformer primary coil,power factor and duty cycle are raised.