LOAD-LIFTING ELECTROMAGNET CONTROL DEVICE Russian patent published in 2003 - IPC

FIELD: materials handling facilities. SUBSTANCE: invention relates to load-lifting electromagnets and it can be used to control electromagnetic separators. Proposed device contains thyristor converter built around single-phase bridge rectifying circuit controlled by single-phase self-saturating magnetic amplified with ac putout and pulse shaper built around relaxation generator circuit on unijunction transistor and two RC- circuits operating in antiphase with primary windings of pulse transformers connected to capacitor circuit, two secondary windings of each transformer being connected to control junctions of pair of simultaneously operating thyristors of converter and supplied by trapezoidal amplitude ac voltage synchronized with supply circuit of converter, limited by resistor and stabilized by voltage-stabilizing diode connected through rectifying bridge. To decrease current rise time in winding of electromagnet, stabilize current at preset level irrespective of winding heating temperature or supply circuit voltage fluctuations, and limit voltage across winding at switching off of electromagnet to level of voltage of supply circuit at forced reduction of current, converter is built on symmetrical thyristors, magnetic amplifier current control winding in placed in circuit of electromagnet winding and other winding of amplifier is connected opposite to ampere-turns of magnetic amplifier current control winding from rectifying bridge of control circuit supply source through two series-connected resistors one of which is shunted by capacitor. Collector-emitter junctions of two optoelectronic transistors are connected in parallel to resistors of RC-circuits of relaxation pulse generator through limiting resistors. Control light-emitting diodes of two optoelectronic transistors are connected in parallel opposition and are connected, through series resistor, to diagonally-opposite pairs of junctions of bridge formed by working windings of magnetic amplifier and its load resistor and RC-circuit with capacitor connected in parallel with said circuit of amplifier. Capacitor is shunting through rectifying bridge by collector-emitter junction of one more optoelectronic transistor whose control light-emitting diode is connected in series with additional thyristor and relay coil shunted by capacitor and is connected to electromagnetic winding through voltage dividing and rectifying bridge. EFFECT: reduced current rise time in electromagnetic winding. 1 dwg