HOT-WIRE RELAY Russian patent published in 2003 - IPC

FIELD: automatic check-up and regulation devices; overcurrent protective gear for electrical installations. SUBSTANCE: proposed relay with drooping time-current characteristic that may be used as overcurrent relay for power installations or as timer for automatic-control devices has differential heat-sensing system made in the form of fully identical main and compensating hollow sealed metal cylinders filled with fluid characterized in constant volumetric coefficient of thermal expansion in operating temperature range; passed through one of butt-end walls of each cylinder is rod of greatly smaller diameter than inner diameter of cylinder; compensating cylinder is fixed in position and its rod is fixed to cleat carrying main wound cylinder fixed thereon in position; winding of this cylinder carries ac current of electric circuit under protection when relay is used as overcurrent device or it is connected to regulated ac current supply when relay functions as timer; initial gap is set between end of main-cylinder rod and butt-end of contact-system adjusting screw or trip-free mechanism (depending on relay function) with aid of this adjusting screw; this gap governs timer delay time or overcurrent I²t, where I is operating current; t is operating time of relay. EFFECT: enhanced precision of operating thresholds and reliability of relay which is practically immune to ambient temperature fluctuations. 1 cl, 1 dwg