REED RELAY UNIT Russian patent published in 2002 - IPC

FIELD: electrical engineering; switching lowcurrent circuits. SUBSTANCE: relay is designed for operation at minimum 5•10⁶ switching cycles for low-current circuits due to changeover reed switches limited by inequality 0,3≤Fr≤0,9. Reed switches with 0,3≤Fr≤0,6 inequality are proposed to have control winding of nonuniform density lengthwise of its cylinder; ratio of magnetic field strength above normally open pair to that above normally closed pair should be minimum 1.5 for Fr = 0.6 and maximum 3 for Fr = 0.3. For reed switches with 0,6≤Fr≤0,9 inequality control winding should be made in the form of two coils wound in opposition whose turn number is found through reed switch reset factor from empirical equation 1 - Fr = N1/N2, where Fr is reset factor of reed switch; N1 is turn number in coil placed between normally closed pair and butt end of reed switch with two leads; N2 is turn number of coil placed above two contact pairs of reed switch. Optimization of relay magnetic system is attained by fitting ferromagnetic inserts at butt end of reed switch which are electrically insulated from relay unit leads and outer ferromagnetic screens provided with arbitrary-configuration holes locally arranged above normally closed pair, hole area being equal to that of square whose side equals overlapping length of contact members in vicinity of normally closed pair. Such optimization makes it possible to increase high value of magnetomotive force of reed switches from 30 to 50 A and to ensure relay switching and minimum 5•10⁶ switching cycles for low-current circuits. EFFECT: enhanced reliability, enlarged number of switching cycles. 5 cl, 5 dwg