THREE-POSITION CURRENT RELAY Russian patent published in 2006 - IPC H01H51/16 

FIELD: electric engineering, relays of minimum and maximum currents.

SUBSTANCE: when the electric motor is started the suction armature with a joined contact stem and with a valve at the end is sucked in the cavity, closes the upper contacts and cuts in the time relay, but the time relay contact doesn't break. The valve, being retained on the arm of the expanded cavity of the body, retains the suction armature in magnetic attraction in the neutral position, the upper and lower contacts are broken. At a break of the phase connected to the relay the valve lowers the suction armature onto the lower contact, the time relay is cut in, after a preset time the broken contact of the time relay cuts off the motor. At a prolonged starting of the motor, phase break, not connected to the relay, and an overload the suction armature with the valve at the end is sucked in the cavity, closes the upper contacts, cuts in the time relay, which after a preset time breaks the contact, cuts off the motor from the mains. The adjusting screw with the contact fastened at the end adjusts the travel of the suction armature to the cavity depending on the set-point current. The nonferromagnetic plate restricting the approach is fastened on the lower plane of the valve or on the end of the suction armature.

EFFECT: enhanced reliability of protection of electric motor against overload, phase break, and of the immersion pump motor against idle running.

2 cl, 2 dwg