摘要:
A railroad vital relay control circuit has a first input for receiving a reference alternating current signal of a selected frequency and a second input for receiving a track alternating current signal having the selected frequency of the reference signal and a predetermined phase and magnitude relationship therewith. A magnetic core provides a logical AND function and has two input arms and an intermediate output arm. There is a winding on each of the input arms and a winding on the output arm. There are frequency tuned voltage limiting circuit elements connecting the first input and a first one of the magnetic core input windings and the second input and the second input winding of the magnetic core. The magnetic core has an output winding on the intermediate arm which is connected to a vital relay. The input windings on the magnetic core are connected to produce flux in the same direction in the output arm. In phase signals of the selected frequency at the magnetic core input windings provide sufficient flux in the output arm to induce a signal in the output winding to hold the vital relay in an operated position.
摘要:
A temperature compensated, regulated power supply and battery charger for supplying power to railroad warning lights and crossing gates utilizes a ferroresonant transformer having a primary winding, a secondary winding, and a resonant circuit in magnetic circuit therewith. Voltage regulation is accomplished at essentially no load conditions by the use of a temperature sensing element and a shunt regulator connected in circuit with the output terminals of the secondary winding. The shunt regulator varies the output voltage at the output terminals in response to temperature sensed by the temperature sensing element during essentially no load conditions.
摘要:
A railroad crossing gate electrical control system for moving a crossing gate in up and down directions and providing snubbing protection to gate movement in failure modes includes an electrical motor having two diametrically positioned permanent magnet poles and two series connected electromagnet poles. There is an armature which rotates inside of the poles. There is a motor and snub relay which has contacts connected to the armature and the series connected electromagnet poles. A terminal board has movable contacts which are connected to the motor and snub relay and to a relay coil for moving the contacts of the motor and snub relay. A source of power is connected to the terminal board, with the movable terminal board contacts controlling the application of power to the motor snub relay coil and the relay contacts for causing up and down movement and for providing snubbing of armature movement during up and down gate movement and gate failure modes. An overspeed control is connected across the armature for limiting armature speed.
摘要:
An apparatus for detecting an approaching train within a track section utilizes a transmitter coupled to the rails at a feed point for applying a current to the track section. There is a receiver coupled to the track section for producing a signal representative of the impedance of the track section. There are devices for utilizing the received signal for detecting train motion, abnormally low impedance and abnormally high impedance of the track section. A normalizer circuit is connected to the receiver for increasing or decreasing the received signal gain within predetermined limits in accordance with variation in impedance of the track section.