Westinghouse Electric Corporation

Ernest F Conroy, Jr

Robert Tracy Elms

Wardell Gary

John G Dorman

Charles W Maiden

Daniel P Orange

An escalator having improved brake control, to limit the rate of deceleration immediately following a stop command, and to quickly cause the actual speed of the escalator to closely follow a linearly declining speed ramp of a speed pattern signal. The signal controlling the brake is pulse duration modulated such that the brake responds to the average pulse duration, and braking torque is applied gradually and essentially linearly. The reference speed pattern has a substantially constant portion and a declining ramp portion. To limit the initial deceleration, the constant portion of the speed pattern is controlled to be a function of the actual speed signal, and the declining ramp portion of the reference signal is controlled to start when the actual speed is equal to the constant portion of the reference speed signal.

Escalator with controlled brake

A solid state load protection system whereby the current supplied to a load is monitored enabling a test feature to be used. A current sensing function is utilized so as to produce an output current which is proportional to the current in an electrical circuit. Attached to the current sensing function is a load resistor module which converts the current produced by the current sensing function to a voltage which is also proportional to the current utilized by a load. Attached to the module is an overcurrent and timing function and an output function. The overcurrent and timing function monitors the level of voltage from the load resistor module initiating a timeout sequence when the voltage across the load resistor function, which is proportional to the current utilized by the load exceeds a predetermined level for a predetermined period of time thereby initiating a trip signal to the output function which deenergizes the motor by disconnecting it from its source of power. Upon the removal of the load resistor module and all other modules the input impedance of the overcurrent and timing function becomes very high allowing the test function to simulate an overcurrent condition in a load by causing a higher voltage to appear at the overcurrent and timing function and after a predetermined period of time, initiates a trip signal to the output function. The output function upon receiving a trip signal allows a light emitting diode to conduct and also deenergizes a contactor through which a current source is connected to the load.

Solid-state load protection system having a test feature

A solid-state load protection system whereby a poly-phase alternating current system is monitored enabling a loss of phase feature to be used. A current sensing function is utilized so as to produce an output signal which is related to the current in an electrical circuit. Attached to the current sensing function are two capacitors each having their own signal path so as to have different charging and discharging rates. During a loss of phase condition, one capacitor discharges more quickly than the remaining capacitor with the result that the voltage across the quickly discharging capacitor, which during normal conditions is greater than the remaining capacitor, now becomes less than the remaining capacitor. A loss of phase sensing function detects this difference in potential levels thereby initiating a trip signal to the output function. The output function upon receiving a trip signal causes a light-emitting diode to conduct and also deenergizes a contactor through which a current source is connected to the load.

Solid-state load protection system having loss of phase sensing

A solid state load protection system having an inverse time delay circuit. A current sensing function is utilized so as to produce an output current which is proportional to the current in an electrical circuit. Attached to the current sensing function is a load resistor which converts the current produced by the current sensing function to a voltage which is proportional to the current utilized by the load. Attached to the load resistor is an inverse time delay circuit which serves as an overcurrent and timing function. The overcurrent and timing function monitors the level of voltage from the load resistor initiating a time-out sequence when the voltage across the load resistor, which is proportional to the current utilized by the load, exceeds a predetermined level for a predetermined period of time. The overcurrent and timing function utilizes two diode paths for prohibiting the charging or discharging of a capacitor during a normal or overcurrent condition, respectively. Encircling the connections to the capacitor is a guardband for minimizing impedances from associated circuitry which affect the timing of the inverse timing circuit. During an overcurrent condition, the capacitor charges up to a specific value initiating a trip signal which is sent to an output function. The output function upon receiving a trip signal causes a light-emitting diode to conduct and also deenergizes a contactor through which a current source is connected to a load.

Solid-state load protection system having an improved inverse time delay

A solid state load protection system whereby the current supplied to a load is monitored enabling ground fault sensing to be used. A current sensor is utilized so as to produce an output current which is proportional to the current in the electrical circuit. Attached to the current sensing function is a resistive load which converts the current produced by the current sensing function to a voltage which is also proportional to the current utilized by the motor. Attached between two resistors which comprise the resistive load is a ground fault resistor which has its remaining end connected to the neutral leg of the current transformers of the current sensing function. The ground fault sensor monitors the voltage across the resistors in the resistive load and the current in the neutral leg of the current sensors. A ground fault condition is indicated when a current in the neutral leg of the current sensor is detected and thereby causes voltages across each of the resistive load resistors to be unequal to each other. If this condition is in excess of a predetermined level, for a predetermined period of time a trip signal to the output function is initiated, in turn causing a light-emitting diode to conduct and indicating a ground fault condition. The output function upon receiving a trip signal causes a second light-emitting diode to conduct and also de-energizes a contactor through which a current source is connected to a load.

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Monroeville, PA, United States of America

Ernest F Conroy, Jr