Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.