US 5,644,463 A · Adaptive sequential controller with minimum switching energy

Abstract

An adaptive sequential controller (480) for controlling a single-phase circuit breaker, multiple circuit breakers in a multi-phase configuration, or a multi-phase circuit breaker to substantially eliminate transients upon closing the circuit breaker and to minimize switching energy when the circuit breaker for any phase of the line is open. The device adaptively compensates for changes in the response time of the circuit breaker due to aging and environmental affects. To control the circuit breaker so that is closes at a zero crossing of the voltage waveform, the adaptive sequential controller includes a potential transformer (70) that is connected to the distribution line. The potential transformer provides a reference signal corresponding to the zero crossing or zero instance of the voltage waveform. If the power factor of the load coupled to the line is known and remains relatively constant, a current transformer is not required. In multi-phase systems with imbalanced and varying loads, a potential transformer and current transformer may be required for each phase so that the power factor of the load can be determined. The response time of the circuit breaker is determined by monitoring an auxiliary switch in the circuit breaker that is coupled to the main breaker contacts. Based upon the response time that was last measured, the adaptive sequential controller responds to an open or close external command to apply the appropriate compensation for the delay of the circuit breaker opening and closing coils so that the circuit breaker closes at a selected time during the periodic voltage waveform and opens at a time appropriate to minimize the switching energy.

Claims50

Dependent claims

An adaptive sequential controller for controlling a switching device to interrupt and enable electrical current flow through an alternating current (AC) power line, comprising:

(a) transformer means, couplable to the power line, for producing a timing signal indicative of a zero crossing of at least one of a periodically varying current and a periodically varying voltage on the power line;
(b) switching-time sensing means, couplable to an auxiliary switch within the switching device, for producing a response signal indicative of a time interval required for the switching device to open or dose after being activated;
(c) delay adjustment means, coupled to the switching-time sensing means to receive the response signal and coupled to the transformer means to receive the timing signal, for producing a triggering signal relative to the timing signal and as a function of the response signal, after receipt of an externally produced switching command;
and
(d) control means, coupled to the delay adjustment means to receive the triggering signal, for producing control signals in response thereto, said control signals activating the switching device to cause it to enable and interrupt the electrical current flow through the power line, said triggering signal determining a time at which the control means produce the control signals for initiating interruption and enablement of electrical current flow through the power line by the switching device so as to adaptively compensate for changes within the switching device that affect its response time and to ensure that the switching device opens and closes at a desired relative value of at least one of the periodically varying current and the periodically varying voltage on the power line.

2 more elements

An adaptive sequential controller for controlling a switching device that is disposed on an AC power line so as to ensure that the switching device responds to a switching signal so as to achieve a substantially minimum switching energy, comprising:

(a) a potential transformer couplable to the power line, said potential transformer producing a potential signal indicative of zero crossings of a periodic electrical voltage on the power line;
(b) switching-time sensing means, couplable to an auxiliary switch within the switching device, for determining a response time of the switching device after it is activated to enable or interrupt current flow in the AC power line, said auxiliary switch being linked to primary contacts of the switching device that carry line current on the AC power line when closed and having a response time that is indicative of the response time of the primary contacts of the switching device;
and
(c) control means, coupled to the potential transformer to receive the potential signal and to the switching-time sensing means to determine the response time of the switching device, for activating the switching device in response to an externally produced switching command after a compensatory delay and for determining said compensatory delay so that said minimum switching energy is achieved when the switching device operates, said switching-time sensing means enabling the control means to produce a control signal that activates the switching device at a time appropriate to compensate for any changes in the response time of the primary contacts of the switching device.

1 more element

A method for controlling a switching device disposed on a power line to ensure that primary contacts of the switching device open and close at desired points in one of a periodically varying electrical current and a periodically varying voltage of the power line, said switching device having primary contacts and a corresponding auxiliary switch that is mechanically linked to the primary contacts, comprising the steps of:

(a) producing a timing signal synchronized to zero crossings of at least one of the periodically varying electrical current flowing in the power line and the periodically varying voltage on the power line;
(b) producing a switch signal indicating when the auxiliary switch opens and closes;
(c) determining a response time for the primary contacts of the switching device when activated by a control signal, based upon both:
(i) a time difference between activation of the switching device with the control signal and a change of state of the switch signal, and
(ii) any difference between a response of the auxiliary switch and the primary contacts to the control signal;
(d) producing an adjusted delay signal as a function of the response time and the timing signal;
and
(e) initiating operation of the switching device in response to an externally produced switching command, at a time adaptively determined as a function of the adjusted delay signal said time being determined so as to ensure that the switching device enables and interrupts the flow of electrical current through the power line at said desired point in said one of the periodically varying potential and the periodically varying electrical current flow in the power line, any changes in the response time of the primary contacts of the switching device being compensated by varying said time at which operation of the switching device is next initiated after receipt of the externally produced switching command.

5 more elements

Dependencies are inferred from the claim text.

Adaptive sequential controller with minimum switching energy

Life of this patent

Adaptive sequential controller with minimum switching energy

Life of this patent

Abstract

Claims50