Patent Description:
The present disclosure generally relates to power management, and more particularly to continuously monitored remote power shutdown.

Remote power shutdown (also known as Emergency Power Off or EPO) is typically provided as a safety measure for quickly disconnecting electrical power to a particular piece of equipment (e.g., diagnostic image scanner) in the event of an emergency. Such emergency event may occur in an immediately hazardous situation that needs to be ended or averted quickly in order to prevent injury or damage. A remote actuator (e.g., Remote Power Off or RPO, Emergency Power Off or EPO) may be used to facilitate remote removal of power, and allow all power to be shut down safely from a central location.

Remote power shutdown may be achieved using a continuously powered circuit or non-continuously powered circuit. A continuously powered circuit requires continuous energization of a trip device. This unfortunately results in system shutdown during brief power losses, and a non-operational equipment or system when there is a circuit fault. Additionally, such design may require additional hardware and cost, which needs to be added to maintain power on. Higher power circuits require additional current draw to maintain power to the equipment. Increasingly larger sized components and multiphase systems are also required, which add additional hardware requirements as well as hardware and operational costs.

A non-continuously powered circuit, on the other hand, applies power to a trip device only during activation to remove power to the equipment. Although this solution allows continued operation of the equipment during a circuit fault (e.g., disconnection due to wire break or coil burnout), the circuit fault is not known until the emergency shutdown requires it to operate. This results in a failure to remove power during the emergency, thereby creating a hazardous situation. Operational verification requires additional costs for testing, equipment downtime and personnel. Examples of fault interrupters, in particular ground fault circuit interrupters (GFCI) or circuit breakers for providing protection against current overload and inrush, are described in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <CIT>.

Described herein is a framework for continuously monitored remote power shutdown. In accordance with the present invention, a system comprises a power removal circuit, a monitoring circuit and a notification system. The power removal circuit enables remote triggering of a power shutdown of an equipment coupled to the power removal circuit. The monitoring circuit is coupled to the power removal circuit. The monitoring circuit generates an output signal indicative of circuit integrity based on one or more electrical characteristics of the power removal circuit. A notification system is coupled to the monitoring circuit. The notification system generates a notification based on the output signal.

A more complete appreciation of the present disclosure and many of the attendant aspects thereof will be readily obtained by reference to the following detailed description when considered in connection with the accompanying drawings.

In the following description, numerous specific details are set forth such as examples of specific components, devices, methods, etc., in order to provide a thorough understanding of implementations of the present framework.

A framework for a continuously monitored remote power shutdown is described herein. In accordance with one aspect, the framework includes a monitoring circuit that continuously monitors circuit integrity of a non-continuously powered power removal circuit and provides automated notification of circuit status. The present framework provides the benefits of the continuously powered and non-continuously powered circuits without the associated issues, such as system unavailability during brief power losses, failure to remove power during emergencies due to faulty power removal circuits, partial circuit monitoring, high operational and hardware costs, and so forth.

The present framework advantageously provides power removal even with a faulty power removal circuit. Additionally, the framework continuously monitors all the elements in the power removal circuit, including elements (e.g., trip device) that are described herein as well as any additional elements that are not described herein. Notification of any circuit faults or conditions may be immediately issued. The present framework may ride through brief power losses, thereby allowing the power removal circuit to remain operational to effect an emergency power shutdown. Advantageously, there is an absence of nuisance trips during brief power losses. Moreover, minimal hardware is required and minimal additional power is needed to implement the present framework. In addition, high reliability of the remote power shutdown function is achieved. These and other exemplary features and advantages will be described herein.

<FIG> shows an exemplary remote power shutdown system <NUM>. Remote power shutdown system <NUM> is coupled to a powered equipment (or system) <NUM>. Equipment <NUM> receives three-phase system power via power lines A, B and C. It should be appreciated that although remote power shutdown system <NUM> is shown as a three-phase alternating current (AC) circuit, the present framework is also applicable to other types of circuits including, but not limited to, single phase, two phase, split phase, direct current (DC), or a combination thereof.

Equipment <NUM> may be any powered system that may require power removal or electronic stopping in the event of, for example, an emergency. For instance, equipment <NUM> may be an industrial curing press, industrial furnace or elevator. Equipment <NUM> may also be a medical imaging modality that acquires medical image data. Such medical imaging modality may be a radiology or nuclear medicine imaging scanner. Such medical imaging modality may acquire the medical image data by magnetic resonance (MR) imaging, computed tomography (CT), helical CT, x-ray, positron emission tomography (PET), PET-CT, fluoroscopy, ultrasound or single photon emission computed tomography (SPECT). Other types of imaging modalities or equipment may also be used.

In some implementations, remote power shutdown system <NUM> includes a power removal circuit <NUM> coupled to a monitoring circuit <NUM>. Power removal circuit <NUM> enables remote triggering of a power shutdown of the powered equipment <NUM>. In some implementations, power removal circuit <NUM> includes a disconnector (or breaker) <NUM> and an actuator <NUM> coupled to a trip device <NUM>. When the actuator <NUM> is activated, control power becomes available to and activates the trip device <NUM>, which then activates (e.g., opens the contacts) the disconnector <NUM>, thereby removing system power to equipment <NUM>. While <FIG> illustrates a single actuator <NUM> and a single trip device <NUM>, it should be appreciated that multiple instance of each may be provided. Additionally, one or more elements other than those depicted in <FIG> may be provided.

Disconnector <NUM> may include, but is not limited to, a power disconnector, breaker, contacts of a contactor, relay, or a combination thereof. Actuator <NUM> may be, for example, a remote actuator, such as an RPO or EPO button. Actuator <NUM> may include one or more actuator contacts (e.g., relay contact, contactor contact, breaker auxiliary contact), a solid state transistor-based switch, or a combination thereof. For example, actuator <NUM> may include a relay with normally open (NO) contacts actuated by a series of normally closed (NC) contacts in an RPO station.

Trip device <NUM> may include at least one electromagnetic coil that is non-continuously powered by control power lines <NUM> and <NUM> (L1, L2). Control power is applied to the trip device <NUM> only upon activation of the actuator <NUM>. When the actuator <NUM> is activated by the control power, trip device <NUM> receives the control power and actuates (or applies control power to) the disconnector <NUM> to remove system power to the equipment <NUM>. Advantageously, since the trip device <NUM> is non-continuously powered, a brief power loss does not actuate the disconnector <NUM>. Equipment <NUM> may ride through and remain operational during brief power losses.

Trip device <NUM> may include, but is not limited to, a shunt trip, a motorized breaker, contactor, power shutdown circuit of an uninterruptible power supply (UPS), undervoltage trip (UVT) circuit, or a combination thereof. It should be appreciated that the control power may be any type of power, such as alternating current (AC) power, direct current (DC) power, single-phase power, multi-phase power, or a combination thereof. The power may include any frequency or voltage level with the appropriate choice of the component(s) of the monitoring circuit <NUM>.

Monitoring circuit <NUM> is coupled to actuator <NUM> to continuously monitor the power removal circuit <NUM> and provide an output signal that may be indicative of circuit integrity (or continuity). Monitoring circuit <NUM> advantageously enables equipment <NUM> to remain operational in the event of a fault in the power removal circuit <NUM>, while providing a high reliability of the power shutdown function in the event of an emergency. In some implementations, monitoring circuit <NUM> is coupled across the normally open contacts of actuator <NUM> to provide circuit integrity indication. Circuit integrity generally refers to the operability of the power removal circuit <NUM> during activation of the actuator <NUM> in the event of, for example, an emergency that requires power shutdown for equipment <NUM>. Circuit integrity may be impacted by, for example, line breaks, as well as coil integrity and/or coil burn-out in trip device <NUM>.

Monitoring circuit <NUM> generates an output signal that is indicative of circuit integrity based on one or more electrical characteristics of the power removal circuit <NUM>. The output signal may be, for example, a discrete signal that represents a circuit status of the power removal circuit <NUM>. For example, when the output signal is "off' (or at a predetermined low level), it may indicate a fault status. When the output signal is "on" (or at a predetermined high level), it may indicate an operational or normal status. The electrical characteristics of the power removal circuit <NUM> may include, but are not limited to, a closed loop current, a closed loop voltage, a frequency, or a combination thereof.

In some implementations, monitoring circuit <NUM> includes a high impedance (or low current) device <NUM> to generate the output signal. The high impedance device <NUM> may include, but is not limited to, a high impedance switch, relay, optical isolator or a combination thereof. For example, high impedance device <NUM> is a solid-state relay with optical isolation. The high impedance device <NUM> may be de-energized in response to a fault occurring in the power removal circuit <NUM>, thereby producing a low output signal that is provided to a notification system <NUM>.

Monitoring circuit <NUM> is coupled to the notification system <NUM> to automatically generate notification <NUM> based on the output signal. Notification system <NUM> may be a computer system, an alarm circuit or any other system capable of generating a notification <NUM> based on the output signal. Notification system <NUM> may be coupled to the high impedance device <NUM> to receive the output signal. The notification <NUM> may inform the user (or system) of the status (e.g., fault or operational status) of the power removal circuit <NUM>. The notification <NUM> may include, for example, a visual alarm, an audible alarm, electronic text message, electronic mail message, or a combination thereof. The notification <NUM> may also be communicated to a monitoring system (not shown) associated with the powered equipment <NUM> to perform one or more actions in response to the notification <NUM>.

Advantageously, circuit faults in the entire power removal circuit <NUM> may be continuously and automatically monitored by the monitoring circuit <NUM>. The user (or system) may be notified immediately of a fault condition in the power removal circuit <NUM>, so that action may be taken to correct the fault. The circuit <NUM> advantageously requires minimal hardware, thereby reducing the cost, size and installation effort. Additionally, minimal additional power is required. High reliability of the remote power shutdown function is achieved in the event of an emergency.

<FIG> shows another exemplary remote power shutdown system <NUM>. Remote power shutdown system <NUM> is coupled to a powered equipment <NUM>. Remote power shutdown system <NUM> includes a power removal circuit <NUM> coupled to a monitoring circuit <NUM>. Power removal circuit <NUM> enables remote triggering of a power shutdown of the powered equipment <NUM>. In some implementations, power removal circuit <NUM> includes a disconnector (or breaker) <NUM> and an actuator <NUM> coupled to a trip device <NUM>. When the contacts in the actuator <NUM> close, current becomes available to the trip device <NUM>, which then opens the contacts in the disconnector <NUM>, thereby removing system power to equipment <NUM>.

Monitoring circuit <NUM> is coupled to actuator <NUM> to continuously monitor the circuit <NUM> and provides an output signal that is indicative of full circuit integrity (or continuity) based on one or more electrical characteristics of the power removal circuit <NUM>. In some implementations, monitoring circuit <NUM> is coupled across the normally open contacts of actuator <NUM> to provide circuit integrity indication. Monitoring circuit <NUM> may include a high impedance (or low current) device <NUM> and a current transformer <NUM> coupled across the actuator <NUM>. High impedance (or low current) device <NUM> may include, for example, a current limiting resistor, a relay coil, or a combination thereof. A current meter <NUM> may be coupled across the current transformer <NUM> for measuring the current and generate the output signal. The output signal of the current meter <NUM> is indicative of the circuit integrity (or circuit status) of the power removal circuit <NUM>. Accordingly, monitoring circuit <NUM> continuously and automatically monitors the power removal circuit <NUM> (e.g., trip device <NUM>) and provides verification of circuit integrity, while allowing the powered equipment <NUM> to remain operational in the event of a circuit fault and providing high reliability of power shutdown function in the event of an emergency.

Monitoring circuit <NUM> is coupled to a notification system <NUM> to provide automatic user notification <NUM> of a circuit fault. Notification system <NUM> may be coupled to the current meter <NUM> to receive its output and generate the user notification <NUM> based on the output signal. The output signal may be, for example, a discrete signal that represents a circuit fault status when "off' (or a predetermined low level) and an operational circuit status when "on" (or at a predetermined high level). The output signal may be monitored by notification system <NUM>, which reports a notification <NUM> to the user. The user notification <NUM> may include, for example, a visual alarm, an audible alarm, electronic text message, electronic mail message, or a combination thereof.

<FIG> shows an exemplary method <NUM> of continuously monitoring remote power shutdown. It should be understood that the steps of the method <NUM> may be performed in the order shown or a different order. Additional, different, or fewer steps may also be provided. Further, the method <NUM> may be implemented with the system <NUM> of <FIG>, system <NUM> of <FIG>, a different system, or a combination thereof.

At <NUM>, disconnector <NUM> is deactivated and actuator <NUM> is also deactivated. At <NUM>, system power and control power are applied to the remote power shutdown system (<NUM> or <NUM>). Equipment <NUM> receives system power via the deactivated (e.g., closed) disconnector <NUM>. At <NUM>, if no fault exists in power removal circuit <NUM>, method <NUM> proceeds to <NUM>. If a fault exists, method <NUM> proceeds to <NUM>.

At <NUM>, monitoring circuit (<NUM> or <NUM>) generates a first predetermined level of an output signal based on one or more electrical characteristics of power removal circuit <NUM>. For example, high impedance device <NUM> may change state from a high to a low output signal in response to an occurrence of a fault. At <NUM>, notification system <NUM> is activated in response to the first predetermined level of the output signal. At <NUM>, in response to activation, notification system <NUM> generates a notification <NUM> indicating the fault status of the power removal circuit <NUM>. During this fault event, trip device <NUM> is deactivated and disconnector <NUM> remains deactivated (e.g., closed), thereby allowing system power to pass through to equipment <NUM>. Therefore, equipment <NUM> remains powered and operational, and does not shut down with the power removal circuit <NUM>.

If no emergency event occurs, the method <NUM> may continue directly from <NUM> to <NUM>. If an emergency event occurs at <NUM>, however, equipment <NUM> needs to be shut down. At <NUM>, system power may be removed from the equipment <NUM> by activating the disconnector <NUM>, rather than remotely activating the actuator <NUM> of the power removal circuit <NUM>. At <NUM>, in response to activation of disconnector <NUM>, system power is removed from the equipment <NUM> and equipment <NUM> shuts down. The fault in the power removal circuit <NUM> may be repaired during this emergency event.

At <NUM>, the fault in the power removal circuit <NUM> is repaired and therefore fully functional. At <NUM>, disconnector <NUM> and actuator <NUM> are deactivated. At <NUM>, system power and control power are applied to the remote power shutdown system (<NUM> and <NUM>). System power then passes through to equipment <NUM>.

At <NUM>, when no fault in the power removal circuit <NUM> exists or the previous fault has been repaired, a second predetermined level of the output signal is generated based on the one or more electrical characteristics of the power removal circuit <NUM>. For example, high impedance device <NUM> may be activated and sends a high output signal to the notification system <NUM> indicating that the power removal circuit <NUM> is operational. At <NUM>, notification system <NUM> is deactivated in response to the second predetermined level of the output signal. At <NUM>, in response to the deactivation, notification system <NUM> may send a notification <NUM> indicating that the remote power shutdown system is operational (i.e., operational or normal status). While there is no fault in the power removal circuit <NUM>, trip device <NUM> is not powered when the actuator <NUM> is deactivated. Disconnector <NUM> is thereby deactivated (e.g., closed), allowing system power to pass through to equipment <NUM>. Equipment <NUM> remains powered and operational. Trip device <NUM> may allow a small current flow which powers the high impedance monitoring device <NUM> but does not actuate the disconnector <NUM>.

At <NUM>, an emergency event occurs that requires equipment <NUM> to be shut down. At <NUM>, since there is no fault in the power removal circuit <NUM>, actuator <NUM> may be used by the user (or an external device) to remove system power from equipment <NUM>. At <NUM>, notification system <NUM> is activated in response to, for example, the deactivation (e.g., removal of control power) of high impedance device <NUM>. At <NUM>, in response to receiving, for example, a low output signal from the high impedance device <NUM>, notification system <NUM> sends a notification <NUM> indicating that the actuator <NUM> is activated. During the emergency event, trip device <NUM> may receive control power and be activated, thereby activating (e.g., opening) disconnector <NUM>. At <NUM>, equipment <NUM> no longer receives system power and is successfully shut down.

Claim 1:
A system (<NUM>) comprising:
a power removal circuit (<NUM>) for enabling remote triggering of a power shutdown of an equipment (<NUM>) coupled to the power removal circuit (<NUM>),
a monitoring circuit (<NUM>, <NUM>) coupled to the power removal circuit (<NUM>), wherein the monitoring circuit (<NUM>, <NUM>) generates an output signal indicative of circuit integrity based on one or more electrical characteristics of the power removal circuit (<NUM>); and
a notification system (<NUM>) coupled to the monitoring circuit (<NUM>, <NUM>) to receive the output signal, wherein the notification system (<NUM>) generates a notification (<NUM>) based on the output signal.