WO2016007164A1

WO2016007164A1 - Apparatus and method for control of switching circuitry

Info

Publication number: WO2016007164A1
Application number: PCT/US2014/046214
Authority: WO
Inventors: John Robert BOOOTH; Fred Henry Boettner; Richard Joseph GLOSSER
Original assignee: Ge Intelligent Platforms, Inc.
Priority date: 2014-07-10
Filing date: 2014-07-10
Publication date: 2016-01-14

Abstract

A protection circuit includes one or more electro-mechanical force-guided safety relays and one or more solid state relays. The solid state relays are coupled electrically in series to the electro- mechanical force-guided safety relays. The electro-mechanical force-guided safety relays and the solid state relays are disposed between a power source and one or more controlled devices, and regulate current flow between the power source and the one or more controlled devices. The electro-mechanical force-guided safety relays and solid state relays are selectively instructed to open upon a determination of an unsafe operating condition in a system. The electro-mechanical force-guided safety relays open when the solid state relays malfunction and fail to open.

Description

APPARATUS AND METHOD FOR CONTROL OF SWITCHING CIRCUITRY

Background of the Invention Field of the Invention

[0001] The subject matter disclosed herein generally relates to controlling the operation of electrical components, and more specifically, activating or deactivating switching

arrangements that control these devices.

Brief Description of the Related Art

[0002] Control systems are also used in factories, businesses, offices, or schools sometimes and these sometimes utilize solenoids. The solenoids can be used to actuate a wide variety of electrical and mechanical components or devices such as motors. Often, safety concerns arise in the place where the control system is located. When these safety issues arise, the solenoids may need to be shut off so as to remedy or address the unsafe operating conditions.

[0003] Electromechanical force relays are sometime exclusively used to actuate the solenoids utilized in these control systems. Unfortunately, these relays are typically large (with a large footprint), limited in lifetime, subject to welded contact failures, operate slowly, and are expensive.

[0004] Solid state relays have also have been exclusively used in some other previous systems. However, these relays are also expensive, have a smaller selection of contacts per package, and are subject to damage caused by voltage transients.

[0005] As a result, the solenoid control systems have become bulky, unreliable and/or expensive. The above-mentioned problems have resulted in some user dissatisfaction with previous approaches. Brief Description of the Invention

[0006] The approaches described herein provide high integrity, high reliability solenoid control solutions for safety systems. In one example, the present approaches utilize an arrangement of electromechanical and solid state relays that leverages the strengths of each device type while minimizing the weaknesses of each type to provide a reliable system tripping capability.

[0007] In many of these embodiments, a protection circuit includes one or more electromechanical force-guided safety relays and one or more solid state relays. The solid state relays are coupled electrically in series to the electro-mechanical force-guided safety relays. The electro-mechanical force-guided safety relays and the solid state relays are disposed between a power source and one or more controlled devices, and regulate current flow between the power source and the one or more controlled devices. The electro-mechanical force-guided safety relays and solid state relays are selectively instructed to open upon a determination of an unsafe operating condition in a system. The electro-mechanical force-guided safety relays open when the solid state relays malfunction and fail to open.

[0008] In some aspects, the solid state relays open when the electro-mechanical force- guided safety relays malfunction and fail to open. In other aspects, the electro-mechanical force- guided safety relays and the solid state relays are closed during normal operating conditions. In some other examples, the one or more controlled devices comprise a solenoid. Other examples of controlled devices are possible.

[0009] In other examples, the determination of an unsafe operating condition is made by one or more controllers. In one aspect, the one or more controllers provide one or more indications of at least one operating condition to a voting circuit. In other aspects, the voting circuit determines a voltage level to apply to the electro-mechanical force-guided safety relays or the solid state relays based upon the one or more indicators. In yet other aspects, the voting circuit comprises a first voting circuit configured to control the electro-mechanical force-guided safety relays and a second voting circuit configured to control the solid state relays. [0010] In some aspects, the unsafe condition is determined, the solid state relays are opened at a first time and the electro-mechanical force-guided safety relays are opened at a second and later time.

[0011] In other examples, the relay protection circuit is disposed between a power source and one or more controlled devices. The relay protection circuit includes at least one electromechanical force-guided safety relay and at least one solid state relay. The solid state relays are coupled electrically in series with the electro-mechanical force-guided safety relays. An existence of an unsafe operating condition in a system is determined. The electro-mechanical force-guided safety relays and the solid state relays are selectively opened upon detection of the existence of the unsafe operating condition in the system. The electro-mechanical force-guided safety relays open when the solid state relays malfunction and fail to open.

Brief Description of the Drawings

[0012] For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawings wherein:

[0013] FIG. 1 comprises a block diagram of a system for controlling various devices according to various embodiments of the present invention;

[0014] FIG. 2 comprises a flow chart of one approach for controlling the actuation and de-actuation of various devices according to various embodiments of the present invention;

[0015] FIG. 3 comprises a block diagram of an approach for controlling the actuation and de-actuation of various devices according to various embodiments of the present invention.

[0016] Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity. It will further be appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. It will also be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein.

Detailed Description of the Invention

[0017] Highly reliable control circuits (e.g., solenoid safety control circuits) are provided at a lower cost and smaller footprint than previous systems. The smaller size and lower cost allows electronic panel designs (where the control system elements are disposed) to be smaller and more cost effective. It will be appreciated that approaches described herein with respect to the control of solenoids can be used for applications other than solenoids (or solenoid control) in circumstances or situations when high integrity reliability is necessary or advantageous. In these regards, the approaches described herein can also be used in non-safety control systems or in any control system or arrangement.

[0018] The approaches described herein simultaneously utilize electromechanical and solid state relays, and dispose and control the operation of these different relay types in a manner that accentuates the best features of each type, while minimizing the negative features of each of these types. Generally speaking, the control circuits described herein can be thought of as having two relay portions. A first part of the circuit consists of one or more electromechanical force guided safety relays. The two electromechanical relays are connected electrically in parallel so that online proof testing can be conducted at some interval. Each electromechanical relay has, in one aspect, multiple contacts with one of the contacts reserved for a monitor feedback. The remaining contacts will feed an independent set of sold state relays. The independence allows different voltage sources to be fed to the different relay groupings.

[0019] The second part of the circuit includes one or more solid state relays. The number of solid state relays used is based, in part, upon the current capability of the upstream

electromechanical relay and the number of terminal points available for access to the contacts.

[0020] Electromechanical force guided safety relays include high voltage/current capacity, multiple contacts per package, and the state of all contacts is often guaranteed to correspond, thereby allowing a contact to be used as feedback. However, these relays are large and typically have a large footprint, have a lifetime that is limited to a fixed number of mechanical cycles, are subject to welded contact failure mode, are relatively slow in operation time, may have ATEX safety concerns, and are expensive

[0021] Solid state relays typically fast operation times, are small with a small footprint for single package, are inherently safe from an ATEX perspective, and have a lifetime that is not limited by mechanical operation. However, these relays offer a smaller selection of contacts per package, are subject to damage due to voltage transients, and are expensive.

[0022] In the present approaches, the weakness of one relay type is offset by a strength of the other type. While both types can be expensive in some situations, using an optimized configuration can reduce the number of relays when compared to previous solutions. Therefore the present approaches have a lower system cost as compared to previous approaches. For example, an existing solid state solution requires 6 relays for one output to ensure that the relay output will always open despite any failure modes. Neglecting the second proof test relay, the same function in the present approaches only requires two relays.

[0023] In some aspects, the arrangement of the relays is made to increase tripping reliability. The approaches open the relay contacts when commanded despite any single failure mode that might be in the system. In some examples, the solid state relays are the relays that are operated. They are quicker and not subject to the same lifetime limitations as the

electromechanical relays. By monitoring the output side of the solid state contacts, the system can determine when relays fail to open. Upon detection of this event, the electromechanical relay can be opened. Under normal operation, this relay would only change states at power up and power down. In addition, the two electromechanical relay can toggle at a slow enough period to confirm their ability to operate via monitoring a contact feedback without significant impact on their lifetime.

[0024] In other aspects, the relays are commanded or controlled by a voted signal. In this sense, a failure in one of the controllers cannot create a trip. It also allows a single controller to be taken down for maintenance without affecting the online state of the system. [0025] Referring now to FIG. 1, one example of a system 100 for controlling various devices such as solenoids is described. The system includes an electromagnetic (EM) relay portion 104 and a solid state relay portion 126. The EM relay portion 104 is coupled to a direct current (DC) or alternating power (AC) source 102. The solid state relay portion 126 is coupled to one or more controlled devices 136 via a connector 134.

[0026] The EM relay portion 104 includes a first electro-mechanical force-guided safety relay 106 (with contact pairs 110 and 112) and includes a second electro-mechanical force- guided safety relay 108 (with contact pairs 114 and 116). The contact pairs 114, 116 open and close (allowing current to flow when closed, and preventing current from flowing when open) upon application of an electrical signal to a coil. A first monitor 118 and first DC source 120 are coupled through contact pair 112. A second monitor 122 and second DC source 124 are coupled through contact pair 116. The purpose of the monitors 118, 122 is to leverage the nature of a force guided relay to monitor the state (e.g., open or closed) of the contact pairs 110 and 114. The information obtained by the monitors 118, 122 may be utilized by any process, internal or external to the overall control system.

[0027] The solid state relay portion 126 includes a first solid state relay 128, a second solid state relay 130, and a third solid state relay 132. The first solid state relay 128, the second solid state relay 130, and the third solid state relay 132 are solid state relays that utilize, for example, transistors as known in the art. The solid state relays 128, 130, 132 are solid-state switches that open and close upon direct application of an electrical signal.

[0028] A first voting circuit 144 receives input signals from a first controller 138, a second controller 140, and a third controller 142. The first voting circuit 144 forms a coil control signal for the first electro-mechanical force-guided safety relay 106 and the second electro-mechanical force-guided safety relay 108.

[0029] A second voting circuit 146 receives input signals from the first controller 138, the second controller 140, and the third controller 142. The second voting circuit 146 forms an on/off signal for the first solid state relay 128. Additional repetitions of 146 are used to form on/off signal for the second solid state relay 130, and the third solid state relay 132. [0030] The first controller 138, the second controller 140, and the third controller 142 are any appropriate combination of hardware and/or software that monitor a control system.

[0031] The one or more controlled devices 136 may be a solenoid, any machine, or any other type of electronic or mechanical devices. The controlled devices 136 may operate in any setting or environment such as a factory, power plant, business, school, and home, to mention a few examples.

[0032] In some examples, the first voting circuit 144 and the second voting circuit 146 operate according to a majority vote. For example, when two out of three of the first controller 138, the second controller 140, and the third controller 142 indicate that there is a problem, then the output of the first voting circuit 144 and the second voting circuit 146 goes from a first voltage level (that has kept the associated relay closed) to a second voltage level (that closes the associated relay).

[0033] In some aspects, a protection circuit includes the EM relay portion 104 and the solid state relay portion 126. The protection circuit regulates current flow between the direct current (DC) or alternating power (AC) source power source 102 and the one or more controlled devices 136. The various electro-mechanical force-guided safety relays 106, 108 and various solid state relays 128, 130, and 132 are selectively instructed to open upon a determination of an unsafe operating condition in a system. In these regards, the electro-mechanical force-guided safety relays 106, 108 open when at least one of the solid state relays 128, 130, and 132 malfunction and fail to open.

[0034] In some aspects, the solid state relays 128, 130, and 132 open when one or more of the electro-mechanical force-guided safety relays 106, 108 malfunction and fail to open. In other aspects, the electro-mechanical force-guided safety relays 106, 108 and the solid state relays 128, 130, and 132 are closed during normal operating conditions. In some examples, the one or more controlled devices 136 comprise a solenoid. Other devices are possible.

[0035] In other examples, the determination of an unsafe operating condition is made by one or more of the controllers 138, 140, 142. In one aspect, the controllers 138, 140, 142 provide one or more indications of at least one operating condition to the voting circuits 144, 146. In other aspects, the voting circuits 144, 146 determines a voltage level to apply to the electromechanical force-guided safety relays 106, 108 or the solid state relays 128, 130, 132 based upon the one or more indicators. In some aspects, when the unsafe condition is determined, the solid state relay 128, 130, 132 is opened at a first time and the electro-mechanical force-guided safety relay 106, 108 is opened at a second and later time.

[0036] Referring now to FIG. 2, an approach for operating a protection circuit is described. In this example, the relay protection circuit is disposed between a power source and one or more controlled devices. The relay protection circuit includes one or more electromechanical force-guided safety relays and one or more solid state relays. The solid state relays are coupled electrically in series to the electro-mechanical force-guided safety relays.

[0037] At step 202, an existence of an unsafe operating condition in a system is determined. The unsafe operating condition may relate to voltage levels, temperature levels, pressure levels, frequency levels, states, or any other measurable or determinable condition. Other examples are possible.

[0038] At step 204, the electro-mechanical force-guided safety relays or the solid state relays are selectively opened upon the existence of the unsafe operating condition in the system. The opening of the relays removes power and or current from the one or more controlled devices (e.g., the one or more controlled devices 136) thereby restoring or attempting to restore safe operating conditions in the system.

[0039] At step 206, the electro-mechanical force-guided safety relays open when the solid state relays malfunction and fail to open. The opening of the relays removes power and or current from the one or more controlled devices (e.g., the one or more controlled devices 136) thereby restoring or attempting to restore safe operating conditions in the system.

[0040] In addition, there may be situations when the solid state relay opens and the mechanical safety relay fails to open. In this case, monitors (e.g., monitors 118,122 of FIG. 1) detect this failure and the system has both the diagnostic information of the mechanical safety relay failure and the ability to preclude the system from exiting the safe state until the failed relay is repaired. [0041] Referring now to FIG. 3, one example of an approach for control of solenoids is described. One or more controllers 302 are coupled to a processing block 304. The processing block 304 is coupled to relays 306. The relays may be combination of solid state relays or electro-mechanical force-guided safety relays. There are also n-lines from the one or more controllers 302. For example, one line may come from each one of four controllers. It will be appreciated that the controllers can be physically integrated and operate together or physically separate and operate independently from each other. It will also be understood that the controllers can be located in the same physically location (or in close physical proximity) to the protection circuit or can be located remotely from the protection circuit.

[0042] For the processing block 304, if one or more indicators received from the controllers indicate a failure, then the voltage may be set to VI and this opens the contacts. Otherwise, the voltage is set to a voltage level V2 and this keeps the contacts closed. In one example this may control solenoids but this is not limited to controlling solenoids.

[0043] It will be appreciated by those skilled in the art that modifications to the foregoing embodiments may be made in various aspects. Other variations clearly would also work, and are within the scope and spirit of the invention. The present invention is set forth with particularity in the appended claims. It is deemed that the spirit and scope of that invention encompasses such modifications and alterations to the embodiments herein as would be apparent to one of ordinary skill in the art and familiar with the teachings of the present application.

Claims

What is claimed is:

1. A protection circuit, the circuit comprising:

at least one electro-mechanical force-guided safety relay;

at least one solid state relay, the at least one solid state relay coupled electrically in series to the at least one electro-mechanical force-guided safety relay;

wherein the at least one electro-mechanical force-guided safety relay and the at least one solid state relay are disposed between a power source and one or more controlled devices, and regulate current flow between the power source and the one or more controlled devices;

such that the at least one electro-mechanical force-guided safety relay and the at least one solid state relay are selectively instructed to open upon a determination of an unsafe operating condition in a system;

such that the at least one electro-mechanical force-guided safety relay opens when the at least one solid state relay malfunctions and fails to open;

2. The protection circuit of claim 1, wherein the at least one solid state relay opens when the at least one electro-mechanical force-guided safety relay malfunctions and fails to open.

3. The protection circuit of claim 1, wherein the at least one electro-mechanical force-guided safety relay and the at least one solid state relay are closed during normal operating conditions.

4. The protection circuit of claim 1, wherein the one or more controlled devices comprise a solenoid.

5. The protection circuit of claim 1, wherein the determination of an unsafe operating condition is made by one or more controllers.

6. The protection circuit of claim 5, wherein the one or more controllers provide one or more indications of at least one operating condition to a voting circuit.

7. The protection circuit of claim 6, wherein the voting circuit determines a voltage level to apply to the at least one electro-mechanical force-guided safety relay or the at least one solid state relay based upon the one or more indicators.

8. The protection circuit of claim 6, wherein the voting circuit comprises a first voting circuit configured to control the at least one electro-mechanical force-guided safety relay and a second voting circuit configured to control the at least one solid state relay.

9. The protection circuit of claim 1 , wherein when the unsafe condition is determined, the at least one solid state relay is opened at a first time and the at least one electromechanical force-guided safety relay is opened at a second and later time.

10. A method of operating a relay protection circuit, the relay protection circuit being disposed between a power source and one or more controlled devices, the relay protection circuit including at least one electro-mechanical force-guided safety relay and at least one solid state relay, the at least one solid state relay coupled electrically in series to the at least one electromechanical force-guided safety relay, the method comprising:

determining an existence of an unsafe operating condition in a system;

selectively opening the at least one electro-mechanical force-guided safety relay and the at least one solid state relay are selectively opened upon the existence of the unsafe operating condition in the system;

such that the at least one electro-mechanical force-guided safety relay opens when the at least one solid state relay malfunctions and fails to open.

11. The method of claim 10 wherein the at least one solid state relay opens when the at least one electro-mechanical force-guided safety relay malfunctions and fails to open.

12. The method of claim 10 further comprising closing the at least one electromechanical force-guided safety relay and the at least one solid state relay during normal operating conditions.

13. The method of claim 10 wherein the one or more controlled devices comprise a solenoid.

14. The method of claim 10 wherein the determining of an unsafe operating condition is made by one or more controllers.

15. The method of claim 14 further comprising providing one or more indications of at least one operating condition to a voting circuit.

16. The method of claim 15 further comprising determining a voltage level to apply to the at least one electro-mechanical force-guided safety relay or the at least one solid state relay based upon the one or more indications.

17. The method of claim 10 further comprising when an unsafe operating condition is determined, opening the at least one solid state relay is opened at a first time and the at least one electro-mechanical force-guided safety relay is opened at a second and later time.