Safety relay having independently testable contacts
AssigneeFisher-Rosemount Systems, Inc.
InventorsKent Allan Burr, Gary Keith Law
Life of this patent
Estimating the term…
Abstract
Methods, apparatus, and articles of manufacture related to safety relays having independently testable relay contacts are disclosed. In one disclosed example, a safety relay includes a plurality of relay coils, each of which is coupled in parallel to a first node via a respective one of a plurality of switches. The disclosed example also includes and a plurality of relay contacts, each of which corresponds to a respective one of the plurality of relay coils. The relay contacts of the safety relay are coupled in series and independently controllable by respective ones of the switches.
Claims27
A safety relay comprising:
- a first relay including a first relay contact and a first relay coil to change the state of the first relay contact when the first relay coil is energized;
- a first switch coupled in series with the first relay coil;
- a second relay including a second relay contact and a second relay coil to change the state of the second relay contact when the second relay coil is energized;
- a second switch coupled in series with the second coil, wherein the first switch and the first relay coil are coupled in parallel with the second switch and the second relay coil between a first node and a second node, and wherein the first relay contact and the second relay contact are coupled in series between a third node and a fourth node;
- a third relay including a third relay contact and a third relay coil to change the state of the third relay contact when the third relay coil is energized;
- and
- a third switch coupled in series with the third coil, wherein the third switch and the third relay coil are coupled in parallel with the first switch and the first relay coil between the first node and the second node, and wherein the third relay contact is coupled in series with the first relay contact and the second relay contact between the third node and the fourth node.
A safety relay as defined in claim, 1 further comprising a light-emitting diode coupled between the first node and second node.
A safety relay as defined in claim, 1 further comprising a bypass switch to decouple the first relay contact and the second relay contact from at least one of the third node or the fourth node and to provide an electrical path between the third node and the fourth node.
A safety relay as defined in claim, 1, wherein the first switch is configured to be responsive to a signal from a controller to automatically open or close.
A safety relay as defined in claim, 1, wherein the third node and the fourth node are configured to provide contacts to measure an electrical characteristic.
A safety relay comprising:
- a first relay including a first relay contact and a first relay coil to change the state of the first relay contact when the first relay coil is energized;
- a first switch coupled in series with the first relay coil;
- a second relay including a second relay contact and a second relay coil to change the state of the second relay contact when the second relay coil is energized;
- a second switch coupled in series with the second coil, wherein the first switch and the first relay coil are coupled in parallel with the second switch and the second relay coil between a first node and a second node, and wherein the first relay contact and the second relay contact are coupled in series between a third node and a fourth node;
- a diode coupled in parallel with the first relay coil;
- and
- a transistor coupled between the diode and the first switch.
A safety relay comprising:
- a plurality of relay coils coupled in parallel;
- and
- a plurality of series coupled relay contacts associated with the relay coils, wherein the operation of each of the relay contacts is testable in response to a signal applied to the relay coils;
- and
- a bypass switch selectively coupled in series with the plurality of relay contacts to decouple the plurality of relay contacts from an electrical path between a first and second node.
An apparatus comprising:
- a plurality of relay coils, each of which is coupled to a first node via a respective one of a plurality of switches;
- and
- a plurality of relay contacts, each of which corresponds to a respective one of the plurality of relay coils, wherein the relay contacts are coupled in series and wherein each of the relay contacts is independently controllable by its respective one of the switches;
- and
- a plurality of transistors each of which is coupled in series with respective ones of the plurality of relay coils and switches.
Dependencies are inferred from the claim text.