Thermal switch with self-test feature

• US 7,358,740 B2
• Filed: 03/18/2005
• Issued: 04/15/2008
• Est. Priority Date: 03/18/2005
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Davis, George D., Scott, Byron G.
• Primary Examiner(s): Nguyen; Vincent Q.
• Application Number:
  US10/907,086
• Publication Number:
  US 20060208846A1
• Time in Patent Office: 1,124 Days
• Field of Search: 324/415, 324/417, 337/14
• US Class Current: 324/417
• CPC Class Codes: H01H 2300/052 Controlling, signalling or testing correct functioning of a switch see also H01H2300/056 - H01H2300/066 and H01H11/0062
• CPC Class Codes: H01H 37/54 wherein the bimetallic element is inherently snap acting

Abstract

A normally open thermal switch (200) having a bimetallic disk (18) is configured for operational testing in its installed position when exposed to a changing temperature by a test box (400) having a power source (400a). The in-place testing advantageously confirms triggering action of the switch by an event indicator (400c) at the operational temperatures designed into the switch (200). The temperature of the triggering action is presented on a temperature display (400b) and recorded by a data recorder (400d) of the test box (400). The switch (200) incorporates a heating element (24c) to heat changing the bimetallic disk (18) to snap activate at the operative temperatures. The thermal switch (200) is coupled with the test box (400) to confirm its operation without having to remove the switch from its installed location.

Claims

1. A thermal switch testing system for detecting switch operation, comprising:

a housing;

a heating element disposed within the housing;

a switch device disposed within the housing;

a temperature sensing element;

a test box coupled with the switch device and the heating element, the test box comprising;

a heater component for causing the heating element to apply heat within the housing;

a sensing component for sensing when the switch device toggles,

a component coupled to the temperature sensing element and the sensing component for determining a temperature within the housing at which the switch device toggled; and

a display for displaying the determined temperature.

2. The system of claim 1, wherein the switch device includes a bimetallic disk.

3. The system of claim 1, wherein the test box further includes an event indicator configured to indicate when the switch device toggles.

4. The system of claim 3, wherein toggling of the switch device includes at least one of going from a closed position to an open position or going from an open position to a closed position.

5. The system of claim 1, wherein the test box further includes a storage device for storing the determined temperature.

6. The system of claim 1, wherein the test box is coupled to the thermal switch at a thermal switch installed position.