# US 4,395,694 A · Thermostat construction employing aramide insulation

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- Number: US 4,395,694 A
- Document ID: US4395694A
- Status: Granted
- Kind: A
- Application number: 06/391,128
- Filed: 1982-06-23
- Granted: 1983-07-26
- Earliest claimed: 1982-06-23
- Assignees: Portage Electric Products, Inc.
- Inventors: Glenn E. Wehl
- Web page: https://patentgrep.com/patent/US4395694A

## CPC

- H01H 37/04: Bases; Housings; Mountings {(H01H37/5427 takes precedence)}
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)

## Abstract

A standard thermostatic switch, particularly one enclosed within a metallic casing, is provided with an insulating material, in the form of a sleeve, between the contacts or bimetallic elements and the metallic casing of the thermostat to aid in sealing the internal elements. The material is an aramide, particularly a copolymer of metaphenylenediamine and isophthaloyl chloride, particularly one marketed under the trademark "Nomex" by E. I. duPont deNemours & Co.

## Claims

### Claim 1

In a thermostatic device comprising a casing, at least one bimetallic element, a contact associated with that bimetallic element, a second contact within the casing for mating with said first contact in order to complete an electric circuit, means for electrically connecting said bimetallic element to an external circuit and means for connecting said second contact to an external electrical circuit, the improvement which comprises the use of an aramide insulating sleeve in an open end of said casing to electrically insulate said bimetallic element and associated electrically conductive parts from other parts of said thermostatic device.

### Claim 2 (depends on 1)

The device of claim 1 wherein said aramide is a copolymer of meta-phenylenediamine and isophthaloyl chloride.

### Claim 3 (depends on 1)

The thermostatic device of claim 1 wherein said casing is a live-case casing.

### Claim 4 (depends on 1)

The thermostatic device of claim 1 wherein said casing is a dead-case casing.