CPI Plugstat Thermal Switches – Getting There Slowly

For engineers looking to solve demanding temperature switching applications, robust, standalone thermal switches are surprisingly hard to come by. A quick google search yields hundreds of parts in a confused presentation of thermals, with every shape and size represented, sold everywhere from Alibaba to Amazon. But for the endurance focused designer, there might as well be 0 results.

Sometimes Slow is Good…

In the world of thermal switches, bimetallic switches generally belong to one of two categories:

  1. Snap Action Switches – As the name implies this group of switches has a quick make/break switching action, ideal when there is a fairly large differential between the opening and closing temperatures of activation.
  2. Slow make/break or “Creep Action” devices – These are excellent in temperature control or high limit control applications. They are designed for a narrow temperature differential between opening and closing temperatures where slower cycling characteristics provide some immunity from chattering in precision thermal sensing. This is the CPI Plugstat thermal switch line.

Accurate, and Durable Standalone Thermal Detection and Switching

The primary difference between CPI’s Plugstat Thermal Switches and others is their high endurance design. The PlugStat Series of close tolerance, bimetal thermal switches serve as a robust and accurate temperature control switch at temperature ratings from 17C (0F) to 343C (650F).  This slow make and break thermal switch, open-on-rise device is hermetically sealed, with 1/2-20UNF-3A  thread mounting or other custom mountings available.

Electrically, our switch handles up to 2A at 28V off the shelf, but custom values are possible. No matter what variation you get, the quality of this thermal is in keeping with the quality of the parts that make it.

  • Stainless Steel type 304
  • Stainless Steel type 321
  • Inconel Alloy 600
  • Stycast type 2651
  • Platinum Contacts

Hey, it was Good Enough for NASA…

Despite NASA’s stringent material and electrical requirements for the International Space Station, CPI’s off-the-shelf Plugstat model M1102 met their need for a reliable, space deployable, thermal safety switch solution. In this application, CPI’s switch was used to sense the temperature of a highly specialized liquid to prevent it from turning into a toxic gas during heating. Additionally CPI provided all applicable CoC’s, Material Test Reports, and Chemical Analysis’ required to meet NASA’s stringent quality control. The application is fascinating and can be read about here.

CPI Plugstat switches have been used on tanks and planes both military and commercial for oil overtempt, and hydraulic fluid temperature sensing where designers wanted a reliable, long lasting, standalone thermal sensor in places not so easy to service.  These kinds of applications are really made for the CPI M-series Plugstat switches.

Also available in hermetically glass sealed version.

Contact CPI Thermal engineers today to discuss your application or visit https://cpi-nj.com