Machine Design

ISO relays

Many of the electromechanical relays used in automotive applications are termed ISO relays.

Examples of ISO-style relays in small packages include the G8HE 40-A (foreground) and G8V-RH 35-A (background) micro 280 relays.

Edited by Leland Teschler

Many of the electromechanical relays used in automotive applications are termed . An ISO relay is one which adheres to a standard pattern for its electrical terminals that has been spelled out by the International Standards Organization. Generally speaking, types of ISO relay terminal patterns include Super ISO, ISO 280, Mini 280 ISO and Micro 280 ISO. They are widely used in both Europe and the U.S.

Devices in the Super ISO format generally handle about 70-A loads. Those with the 280 ISO footprint have generalpurpose applications within automotive power control. Typical specs for such relays include ratings of between 35 and 40 A at 125°, SPST or SPDT contact forms, coil voltages of 6, 12, or 24 Vdc (though most in vehicular use are spec'ed at 12 V), and options in packaging that include flux-tight or sealed covers. ISO-style relays also generally plug into their end application via sockets. Users can also get these relays with coil bypass resistors or diodes to eliminate inductive surges.

Most new developments in relate to fielding smaller devices able to fit into more compact spaces. An example of this trend are micro .

These are about half the size and weight of traditional 280 ISO devices but provide roughly equivalent performance. These 40-A relays are typically used in switching applications such as motors, lamps, resistive loads, engine cooling fans, HVAC, and window defrost systems.

Omron Automotive Electronics ( provided information for this article.

TAGS: Technologies
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