ISO 7588-3:1998

Overview

ISO 7588-3:1998 is an international standard published by the International Organization for Standardization (ISO) that specifically addresses microrelays used in road vehicles. This standard is part 3 of the broader ISO 7588 series on electrical and electronic switching devices applied in automotive settings. It focuses on defining the dimensional characteristics and functional allocation of terminals for microrelays, which are critical components in vehicle electrical systems interacting with sensors, control units, and various actuators.

By standardizing microrelay dimensions and terminal functions, ISO 7588-3 ensures interchangeability, safety, and reliable performance of microrelays in automotive electrical/electronic systems. This consistency supports manufacturers and suppliers in harmonizing designs and connectors, reducing compatibility issues in road vehicle assemblies.

Key Topics

• Dimensional Characteristics
  ISO 7588-3 specifies detailed sizes for microrelay bodies and terminal tabs. The dimensions ensure correct fit within sockets and consistent positioning to avoid installation errors. Key dimensions include tab sizes of 6.3 x 0.8 mm and 4.8 x 0.8 mm without shoulders, with allowed variations defined for socket aperture acceptance.

• Terminal Functional Allocation
  The standard assigns specific functions to relay terminals, facilitating uniform wiring and integration. Typical terminal designations include coil plus and minus, switching contact inputs, and outputs for break, make, or changeover contacts. These assignments support both normal and specialized microrelay configurations.

• Socket Aperture Dimensions
  Annex A of the standard provides recommended dimensions for socket apertures that accommodate microrelay tabs safely and without excessive withdrawal force. These apertures ensure secure electrical connections while allowing ease of maintenance.

• Compliance References
  ISO 7588-3 references related standards like ISO 8092-1 and ISO 8092-2, which cover electrical connector dimensions and testing methods for on-board wiring. This cross-standard alignment supports holistic vehicle electrical system design.

Applications

ISO 7588-3 microrelays are extensively used in road vehicle electrical/electronic control units where miniature switching devices are needed. Practical applications include:

• Engine management systems
  Controlling ignition, fuel injection, and emissions-related actuators.

• Lighting and signaling circuits
  Managing headlights, brake lights, turn indicators with precise switching.

• Safety and convenience features
  Operating door lock actuators, power window controls, and alarm systems.

• Electrical protection and load switching
  Isolating circuits and managing battery loads with minimal space requirements.

Standardization of microrelay dimensions and terminal functions helps automotive manufacturers, relay suppliers, and vehicle service providers guarantee component compatibility and simplify vehicle wiring harness design.

Related Standards

• ISO 7588-1: Relays and flashers for road vehicles
• ISO 7588-2: Electronic switching devices for automotive use
• ISO 8092-1: Tabs for single-pole connections in on-board wiring harnesses
• ISO 8092-2: Definitions, test methods, and performance requirements for wiring connections

These related ISO standards complement ISO 7588-3 by covering broader aspects of electrical-electronic switching devices, connections, and performance testing within road vehicle applications.

Keywords: ISO 7588-3, microrelays, road vehicles, automotive electrical standards, relay terminal allocation, electrical switching devices, automotive microrelays dimensions, relay socket aperture, vehicle electrical connectors, ISO automotive standards