Power Distribution Relay: Description and Operation
ISO RELAYFig.8 ISO Relay:
A relay (Fig. 8) is an electromechanical device that switches fused battery current to a electrical component when the ignition switch is turned to the Accessory or Run positions, or when controlled by a electronic module. The relays are located in the integrated power module.
The relay is a International Standards Organization (ISO) relay Relays conforming to the ISO specifications have common physical dimensions, current capacities, terminal patterns, and terminal functions.
A relay cannot be repaired or adjusted and, if faulty or damaged, it must be replaced.
The ISO relay consists of an electromagnetic coil, a resistor and three (two fixed and one movable) electrical contacts. The movable (common feed) relay contact is held against one of the fixed contacts (normally closed) by spring pressure. When the electromagnetic coil is energized, it draws the movable contact away from the normally closed fixed contact, and holds it against the other (normally open) fixed contact.
When the electromagnetic coil is de-energized, spring pressure returns the movable contact to the normally closed position. The resistor is connected in parallel with the electromagnetic coil in the relay and helps to dissipate voltage spikes that are produced when the coil is de-energized.
MICRO ISO RELAY
Fig.9 DR ISO Micro Relay:
A micro-relay is a conventional International Standards Organization (ISO) micro relay (Fig. 9). Relays conforming to the ISO specifications have common physical dimensions, current capacities, terminal patterns, and terminal functions. The relay is contained within a small, rectangular, molded plastic housing and is connected to all of the required inputs and outputs by five integral male spade-type terminals that extend from the bottom of the relay base.
Relays cannot be adjusted or repaired and, if faulty or damaged, the unit must be replaced.
A micro-relay is an electromechanical switch that uses a low current input from one source to control a high current output to another device. The movable common feed contact point is held against the fixed normally closed contact point by spring pressure. When the relay coil is energized, an electromagnetic field is produced by the coil windings. This electromagnetic field draws the movable relay contact point away from the fixed normally closed contact point, and holds it against the fixed normally open contact point. When the relay coil is de-energized, spring pressure returns the movable contact point back against the fixed normally closed contact point. A resistor is connected in parallel with the relay coil in the relay, and helps to dissipate voltage spikes and electromagnetic interference that can be generated as the electromagnetic field of the relay coil collapses.