BEX100 – Basic Electricity

Relays

(Magnetic Switches)

Objectives

Know the definition of a relay

Understand relay operating principles

Properly test relay operation

Relay Principles

A relay may also be called an “electromagnetic switch”

Relays use a “low amperage circuit” to control a “high amperage circuit”

The low amperage circuit controls an electromagnetic device

The electromagnetic device “closes/opens” the high amperage circuit

Relay Operation

Typical 4 Pin Relay“ISO RELAY”

Typical 5 Pin Relay“ISO RELAY”

Typical 5 Pin RelayPin Identification

HALF ISO

Relay Applications

Relay Applications

Relay Applications

Relay Applications

Testing Relay OperationRelays can be tested using:

A test light

A continuity light

A DVOM

A jumper wire

Testing Procedures

Testing Procedures

RELAY DIAGNOSIS

SHOULD HAVE POWER ON TWO CONNECTIONS IN KEY ON; DEVICE OFF POSITION (ISO TERMINALS 30 AND 85 OR 86)

RELAYS ARE MOST ALWAYS ACTIVATED WITH GROUND

LISTEN FOR CLICK WHEN ACTIVATED= BETTER YET CHECK OUTPUT VOLTAGE ( ISO PIN 87)

WHEN ALL ELSE FAILS...

EXCHANGE SUSPECT RELAY WITH ANOTHER RELAY OF THE SAME NUMBER IN THE RELAY CENTER

LET’S REVIEW...

WHY ARE RELAYS CALLED MAGNETIC SWITCHES?

HOW MUCH CURRENT DOES THE CONTROL CIRCUIT USE?

HOW MUCH CURRENT DOES THE LOAD CIRCUIT USE?

NAME SOME ADVANTAGES OF USING RELAYS?

LET’S REVIEW…..

WHAT IS AN “ISO” RELAY?

WHAT IS A HALF “ISO” RELAY?

HOW CAN RELAYS BE TESTED?

WHAT RESISTANCE SHOULD THE RELAY COIL READ?

WHAT SHOULD THE “NC” CONTACTS OF A RELAY READ?

WHAT SHOULD THE “NO” CONTACTS OF A RELAY READ?

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Elizabethtown Technical CollegeBEX100 – Basic Electricity