Magnetism Auto 2 after series circuits Magnets & Magnetic Fields

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Text of Magnetism Auto 2 after series circuits Magnets & Magnetic Fields

  • MagnetismAuto 2 after series circuits

  • Magnets & Magnetic Fields

  • Magnetic flux linesFlux Always flows from North to South

  • Opposites Attract / Likes repel

  • Arrangement of atoms In metal that has not been magnetized

  • Arrangement of atomsIn metal that has been magnetized

  • PermeabilityAbility of materials to become magnetized

  • ReluctanceResistance to magnetic lines of fluxHigh reluctance = AirLow reluctance = Soft Iron

  • ElectromagnetismAny time current flows thru a conductor,A magnetic field is created around the conductor

  • ElectromagnetsCan increase the strength by;Adding more windingsIncreasing the currentMore voltageless resistanceWrap windings around something with low reluctance

  • Conventional TheoryLeft hand thumb rule applies:With left thumb pointing the way currentFlows, your fingers show you whichWay the magnetic field is built around.Says:Current flowsFrom Positive + to Negative -

  • Electron TheoryRight hand thumb rule applies:With right thumb pointing the way currentFlows, your fingers show you whichWay the magnetic field is built around.Says:Current flowsFrom Negative -To Positive +

  • SaturationIs the point where the magnetic strength eventually levels off

    More windings, the longer it takes but the stronger the field

  • SaturationTurn on pointSaturation pointTurn on pointSaturation pointTwo coil ramps Taken with a Lab Scope and An amp probe.Shorted coilAbout 4.25 mS

  • Electromagnet questions?

  • Relays

  • RelaysUse a small amount of current to control (switch) a large amount of currentControl circuit has a winding to create a magnetic field (#1 & #3)Low amp circuitAlso called the primaryControlled circuit has a switch to control current flow to a higher amp load (#2 & #4)Also called the secondaryHigh amp circuit

  • Relay in operation1 & 3 the control circuit2 & 4 the controlled circuitSend currentThru 1 & 3 toCreate fieldVoltage present at #4Trying to push currentOut #2 to high current loadHigh currentSwitched to Load out #2

  • Normally Open and Normally Closed

  • Normally Open Relay

  • ISO Mini RelayMost manufactures went to this standardTerminals #30 to #87a are NC and terminals #30 to #87 NONCNO

  • ISO Mini RelayTerminal #30 comes from B+Terminal #87 goes to loadTerminal #87a is rarely used (wiper park circuit)Terminals #85 & #86 are the controlCircuit (winding) usually 70 ohms

  • ISO Mini Relay

  • ISO Micro Relay

  • Checking Relays

  • Typical horn circuitIn steering wheel

  • Relay Questions?

  • Parallel circuit review

  • Parallel Circuit RulesMore than one pathHas a splice in the circuitVoltage stays the sameTotal Amperage is divided between the pathsTotal Resistance is always lower that the smallest path or branch

  • OHMS LAW STILL WORKS THE SAMEIf volts and ohmsAre equal, thenOne amp will flow.

  • Parallel circuit questions?Lets apply what weHave learned.

  • Dont panic!Apply what you have learned about relays and parallel circuitsDraw up a typical horn circuitRemember the horn switch is in the steering wheelWe dont want to send the high current through the horn switch, so we will use a relayThe horn is the load that will use high ampsMake sure there is a complete path in the control circuit and the controlled circuit

  • YOU CAN DO IT!Apply what you have learned about relays and parallel circuitsDraw up a typical horn circuitRemember the horn switch is in the steering wheelWe dont want to send the high current through the horn switch, so we will use a relayThe horn is the load that will use high ampsMake sure there is a complete path in the control circuit and the controlled circuit

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