Flashcards
Topic 6 Output Devices
Cards in this deck (7)
- 1RelayA relay is an electrical switch that opens and closes under the
control of another electrical circuit - 2Circuit Symbol of a Relay - COM = Common, it is the moving part of the switch. - NC = Normally Closed. - NO = Normally Open.Points to take note
- Connect to COM and NO and the circuit will switch on only when the
relay coil is on.
- Connect to COM and NC and the circuit is switch on when the relay
coil is off. - 3Advantages of relaysRelays can switch AC and DC, transistors can only switch DC.
- Relays can switch high voltages, transistors cannot.
- Relays are a better choice for switching large currents (> 5A).
- Relays can switch many contacts at once. - 4Disadvantages of relays- Relays are bulkier than transistors for switching small currents.
- Relays cannot switch rapidly (except reed relays), transistors can
switch many times per second.
- Relays use more power due to the current flowing through their coil.
- Relays require more current than many chips can provide, so a low
power transistor may be needed to switch the current for the relay's
coil - 5Application of relaysA relay is capable of switching on higher power devices or
circuits using a much lower power circuits.. - 6The Right-Handed RuleThumb points in direction of
convectional current flow.
Finger points in direction of
magnetic field generated. - 7Fleming's left hand rule (for electric motors)• The Thumb represents the direction of the Thrust or resultant Motion.
• The First finger represents the
direction of the Field
• The Second finger represents the
direction of the Current (in the
classical direction, from positive to
negative )
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- marine electronics Flashcards on Topic 6 Output Devices, created by izz azman on 25/08/2020.
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- izz azman
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