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Difficulty: MediumSwitches and Relays

Match each specialized switching or relay device to its corresponding operational characteristic and actuation method.

  • Reed switchContains ferromagnetic flexible metal reeds sealed in glass that close in the presence of an external magnetic field
  • Rotary switchUses a rotating shaft and wiper contact to select between three or more discrete circuit positions
  • ContactorHeavy-duty electromechanical switching device designed to switch high-current power loads directly using an electromagnetic coil
  • Thermal overload relayMonitors sustained motor overcurrent using a bimetallic strip that bends when heated to open auxiliary control contacts

Answer

Reed switch matches ferromagnetic flexible metal reeds sealed in glass; Rotary switch matches rotating shaft and wiper contact selecting between three or more positions; Contactor matches heavy-duty electromechanical device for high-current power loads; Thermal overload relay matches monitoring sustained overcurrent using a bimetallic strip.
Each switching component is matched according to its fundamental physics of operation: the reed switch relies on magnetic field induction on ferrous contacts; the rotary switch provides multi-position manual circuit routing; the contactor uses an electromagnetic solenoid for high-amperage switching; and the thermal overload relay uses thermal deflection of a bimetallic strip for motor overload protection.

Step-by-Step Solution

1
Identify the actuation mechanism of a reed switch.
Recognize that reed switches operate magnetically via enclosed flexible ferrous blades.
Reed switches rely on external magnetic flux rather than manual toggling or internal thermal deflection.
2
Analyze the mechanical multi-position selection function of a rotary switch.
Associate the rotary switch with angular shaft rotation routing a signal to multiple switch poles/throws.
Rotary switches provide multi-throw circuit selection through rotational movement.
3
Distinguish between standard low-power control relays and contactors.
Connect contactors to high-current power switching controlled via electromagnetic coils.
Contactors feature heavy-duty contacts built specifically to handle high current without contact welding.
4
Determine the protective operation of a thermal overload relay.
Pair the thermal overload relay with bimetallic thermal expansion sensing excessive motor current.
Thermal overload relays protect motor windings by converting persistent current into heat that mechanically triggers auxiliary contacts.

Key Concept

Specialized switch and relay actuation mechanisms and circuit roles
Estimated Time:1m 0s
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Topics

Switches and Relays

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