Advantages of Reed Switch | disadvantages of Reed Switch

This page covers advantages and disadvantages of Reed Switch. It mentions Reed Switch advantages or benefits and Reed Switch disadvantages or drawbacks.

What is Reed Switch?

• It is magnetically activated mechanical switch.
• It consists of two metallic contacts enclosed in a small enclosure usually glass capsule.
• The contacts are magnetic and move in response to a magnetic field. Permanent magnet is needed to activate the switch.
• There are two types of reed switches viz. SPST and SPDT. Most common one is SPST which is either normally open or normally closed type.

Reed Switch construction and symbol

• Most common everyday application of reed switch is alarm system. In this product reed switch and magnet are mounted very close to each other on door/window. Normally switch is closed. When door/window opens, switch opens and as a result circuit is broken and consecutively alarm is triggered.
• The figure depicts construction of the reed switch and its symbol.
• Physical size of the reed switch depends on current switching capability.

Benefits or advantages of Reed Switch

Following are the benefits or advantages of Reed Switch:
➨Additional components are not needed except a magnet for its operation.
➨It can switch both AC as well as DC.
➨It can switch voltages up to 200 V in certain cases.Some variants are capable of switching 500 mA.
➨It can be used by magnet in open or closed state indefinitely without any power consumption.
➨It's performance is not affected due to dust or dirt unlike optical switch.
➨It can be activated through nonmagnetic materials such as plastic or paper.

Drawbacks or disadvantages of Reed Switch

Following are the drawbacks or disadvantages of Reed Switch:
➨It requires separate magnet for its operation. Moreover it does not work satisfactorily when magnet is more than few millimeters away from the switch part.
➨Reed switch can not be miniaturized similar to any other surface mount chips.
➨Glass envelope can easily be damaged.
➨Arcing may occur between contacts.
➨Only ferrous object can be used for sensing an object which comes between switch and magnet.
➨It can be activated accidently by other magnetic fields.
➨It must be denounced when connected with controller/logic chip.

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