Electronics and Electrical Engineering interview Question and Answers for fresh engineers (Part 9)

Electronics and Electrical Engineering interview Question and Answers for fresh engineers (Part 9)

In this topic we will know about motor protection

In the nameplate of the motor we see IP XY . i.e. IP 55
Example: With the IP rating IP 23, 

• 2 describes the level of protection from solid objects and 
• 3 describes the level of protection from liquids.

IP stands for 

Ingress Protection Ratings

 IP rating normally has two (or three) numbers:

1. Protection from solid objects or materials
2. Protection from liquids (water)
3. Protection against mechanical impact 

specifying the environmental protection the enclosure provides.

Ingress Protection (IP) ratings are Introduced by the European Committee for Electro Technical Standardization .

 NEMA IEC 60529 Degrees of Protection Provided by Enclosures - IP Code,

IP First number - Indicates the Protection against solid objects. Which we indicates as X in the example

0	No special protection
1	Protected against solid objects over 50 mm, e.g. accidental touch by persons hands.
2	Protected against solid objects over 12 mm, e.g. persons fingers.
3	Protected against solid objects over 2.5 mm (tools and wires).
4	Protected against solid objects over 1 mm (tools, wires, and small wires).
5	Protected against dust limited ingress (no harmful deposit).
6	Totally protected against dust.

IP Second number -Indicates the Protection against liquids.Which we indicates as Y in the example 

0	No protection.
1	Protection against vertically falling drops of water e.g. condensation.
2	Protection against direct sprays of water up to 15o from the vertical.
3	Protected against direct sprays of water up to 60o from the vertical.
4	Protection against water sprayed from all directions - limited ingress permitted.
5	Protected against low pressure jets of water from all directions - limited ingress.
6	Protected against temporary flooding of water, e.g. for use on ship decks - limited ingress permitted.
7	Protected against the effect of immersion between 15 cm and 1 m.
8	Protects against long periods of immersion under pressure.

Example - IP 35

An electrical socket rated IP22 is protected against

• Protected against solid objects over 2.5 mm (tools and wires).
• Protected against low pressure jets of water from all directions - limited ingress.

IP stands for 

Ingress Protection Ratings

IP Third number - Indicates the Protection against mechanical impacts .

Its not used in normal cases. 

the third number is not available in IEC 60529

0	No protection.
1	Protects against impact of 0.225 joule (e.g. 150 g weight falling from 15 cm height).
2	Protected against impact of 0.375 joule (e.g. 250 g weight falling from 15 cm height).
3	Protected against impact of 0.5 joule (e.g. 250 g weight falling from 20 cm height).
4	Protected against impact of 2.0 joule (e.g. 500 g weight falling from 40 cm height).
5	Protected against impact of 6.0 joule (e.g. 1.5 kg weight falling from 40 cm height).
6	Protected against impact of 20.0 joule (e.g. 5 kg weight falling from 40 cm height).

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