Types of Motor Enclosures and Their Applications

The part of an electric motor that protects the motor from the contaminants in the environment in which it is operating and persons being from touch is called the motor enclosure.

The motor enclosures are necessary for the following reasons −

  • It protects the motor against foreign body and severe conditions.

  • It protects the inner parts of the motor.

  • It protects the operating personal from live parts of the motor such as winding terminals, slip rings, brushes, etc.

Types of Motor Enclosures

Indian Standards (IS) 4691 have described codes for different types of enclosures. The most common types of electric motor enclosures are given as follows −

  • Open Protected Type − This enclosure provides free access to air and sufficient mechanical protection to the motor.

  • Scree Protected Type − This type of enclosure provides addition protection to the motor. It has metal grids or perforated covers.

  • Drip Proof Type − This type of enclosure has openings for ventilation which are so provided that it prevents vertically falling water or dirt from entering inside the motor.

  • Splash Proof Type − With this type of enclosure, liquid or solid particles falling on the motor at any angle between the vertically downward direction and 100° from that direction cannot enter the motor.

  • Totally Enclosed Type − In this type of enclosure, there will be no free circulation of air between the inside and outside of the motor.

  • Pipe Ventilated Type − In this type of motor enclosure, pipes or ducts are provided for the continuous supply of fresh ventilating air.

  • Explosion Proof Type − These enclosures are manufactured in such a way to withstand an internal explosion and the motor frame will not rupture or burst.

  • Weather Proof Type − In these enclosures, additional screens are installed to prevent entrance of large particles of debris and rain into the motor.

Applications of Various Types of Motor Enclosures

The following table shows the details about the enclosures used for motors −

Industrial LocationType of ContaminationType of Motor Enclosure Recommended
General industrial installations (non-explosive atmosphere)
  • No contamination

  • Clean & dry air

  • High humidity

  • Water jets splashing

  • Conducting or oily textile dust

  • Open protected type

  • Screen protected type

  • Drip proof type

  • Splash proof type

  • Totally enclosed type

  • Pipe ventilated type

Outdoor installation
  • Rain

  • Snow

  • Dusty storms

  • Nearly clean

  • Weather proof type

  • Totally enclosed

  • Open drip proof type

Metal working machinery (non-explosive atmosphere)
  • Oily metallic dust

Totally enclosed type
Chemical plant (Non-explosive atmosphere)
  • Dust

  • Corrosive acid vapors & gases, etc.

Totally enclosed type
Mines and other hazardous locations
  • Explosive gases or vapors

  • Dust

Explosive proof type

Updated on: 28-Apr-2022

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