Electrical Enclosures, Motors, and Protection: Key Components

Posted on Jan 23, 2025 in Electronics

Electrical Enclosures and Components

Enclosure Classification:

  • Construction Materials: Metallic or insulating (fiberglass).
  • Functional Assembly: Monomodular, Multimodular, plug boxes.
  • Applications: Distribution boards, terminal covers, cabinets, machine or automation control panels (housing protection and control elements).

Terminals: Buttonhole, fork, pin sharp, laminate, and splice sleeves.

Busbar Types: Vertical side, bottom vertical, horizontal and vertical, horizontal.

IP Rating: Protection against solid objects and liquids.

IK Rating: Protection against mechanical impacts.

File Types: Flat, half-round, triangle, square, round.

Moderation: Parallelogram for intensity and series voltages.

Circuit Protection

Fuses: Monopolar, bipolar, tripolar, tripolar isolator, cylindrical, knife, diazo.

Curves: The curve type determines the operation of magnetothermal switches, tripping time, and how the trigger acts based on intensity values.

Curve Types:

  • Curve B: Protection for conductors with low short-circuit intensities, such as resistive circuits for heating and lighting.
  • Curve C: Protection for general-use installations, with the possibility of connecting small motors.
  • Curve D: Used in installations with equipment that has high pulse currents, such as large motors and capacitive loads.
  • ICP: Used as a power control switch.

Electric Motors

Internal Parts of an Electric Motor:

  • Rotor: Rotating part of the machine.
  • Stator: Fixed part of the machine.

External Parts of an Electric Motor:

  • Terminal Box: Allows connections to the power supply system.
  • Nameplate: Displays significant motor data.
  • Shaft: Transmits the motor’s rotational movement.
  • Housing: Covers the entire motor.
  • Fan Cover: Covers the motor’s ventilation system.
  • Fixing Base: Part of the housing that allows the motor to be fixed to its mounting surface.

Three-Phase Motor Types:

Two types based on the strain: Squirrel cage and wound rotor.

Squirrel Cage Motor:

  • Modern: U1 V1 W1
  • Old: UVW
  • W2 U2 V2 X Y Z

Motor Connections:

  • Delta Connection: Connects the top terminals to the bottom terminals in a line.
  • Star Connection: Connects the bottom terminals together, and the top terminals to the line.

Reversing Rotation: Achieved by inverting two phases.

Phase Loss: If one of the three phases is lost, it can cause overcurrent and damage to the internal windings.

Torque: The force a motor exerts at each turn.

Motor Starting

When an induction motor starts, the current initially spikes before settling. To mitigate this, a star-delta starter is used. This method starts the motor in two stages. First, the motor is connected in a star configuration, consuming approximately 1/3 of the nominal current. Then, it switches to a delta configuration for normal operation.