Electrical Protection Systems: Components and Functions

Electrical Fundamentals

Tension: Voltage or potential difference exists between two points when there is an imbalance between loads. It is measured using a voltmeter.

Intensity: The movement of electric charges through a material. It is measured using an ammeter.

Clamp Meter: A highly useful tool that allows you to take current readings of an AC circuit without interrupting the flow. Simply clamp the device around the conductor you wish to measure.

Common Electrical Faults

• Overcurrent: Occurs when a circuit demands more power than it is designed to handle.
• Short Circuit: An accidental connection between two conductors of different phases, or between a conductor and the neutral/ground.
• Insulation Defects: Proper insulation between conductors and ground masses ensures no unwanted contacts occur. If insulation is inadequate, it results in short circuits or leakage currents.
• Surges: Occurs when voltage exceeds the rated network voltage. There are two types:
  • Transient Surges: High-value surges occurring over a very short period.
  • Temporary Overvoltages: Also called permanent, these have a lower surge value (10% above nominal) but last for a longer duration.

Protection Devices

Fuses

Operation: Fuses are protective elements connected in series with the circuit. They are designed to melt before any other element in the installation when excessive intensity is detected.

Features:

• Rated Current: The current flowing through the installation under normal conditions.
• Voltage: The rated operating voltage.
• Switching Capacity: The maximum intensity the fuse can support.
• Hammer Element: An indicator showing that the fuse has blown.
• Fuse Type: Refers to the specific design application.

Types of Construction:

• Cylindrical Fuses: Traditional blade-style fuses.
• NH Fuses: Low-voltage, high-breaking-capacity fuses with a parallel wire element.
• Diazed Fuses: Also known as bottle fuses.

Magnetothermic Switch (Circuit Breaker)

Operation: A protective device against overloads and short circuits. It features two opening methods: a magnetic trigger for fast short-circuit protection and a thermal trigger for slow overload protection.

Features: Number of poles, rated current, breaking capacity, and curve type (which determines trigger time based on intensity).

GFCI (Ground Fault Circuit Interrupter)

Operation: A device that protects against insulation defects and guards people against indirect contact.

Features:

• Rated Intensity: The current capacity of the facility.
• Rated Voltage: The operating voltage.
• Sensitivity: The minimum fault current value that triggers the switch.
• Number of Poles: Available in bipolar and tetrapolar configurations.