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Question

Which component in a wiring diagram is specifically used to protect against overcurrent?

This question was previously asked in
RRB NTPC 2025 Graduate Level CBT 1 Question Paper (25-Mar-2026) (Shift 3)
The correct answer is

Fuse symbol

To answer the question about which component in a wiring diagram is specifically used to protect against overcurrent, let's break down and understand the options provided:

  1. Pushbutton symbol: This component is primarily used to activate or deactivate a circuit manually. It is not designed to protect against overcurrent.
  2. Lamp symbol: A lamp symbol is used to represent light sources in a circuit. Lamps illuminate when a current passes through but do not offer any protective function regarding overcurrent.
  3. Relay symbol: A relay is an electrically operated switch used in control applications. It does not inherently provide overcurrent protection in a circuit.
  4. Fuse symbol: A fuse is a safety device that interrupts the flow of electrical current when the current exceeds a certain level. This effectively protects against overcurrent and short circuits.

Given these explanations, the correct answer is the 'Fuse symbol' because it is specifically designed to protect circuits from overcurrent by breaking the circuit if the current exceeds a safe level.

Let's dissect the functionality of a fuse:

  • A fuse consists of a metal wire or strip that melts or vaporizes when too much current flows through it, thereby breaking the circuit.
  • It acts as a protective device, ensuring the electrical system or devices remain safe from potential damage due to the excessive current.

Fuses come in various types (e.g., cartridge, glass tube, blade type) and can be selected based on the requirements of the specific application.

The choice of fuses over other protection devices in some cases is because of their simplicity, reliability, and cost-effectiveness for overcurrent protection.

ComponentFunction
PushbuttonManual circuit activation/deactivation
LampProvides illumination
RelaySwitches connected circuits electrically
FuseProtects circuit from overcurrent

In conclusion, the component that is specifically used to protect against overcurrent in a wiring diagram is the fuse symbol.

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