EXPERIMENT -05 :- FUSES AND SWITCHES

 

1. Aim of the Experiment

• To visually identify and classify various AC/DC fuses used in electronic equipment, IT power supplies (SMPS), and electrical distribution panels.
• To read, interpret, and record ratings (Current, Voltage, Interrupting Capacity) and specifications of different fuses.
• To identify mechanical and electronic switches based on contact configurations (SPST, SPDT, DPST, DPDT, Rotary, Toggle, Push Button, DIP).
• To test fuse continuity and switch switching actions using a Digital Multimeter (DMM).

2. Tools & Components Required

S.No.	Item / Tool	Specification / Application
1	Fuse Sample Tray	Glass Cartridge, Ceramic Tube, HRC (High Rupturing Capacity), Automotive Blade, Rewireable Kit-Kat, Resettable PTC.
2	Switch Sample Tray	SPST Toggle, SPDT Slide, DPST Rocker, DPDT Push-Button, Tactile Push-Button, Rotary Switch, DIP Switch, Microswitch.
3	Digital Multimeter (DMM)	With continuity buzzer test mode & resistance measurement range.
4	Magnifying Glass	For reading tiny laser-etched voltage and current body specifications.

3. Technical Background & Diagrams

A. Structural Types of Fuses

Figure 1: Internal and External Construction of Common Fuses

B. Switch Contact Configurations

Figure 2: Electrical Schematic Contact Symbols for Switches

4. Practical Observation Tables

Table 5.1: Specification & DMM Testing Data for Fuses

S.No.	Fuse Type	Current Rating	Voltage Rating	Body Material	DMM Continuity
1	Glass Tube Fuse	2 A (Fast-Blow)	250 V AC	Transparent Glass	Pass (0.1 Ω)
2	Ceramic Tube Fuse	10 A (Slow-Blow)	250 V AC	Ceramic with Sand	Pass (0.05 Ω)
3	Blade Fuse (ATC)	15 A (Blue)	32 V DC	Plastic Housing	Pass (0.02 Ω)
4	HRC Cartridge Fuse	63 A	415 V AC	Porcelain Shell	Pass (0.01 Ω)
5	Rewireable (Kit-Kat)	16 A	240 V AC	Porcelain Base	Pass (0.1 Ω)

Table 5.2: Specification & Switching Action Data for Switches

S.No.	Switch Type	Configuration	Contact Rating	Terminals Count	Action Check
1	Toggle Switch	SPST	6 A / 125 V AC	2 Pins	OK (ON/OFF)
2	Rocker Switch	DPST	16 A / 250 V AC	4 Pins	OK (Dual Disconnect)
3	Push-Button (Tactile)	SPST (Momentary)	50 mA / 12 V DC	4 Pins (Paired)	OK (Pulse Output)
4	Slide Switch	SPDT	0.3 A / 50 V DC	3 Pins (COM/NO/NC)	OK (Two-Way Route)
5	DIP Switch Module	4-Position SPST	100 mA / 24 V DC	8 Pins (DIP)	OK (Individual Ch.)

SAFETY PRECAUTIONS:

NEVER REPLACE A BLOWN FUSE WITH A HIGHER CURRENT RATED FUSE OR COPPER WIRE JUMPER! Doing so bypasses overcurrent protection and presents a critical risk of electrical fire or total hardware failure. Always isolate electrical circuits before testing switches or replacing protective devices.

Instructor Feedback & Result

The physical identification, technical specification decoding, and Digital Multimeter testing for various fuse types and switch configurations were performed successfully.