Study of Electrical Accessories & Their Functions and Refrigerator Cabinet Volume Calculation

In the Refrigeration and Air Conditioning (RAC) trade, electrical accessories play a vital role in the efficient and safe operation of refrigerators. The book “Frost Free Refrigerator” explains the working and functions of important electrical components such as timer, heater, bimetal, relay, overload protector (OLP), and thermostat. It also covers the method of calculating refrigerator cabinet volume, which is essential for design and performance evaluation.

Introduction to Electrical Accessories

Electrical accessories are components that control, protect, and regulate the operation of refrigeration systems. These accessories ensure proper functioning, energy efficiency, and safety of the refrigerator.

Defrost Timer

The defrost timer is used in frost free refrigerators to control the defrost cycle.

Function

• Switches between cooling and defrost modes
• Activates defrost heater periodically

It ensures automatic removal of frost from the evaporator.

Defrost Heater

The defrost heater is used to melt ice formed on the evaporator coil.

Function

• Heats evaporator during defrost cycle
• Prevents frost accumulation

It improves cooling efficiency and prevents blockage of airflow.

Bimetal (Defrost Thermostat)

The bimetal is a temperature-sensitive device used to control the defrost process.

Function

• Switches OFF heater after frost is removed
• Protects system from overheating

It ensures safe operation of the defrost system.

Starting Relay

The relay is used to start the compressor motor.

Function

• Supplies current to starting winding
• Disconnects after motor starts

It helps in smooth starting of the compressor.

Overload Protector (OLP)

The overload protector protects the compressor from overheating and excessive current.

Function

• Cuts off power during overload
• Prevents damage to compressor

It ensures safety of the system.

Thermostat

The thermostat controls the temperature inside the refrigerator.

Function

• Switches compressor ON and OFF
• Maintains desired temperature

It improves energy efficiency and performance.

Working of Electrical Accessories

When the refrigerator is switched ON, the thermostat allows current to flow to the compressor. The relay and capacitor help in starting the compressor motor. During operation, the defrost timer periodically activates the defrost heater, and the bimetal ensures safe temperature control.

The overload protector protects the compressor from damage during abnormal conditions.

Importance of Electrical Accessories

• Ensure proper system control
• Improve efficiency
• Provide safety
• Prevent damage to components

These accessories are essential for reliable operation of refrigerators.

Refrigerator Cabinet Volume Calculation

The cabinet volume of a refrigerator is the total internal space available for storage. It is usually measured in liters.

Formula

Volume = Length × Width × Height

The dimensions are measured in meters or centimeters and converted into liters.

Example

If the internal dimensions are:

• Length = 1 m
• Width = 0.5 m
• Height = 0.5 m

Volume = 1 × 0.5 × 0.5 = 0.25 cubic meters

1 cubic meter = 1000 liters So, volume = 250 liters

Importance

• Helps in selecting refrigerator capacity
• Determines storage space
• Used in system design

Applications

Electrical accessories and volume calculations are used in:

• Domestic refrigerators
• Commercial refrigeration
• Cold storage systems

These concepts are essential for practical work.

Maintenance Tips

• Check electrical components regularly
• Replace faulty parts
• Ensure proper wiring

Regular maintenance ensures efficient operation.

Safety Precautions

Safety must be followed while working with electrical components:

• Disconnect power before repair
• Use insulated tools
• Avoid contact with live parts

These precautions help prevent electrical hazards.

Conclusion

Electrical accessories such as timer, heater, bimetal, relay, OLP, and thermostat are essential for controlling and protecting refrigeration systems. Understanding their functions helps in maintenance and troubleshooting.

Cabinet volume calculation is important for determining storage capacity. The book “Frost Free Refrigerator” provides detailed knowledge of these topics, helping students develop practical skills and build a successful career in refrigeration and air conditioning.