The Definition of Leakage Current
Leakage current, also known as earth leakage current or residual current, refers to the flow of electric current from a conductive part of an electrical appliance or equipment to the earth or ground. It is an essential consideration in electrical safety standards, such as IEC 60335, which sets limits on the acceptable level of leakage current.
Types of Leakage Currents
There are two main types of leakage currents: touch currents and transfer currents.
Touch current occurs when a person comes into contact with a conductive part that has been subjected to leakage current. This type of current can be dangerous, especially if it exceeds the safe limit. Transfer current, on the other hand, refers to the current that flows through a person or an object unintentionally acting as a conductor between two conductive parts of an electrical device.
Causes of Leakage Current
Leakage current can be caused by various factors, including insulation breakdown, moisture or humidity, dirt accumulation, improper grounding, and faulty components. Insulation breakdown occurs when the dielectric material separating the conductive parts within an electrical device fails, allowing current to flow where it shouldn't. Moisture or humidity can also decrease the insulating properties and increase the likelihood of leakage current.
Implications and Measurements
Excessive leakage current can pose serious risks to both humans and equipment. It can result in electric shock, fire hazards, equipment damage, and even fatalities. Electrical safety standards, such as IEC 60335, set specific limits on the acceptable leakage current levels to ensure proper protection. Leakage current is measured by using specialized devices called leakage current testers or earth bond testers, which measure the amount of current flowing to the earth or ground.
In conclusion, leakage current is an important aspect of electrical safety and is regulated by standards such as IEC 60335. Understanding the types, causes, and implications of leakage current can help ensure the proper design, installation, and use of electrical appliances and equipment, ultimately enhancing safety for both individuals and property.