Table of Contents
What is leakage current in the biomedical measurement?
A medical leakage current is an electric current in an unwanted conductive path of an electrical medical device that is operating in a normal, faultless state, known as Normal Condition (NC).
What is Type B BF and CF?
Applied parts fall into three classifications: B (body), BF (body floating), and CF (cardiac floating) are used according to the nature of the medical device and the type of contact. Each classification must have a different protection level against electrical shock.
What is leakage circuit?
An Earth-leakage circuit breaker (ELCB) is a safety device used in electrical installations with high earth impedance to prevent shock. It detects small stray voltages on the metal enclosures of electrical equipment and interrupts the circuit if the voltage level exceeds danger threshold.
What are the types of leakage current?
There are two types of leakage current: ac leakage and dc leakage.
What are different types of leakage current?
Leakage Current Classifications
- Earth Leakage Current.
- Enclosure Leakage Current.
- A. Patient Leakage Current path from equipment.
- B. Patient leakage current path to equipment.
- Patient auxiliary current.
What is DC leakage current?
The DC leakage current refers to this small current that flows through a capacitor when voltage is applied. The value of this current mainly depends on applied voltage, capacitor temperature, and charging period.
What is type CF?
Type CF (cardiac floating) is the most stringent classification, and is used for applied parts that may come into direct contact with the heart, such as dialysis machines.
What causes leakage current in a circuit?
The leakage current in equipment flows when an unintentional electrical connection occurs between the ground and an energized part or conductor. The ground may be the reference point of zero voltage or the earth ground.
What is the most common cause for leakage current?
Ac leakage current is caused by a parallel combination of capacitance and dc resistance between a voltage source (ac line) and the grounded conductive parts of the equipment. The leakage caused by the dc resistance usually is insignificant compared to the ac impedance of various parallel capacitances.
What are the hazards in leakage current?
On circuits protected by GFCIs (Ground Fault Current Interrupters), leakage current can cause unnecessary and intermittent tripping. In extreme cases, it can cause a rise in voltage on accessible conductive parts. Insulation has both electrical resistance and capacitance—and it conducts current through both paths.
What is leakage current in electrical medical products?
Leakage current is one of the most stringent, yet telling, parameters of possible danger to patients or caregivers. The potential risk is why measurement of leakage current in electrical medical products is so critical. Leakage current is one of the most stringent, yet telling, parameters of possible danger to patients or caregivers.
What is the maximum leakage current allowed in a circuit?
Typical leakage current limits by an application are: The permissible leakage current under normal conditions is 0.5mA and 1mA under a single fault condition. The leakage current is very dangerous if it exceeds the permissible safe limit. It is even worse in medical applications due to both the risk it poses to both patients and caregivers.
How much leakage current is harmful to a patient?
A patient can be injured by a leakage current of as little as 10 to 180 μA. Ventricular fibrillation can also occur from exposure to this leakage current.
Are leakage currents fault currents?
Leakage currents are involuntary currents which flow when a resource or electrical medical device is operating in normal, faultless state. Therefore, leakage currents are not fault currents. Fault currents only occur in the event of a fault (e.g., defective insulation).