Saturday, July 16, 2022

IEC 60601-1 Leakage Currents and Patient Auxiliary Currents

Hi friends!!!


In our previous blogs, we have discussed about the following topics.


IEC 60601-1 Definitions


IEC 60601-1 Classification of Medical Electrical Equipment


IEC 60601-1 General Requirements for Testing Medical Electrical Equipment


IEC 60601-1 Medical Electrical Systems


IEC 60601-1 Protection against unwanted and excessive radiation hazards


IEC 60601-1 General Requirements


IEC 60601-1 Programmable Electrical Medical Systems 


IEC 60601-1 Hazardous situations and fault condition


IEC 60601-1 Construction of Medical Electrical Equipment


EU MDR Assessment Routes


EU MDR Timeline, Annex, Chapter


EU MDR Post Market Surveillance


EU MDR Clinical Evaluation


EU MDR Technical Documentation - Part 1


EU MDR Technical Documentation - Part 2


EU MDR General Safety and Performance Requirement


EU MDR Information on the Label


EU MDR Post Market Clinical Follow Up


EU MDR Unique Device Identification - Part 1 


EU MDR Unique Device Identification - Part 2


EU MDR Classification Rules


EU MDR EUDAMED


EU MDR Economic Operators


EU MDR Chapter & Articles - Part 1


EU MDR Chapter & Articles - Part 2


In today's blog, we are going to discuss about IEC 60601-1.


IEC 60601-1 states the Basic safety requirements for Medical Electrical Equipment's. Satisfying the requirements of IEC 60601-1 is an important task in order to commercialize the Medical Electrical Equipment's


Therefore, it is important for Medical Device QA/RA Professionals to know in detail about Sub Clause 8.7: Leakage Current and Patient Auxiliary Currents as per IEC 60601-1.


Let's get into the topic.


Sub Clause 8.7: Leakage Currents and Patient


Auxiliary Currents


The Sub Clause 8.7 of IEC 60601-1 states the requirements for Leakage Currents and Patient Auxiliary Current. It is further classified as following.


General Requirements

Single Fault Conditions

Allowable Values

Measurements

 

Let’s discuss in detail about the important requirements of above-mentioned Sub Clause.

IEC 60601-1 Discusses about the following types of Current.

 

Touch Current:

The Touch Current is the amount of current that flows through a person when they touches one or more accessible parts of the Medical Electrical Equipment.


Earth Leakage Current:

The Earth Leakage Current is an electric current that flows into the Protective Earth Conductor through or via the insulation of the Medical Device.


Patient Auxiliary Current:

The Patient Auxiliary Current is an electric current which flows from one part of applied part to another part of applied part through the patient.


Patient Leakage Current:

The Patient Leakage Current is a leakage current which flows through the patient who is connected to a applied part or parts to the earth.


 

Allowable Values

 

The Protection against electric shock shall be provided by Electrical Isolation. The Electrical Isolation shall have a quality such that the current flowing through it shall be limited to the values specified in Clause 8.7.3 Allowable Values of IEC 60601-1.


The Below mentioned Allowable values shall be applicable in Single Fault Conditions mentioned in IEC 60601-1.


For Touch Current, the allowable value under Normal Condition is 100 μA and the allowable value under Single Fault Condition is 500 μA.


For Earth Leakage Current, the allowable value under Normal Condition is 5 mA and the allowable value under Single Fault Condition is 10 mA.

 

The Higher value of Earth Leakage Current is allowed for Medical Electrical Equipment which are permanently installed and are connected to supply circuit which supplies only this Medical Electrical Equipment.

 

The Allowable value for Patient Leakage Current & Patient Auxiliary Current shall be as per the requirements stated in Table 3 & 4 of IEC 60601-1


 

Measurements

 

General:

 

The Medical Electrical Equipment shall be in an operating temperature before measuring the Touch Current, Earth Leakage Current, Patient Auxiliary Current, Patient Leakage Current.

 

The Number of Tests shall be reduced when there is no possibility of any hazardous situations based on the arrangement of components and materials of Medical Electrical Equipment and examination of circuit arrangement.

 

Measuring Supply Circuits:

 

The Medical Electrical Equipment shall be connected to an appropriate power source when it is specified for connection to a Supply Mains.

 

The Medical Electrical Equipment which is supposed to be internally powered is tested without any connection to measuring supply circuit.

 

Connection to a Measuring Supply Circuits:

 

The Medical Electrical Equipment is tested while connected to the Measuring Supply Circuit when it is provided with an appliance inlet. In this case, the Medical Electrical Equipment is connected to Measuring Supply Circuit via detachable power cord of Length & Type as per the requirements of IEC 60601-1.

 

The Permanently Installed Medical Electrical Equipment is also tested while connected to the Measuring Supply Circuit.

 

Measurement of Touch Current, Patient Leakage Current & Patient Auxiliary Current:

 

The Circuit represented in Figure 14 – Figure 20 of IEC 60601-1 shall be used in the Measurement of Touch Current, Patient Leakage Current & Patient Auxiliary Current.

 

Multiple Patient Connection:

 

When there are Multiple Patient connections in a Medical Electrical Equipment, it is investigated to ensure that the allowable values do not exceed for Leakage Current and Patient Auxiliary Current when one or more patient connections are disconnected from the patient or disconnected from the patient and earthed.


Now I hope you have acquired some knowledge about IEC 60601-1 Sub Clause 8.7: Leakage Current and Patient Auxiliary Currents. We will meet again with another valuable topic related to Biomedical Engineering, Medical Device, Healthcare.


NOTE: Dear friends!!!... Please do comment a topic related to Biomedical, so that we can discuss it in future blogs.


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