Th Edition Voltage Dips In Addition To Interruptions

Medical might supplies coming together IEC 60601-1-2 4th edition voltage dips as well as interruptions

Customers telephone vociferation upward TDK-Lambda wanting their medical production to run into the strict IEC 60601-1-2:2015 4^th edition immunity standard, as well as inquire us if our medically certified might supplies fully comply.  In particular, concerns are raised almost coming together the department dealing alongside voltage dips as well as brusk interruptions to the air-conditioning supply.

IEC 60601-1-2 is derived from the IEC 61000-4 standard, which covers Electromagnetic compatibility (EMC).  The testing as well as mensuration methods are rattling similar, simply unopen to of the essay levels for dips as well as interruptions inward the department based on IEC 61000-4-11 are much tougher.  The respite essay of removing the air-conditioning render for 5 seconds, without the loss of the output, is almost impossible without a custom solution alongside unopen to shape of battery back-up.  One may good inquiry why are criterion medical power-supplies existence sold if they orbit non run into that standard.

Firstly, might supplies are non classified every bit medical devices, it is the customer’s production or system that is the medical device.

Secondly the term “essential performance” used inward the criterion has to move examined.  In the 3^rd edition of IEC 60601-1 it is defined every bit “the functioning necessary to accomplish liberty from unacceptable risk”.  To clarify, the designer/manufacturer has to determine if a loss of functioning or functionality of their medical device production or organisation volition effect inward an acceptable endangerment or an unacceptable risk.  That endangerment is the potential to harm a patient, operator or the environment.  Analysis must move made of the probability or the frequency of an lawsuit happening compared to the severity of that event.

Let’s give a elementary example.  Diabetics depository fiscal establishment agree their blood glucose grade on a regular solid soil as well as most work a handheld battery-operated meter that accepts disposable essay strips.  If that meter was to halt working, tell due to a faulty display, it would move classified every bit an acceptable risk.  Replacement meters are readily available from supermarkets as well as pharmacies as well as a brusk delay inward testing would non unremarkably effort harm.  An unacceptable endangerment would move if the internal sensor measuring the blood glucose grade was to orbit wrong readings as well as the diabetic administered likewise much or likewise piffling insulin.

Power supplies, although non classified every bit medical devices, tin get got an touching on on the IEC 60601-1-2 immunity functioning of the device they are powering.  For the voltage dips as well as interruptions department of the standard, in that location are v tests performed.  Table 1 below shows the input voltage dip as well as the duration.  100Vac input as well as 50Hz weather condition are shown every bit they could correspond the worst case.

Test results are judged against iv functioning criteria levels:

Performance Criteria Influenza A virus subtype H5N1 – ‘Performance within specification limits’

This is the best result.  Influenza A virus subtype H5N1 rattling slight driblet inward output of a few milli-volts (within the rule limits) should non effort the goal device to malfunction.

Performance Criteria B – ‘Temporary degradation which is self-recoverable’

Criteria B is usually acceptable inward the bulk of cases.

Performance Criteria C – ‘Temporary degradation which requires operator intervention’

This would move classified every bit unacceptable from a user indicate of view, without fifty-fifty considering a endangerment analysis.  If the air-conditioning might was interrupted as well as the might render had to move reset past times a patient or operator, it would move much likewise inconvenient.

Performance Criteria D – ‘Loss of role which is non recoverable’

Criteria D is actually a “fail” essay result.  If a might render is damaged as well as needs replacing later the test, it is rattling unlikely that a production alongside this functioning grade would move placed on the market.

AC Input Voltage	Actual Voltage Dip for 100Vac nominal	Voltage Dip past times air-conditioning Input Cycle (50/60Hz)	Voltage Dip Time Period for 50Hz	Suggested Performance Criteria Level
Dip downward to 0%	0Vac	0.5 of a cycle	10ms	A
Dip downward to 0%	0Vac	1 cycle	20ms	A
Dip downward to 40%	40Vac	10/12 cycles	200ms	B
Dip downward to 70%	70Vac	25/30 cycles	500ms	A
Dip downward to 0%	0Vac	250/300 cycles	5000ms (5s)	B

Table 1: Test Levels

Referring to Table 1, most might supplies volition overstep the outset ii tests alongside a Performance Criteria grade Influenza A virus subtype H5N1 alongside unopen to output derating to growth the hold-up time.

The 3rd as well as 4th tests requires the might render to snuff it on to operate for 200ms when the input drops to 40% of nominal or for 500ms at 70% of nominal.  Criteria Influenza A virus subtype H5N1 could move achieved past times having the might supply’s depression voltage input protection circuitry modified to allow the might render to operate at the lower input voltage for a brusk time.  As the air-conditioning input electrical flow volition move higher, it is best to ensure that the might render is non operated at total load.  As hold-up fourth dimension is related to the actual output might drawn, operating the might render at 50% charge volition effect inward a meaning “ride through” capability during the interruption.

The 5th essay of a 5 minute respite to the air-conditioning render is usually met alongside the installation of battery back-up or a UPS (Uninterruptible Power Supply).  Adding sufficiently large liberate energy storage within the might render would effect inward a meaning growth inward size.

In summary, the medical device designer/manufacturer must create upward one's heed which functioning criteria is needed, based on their endangerment analysis to run into IEC 60601-1.  Unless continuous functioning is critical, most manufacturers volition opt for the criteria inward Table 1.