Isolation Calculator IEC 60601-1

• Isolation Calc.
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Overview

Every electrical engineer who develops medical devices has to know about the IEC 60601-1. This is the main international standard for basic safety and essential performance. For a long time the second edition of this standard was valid, but since 2005 there is a third edition which makes the life of an engineer much more complicated than before. In addition there exists an ammendmend A1 since 2012. The new edition of the IEC 60601-1 is called 3.1.

When a medical device is developed, isolation between patient and mains voltage is a main concern. In the second edition of the 60601-1, the necessary air clearances and creepage distances were defined in a single table. It was an easy task to get the right values, also for the test voltages.

With the introduction of the 3rd edition, the procedure to get the air clearance and creepage got much more complicated. Now it's not only the type of the isolation barrier and the working voltage which defines the distances. The values depend on operating altitude, pollution and PCB material. Also, the overvoltage category of the mains supply has to be taken into account. For air clearances, the values are given by tables. Creepage distances are allowed to be calculated by interpolation of table values, which makes the situation worse.

Another problem is, that not all countries use the 3rd edition or edition 3.1. To be on the safe side, a medical device should be developed so that it fulfills the requirements of all versions of the IEC 60601-1, the 2nd, the 3rd and 3.1!

Because of this, I developed the Isolation Calculator 60601-1. It is a tool to help finding necessary air clearance, creepage distances and the appropriate test voltages for individual isolation barriers in a medical device. The user can enter the needed information and gets the results. The results of multiple isolation barriers can be collected and exported into a CSV file for documentation, for example a supplement to an isolation diagram.

Some screen shots from the input screens

Result screen

The results are calculated as the maximum of the requirements of the three different editions of the IEC 60601-1. The user can choose which edition of the 60601-1 shall be applied. For more information see the manual.

The program is written and tested for Android 2.1 to 4.4.