IEC 80601-2-60 clause 201 - SECONDARY CIRCUITS

[Michael.K.]

Hi,

I am reviewing a specific standard for dental equipment and encountered a requirement for the primary circuit to withstand a 4kV impulse, while ensuring the voltage on the secondary does not exceed 1kV. This test, as defined in clause 201, appears similar to the surge test in IEC 60601, which typically involves applying 1.5kV between line (L) and neutral (N).

Could you please clarify the following points:

1. If the power supply is certified to IEC 60601-1, would it comply with clause 201?
2. Are there specific procedures or considerations I should be aware of when conducting the 4kV impulse test on dental equipment?

Thank you for your assistance.

Clause 201 (IEC 80601-2-60)
The transient impulse voltage of max. 1 kV shall be checked by testing as follows: Apply a
test voltage of 4 kV of 1,2/50 μs waveform to the primary circuit (mains). Verify that a limit of 1 kV
is not exceeded in the secondary circuit. The waveform has to be in accordance with
IEC 61180-1. The generator must comply with IEC 61180-2 (internal resistance of 2 Ω).

 

[Avidan B]

This test is intended for medical eq. which has more than one applied part (in the secondary circuit). is that your case?

 

[Michael.K.]

We have only one AP and the device is considered an ME dental equipment. It is an optic scanner that is used for teeth mapping.

The standard says "within" the secondary circuit. Why should I ignore it?

Within SECONDARY CIRCUITS, for the separation within and between APPLIED PARTS of
DENTAL EQUIPMENT for AIR CLEARANCES and CREEPAGE DISTANCES, the following apply:

 

[Avidan B]

As far as I understand, the clause starts with "The transient impulse voltage of max. 1 kV " explains how to test the 1Kv impulse required only for "separation between applied parts" ...

 

[Bryan Ye]

Hello all,

First I would like to say, that the mentioned requirement in this post is not mandatory. see clause 201.8.9.

For sure you could use this alternative method. clause 201.8.9.1.12 replaced the requirement in the IEC 60601-1 standard.

In clause 201.8.9.1.12, the requirements from SUPPLY MAINS to SECONDARY CIRCUITS and from SUPPLY MAINS to APPLIED PARTS are very clear.

It is not easy to understand the separation requirement from the secondary circuit to the applied part/accessible part and from the secondary circuit to another secondary circuit.

The requirement in clause 201.8.9.1.12 is nothing about one applied part or two or more applied parts, as applied parts are defined by the manufacturer. You could not avoid this requirement by changing the definition of the applied part.

Let's come back to the question of the post's owner.

1. If the power supply is certified to IEC 60601-1, would it comply with clause 201?
   

Answer: No. if the primary circuit is overvoltage category II, we will consider the secondary circuit to be overvoltage category I.
If the input voltage is 240V, then the voltage on the secondary circuit defaults to 1500V.
The standard IEC 80601-2-60 is required to test on the primary circuit at 4000V and the limit voltage is 1000V. This is a higher requirement than that in IEC 60601-1.

1. Are there specific procedures or considerations I should be aware of when conducting the 4kV impulse test on dental equipment?

Answer: I guess the power supply unit is SMPS (switched-mode power supply), so in the worst condition, you need to apply the voltage directly on the transformer (not on the input terminal) and measure the voltage on the output of the transformer.

Please imagine that in normal conditions transient impulse voltage will apply when SMPS is operating, which means transient impulse voltage will nearly apply on the input of the transformer completely.
If SMPS does not operate during the test then voltage will be limited by various components before the transformer.

Hope this is helpful.

201.8.9 * CREEPAGE DISTANCES and AIR CLEARANCES
Amendment:
For CREEPAGE DISTANCES and AIR CLEARANCES, 8.9 of the general standard shall be used
without modification or with the following changes.
Alternatively CREEPAGE DISTANCES and AIR CLEARANCES of this particular standard may be
applied. In this case, 8.9 of the general standard applies except as follows:

 

[Michael.K.]

Thank you for detailed information, seems much clearer now!