Dielectric strength test for ultrasonic probe

kfloeng

Registered
Hello everyone,

This is my first time posting here, but I am hoping you can help me clarify some questions
regarding the dielectric strength test voltages mentioned in Table 6 and clause 8.9.3.2/3 in 60601-1.

We are working on a medical ultrasound probe using MEMS transducers.
The transducer is biased by +-90 VDC rails from an ultrasound scanner.
Both rails are current-limited and power the device through a 1 MOhm resistor.
The excitation voltage to the transducer is +-80 VAC @ 15MHz from the pulser in the scanner.

Similar to conventional ultrasound probes, our transducer
is covered with an insulating layer that forms a joint with the plastic housing of the probe (Class BF).
So far we have assumed that 8.9.3.3 for cemented joints applies in this case.

My questions are:
  1. How should we calculate the maximum working voltage in this scenario?
    - Our current best guess is to add the peak voltage of the DC and AC components, resulting in 170 Vpeak.

  2. Should we consider the power supply delivering the bias voltages and
    the pulser as secondary circuits?

  3. Does clause 8.9.3.3 apply in this case?

Depending on the answers to these questions, we gather that we should be testing somewhere between 1000 VAC and 1.6*1500 = 2400 VAC (one MOPP).
This difference could significantly influence our design, so I'm hoping you can help alleviate some of the confusion.

Kind regards
Kasper
 
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