Leakage current

Hi,

It depends upon the method of testing being used. There are too many variables to discuss here.  If you'd like to email me with your contact info, I'd be glad to discuss.  My email is ted.lucidi@innovatusimaging.com

Hope to hear form you.

They were using a TD100, but I think it stopped working. Now they’re using the pocket bit hole tester with the probes submerged in a bucket of warm salt water. 

HondaTech739,

Acertara has a document as part of our Blue Paper series titled, "A Thinker's Guide for Electrical Leakage Testing of Ultrasound Probes" that will provide the information you need.  The document collects international standards and manufacturers recommendations along with Acertara's 20-year track record of developing leading-edge ultrasound test equipment and probe repair for the healthcare market.  If interested in the paper or you have other questions, please drop us a line at Acertara_Cares@acertaralabs.com.

Cheers, Dave

Have to be careful as the off the shelf meters have a lower threshold as well as a high threshold.  The Fluke ULT 800 can indicate a fail if enough of the probe is NOT submerged in the test liquid (or if there is a poor connection somewhere.  This COULD be the issue. Look closely at the fail LED. If it flashes (once per second), this is the issue.  If the LED is solid, there is a definte failure.  Can you determine the make/model of leakage meter?  This probe model usually has a leakage value ranging from 70 - 120 uA.

The GE bite hole indicator has a maximum output of only 260 microAmps. If the test is being done correctly, it sounds like the probe is definitely failing.

There are better electrical leakage testers available, and GE is recommending the use of the BC Group ULT-2010 with special adapters for GE 6Tc and 9T probes.

I can't recommend the BC Group meter enough.  It's what we use in our Center of Excellence for Ultrasound.  It offers simplicity and ease of use for end-users, but also a more technical mode for the service engineer.  BC group has worked with both GE and Philips and has programmed the proper defaults into their meter.  The meter also allows for custom limits,but the defaults are 185uA for Philips and 350uA for GE.

Even though the upper leakage current limit given by Philips is higher, experience has shown that any TE (TEE/TOE) probe that is exceeding the normal, like new leakage current is already posing a risk to the patient. I once did a demonstration of the BC Group ULT-2020 (also called iTest) and the Philips TE probe I was given to use had just over 140uA of leakage, and after holding it for only a few minutes it turned the palm of my hand black from the insertion tube. Imagine what it does to the patient when it is in their esophagus! Plus, elevated leakage current indicates something is starting to fail and the sooner that is repaired, and in general the sooner it gets fixed, the less it will cost.