M2540-92000-01 A M2540 Ultrasound System Field Service Manual Page 102
Performance Tests: Electrical Safety Tests
Values exceeding the limits may indicate a fault in the transducer housing or the cable sheath.
To locate a fault precisely, repeat the measurement while slowly inserting the transducer into
the saline. The aberrant reading appears when the fault in the cable enters the saline.
NOTE TEE and endocavity transducers have a grounded jacket just under the outer plastic skin
of the cable. Their leakage currents can measure within the specified limits even if there
is a fault in the outer skin. Step 11 tests for this condition.
11. In normal polarity with an open ground condition imposed, measure ground wire leakage
(see “Ground Wire Leakage Current Test” on page 92). Compare this to the highest value
for transducer leakage current, Single Fault condition obtained in step 10.
If the transducer leakage is greater than 80% of the chassis leakage, there is a fault in the
transducer. To locate the fault, slowly insert the transducer in the saline, as in step 10.
Transducer Isolation Leakage Current Test Figure 6-6 on page 103 shows the basic electrical concept of the Transducer Isolation Leakage
Current test. The transducer is submerged in a container of saline solution. Mains AC voltage is
introduced into the saline solution, and leakage current in the transducer is measured using a
safety analyzer. Complete the procedure that follows the figure.