M2540-92000-01 A M2540 Ultrasound System Field Service Manual Page 57
Theory of Operation: Transducer Safety Testing: Test Setup and Theory
Imposing an open neutral condition prevents all system current from flowing. This creates a
higher potential for leakage current I
chassis
. Most flows safely through the ground wire; some
flows through the transducer. This I
transducer
is still fairly low, unless the chassis is not properly
grounded.
Figure 4-8 Ground Wire Leakage Test Diagram (for Comparison with 1st Single Fault
Condition)
With the transducer circuit disconnected, all of the leakage current I
chassis
flows through the
analyzer by way of the ground wire.
In the 1st single fault condition transducer leakage test (Figure 4-6 on page 56), all the leakage
current I
chassis
flows through the analyzer by way of the transducer. In that condition, only the
resistance or impedance of the respective paths varies.
• If the transducer sheath is intact, its resistance is high, and I
measured
in the transducer leakage
test is low when compared with I
measured
in the ground wire leakage test.
A
I
7ASW030-5
Hot
Neutral
Ground
I
C
I
I
measured
system
chassis
transducer
S
Z
