User's Manual

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.

7ASW030-5

Hot

Neutral

Ground

measured

system

chassis

transducer