Tektronix TCPA300 SERIES, Instruction Manual

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Application Notes
3- 12
TCPA300/400 Amplifiers and TCP300/400 Series Current Probes Instruction Manual
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+
Battery Alternator
+
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To
ground
To current probe amplifier
To ground
TCP303/404XL
Figure 3- 7: Setup for measuring charging current
The waveform in Figure 3--8(a) shows the three-phase ripple frequency. The
average charge current is approximately 27 A with a minimum peak of approxi-
mately 23 A and a maximum peak of approximately 31 A. The waveform shows
a continuous cycle with no dropouts, so the alternator circuit appears to be
functioning properly. A single-phase diode failure normally appears as an
extreme drop in charge current every third cycle, as shown in Figure 3--8(b).
(a) Normal waveform (b) Waveform with one bad phase
40A
0A
Figure 3- 8: Charge current waveforms