Tektronix TCP300A, User Manual

Page: 30 / 82

Getting Started
Degaussing and Autobalancing the Current Probe
Degaussing the probe removes any residual magnetization from the probe core.
Such residual magnetization can induce measurement error. Autobalancing
removes unwanted DC offsets in the ampli
fi er circuitry. Failure to degauss the
probe is a leading cause of measurement errors. The DEGAUSS LED fl ashes
until you degauss the probe.
To degauss the probe, disconnect the probe from the test circuit, or ensure that
the conductor under test has no power, close and lock the slide, and then press
the ampli
fi er PROBE DEGAUSS AUTOBALANCE button on the front panel of
the ampli fi er. To maintain measurement accuracy, degauss your probe in each of
these cases:
After you turn on the ampli fi er and allow a 20-minute warm-up period.
Before you connect the probe to a conductor.
Whenever a current or thermal overload condition occurs.
Whenever you connect a new probe.
Whenever you subject the probe to a strong external magnetic fi eld.
Periodically during normal use.
To degauss and autobalance a current probe, perform these steps:
1. Verify that the current probe is connected to the ampli fi er.
2. Remove the current probe from the conductor under test.
3. Lock the probe slide closed. (See Figure 6.) (See Figure 7.)
4. Press the ampli fi er PROBE DEGAUSS AUTOBALANCE button.
5. Wait about fi ve seconds for the degauss procedure to complete.
The PROBE DEGAUSS AUTOBALANCE LED glows green when the
operation has successfully completed. If the LED is blinking orange, the degauss
operation is still in progress. If the LED is red, the operation failed, and the cause
of the failure needs to be found and
fi xed. (See page 18, PROBE DEGAUSS
AUTOBALANCE Button and Indicator .)
NOTE.
The degauss procedure will fail if the ampli fi er is not properly connected
to an oscilloscope having 50 Ω input impedance. If this occurs, the NOT
TERMINATED INTO 50 Ω LED lights on the ampli fi er front panel.
After you have completed the oscilloscope adjustments and the ampli fi er
degauss/autobalance procedure, your system is ready to measure current.
12 TCPA300/400 Ampli fi ers and TCP300A/400 Series Current Probes User Manual