Teledyne HVD3000, Operating Manual

Page: 38 / 48

HVD3000 / HVD3000A High-Voltage Differential Probes
32
Overload Indicator (A models only)
On HVD3000A probes, an indication will appear in the oscilloscope message bar when the
differential or common mode voltages are beyond the operating ranges of the probe. Note
that the warning message below may trigger before any saturation occurs. It is designed to
guarantee that the system will not fail to indicate an overload.
Overload Indicator Thresholds
3102A X1000 Attenuation X100 Attenuation
Differential Mode: ± 1.78 kV
Common Mode: ± 1.78 kV
Differential Mode: ± 158 V
Common Mode: ± 1.8k V
3206A X500 Attenuation X50 Attenuation
Differential Mode: ± 2.1 kV
Common Mode: ± 2.1 kV
Differential Mode: ± 180 V
Common Mode: ± 2.1 kV
3605A X2000 Attenuation X200 Attenuation
Differential Mode: ± 7.7 kV
Common Mode: ± 7.7 kV
Differential Mode: ± 760 V
Common Mode: ± 7.7 kV
Auto Zero
Auto Zero corrects for DC offset drifts that naturally occur from thermal effects in the
differential amplifier. For example, the DC offset drift of the HVD310x and HVD310xA
probes is 70 μV/°C (worst case) referred to the output. If the probe is set to 50x attenuation
and the ambient temperature changes by 10 °C, the DC offset drift could be as high as (70
μV/°C)(50)(10 °C) = 35 mV referred to the probe tip. If measuring a 3 Vp-p signal, the DC
offset drift could be a little more than 1%. If the signal was 1400 Vp-p in 500x attenuation
mode, the DC offset drift at same ambient temperature could be as high as (70
μV/°C)(500)(10°C) = 350 mV due to the probe tip ( although any offset accuracy error from
the oscilloscope itself would likely dominate the measurement).
Auto Zero is invoked manually from the Probe dialog that appears behind the Channel
setup dialog when the probe is connected to the oscilloscope.
NOTE: When using HVD3000 probes, disconnect the probe from the test circuit before
performing Auto Zero. HVD3000A probes may remain connected during Auto Zero.
Always perform Auto Zero after the probe has been warmed-up (20 min. recommended).
Depending on the measurement accuracy desired and/or the change in the ambient
temperature where the probe is located, it may be necessary to perform Auto Zero more
often. If the probe is disconnected from the oscilloscope then re-connected, repeat Auto
Zero after a suitable warm-up time.
Auto Zero is disabled when AC coupling is selected.