THDP-TMDP_Instructions-077054003.pdf - 第18页
Bandwidth limit button and indicators Press the BANDWIDTH LIMIT button to limit the probe bandwidth to 5 MHz. 5 MHz is close to the switching frequency of most switching transistors (FET s) in switch mode power supplies …
The remaining controls and features of the probe are located on the probe head.
Probe inputs
The maximum voltage that the probe inputs can accept depend on the probe model and the measurement points.
For example, the THDP0200 probe (shown) can measure a maximum of 1,000 V
RMS
CA
T II between either input and ground, and a
maximum difference of 1,500 V (DC + peak AC) between the (–) and (+) inputs. These input ratings are valid for both range settings.
The other probes covered in this manual have different limits; refer to Specifications.
CAUTION: Do not use these probes above the input limits shown on the probes. The input voltage limits vary by probe model.
Overrange indicator
The OVERRANGE indicator lights red if the voltage of the input differential signal exceeds the linear range of the range setting. When this
happens, the signal on the probe output does not accurately represent the signal on the probe input.
WARNING: The Overrange indicator does not detect overrange condition of common-mode voltages or voltage-to-earth potential
at the probe inputs. The Overrange indicator only detects dif
ferentially between the + and – inputs (not relative to ground).
Do not exceed the common-mode voltage or input voltage-to-earth ratings of the probe when taking measurements. See
Overrange detection on page 37.
If you are not sure, make a single-ended measurement of each point you are intending to measure differentially first. Make a
single-ended measurement by tying one input lead to ground (the "–" input) and then connecting the other lead (the “+" input) to
the points of interest, one at a time.
Voltage range button and indicators
Press the RANGE button to select between the voltage range (attenuation) settings of the probe. The voltage range is indicated by two
LEDs on the probe and may be displayed on the oscilloscope screen, depending on the oscilloscope model.
The OVERRANGE LED lights if the applied voltage exceeds the selected range. T
o extinguish the LED, select a higher range. If a higher
range is not available, do not attempt to take the measurement with the probe.
Probe operating information
High Voltage Differential Probes THDP0100/0200 and TMDP0200 User Manual 17
Bandwidth limit button and indicators
Press the BANDWIDTH LIMIT button to limit the probe bandwidth to 5 MHz. 5 MHz is close to the switching frequency of most switching
transistors (FET
s) in switch mode power supplies (SMPS).
The 5 MHz filter assists in the characterization and testing of power supplies in switch mode by removing all high frequency content, noise
and harmonics from the measurement.
Press the button again to return to the FULL position, which selects the full specified bandwidth of the probe.
Audible overrange on/off button and indicators
The audible overrange is an audible alarm that indicates when the measured signal exceeds the selected range. The alarm is enabled
when the probe is first powered on.
Press the AUDIBLE OVERRANGE button to light the OFF LED and disable the feature. T
o enable the alarm, press the button again to light
the ON LED.
Probe operating information
18
Functional check
Using accessories that are shipped with your probe and a source that supplies AC line voltage, perform the following procedure:
WARNING: T
o reduce risk of shock or fire, ensure that the accessories are fully mated before you connect to voltage sources
above 42 Vpk.
1. Connect the output of the probe to the oscilloscope input channel.
2. Connect the probe inputs to the AC voltage source.
3. Connect the inputs, set the voltage range, and perform the check as each row of the following table indicates.
Figure 4: Functional check setup
Input 1 (+ or
–)
Input 2 (– or +) Mode Range setting Check
Hot Ground or
Neutral
Differential High (6000 V, 1500 V,
or 750 V)
Measurement instrument displays or indicates the line
voltage
Hot Ground or
Neutral
Differential Low (600 V, 150 V, or
75 V)
Measurement instrument displays or indicates the line
voltage. Overrange indicator lights if the input is ~20% over
Hot Hot (same
connection)
Common Mode High or low
No signal. If a DC offset voltage is present, zero the DC
offset using the AutoZero function.
Probe operating information
High Voltage Differential Probes THDP0100/0200 and TMDP0200 User Manual 19