Teledyne Lecroy HVFO108 User manual

Operator’s Manual
HVFO108
High
-Voltage
Fiber Optically Isolated Probe

HVFO108
High-Voltage Fiber Optically Isolated Probe
Operator’s Manual
June, 2020

HVFO108 High-Voltage Fiber Optically Isolated Probe Operator's Manual
© 2020 Teledyne LeCroy, Inc. All rights reserved.
Unauthorized duplication of Teledyne LeCroy documentation materials is strictly prohibited.
Customers are authorized to duplicate and distribute Teledyne LeCroy documentation for
internal training purposes.
Information contained herein is classified as EAR99 under the U.S. Export Administration
Regulations. Export, reexport or diversion contrary to U.S. law is prohibited.
Teledyne LeCroy is a trademark of Teledyne LeCroy, Inc. Other product or brand names are
trademarks or requested trademarks of their respective holders. Information in this publication
supersedes all earlier versions. Specifications are subject to change without notice.
932301-00 Rev A
hvfo108-probe-om-eng_15jun20.pdf
June, 2020

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Contents
Safety.............................................................................................................................1
Symbols .............................................................................................................................1
General Precautions..........................................................................................................1
High Voltage Precautions.................................................................................................2
Battery Precautions ..........................................................................................................2
Safety Ratings for Accessories........................................................................................3
Safe Operating Environment ............................................................................................4
Introduction....................................................................................................................5
Key Features......................................................................................................................5
Method of Operation .........................................................................................................5
Compatibility......................................................................................................................9
Required Firmware Versions ............................................................................................9
HVFO Probe System .....................................................................................................10
HVFO108 Probe ...............................................................................................................10
Attenuating Tips (one required) .....................................................................................11
Optional Accessories ......................................................................................................11
HVFO108 Probe Specifications ....................................................................................12
Performance ....................................................................................................................12
Electrical Characteristics................................................................................................12
Vertical Sensitivity...........................................................................................................13
Amplifier/Modulating Transmitter Battery....................................................................13
Dimensions ......................................................................................................................13
Bandwidth ........................................................................................................................14
Common Mode Rejection Ratio .....................................................................................15
Input Impedance..............................................................................................................16
Operation .....................................................................................................................17
Assembling the Probe.....................................................................................................17
Connecting to the Test Circuit........................................................................................18
Connecting to the Test Instrument................................................................................20
Operating with an Oscilloscope .....................................................................................20
Recharging the Amplifier/Modulating Transmitter ......................................................22

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Performance Verification..............................................................................................23
Required Test Equipment ...............................................................................................23
Functional Check.............................................................................................................24
Performance Verification Test Setup ............................................................................25
Check Gain Accuracy ......................................................................................................25
Adjust Gain Accuracy.....................................................................................................26
HVFO108 Performance Verification Test Record ..........................................................27
Care and Maintenance..................................................................................................28
Cleaning the Probe Body ................................................................................................28
Cleaning the Optical Ports..............................................................................................28
Cleaning the Fiber Optic Cable .......................................................................................28
Replacing the Transmitter Battery.................................................................................28
Calibration Interval ..........................................................................................................28
Service Strategy ..............................................................................................................28
Attenuating Tip Compensation ......................................................................................29
Returning a Product for Service.....................................................................................30
Technical Support ...........................................................................................................31
Reference.....................................................................................................................32
Common Mode Rejection Ratio .....................................................................................32
Common Mode Range ....................................................................................................33
Warranty...........................................................................................................................34
Certifications ...................................................................................................................35
Appendix A: Battery Safety and Handling .....................................................................37

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Safety
Follow these instructions to keep the probe operating in a correct and safe condition. Observe
generally accepted safety procedures in addition to the precautions specified here. The overall
safety of any system incorporating this accessory is the responsibility of the system owner.
Symbols
These symbols appear on the probe and accessories or in this manual to alert you to important
safety considerations.
DANGER, HIGH VOLTAGE. Risk of electric shock or burn.
CAUTION of damage to probe or instrument, or WARNING of hazard to health. Attend to the
accompanying information to protect against personal injury or damage. Do not proceed until
conditions are fully understood and met.
ESD CAUTION. Risk of Electrostatic Discharge (ESD) that can damage the probe or instrument
if anti-static measures are not taken.
Laser Safety WARNING.
General Precautions
To avoid personal injury or damage to your equipment:
Use only as specified. The probe is intended to be used only with compatible Teledyne LeCroy
instruments. Using the probe and/or the equipment it is connected to in a manner other than
specified may impair the protection mechanisms.
Do not overload; observe all ratings. Do not connect the probe to any circuit that exceeds the
ratings of the oscilloscope terminal, probe, or probe-accessory combination.
Use only accessories compatible with the probe. Use only accessories that are rated for the
application. Substituting other accessories than those specified in this manual may create an
electrical hazard.
Connect and disconnect properly. Connect the probe to the measurement instrument before
connecting to the circuit being measured. Avoid excessive bending that can damage cables.
Keep the probe body and output cable away from the circuits being measured. Only tips are
intended for contact with electrical sources.
Do not use the probe for measurements on Mains circuits. This probe does not have a CAT
rating for use on circuits in Measurement Categories II, III or IV.

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Except for gain accuracy adjustment, do not remove the probe's casing. Touching exposed
connections may result in electric shock.
Use only indoors and within the operational environment listed. Do not use in wet or explosive
atmospheres.
Keep product surfaces clean and dry.
Handle with care. Probe tips are sharp and may cause injury if not handled properly.
Do not disassemble the probe body or remove inside parts. There are no user replaceable parts.
Refer all service to qualified personnel.
Do not operate with suspected failures. Before each use, inspect the probe and accessories for
damage such as tears or other defects in the body, cable jacket, etc. If any part is damaged,
cease operation immediately and sequester the probe from inadvertent use.
High Voltage Precautions
To avoid injury or death due to electric shock or burn:
Do not handle probe tips, leads or any part of the amplifier/modulating transmitter at any time if
DC bus voltages are >60 V.The probe is not rated for hand-held use above 60 V. If there is any
question as to whether >60 V voltages are present in the circuit, use caution and DO NOT touch
these components.
Always ensure that, when not hand-held, the amplifier/modulating transmitter and attached tip
are positioned to maintain adequate spacing between these two components and earth ground.
Some of the probe components float at the common-mode voltage and some do not. The
spacing requirements depend on the common-mode voltage present in the test setup.
Battery Precautions
To avoid personal injury or property damage due to explosion or fire, follow all warnings
listed in Appendix A: Battery Safety and Handling. Most importantly:
•Do not disassemble or modify the probe or the internal battery. The Lithium polymer
battery contained in the probe body is not user replaceable. Return the probe to
Teledyne LeCroy Service if the battery needs to be serviced or replaced.
•Do not heat the probe, or use it near heat sources or in excessive heat.
•Do not expose the probe to static electricity or excessive voltage.
•Do not throw, hit or step on the probe or otherwise cause mechanical stress.
•Do not reverse-charge or otherwise reverse the battery polarity.

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•Do not use the probe with accessories other than those with which it is shipped.
•Do not use the probe other than as specified in this manual.
•Do not use the probe if it is damaged.
Safety Ratings for Accessories
Accessory
Part Number
CAT Rating*
Max. Input Voltage Probe &
Accessory (input to ground)
1x Attenuating Tip
HVFO100-1X-TIP-U
No Rated Measurement Category
+/-1 V (DC + Peak AC)
(5 V maximum non-destruct)
5x Attenuating Tip HVFO100-5X-TIP-U No Rated Measurement Category +/-5 V (DC + Peak AC)
(25 V maximum non-destruct)
10x Attenuating Tip
HVFO100-10X-TIP-U
No Rated Measurement Category
+/-10 V (DC + Peak AC)
(50 V maximum non-destruct)
20x Attenuating Tip
HVFO100-20X-TIP-U
No Rated Measurement Category
+/-20 V (DC + Peak AC)
(100 V maximum non-destruct)
40x Attenuating Tip HVFO100-40X-TIP-U No Rated Measurement Category +/-40 V (DC + Peak AC)
(100 V maximum non-destruct)
* Per IEC/EN 61010-031:2015 definitions, No Rated Measurement Category applies to other circuits that are not directly
connected to the mains supply.
WARNING: The probe and its accessories are not rated for measurements within
Measurement Categories II, III or IV.

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Safe Operating Environment
Temperature, Operating 10 °C to 40 °C
Temperature, Charging 0 °C to 40 °C
Temperature, Non-operating 20 °C to 70 °C
Relative Humidity, Operating 5% to 80% RH (non-condensing) up to 30 °C
decreasing linearly to 45% RH at 50 °C
Relative Humidity, Non-operating 5% to 95% RH (non-condensing)
80% RH above 30 °C
45% RH above 50 °C
Altitude, Operating 3000 m (9842 ft.) maximum
Altitude, Non-Operating 10,000 m (32,807 ft.) maximum
Usage Indoor Use Only
Pollution Degree* 2, an operating environment where normally only dry,
non-conductive pollution occurs. Conductivity caused
by temporary condensation should be expected.
* Per IEC/EN 61010-031:2015.
The SAC-01 case and packaging materials shipped with the probe may not be suitable
for certain ESD sensitive areas, such as EPAs (ESD Protected Areas). If this is a
concern for your application, please take the necessary steps required for your test
environment.
.

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Introduction
The HVFO108 High Voltage Fiber Optically-isolated probe is an affordable, optimally designed
probe for measurement of small signals floating on an HV bus in power electronics designs, or
for EMC, EFT, ESD, and RF immunity testing sensor monitoring. It far surpasses the
measurement capabilities and signal fidelity of conventional high attenuation, high voltage
differential probes and acquisition systems that rely on galvanic channel-channel and channel-
ground high voltage isolation. Furthermore, it mitigates the need to rely on dangerous test
setups that require floating the oscilloscope and probe.
Key Features
•150 MHz bandwidth
•35 kV common-mode voltage rating (fiber optic isolation)
•Signal voltage measurement range from +/-1 V to +/-40 V with selectable tips
•Superior noise and rejection:
o>100 dB common mode rejection ratio (CMRR)
oLow loop inductance
oLow attenuation
•Gain accuracy of 2.5% typical, 4% guaranteed
•ProBus interface with automatic scaling
•Auto Zero capabilities
Method of Operation
The low-attenuation tip makes a three-wire (Signal, Reference, and Shield) electrical connection
to the device under test (DUT). The Signal connection wire is coaxial and attaches to the high
side of the signal measurement. The Reference wire and Shield wires are non-coaxial and attach
to the low side of the signal measurement. The Reference wire carries the signal return current,
while the Shield wire carries the current that is associated with the stray parasitic capacitances.
The output of the tip is input to the transmitter where an integrated, low-noise electrical amplifier
amplifies the attenuated signal, which is then frequency modulated in optical form for transmission
across the fiber optic cable. A subcarrier to the main modulation signal carries tip identifying
information so that attenuation and voltage scaling can be communicated to the oscilloscope.
The receiver demodulates the fiber optic signal to an electrical signal for input to the
oscilloscope. The subcarrier tip attenuation information is communicated through the
oscilloscope ProBus interface for proper voltage scaling.

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Probe Design Compared to a Differential Probe
When properly used in its intended application, the HVFO108 will achieve much better results
than a conventional, high-attenuation HV differential probe due to the dramatically different
probe design.
Consider the case where a conventional,
high- attenuation HV differential probe is
connected in-circuit to measure a small
signal floating on a HV DC bus (left).
The differential leads are connected across
a sense resistor at a voltage VSthat is
floating above ground by the DC bus
common-mode (VCM) voltage. The probe
must use high attenuation to reduce the
measured voltage (VCM+VS) to a low enough
level to use safely with an oscilloscope.
The two input leads are connected across
the low voltage VS, but due to the probe
construction, these leads are actually
measuring VCM and (VCM+VS), and the
difference between them is VS.
The high VCM value (typically 500 to 1000 VDC) results in large current flows (based on the
proportion of RLEAD to RSENSE) when RLEAD is not >> RSENSE. These large current flows may load the
circuit and inhibit proper DUT operation.
The input lead capacitance CLEAD has a very high voltage (either VCM or VCM+VS), which will result
in a large capacitive charging current that will further load the DUT and likely affect the fidelity
of the measured signal. These limitations are inherent in this design.
The high attenuation requires that the oscilloscope be operated in a very high sensitivity (small
V/div) setting, which results in higher gain and more noise on the signal―often enough to make
the measurement nearly unusable.
Since the probe is connected to ground, the common mode rejection ratio (CMRR, p.32) of the
differential amplifier in the probe must be very good or else signal noise and interference will
not be rejected and will add to measurement noise. High enough CMRR is difficult and costly to
accomplish, since it requires very precise matching of the + and – probe input leads and
excellent amplifier design.

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Now, consider the advantages of the HVFO
design in a circuit where the HVFO tip wires
are connected only across VS(left).
The VCM has no impact on the loading of the
circuit, since the RLEAD >> RSENSE.
The small CLEAD requires minimal charging
current, since the voltage VSis very low
(volts, not hundreds of volts or kilovolts).
The tip attenuation is very low, so the signal
is not being highly attenuated and then
highly amplified by oscilloscope, which
would result in higher noise.
The CMRR can easily be made very high,
since there is no requirement to identically
match a differential lead pair, and the high
CMRR performance is inherent in the fiber optic isolation from ground.
In the example above, the HVFO will perform better than a conventional, high-attenuation HV
differential probe when some or all of the following are true:
•Common mode voltages (VCM) are higher –170VDC or more.
•DUT impedance is lower.
•Signal rise times are faster (within the limitation of the probe bandwidth).
•Switched energy is higher.
It is unlikely that the HVFO108 will show much improvement on a very low voltage DC bus (~20 V)
floating signal unless the rise time is very fast. However, with typical 120/240 VAC supplied
equipment (340-500 VDC bus voltage), 600 VAC class equipment (1000 VDC bus voltage), or ≥ 5 k VAC
class equipment, the advantages of the HVFO will be obvious, in most cases.

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Effect of Tip Design on Current Paths
The HVFO108 three-wire tip provides
optimal measurement results by
separating the signal return currents from
the currents associated with the probe
stray parasitic capacitance. This reduces
the noise measured in the system, and
improves the CMRR performance of the
probe.
The image at left shows how the tip
construction affects the current paths.
The blue Signal wire conducts the Signal
current, which follows a return path
through the green Reference wire.
The green Reference wire is connected to
the Signal coaxial outer conductor close to
the Signal connection. This ensures that
the Signal and Return currents are equal and opposite through the common-mode choke
(i.e., IRETURN = -ISIGNAL).
The black Shield wire connects to the same in-circuit location as the Reference wire, and then
electrically connects to the tip at the internal shield of the transmitter. The current flowing
through the Shield wire will drive the reference voltage for the single-ended amplifier, including
the effects of any parasitic capacitance.
The HVFO108, by design, is not a differential probe, so the Signal and Reference wires are
imbalanced in impedance. By using separate Reference (signal return) and Shield wires to carry
currents, the probe segregates these currents to overcome any impact of impedance imbalance
between the Signal and Reference wires. If only the Signal and Reference wires were connected
(and not the Shield wire), the probe response at DC and high frequency would be unaffected, but
the CMRR would be degraded. If only the Signal and Shield wires were connected (and not the
Reference wire), the probe response at DC would be unaffected, but the high-frequency
response would be degraded, and CMRR may also be degraded.
CAUTION: The Reference and the Shield wires are electrically connected inside the tip.
Failure to connect them to the same measurement potential will damage the DUT and/or
the HVFO108.
The common-mode capacitance (CPAR in the drawing) is ~7 pF. This value is highly dependent

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on the probe position, and could be larger if the transmitter is positioned close to the DUT
ground. Note that the HVFO uses a dual-reference lead (as described earlier) that separates the
common-mode current from the signal return current. This greatly reduces the effect of the
ground current due to the common-mode capacitance and results in CMRR performance that is
much better than would otherwise be expected for an ~7 pF common-mode capacitance.
Compatibility
The HVFO108 probe is compatible with a wide range of Teledyne LeCroy oscilloscopes equipped
with the ProBus interface. Visit teledynelecroy.com/oscilloscope to confirm compatibility with
your oscilloscope model.
In general, Teledyne LeCroy 12-bit High Definition Oscilloscopes (HDO) provide the most offset
capability over the widest range of V/div settings.
Note: HVFO108 is not compatible with WaveSurfer Xs oscilloscopes, which only run up to 32-bit
XstreamDSO 7.2.0.5. Contact Service for available oscilloscope upgrades.
Required Firmware Versions
Correct operation of the HVFO108 probe requires that the oscilloscope be installed with
firmware version 9.2.x.x. or higher.

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HVFO Probe System
HVFO108 Probe
The parts shown below are delivered standard with the HVFO108 in a soft carrying case.
The amplifier/modulating transmitter
is a frequency modulating optical
transmitter integrated with a high-
performance electrical amplifier. The
transmitter is battery-powered, so
there is no direct connection from the
floating DUT, providing HV isolation
between the device under test (DUT)
and the grounded oscilloscope. The
battery is recharged through the same
USB Micro-B interface used to
connect the tip.
The VersaLink (V-pin) 400/430 µm
fiber optic cable assembly has low
loss and excellent transmission
characteristics, helping to optimize
the battery life of the transmitter. If
the attenuation in the fiber optic cable is too high, or the cable is damaged and not transmitting
properly, the probe will provide a warning to the user. A 1-meter cable is supplied; additional 1-
or 6-meter cables are available as optional accessories. The cable utilizes an Avago VersaLink
connector, enabling it to be interchanged with low cost, off-the-shelf fiber optic cables. Cables
longer than 6 meters may be sourced directly from the manufacturer (Industrial Fiber Optics,
http://www.i-fiberoptics.com/), although HVFO108 accuracy specifications apply only to the
cables shipped in the original box.
Note: If using a cable obtained from another vendor, perform the Performance Verification
procedure and calibration (p.23) with the new cable connected prior to operating the probe.
The demodulating receiver utilizes the ProBus interface to communicate tip attenuation value
and proper voltage scaling to the oscilloscope. With the ProBus interface, the HVFO probe
becomes an integral part of the measuring instrument. Power is provided to the receiver
through the signal interface, so there is no need for a separate power supply or batteries.
Also included are a USB-A – USB Micro-B cable and E-Z Micro-Grippers (1 set of 3).

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Attenuating Tips (one required)
Attenuating tips are sold separately from the probe itself, but at least one tip is required for
proper functioning. Tips can be stored in a compartment in the soft carrying case.
Description Part Number Quantity
1x (+/-1 V) attenuating tip
HVFO100-1X-TIP-U
1
5x (+/-5 V) attenuating tip
HVFO100-5X-TIP-U
1
10x (+/-10 V) attenuating tip
HVFO100-10X-TIP-U
1
20x (+/-20 V) attenuating tip
HVFO100-20X-TIP-U
1
40x (+/-40 V) attenuating tip
HVFO100-40X-TIP-U
1
The attenuating tip makes a three-wire connection to the DUT,
while the other end of the tip connects to the USB Micro-B input on
the transmitter. Each tip communicates identifying information to
the transmitter. The fixed attenuation determines the maximum
voltage level that can be measured. All tips are interchangeable
with any HVFO transmitter and do not require specialized
calibration with a specific HVFO probe. The E-Z Micro-Grippers
may be used with any of the tips.
Note: Tip selection is important to optimize for best noise performance. Using a tip with a wider
dynamic voltage range than necessary will result in more noise.
Optional Accessories
These items may be purchased separately as accessories to the probe.
Description Part Number Quantity
Additional 1-meter fiber optic cable HVFO-1M-FIBER 1
6-meter fiber optic cable HVFO-6M-FIBER 1
Optional 1-meter and 6-meter fiber optic cables

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HVFO108 Probe Specifications
For the current specifications, see the product datasheet at teledynelecroy.com. Specifications
are subject to change without notice.
Performance
Bandwidth (probe + oscilloscope)
150 MHz typical
Risetime 10-90%
3.3 ns typical
Gain Accuracy
+/- 2.5% typical, 4% guaranteed
CMRR (typical, 1x tip attached)
140 dB @ 100 Hz
120
dB @ 100 Hz - 1 MHz
85 dB @ 1 - 10 MHz
60 dB @ 10 - 60 MHz
35 dB @ 150 MHz
Electrical Characteristics
Input Dynamic Voltage Range
1x tip
5x tip
10x tip
20x tip
40x tip
+/
- 1 V
+/
- 5 V
+/
- 10 V
+/
- 20 V
+/- 40 V
Max. Common Mode Voltage
(from either input to ground)
+/- 35 kV (DC + peak AC)
Max. Input Voltage to Earth
(from either input to ground)
+/- 35 kV (DC + peak AC)
Max. Safe Input Voltage
30 V
RMS
/ 60 V
DC
(hand-held)
Max. Non-destruct Voltage
Lower of 5X dynamic range
or 100 V
Noise (probe only)
1x tip
5x tip
10x tip
20x tip
40x tip
7 mVrms
35 mVrms
70 mVrms
140 mVrms
280 mVrms
WARNING: The probe is not intended for hand-held use above 60 VDC. Always maintain
adequate spacing between floating probe components and earth ground when
measuring at high voltage in a stationary test setup.

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Vertical Sensitivity
1x tip
5x tip
10x tip
20x tip
40x tip
10 mV/div – 1 V/div
50 mV/div – 5 V/div
1
00 mV/div – 10 V/div
200 m
V/div – 20 V/div
400 mV/div – 40 V/div
Amplifier/Modulating Transmitter Battery
Charging Interface
USB Micro-B
Typical Life
> 6 hours
Recharge Time
Oscilloscope USB port
USB charger
5
hours
2.5 hours
Cycle Life
> 500 cycles*
* For battery life > 5.5 hours.
Dimensions
Amplifier/Modulating Transmitter
Width
48 mm (1.89 in.)
Length
Body only
With leads attached
90.2 mm (3.55 in.)
245 mm (9.65 in.)
Height
Without feet
With feet
25 mm (0.98 in.)
27.5 mm (1.08 in.)
Attenuating Tips
Insulated Socket Diameter
3 mm (0.12 in.)
Length Green REF Wire
8 cm (3.15 in.)
Overall Length
16 cm (6.3 in.)
Demodulating Receiver
Width
39 mm (1.54 in.)
Length
95.9 mm (3.77 in.)
Height
23.6 mm (0.93 in.)

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Bandwidth
Typical bandwidth of the HVFO108 using the 5x, 10x, 20x and 40x tips, averaged:
Typical bandwidth of the HVFO108 using the 1x attenuating tip:
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
515 25 35 45 55 65 75 85 95 105 115 125 135 145 155 165 175 185 195
Response (dB)
Frequency (MHz)
Frequency Response (typical)
-4
-3.5
-3
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
515 25 35 45 55 65 75 85 95 105 115 125 135 145
Response (dB)
Frequency (MHz)
1x Frequency Response (typical)