N2790A
Differential Voltage
Probe
User’s Guide
For Safety, Regulatory, and publishing information, see the pages at the back of this book.
© Copyright Agilent Technologies 2010
All Rights Reserved.
Contents
Inspecting the Probe 3
Compatibility 4
Probe Parts Supplied 5
Characteristics and Specifications 6
Cleaning the Probe 8
Using the N2790A Probe 9
Service Strategy 10
Characterization Plots 11
Performance Verification Procedures 13
2
Inspecting the Probe
Inspecting the Probe
❏ Inspect the shipping container for damage.
Keep a damaged shipping container or cushioning material until the contents of the
shipment have been checked for completeness and the probe has been checked
mechanically and electrically.
❏ Check the accessories.
Any accessories that were supplied with the probe are listed in the “Probe Parts
Supplied” section of this manual.
• If the contents are incomplete or damaged, notify your Agilent Technologies Sales
Office.
❏ Inspect the instrument.
• If there is mechanical damage or defect, or if the probe does not operate properly
or pass calibration tests, notify your Agilent Technologies Sales Office.
• If the shipping container is damaged, or the cushioning materials show signs of
stress, notify the carrier as well as your Agilent Technologies Sales Office. Keep
the shipping materials for the carrier’s inspection. The Agilent Technologies office
will arrange for repair or replacement at Agilent Technologies’ option without
waiting for claim settlement.
3
Inspecting the Probe
N2790A Differential Voltage Probe
The N2790A differential probe allows you to safely measure high-voltage floating
circuits with the oscilloscope grounded. It is ideal for many applications such as motor
speed controls, power supply designs, and electronic high-power converters. The
N2790A offers sufficient dynamic range and bandwidth for your application to make
the floating measurements found in high-speed power electronic circuits safely and
accurately.
With 100 MHz bandwidth, switchable attenuation of 50:1 and 500:1, and a maximum
differential voltage input of 1400V (DC + peak AC), it provides the versatility for a
broad range of applications including high-voltage circuits. Each probe comes with
sharp browser probe tips for use on small components and in tight places, alligator
clips for connecting to larger cables, and pincher clips.
The probe is powered by the autoprobe interface.
Compatibility
The N2790A differential probe is compatible with the following Agilent oscilloscopes:
• InfiniiVision Series 5000, 6000 (except 100 MHz), and 7000 with version 5.2
software or later
• Infiniium 9000 (with version 2.00 software or later), 8000 (with version 5.61
software or later), and 54830 Series (with version 5.61 software or later)
4
Inspecting the Probe
2
3
4
Probe Parts Supplied
The following diagram and table show the parts supplied with the N2790A Probe.
The probe tips you receive may look slightly different than the ones shown in this
picture.
Parts for N2790A Probe
Item Description Part Number
1 Differential voltage probe N2790-68701
2 Probe tips - browser tip (x2)
3 Probe tips - pincher clip (x2)
4 Probe tips - alligator plunger clip (x2)
5 Plastic pouch
6 Offset adjustment tool
To order the Probe Tip Accessory Kit (consisting of 2 browser tips, 2 pincher
clips, and 2 alligator plunger tips), order part number N2790-68700. Probe tips
are only for use with the N2790A differential voltage probe.
*Probe tips are not orderable separately.
(black and red pair)
(black and red pair)
(black and red pair)
A054*
5
Characteristics and Specifications
Characteristics and Specifications
Characteristics and specifications for the N2790A Differential Voltage Probe are
shown below.
Electrical Characteristics
Attenuation ratios 50:1 and 500:1 (Selectable via switch on probe.)
Bandwidth (-3 dB)* 100 MHz
Gain Accuracy* \4% @ 0-20 oC, \2% @ 20-30 oC, \4% @ 30-
DC CMRR -70 dB @ 500VDC
AC CMRR -80 dB @ 50/60 Hz
Input impedance Between inputs: 8 M , 3.5 pF
Noise referenced to input < 300 mVrms @ 500:1
Propagation Delay 14.0 ns @ 50:1, 12.8 ns @ 500:1
Switch positions 500:1, 50:1
Internal power Autoprobe interface
*Denotes warranted specification after 20 minute warm-up
o
55
C
-50 dB @ 100 kHz
-50 dB @ 1 MHz
< 50 mVrms @ 50:1
Input Characteristics
Cable length 170 cm (66.9 inches)
Length of input leads 40 cm (15.7 inches)
Maximum common mode
operating voltage
(rms or DC + peak AC)
1
Maximum common mode
operating voltage derating
frequency
2
Maximum differential mode
operating voltage
(DC + peak AC)
1
Refer to the warnings on page 8 for further details on the input voltage safety rating
2
Refer to the derating plot on page 12
600V CAT III
1000V CAT II
2 MHz
1400 V @ 500:1
140 V @ 50:1
6
Characteristics and Specifications
Output Characteristics
Output cable Safety designed BNC cable
Maximum output voltage range \2.8 V into 1 M at 500:1
Environmental Specifications
Temperature Operating: -10 °C to +50 °C
Nonoperating: -51 °C to +71 °C
Altitude Operating: 2,000 m (6,561 ft)
Nonoperating: 15,300 m (50,200 ft)
Humidity Operating: 80% room humidity @ 40 °C
Nonoperating: 90% room humidity @ 65 °C
Pollution Degree Pollution Degree 2
Safety Specifications
UL Listed: File No. E326557
Compliant with: UL 61010-031, CSA 22.2 No. 61010-031-07
7
Cleaning the Probe
!!!!
WARNING SHOCK HAZARD!
These probes are designed for use with oscilloscopes that have a common terminal at
GROUND POTENTIAL (in accordance with OSHA requirements and the National
Electric Code). Exposed metallic surfaces of the probe and the oscilloscope MUST BE
GROUNDED. Failure to ground the common terminal during certain applications,
such as those requiring the oscilloscope to be powered from an external battery, might
expose the operator to an electrical shock hazard that could be lethal (depending on
voltage and current conditions.)
The probe inputs are safety rated to a maximum of 1000 Vrms CAT II and 600 Vrms
CAT III between either input and earth ground. These maximum ratings apply
regardless of the attenuation setting of the probe. Do not apply voltages greater than
1000 Vrms CAT II or 600 Vrms CAT III between either input and ground.
The probe tips that are provided are rated for 1000 Vrms CAT II and 600 Vrms CAT
III usage. Other probe tips may be used if they have the appropriate ratings and the
same style connectors.
Cleaning the Probe
Disconnect the probe from all power sources and clean it with a soft cloth dampened
with a mild soap and water solution. Be careful not to get water in the attenuation
switch. Make sure the probe is completely dry before reconnecting it to a power source.
8
Using the N2790A Probe
Using the N2790A Probe
Powering the N2790A
The N2790A probe is powered by the autoprobe interface found on Agilent
InfiniiVision and Infiniium Se ries oscilloscopes.
Selecting the Correct Attenuation on the Probe and the Oscilloscope
The probe has two modes of operation, 50:1 and 500:1 attenuation. Select the desired
attenuation on the probe (via the switch on the probe) and the correct probe attenuation
setting on the oscilloscope. This will ensure that accurate voltage readings can be made
directly from the oscilloscope.
Adjusting the Probe Offset Level
The probe offset level is adjusted using the tool provided with the N2790A probe. Adjust the offset level by turning the potentiometer adjustment located on the autoprobe pod.
Measurement Tips
• Use the 50:1 range on the differential voltage probe for smaller signals, such
as ripple on a high voltage reference lead.
• Connect the red probe cable to a more positive or more negative voltage level
than the black probe cable.
• There is an overrange LED on the probe to indicate when you have exceeded
the maximum voltage of the probe.
9
Service Strat egy
Service Strategy
For repair, calibration, and to ensure the N2790A performs to its warranted
specifications, send the probe to an Agilent Service Center for calibration testing
procedures. The probe should be tested once a year or as required by other standards.
If repair is needed and the N2790A is under warranty, normal warranty services will
apply. If the N2790A is not under warranty, repair costs will be applied.
To return the Probe to Agilent Technologies for Service
Call (877) 477-7278 for further details and the location of your nearest Agilent
Technologies Service Office.
1 Write the following information on a tag and attach it to the probe.
• Name and address of the owner
• Probe model number
• Description of service required or failure indication
2 Retain all accessories.
3 Return the probe in its case or pack the probe in foam or other
shock-absorbing material and place it in a strong shipping container. You can
use the original shipping materials or order materials from an Agilent
Technologies Sales Office. If neither are available, place 3 to 4 inches of
shock-absorbing material around the instrument and place it in a box that does
not allow movement during shipping.
4 Seal the shipment container securely.
5 Mark the shipping container as FRAGILE. In all correspondence, refer to the
instrument by model number and full serial number.
10
Characterization Plots
10
6
10
7
10
8
-9
-6
-3
0
3
6
Vout/Vin
Vin
Vout
BW(-3dB) = 147
10
7
10
8
-80
-70
-60
-50
-40
-30
Characterization Plots
Graph of dB(Vin), dB(Vout), and dB(Vout/Vin) frequency response
Graph of dB (Vout/Vin) frequency response when inputs driven in common
(common mode rejection)
11
Characterization Plots
Derating plot - above 2 MHz, the maximum input operating voltage decreases
as the frequency increases.
12
Performance Verification Procedures
Performance Verification Procedures
The following procedure can be used to test and verify the DC differential gain accuracy
and bandwidth of the N2790A high voltage differential probe.
Required Test Equipment
Description Critical Specifications Recommended Model
Digitizing Oscilloscope Bandwidth: >100 MHz
Signal Generator
Precision DC voltage
source
BNC Adapter BNC (f) to Dual Banana (m)
50 BNC Feed Through
Adapter
1 M/50 selectable input
Amplitude accuracy: greater
than or equal to 0.25%
1 M/50 selectable load
Sine wave greater than or equal
to 25 MHz
Adapter
50 precision feed through Agilent 11048C Termination between
Part Number
Agilent MSO9254A Display probe output
Fluke 9500B or Fluke
5520A for DC source.
Fluke 9500B or Agilent
E8257D +1EU option for
AC source
Agilent 1251-2277 Interconnection
DC Differential Gain Accuracy
WARNING: These procedures require the application of high voltage to the
inputs of the N2790A probe. Because the adapter used in this procedure has
exposed metal surfaces, only qualified personnel should perform any testing with
voltage levels exceeding 30 V rms. All pertinent safety rules and guidelines for
elevated voltage measurements should be followed and adhered to.
WARNING: Generator produces hazardous voltages. To avoid risk of shock, do
not touch exposed metal parts after the generator output is enabled.
1 Set the volts/division on channel 1 of the oscilloscope to 20 mV/div. Set the seconds/
div to 200 s and the acquisition mode to average 32.
2 Set the volts/division on channel 2 of the oscilloscope to 50 mV/div. Trigger on channel
2, select 50 impedance.
3 Set the calibrator 9500B’s channel 2 as the trigger channel (50 load). Connect the
calibrator’s channel 2 active head to channel 2 of the oscilloscope.
4 Connect the active head channel 1 from the Fluke 9500B to channel 1 of the
oscilloscope. Set the calibrator channel 1 to 0.1V peak-to-peak amplitude and 1 KHz
(square wave, 1 M load), enable the output.
Functions
Signal source for DC
gain and bandwidth
between probe and
generator
probe and calibrator
for bandwidth
verification
13
Performance Verification Procedures
5 Select the amplitude measurement on the oscilloscope and record the DC amplitude
(approximately 100 mV) of the square wave. This measurement is only the
oscilloscope.
6 Disable the Fluke calibrator output, disconnect the channel 1 active head from channel
1 of the oscilloscope.
7 Connect the output of the N2790A probe to channel 1 of the oscilloscope.
8 Attach the BNC adapter to the Fluke channel 1 active head.
9 Attach the differential probe input leads by clipping the alligator clamp to the BNC
adapter banana post.
10 Set the probe to 50:1. Set the Fluke calibrator to 10 V and 1 KHz standard amplitude
output (channel 1, square wave, 1 M load).
11 Enable the output of the calibrator.
12 Record the DC amplitude of the square wave and divide 50 into just the amplitude of
the oscilloscope. Verify that the probe gain accuracy is +/-2% + sc ope gain accuracy.
13 Set the calibrator to 100 V output and set the attenuation button on the probe to 500:1.
14 Record the DC amplitude of the square wave and divide 500 into just the amplitude of
the oscilloscope. Verify that the probe gain accuracy is +/-2% + scope gain accuracy.
15 Disable the calibrator output and leave the setup connected for the next procedure.
Bandwidth
1 Connect the 50 BNC feed through adapter to the calibrator’s active head channel 1.
2 Attach the BNC (f)-to-banana post adapter to the BNC feed through adapter.
3 Attach the differential probe input leads by clipping the alligator clamp to the BNC
adapter banana post.
4 Set the probe to 50:1 attenuation.
5 Set the volts/division on channel 1 of the oscilloscope to 10 mV/div and seconds/
division to 20 ns/div. Set the trace to the center of the oscilloscope. Input impedance
shoudl be set to 1 . Disable average mode.
6 Set the calibrator to sine wave, 5 V peak-to-peak amplitude. Set the frequency to 100
MHz, 50 load.
7 Write down the peak-to-peak amplitude measured by the oscilloscope. It should be
greater than or equal to 71 mV + scope error.
8 Disable the generator output and disconnect the probe input.
14
Performance Verification Test Record
Performance Verification Test Record
Agilent Technologies
Recommended Test Interval: 1 Year
Recommended Date of Next Certification:_________
Certification Temperature:_____________________
N2790A 100 MHz Differential Probe
Serial No.:_______________________
Certification Date:_________________
Tested By:_______________________
_______________________________
_______________________________
Test Probe Settings Limits Results
Gain 50:1 196 mV to 204 mV
Gain 500:1 196 mV to 204 mV
Bandwidth 50:1 Greater than or equal to 71 mV
15
Performance Verification Test Record
16
Safety
!
Notices
This apparatus has been
designed and tested in
accordance with IEC Publi
cation 1010, Safety Requirements for Measuring
Apparatus, and has been
supplied in a safe condi
tion. This is a Safety Class I
instrument (provided with
terminal for protective
earthing). Before applying
power, verify that the cor
rect safety precautions are
taken (see the following
warnings). In addition, note
the external markings on
the instrument that are
described under "Safety
Symbols."
Warnings
• Before turning on the
instrument, you must con
nect the protective earth terminal of the instrument to
the protective conductor of
the (mains) power cord. The
mains plug shall only be
inserted in a socket outlet
provided with a protective
earth contact. You must not
negate the protective action
by using an extension cord
(power cable) without a pro
tective conductor (grounding). Grounding one
conductor of a two-conductor outlet is not sufficient
protection.
• Only fuses with the
required rated current, volt
age, and specified type (normal blow, time delay, etc.)
should be used. Do not use
repaired fuses or shortcircuited fuseholders. To do
so could cause a shock or
fire hazard.
• If you energize this instrument by an auto transformer (for voltage
reduction or mains isola
tion), the common terminal
must be connected to the
earth terminal of the power
source.
• Whenever it is likely that
the ground protection is
impaired, you must make
the instrument inoperative
and secure it against any
unintended operation.
• Service instructions are for
trained service personnel.
To avoid dangerous electric
-
-
-
-
shock, do not perform any
service unless qualified to do
so. Do not attempt internal
service or adjustment unless
another person, capable of
rendering first aid and
resuscitation, is present.
• Do not install substitute
-
parts or perform any unau
thorized modification to the
instrument.
• Capacitors inside the
instrument may retain a
charge even if the instru
ment is disconnected from
its source of supply.
• Do not operate the instrument in the presence of
flammable gasses or fumes.
Operation of any electrical
instrument in such an envi
ronment constitutes a definite safety hazard.
• Do not use the instrument
in a manner not specified by
the manufacturer.
To clean the instrument
If the instrument requires
cleaning: (1) Remove power
from the instrument. (2)
Clean the external surfaces
of the instrument with a soft
cloth dampened with a mix
ture of mild detergent and
water. (3) Make sure that
the instrument is com
pletely dry before recon-
necting it to a power source.
-
Safety Symbols
Instruction manual symbol: the product is marked
with this symbol when it is
necessary for you to refer to
-
the instruction manual in
order to protect against
damage to the product..
-
Hazardous voltage symbol.
Earth terminal symbol:
Used to indicate a circuit
common connected to
grounded chassis.
-
-
Agilent Technologies
P.O. Box 2197
1900 Garden of the Gods Road
Colorado Springs, CO 80901
Notices
© Agilent Technologies, Inc.
2010
No part of this manual may
be reproduced in any form
or by any means (including
electronic storage and
retrieval or translation into
a foreign language) without
prior agreement and writ
ten consent from Agilent
Technologies, Inc. as governed by United States and
international copyright
laws.
Manual Part Number
N2790-97002, December
2010
Print History
N2790-97002, Dec 2010
N2790-97001, August 2010
N2790-97000, January 2009
Agilent Technologies, Inc.
1900 Garden of the Gods
Road
Colorado Springs, CO
80907 USA
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WARNING
A WARNING notice
denotes a hazard. It
calls attention to an
operating procedure,
-
practice, or the like
that, if not correctly
performed or adhered
-
to, could result in
personal injury or
death. Do not proceed
-
beyond a WARNING
notice until the
-
indicated conditions
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CAUTION
-
A CAUTION notice
-
denotes a hazard. It
calls attention to an
operating procedure,
practice, or the like
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performed or adhered
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damage to the
product or loss of
important data. Do
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CAUTION notice
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vided “as is,” and is subject to being changed,
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Agilent Technologies
Printed in the Japan
Manual Part Number
N2790-97002
*N2790-97002*
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