Agilent Technologies N2893A User manual


Agilent N2893A
100 MHz Current
Probe
User’s Guide
Publication number N2893-97000
January 2011
For Safety information, Regulatory information, and
publishing information, see the pages at the end of
this book.
© Copyright Agilent Technologies 2011
All Rights Reserved.

2
N2893A 100 MHz Current Probe Introduction
TheN2893A is a wide-band, DC to 100 MHz, active currentprobe. The probe
featureslownoiseandlowcircuitinsertionloss.ItalsofeaturestheAutoProbe
interface which makes current measurements as simple as those made with
active voltage probes.
The N2893A has two operating regions that provide a wide, flat frequency
response. In the DC to low frequency AC region, the probe operation is based
on the negative feedback of the amplifier system that includes the thin film
Hall element as a detector. In the high frequency region, the probe operates
as a current transformer.
The N2893A is ideal for acquiring high transient time signals such as those
found in Motor Controllers, in Switching Power Supplies, and in Current
Amplifiers driving inductive loads.
In order to use this product effectively and to ensure a long operational life,
read this User’s Guide carefully and retain it for future reference.
Features
• Highly accurate current detection
• Easy current measurement
• Broadband frequency characteristics DC to 100 MHz
• Compact
• Permits measurement of low current levels
• Easy protect function at excessive input
Scope Compatibility
• 5000,6000(except100MHzmodels),and7000 Series oscilloscopes with software
version 6.10 or higher
• 9000A Series with software version 3.0 or higher
• 90000 X-Series with the N5449A adapter
Inspection
When the unit is delivered, check and make sure that it has not been damaged
in transit. If the unit is damaged, or fails to operate according to the
specifications, contact your dealer or Agilent representative.

3
Contents
Note on Safety 4
Safety Symbols 4
Safety Considerations 5
Description of Parts 7
Characteristics and Specifications 9
Measurement Characteristics 9
Power Supply Characteristics 9
Mechanical Characteristics 10
Environmental Characteristics 10
Plots 11
Preparations for Measurement 13
Demagnetization Procedure 14
Demagnetization and Zero Offset Procedure 14
Measurement Procedure 14
Service Strategy 18
To return the Probe to Agilent Technologies for Service 18
Calibration Testing Procedures 19
Test Equipment Required 19
Preliminary procedure 19
(1) AC Accuracy 20
Calibration Test Record 21

4
Note on Safety
Note on Safety
This equipment is designed according to IEC 61010-1 Safety Standards, and has been
tested for safety prior to shipment. Incorrect measurement procedures could result in
injury or death, as well as damage to the equipment. Please read this manual carefully
and be sure that you understand its contents before using the equipment. The
manufacturerdisclaimsallresponsibilityforanyaccidentorinjuryexceptthatresulting
due to defect in its product.
Safety Symbols
This User’s Guide provides information and warnings essential for operating this
equipment in a safe manner and for maintaining it in safe operating condition. Before
using this equipment, be sure to carefully read the following safety notes.
ThefollowingsymbolsareusedinthisUser’sGuidetoindicatetherelativeimportance
of cautions and warnings.
Caution refer to accompanying documents.
Indicates DC (Direct Current) or AC (Alternating Current).
Indicates that incorrect operation presents extreme danger of
accident resulting in death or serious injury to the user.
Indicates that incorrect operation presents significant danger of
accident resulting in death or serious injury to the user.
Indicates that incorrect operation presents possibility of injury
to the user or damage to the equipment.
Denotesitemsofadvicerelatedtoperformanceoftheequipment
or to its correct operation.
WARNING
DANGER
WARNING
CAUTION
NOTE

5
Safety Considerations
Safety Considerations
Only trained service personnel who are aware of the hazard involveds (for example,
fire and electric shock) should perform maintenance on the instrument. When
maintenance can be performed without power applied, the power cord must be
disconnected from the instrument.
To ensure safe operation and to obtain maximum performance from the unit, observe
the cautions listed below.
•To avoid short circuits and accidents that could result in injury or death, use the
N2893A only with power lines carrying 300 V or less.
• When conductors being measured carry in excess of the safe voltage level (SELV-
E) and not more than 300 V, to prevent short circuits and electric shock while the
core section is open, make sure that conductors to be measured are insulated with
material conforming to (1) Overvoltage Category I, (2) Basic Insulation
Requirements for Working Voltages of 300 V, and (3) Pollution Degree 2. Never
use this sensor on bare conductors, the core and shield case are not insulated. If a
bare conductor is inevitable to be measured, make sure that the power to the wire
must be turned off, when opening the jaws of the probe to insert or remove the bare
wire so that 300V CAT I is always satisfied.
• Avoid damaging the cable insulation surfaces while taking measurements.
• This instrument is only made for use withthe Infiniium. Do not plug the probe into
anyinterfaceotherthantheAutoProbeinterface,ofwhichInfiniiumhasaprotective
earthing with double-insulation construction.
• Take the following precautions to ensure that the Infiniium does not form a bridge
between the probe and any hazardous live part.
1Isolate the AutoProbe interface to which the probe is connected from other
AutoProbe interfaces using basic insulation conforming to the overvoltage
category, working voltage, and pollution degree requirements of the circuit
being tested.
2Ifbasic insulationrequirements cannot be metbetween the AutoProbe interface
to which this unit is connected and otherAutoProbe interfaces of the measuring
instrument, make sure that the voltage input to the AutoProbe interfaces does
not exceed the safe voltage level (SELV-E).
3Read and observe all warnings and precautions relating to electrical safety for
the Infiniium.
• Refer to the following standards regarding the meanings of underlined terms.
IEC61010-1
IEC61010-2-031
IEC61010-2-032
•To prevent electric shock, do not allow the unit to become wet and do not use the
unit when your hands are wet.
•Do not subject the unit to vibrations or shocks during transport or handling. Be
especially careful to avoid dropping the unit.
WARNING
DANGER
WARNING
CAUTION

6
Safety Considerations
• Do not store the unit where it will be exposed to direct sunlight, high temperature,
high humidity, or condensation. If exposed to such conditions, the unit may be
damaged, the insulation may deteriorate, and the unit may no longer satisfy its
specifications.
• Before using the unit, inspect it and check the operation to make sure that the unit
was not damaged due to poor storage or transport conditions. If damage is found,
contact your dealer or Agilent representative.
• This unit is not constructed to be waterproof or dustproof, so do not use it in a very
dusty environment or in one where it will get wet.
• The sensor head is a precision assembly including a molded component, a ferrite
core, and a Hall effect element. It may be damaged if subjected to sudden changes
in ambient temperature, or mechanical strain or shock, and therefore great care
should be exercised in handling it.
• The matching surfaces of the sensor head are precision ground, and should be
treated with care. If these surfaces are scratched, performance may be impaired.
• Do not bend or pull the sensor cable and power supply cable in order to avoid
damaging the sensor cables.
• Gently wipe dirt from the surface of the unit with a soft cloth moistened with a
small amount of water or milddetergent. Do not try to clean the unit using cleaners
containing organic solvents such as benzine, alcohol, acetone, ether, ketones,
thinners, or gasoline. They may cause discoloration or damage.
• To avoid scratching the surfaces of the Hall effect elements, keep the core section
ofthesensorclosed,exceptwhenclampingit around theconductortobemeasured.
•Accurate measurement may be impossible in locations subject to strong external
magnetic fields, such as transformers and high-current conductors, or in locations
subject to strong external electric fields, such as radio transmission equipment.
NOTE

7
Description of Parts
Description of Parts
1Opening lever
Operating lever for opening the sensor head. Always use this lever to open the sensor
head.
2Sensor head
This clamps the conductor being measured, and carries out the actual current
measurement. It is a precision assembly including a molded component, a ferrite core,
andaHalleffectelement.Itmaybedamagedifsubjectedtosuddenchangesinambient
temperature, or mechanical strain or shock. Care should be exercised when handing
the sensor head.
3Demagnetizing switch (DEMAG)
This demagnetizes the core if it has been magnetized by switching the power on and
off, or by an excessive input. Always carry out demagnetizing before measurement.
The demagnetizing process takes about one second. During demagnetizing, a
demagnetizing waveform is output.
4Coarse adjustment trimmer
This adjustment should only be carried out if the probe offset is outside the range of
the zero adjustment.
Current direction indication
"UNLOCK" indication
Sensor Terminator
Sensor cable
1
2
34
5

8
Description of Parts
•The output of this unit is terminated internally. The high-impedance such as 1 M
input impedance will be automatically selected on the Infiniium, as the Terminator
ispluggedinto the AutoProbeinterface. With aninputimpedanceof 50 , accurate
measurement is not possible.
• The probe output sensitivity 0.1 V/A will be automatically selected, as the
Terminator is plugged into the AutoProbe interface. With an different output
sensitivity, accurate measurement is not possible.
NOTE

9
Characteristics and Specifications
Characteristics and Specifications
Measurement Characteristics
See note 1 below.
Power Supply Characteristics
Probe Bandwidth DC to 100MHz (-3 dB)
Accuracy (Probe Only)* ±1% of reading ±1mV
(DC or 45Hz to 66Hz)
Risetime2~ 7ns
Maximum continuous current 15A (DC + ACrms) continuous
(Refer to frequency derating curve, Fig. 2)
Maximum peak current 50A (for Pulse Widths ~10µs)
Probe sensitivity 0.1V/A
Noise ~2.5mArms(with 20MHz Bandwidth limiting)
Insertion impedance Refer to Fig. 3
Temperature coefficient ~±2% (0%C to 40%C)
Effect of external magnetic fields Equivalent to ~20mA (for a 400A/m magnetic
field, DC to 60Hz)
Maximum circuit voltage 300V Cat I (refer to safety considerations and
product compliances)

*This is a specification and is guaranteed at 23%C ±3%C (73%F ±5%F).
1. Requires 1MWtermination. Valid for 23%C ±3%C (73%F ±5%F), at least 30 minutes after power
on.
2. Rise time is calculated as: Tr = 0.35/Bandwidth.
DC supply voltage requirements ±12Vdc ±1V
Probe power consumption Increases with measured current.
3 VA when measuring 15 A

10
Characteristics and Specifications
Mechanical Characteristics
Environmental Characteristics
See note 3 below.
Maximum cable diameter 5 mm (0.2 inch)
Sensor cable length 1.5 m (59 inches)
Power cable length 1 m (39 inches)
Dimensions Sensor:


Terminator:
175 mm x 18 mm x 40 mm
6.89 in. x 0.71 in. x 1.6 in.

28 mm x 81 mm x 24 mm
1.1 in. x 3.2 in. x 0.94 in
Weight 210 g (7.4 oz.)
Accessories supplied storage case, calibration certificate
Operating temperature range 0%C to 40%C (32%F to 104%F)
Storage temperature range -10%C to 50%C (14%F to 122%F)
Maximum relative humidity
(operating or storage) 80% (no condensation)
Vibration 10 to 55 Hz:

55 Hz:
30 min/axis
10 octave/min
Amplitude 0.3 mm
30 min/axis
Amplitude 0.3 mm
Acceleration 17.91 m/s2
Maximum Altitude 2000 m

3. This probe is intended for indoor use only.

11
Plots
Plots
Frequency response of N2893A
Continuous maximum input rating of N2893A

12
Plots
Insert impedance of N2893A
Amplitude accuracy characteristic of N2893A

13
Measurement Procedure
Measurement Procedure
Preparations for Measurement
1Power on the oscilloscope.
2Connect the probe terminator to one of the scope channels.
Whentheprobeisconnectedtoascopechannel,theAutoProbeinterfacewillrecognize
the probe as an N2893A and will automatically make several settings on the channel
to which the probe is connected:
•This probe is NOT compatible with 50only Infiniium oscilloscopes (e.g. the
90000A series oscilloscopes) unless there is an adapter such as with the 90000 X-
Series.The input coupling is automatically selected to DC, as the terminator is
plugged into the AutoProbe interface.
NOTE

14
Measurement Procedure
Demagnetization Procedure
Referto theDescriptionofPartssectionofthismanualwhenperformingthisprocedure
1Allow both the Infiniium oscilloscope and the probe to warm up for at least
30 minutes before making these adjustments.
2Ensurethatthechanneloffsetissetto0Vontheoscilloscopechanneltowhich
the probe is connected.
3Ensure that the probe sensor is NOT clamped around any conductors.
4Slide the probe sensor Opening Lever into the Locked position.
5Press the DEMAG button on the terminator.
Ademagnetizationwaveformwillbedisplayedforashorttimeonthechanneltowhich
the probe is connected. Wait until this waveform is no longer displayed.


Demagnetization and Zero Offset Procedure
1For InfiniiVision Oscilloscopes: Press the input channel button (1, 2, 3, or
4) on the front panel of the oscilloscope forthe channel you are using and then
press the Probe softkey under the display. You will then see a softkey for
automatically setting the demagnetization and offset. Press this key. The
oscilloscope will then guide you through the process. 

For Infiniium Oscilloscopes: In the Infiniium application, go to Setup >
Probes and click the button in the GUI to automatically start the
demagnetizationandzerooffsetprocess.TheGUIwillthenguideyouthrough
the procedure. 
Measurement Procedure

Ensure all safety warnings and precautions are followed.
1Perform the Demagnetization and Zero Adjustment procedure above.
2Clamp the sensor head around the conductor to be measured.
3To obtain the best accuracy, ensure that:
aThe current direction indicator on the sensor aligns with actual current direction in
the conductor.
bThe sensor opening lever is in the Locked position
cThe cable is centered in the sensor head.
CAUTION

15
Measurement Procedure
•The maximum continuous input range is based on heat that is internally generated
duringmeasurement.Neverinputcurrentinexcessofthislevel.Exceedingtherated
level may result in damage to the probe.
• The maximum continuous input range varies according to the frequency of the
current being measured. See figure 2 in “Characteristics and Specifications”
• If excess current is input, generated heat activates a built-in safety function that
blocks normal output. If this happens, remove the input immediately (unclamp the
sensorfrom the conductorbeingmeasuredorreducetheinputcurrenttozero).Wait
until the sensor has had sufficient time to cool before resuming operation.
• Even if the input current does not exceed the rated continuous maximum,
continuousinputforanextendedperiodoftimemayresultinactivationofthesafety
circuit to prevent damage resulting from heating of the sensor.
• At high ambient temperatures, the built-in safety circuit may activate at current
input levels below the rated continuous maximum.
• Continuous input of current exceeding the rated maximum or repeated activation
of the safety function may result in damage to the unit.
• When opening the sensor head of the probe, be sure to operate with the opening
lever. If an upper core is forced to open when the sensor head is locked, the open-
close mechanism can be damaged.
• DoNOTmeasurecurrentsuchthatthetotalprobe currentconsumptionexceedsthe
allowable AutoProbe interface current consumption. The excess current
consumptioncausesatemporaryshutdownoftheInfiniiumpowersupplyforsafety.
Quitthemeasurementand cyclethepowerofthe Infiniium, if theshutdownoccurs.
The typical probe current consumption from the AutoProbe interface is shown in
figure 4.
WARNING
Do not Press Upper core Lock state

16
Measurement Procedure
•Immediately after powering on, this unit may be subject to an appreciable offset
drift due to the effect of self-heating. To counteract this, allow the unit to warm up
for about 30 minutes before carrying out measurement.
• When performing continuous measurements, it is necessary to be aware that the
zero offset voltage will drift if the ambient temperature changes.
• Under certain circumstances, oscillation may occur if the probe is connected to the
AutoProbeinterfacewhiletheInfiniiumison.Thisdoesnotindicateamalfunction.
Oscillationcan be stoppedandoperation restored tonormalby opening andclosing
the sensor head.
• At some frequencies, somesound may be produced by resonance, this has noeffect
on measurements.
• Measurement accuracy is affected by the position of the conductor being measured
within the clamp aperture. The conductor should be in the center of the clamp
aperture.
• Before making a measurement, press the opening lever until the "UNLOCK"
indicationdisappearsandcheckthatthesensorheadisproperlyclosed.Ifthesensor
head is not properly closed, accurate measurement will not be possible.
• Accurate measurement may be impossible in locations subject to strong external
magnetic fields, such as transformers and high-current conductors, or in locations
subject to strong external electric fields, such as radio transmission equipment.
• At high frequencies, common mode noise may affect measurements taken on the
high voltage side of circuits. If this occurs, reduce the frequency range of the
waveform measuring instrument or clamp onto the low-voltage side of the circuit
(as shown in figure 5), as appropriate.
Current to be measured [A]
Current consumption [mA]
0 5 10 15
0
100
200
300
400
AC (f=50Hz)
DC
Figure 4. Typical probe consumption
NOTE

17
Measurement Procedure
High
Low
Power
Source Load
Figure 5. Low-voltage side of the circuit

18
Service Strategy
Service Strategy
For calibration testing, return the N2893A probe to an Agilent Service Center. If the
probe is under warranty, normal warranty services apply. If the probe is not under
warranty, replacement costs will be applied.
To return the Probe to Agilent Technologies for Service
Call [phone] for further details and the location of your nearest Agilent
Technologies Service Office or go to www.agilent.com for contact information.
1Write 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 indications
2Retain all accessories.
3Return 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-absorbingmaterialaroundtheinstrumentandplaceitin a box that does
not allow movement during shipping.
4Seal the shipping container securely.
5Mark the shipping container as FRAGILE. In all correspondence, refer to the
instrument by model number and full serial number.

19
Calibration Testing Procedures
Calibration Testing Procedures
These procedures are used to test the warranted specifications for the N2893A
Differential Probe. The recommended calibration test interval for the N2893A is once
a year or as required. Use the equipment listed in the “Test Equipment Required”
section to complete the Calibration Testing Procedure.
Test Equipment Required
Preliminary procedure
1Turn on the oscilloscope and then connect the N2893A probe to the it. Turn
on the other equipment.
2Wait 30 minutes to warm up the equipment.
Description Minimum Requirements Recommende
d test
equipment
Used at
Infiniium Bandwidth 250 MHz
Amplitude accuracy: ~0.4
%
Any
oscilloscope
with 1M
input
(1), (2), (3),
(4)
Current loop wire 16AWG, Convenientlength 30 cm (1)
AC current
generator AC 10 Arms, 50 Hz, sine wave
Amplitude accuracy: ~0.3
%
Wavetek 9100 (1)
50current loop N2774-23801 (4)

20
Calibration Testing Procedures
(1) AC Accuracy
1Press the DEMAG button on the Terminator.
2Connect the wire to the current terminals of the AC current generator.
3Clamp the wire with the N2893A and lock the sensor head.
4Set the Infiniium setups as follows:
Averaging: 16
Time: 5 ms/div
Vertical axis: 5 A/div
Trigger level: 0 mV
Trigger slope: Rise
Measurement mode: Vrms (Voltage)
Measurement Area: Entire Display
RMS Type: AC
Other setups: APPROPRIATE
5Set the Generator setups to AC 10 Arms, 50 Hz, and sine wave.
6Generate the wave, measure the current and record it.
7Remove the wire and the generator from the N2893A.
AC current generator Infiniium with
1MΩinput
Current Probe
1147A
Current loop
wire