AEMC 721 User manual

11/03
99-MAN 100066 v2
Chauvin Arnoux®, Inc. d.b.a. AEMC®Instruments
15 Faraday Drive • Dover, NH 03820 USA • Phone: [phone] • Fax: [phone]
www.aemc.com • www.chauvin-arnoux.com
ICLAMP-ON HARMONIC METER
ENGLISH User Manual
721
600V
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Model 721
HARMONIC METER
HOLD
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PEAK
SMOOTH Hz RANGE THD
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RECORD-PAUSE MAX MIN AVG
SMOOTH RANGE
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DF
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TABLE OF CONTENTS
1. INTRODUCTION ..............................................................3
1.1 Receiving Your Shipment..........................................................4
1.2 Ordering Information.................................................................4
2. PRODUCT FEATURES .....................................................5
2.1 Description................................................................................5
2.2 Control Features .......................................................................7
2.3 Digital Display Features............................................................8
2.3.1 Display and Error Indications........................................9
3. SPECIFICATIONS ..........................................................10
3.1 Electrical Specications ..........................................................10
3.2 General Specications............................................................12
3.3 Mechanical Specications ......................................................12
3.4 Safety Specications ..............................................................13
4. UNDERSTANDING ELECTRICAL HARMONICS .............14
4.1 Detection and Measurement...................................................20
4.2 Effects on the System.............................................................21
4.3 Transformer Derating..............................................................22
4.4 Meter Readings ......................................................................23
4.5 Crest Factor ............................................................................23
4.6 Limiting the Effects of Harmonics ...........................................24
5. OPERATION ..................................................................25
5.1 Current Measurements ..........................................................25
5.1.1 Ranging ......................................................................26
5.1.2 Analog Output – Vout..................................................26
5.1.3 Other Functions ..........................................................26
5.1.4 Bargraph .....................................................................26
5.2 Voltage Measurements ...........................................................27
5.2.1 Ranging ......................................................................28
5.2.2 Other Functions ..........................................................28
5.2.3 Bargraph .....................................................................28

5.3 THD Push Button: Power Quality Measurements...................29
5.3.1 %THD: Total Harmonic Distortion ...............................29
5.3.2 %DF: Distortion Factor ..............................................31
5.3.3 CF: Crest Factor .........................................................32
5.3.4 Bargraph .....................................................................32
5.4 Range Push Button: Manual Ranges .....................................33
5.5 Hz Push Button: Frequency Measurement.............................34
5.6 Peak/Smooth Push Button......................................................35
5.6.1 Smooth .......................................................................35
5.6.2 Peak............................................................................36
5.7 MIN/MAX Push Button: Recording Function...........................36
5.8 Vout – Analog Output..............................................................38
5.8.1 Output Level ...............................................................39
5.9 Summary of Accessible Functions..........................................39
5.10 Auto-Off Feature .....................................................................40
5.11 Troubleshooting ......................................................................40
6. MAINTENANCE .............................................................41
6.1 Cleaning..................................................................................41
6.2 Battery Test & Replacement ...................................................41
6.2.1 Battery Replacement ..................................................42
Repair and Calibration...........................................................................43
Technical and Sales Assistance ............................................................43
Limited Warranty ...................................................................................44
Warranty Repairs...................................................................................44

Harmonic Meter Model 721 3
CHAPTER 1
INTRODUCTION
Warning
These safety warnings are provided to ensure the safety of personnel and
proper operation of the instrument.
• Read this instruction manual completely before attempting to use or ser-
vice this instrument and follow all the safety information.
• Use caution on any circuit: Potentially high voltages and currents may be
present and may pose a shock hazard.
• The meter must not be operated beyond its specied operating range.
• Safety is the responsibility of the operator.
• Never open the back of the meter while connected to any circuit or input.
• Always make connections from the instrument to the circuit under test.
• Always inspect the instrument and accessory leads for serviceability prior
to use, and replace defective parts immediately.
• Do not use the meter or any test leads, BNC leads, connectors, probes or
clips if they look damaged.
• Never use the meter on electrical conductors rated above 600Vrms.
International Electrical Symbols
This symbol signies that the instrument is protected by double or
reinforced insulation. Use only specied replacement parts when
servicing the instrument.
This symbol on the instrument indicates a WARNING and that
the operator must refer to the user manual for instructions before
operating the instrument. In this manual, the symbol preceding
instructions indicates that if the instructions are not followed, bodily
injury, installation/sample and product damage may result.
Risk of electric shock. The voltage at the parts marked with this
symbol may be dangerous.

4 Harmonic Meter Model 721
1.1 Receiving Your Shipment
Upon receiving your shipment, make sure that the contents are consis-
tent with the packing list. Notify your distributor of any missing items. If
the equipment appears to be damaged, le a claim immediately with the
carrier and notify your distributor at once, giving a detailed description of
any damage. Save the damaged packing container to substantiate your
claim.
1.2 Ordering Information
Harmonic Meter Model 721............................................... Cat. #1208.52
Includes a 9V battery, two 5 ft (1.5m) leads, two test probes, two grip
probes, one insulated banana to BNC connector, a user manual and a
hard carrying case.

Harmonic Meter Model 721 5
CHAPTER 2
PRODUCT FEATURES
2.1 Description
The Harmonic Meter Model 721 combines the simplicity and familiarity
of digital clamp-ons with today’s critical information on power quality and
harmonics.
Operation is simple and direct, with no menus, calculations or complex
analyzer procedures. Select Amps or Volts on the rotary dial, connect, and
measure. The push of a button gives additional or more specic informa-
tion. You can troubleshoot and measure power quality with the ease of
using a digital clamp-on — simply, safely, and economically.
The Model 721 performs current and voltage measurements in True RMS,
and provides immediate readings of total harmonic distortion (%THD), dis-
tortion factor (%DF), crest factor (CF) and Peak of distorted currents and
complex voltages. It also gives the minimum, maximum, maximum Peak
and average measurement values so you can record for over 24 hours to
monitor daily uctuations. And, you can measure frequency (Hz) through
either the current or the voltage at any time.
In addition, the instrument’s analog output allows display of the current
waveforms on any oscilloscope or hand-held scope while measuring; or
the output may be used for loggers and recorders.
The Model 721 incorporates True RMS electronics and measurement
techniques to ensure correct and accurate readings on distorted wave-
forms. Use the Model 721 as a comprehensive tool for troubleshooting
as well as for daily measurements on circuits supplying traditional and
today’s nonlinear loads.
Beyond the absolute product ruggedness and overall design qualities
—the Model 721 is built with GE Lexan® and meets specic physical
standards — the instrument features a high level of safety. The Model 721
meets IEC 1010-1 Category III for 600 V ratings.

6 Harmonic Meter Model 721
The Model 721 is comfortable to hold, compact and easy to maneuver in
crowded breaker panels. The hooked jaw design facilitates clamping and
accommodates two 500 MCM conductors.
The AEMC Harmonic Meter Model 721 works as easily as a clamp-on mul-
timeter, while permitting True RMS voltage and current measurements.
The rotary switch selects the volt or ampere range and, beneath the large
LCD, ve push buttons provide direct access to additional key measure-
ment and power quality values.
The Model 721 high sensitivity accepts low input levels (300 mA and 300
mV) permitting power quality measurements on even low power or idling
equipment — an advantage not common to many instruments.

Harmonic Meter Model 721 7
2.2 Control Features
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1. Jaw assembly
Transformer jaws opens to 1.7" (43 mm)
Accepts two 500 MCM
2. Lever/Trigger
Opens or closes jaws
3. Display
Liquid crystal display, 9999 count
4. Min/Max
Selects Record mode for A, V, %THD, %DF, CF, Hz
Accesses the following values: Max, Min, AVG

8 Harmonic Meter Model 721
5. Peak/Smooth
Accesses the following modes:
• Smooth for 3-second averaging for easy readings on uctuating
signals.
• Peak measurement values (1 ms) for A and V
6. Hold/Data Hold
• Freezes last measured value on display
• Does not freeze bargraph or analog output
7. Rotary selection switch
OFF, Amps/Vout, Volts
8. Hz
Selects frequency measurement (A or V input)
9. THD
Accesses (in A or V) the following measurement modes:
• %THD (Total Harmonic Distortion referenced to the fundamental)
• %DF (Distortion Factor: THD referenced to RMS)
• CF (Crest Factor)
10. Range
Selects Auto Ranging or Manual Ranging measurement ranges
(A or V)
11. Voltage Jacks and Analog Output Vout
“COM” : black
“+” : red
2.3 Digital Display Features
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The combination digital/analog display gives measurements on a large
9999 count (3 digit) LCD display. A fast responding analog bargraph
display provides indications for trends or surges.
A Displayed when instrument is measuring TRMS amperes
V Displayed when instrument is measuring TRMS voltage

Harmonic Meter Model 721 9
Indicates that internal battery requires replacement
SMOOTH Indicates three second measurement averaging to
smooth uctuating signals
RANGE Displayed during manual range selection
HOLD Displayed when Hold function is activated
RECORD Blinks (1/second) during record mode
PAUSE Interrupts recording mode when Hold is activated in the
Record Mode
MAX Displays maximum measurement value
MIN Displays minimum measurement value
AVG Displays average measurement value
%THD % Total Harmonic Distortion
%DF % Distortion Factor
CF Crest Factor
PEAK Peak (1 ms) measurement (MAX Peak is available in
the recording mode)
Auto-Off feature disabled
Bargraph Analog bargraph for trend measurements A or V and
remaining battery life at power-up
2.3.1 Display and Error Indications
OL-- Input overload: > 999.9 V peak or > 999.9 A peak
– – – Input signal below measurement range
Input exceeds safety, measurement or operating range. The warn-
ing triangle is accompanied by a beeping alarm. Discontinue mea-
surement and refer to the specic function and specication section
in user manual.
Please note that the warning triangle will also be displayed if the
input signals are too low, or if the fundamental signal is not 50 or
60Hz.

10 Harmonic Meter Model 721
CHAPTER 3
SPECIFICATIONS
3.1 Electrical Specications
Reference Conditions: Accuracies are provided under the following reference conditions:
Temperature 23°C ± 5K, 45% to 75% RH; battery voltage 8.5V to 9V; conductor centered in
the probe jaws; DC magnetic eld: earth’s eld; no external AC magnetic eld; no external
electrical eld; sine wave 45 to 65 Hz. In Peak, basic accuracy is based on 1 ms samples and
on a signal from 10 to 500 Hz. In THD and DF, the basic accuracy is provided for a square
wave and a triangular wave with 50% duty cycle at 50 or 60 Hz. R refers to Reading and ct(s)
to count(s). Counts may also be referred to as the least signicant digits (LSD).
CURRENT (TRMS)
Input Range: 0.05 to 700.0 Arms (±999.9 A Peak)
Basic Accuracy: 0.3 to 99.99 A: 2% R ± 20 cts
100.0 to 400.0 A: 2% R
400.0 to 700.0 A: 5% R
Crest Factor: >3.0 below 300 A
Frequency Range: 15 Hz to 10 kHz
CURRENT (PEAK)
Input Range: 0.05 to ± 999.9 A Peak
Basic Accuracy: 0.05 to 99.99 A: 3% R ± 30 cts
100 to 600 A: 3% R
600 to 999.9 A: 8% R
VOLTAGE (TRMS)
Input Range:
0.05 to 600 Vrms (± 1200 V Peak)
Basic Accuracy: 0.3 to 400.0 V: 1.5% R ± 4 cts
400.0 to 999.9 V: 1.5% R
Crest Factor: >4.0 below 300 V
Input Impedance: 1 MΩ, 47 pF
Frequency Range: 15 Hz to 10 kHz

Harmonic Meter Model 721 11
VOLTAGE (PEAK)
Input Range: 0.05 to 999.9 V Peak
Basic Accuracy: 0.05 to 99.99 V: 3% R ± 30 cts
100 to 999.9 V: 3% R
TOTAL HARMONIC DISTORTION (%THD)
Range: 0.5% to 600.0%
Resolution: 0.1%
Minimum Input: 300 mA, 300 mV
Basic Accuracy (50/60 Hz): 3% ± 2 cts
Frequency Range: Fundamental 45 to 65 Hz, 25th harmonic
Display: Digital - %THD; Bargraph - True RMS (A or V)
DISTORTION FACTOR (%DF)
Range: 0.5% to 100%
Resolution: 0.1%
Minimum Input: 300 mA, 300 mV
Basic Accuracy (50/60 Hz): 3% R ± 2 cts
Frequency Range: Fundamental 45 to 65 Hz, 25th harmonic
Display: Digital - %DF; Bargraph - True RMS (A or V)
CREST FACTOR (CF)
Range: 1.00 to 10.00
Resolution: 0.01
Minimum Input: 300 mA, 300 mV
Accuracy (40 to 450 Hz): 10% ± 3 cts
Frequency Range: 15 Hz to 10 kHz
Display: Digital - CF; Bargraph - True RMS (A or V)
FREQUENCY (Hz)
Range: 0.5 to 9999 Hz
Minimum Input: 1 A or 1 V
Accuracy: 0.5 Hz to 999.9 Hz: 0.1% R ± 1 ct
1000 Hz to 9999 Hz: 0.2% R ± 1 ct
Display: Digital - Hz; Bargraph - True RMS (A or V)

12 Harmonic Meter Model 721
ANALOG OUTPUT (Vout)
Range: 1 mV/A (0.05 to 700 Arms) or,
10 mV/A (0.05 to 60 Arms)
Basic Accuracy: 3%
Input: 0.05 A to 999.9 A Peak
Output Impedance: 4 kΩ, 47 pF
Display: Digital - all A and THD functions; Bargraph - Arms
3.2 General Specications
Power Source: 9 V Alkaline battery (NEDA 1604, 6LF22, 6LR61)
Power Source Life: 50 hr continuous use approx
Dimensions: 10 x 3.8 x 1.7” (254 x 97 x 44 mm)
Weight: 1.3 lb (600 g)
Display: Quadriplexed LCD with 12.5 mm digits; 3 digits, 9999cts
Temperature:
Operating: +14° to 131°F (-10° to +55°C)
Storage: -40° to 158°F (-40° to +70°C)
Humidity:
Operating: 0 to 80% RH to +40°C (50% RH @ +55°C)
Storage: 0 to 95% RH
Material:
Case: Gray Lexan® 920A, UL 94 V2
Jaws: Red Lexan® 500R, 10% berglass, UL 94 V0
LCD lens: Crystal Lexan® 920A, UL 94 V1
Altitude:
Operating: 2000 m (6500 ft)
Storage: 5000 m (16,000 ft)
3.3 Mechanical Specications
Envelope Protection: IEC 529: IP 40
Drop Test: IEC 68-2-32: 1m
Vibration: IEC 68-2-6
Shocks: IEC 68-2-27

Harmonic Meter Model 721 13
3.4 Safety Specications
Protection Level:
Double insulation; IEC 1010-1, 600 V Category III, Pollution degree 2.
Working Voltage: 600 Vrms
Dielectric Test: 5.5 kV, 50/60 Hz, 1 minute
Overload Protection:
Voltage: 1.5 kV Peak permanent
Current: 3000 A AC permanent
Analog output: 1.5 kV Peak permanent
Agency Approvals: UL®, CSA, GS, VDE
ELECTROMAGNETIC COMPATIBILITY
Electrostatic Discharge:
IEC 801-2: No inuence: 4 kV class 2
Non-destructive: 15 kV class 4
RF:
IEC 801-3: No inuence: 3 V/m class 2
Minor inuence: 10 V/m class 3
Transients: IEC 801-4: No inuence: 2 kV class 4
Electric shocks: IEC 801-5: No inuence: 1 kV class 3

14 Harmonic Meter Model 721
CHAPTER 4
UNDERSTANDING
ELECTRICAL HARMONICS
Until fairly recently, power quality referred to the ability of the electric
utilities to supply electric power without interruption. Today, the phrase
encompasses any deviation from a perfect sinusoidal waveform. Power
quality now relates to short-term transients as well as steady state distor-
tions. Power system harmonics are a steady state problem with danger-
ous results. Harmonics can be present in current, voltage, or both. Within
the next few years, as many as half of all electrical devices will operate
with nonlinear current draw.
Utility companies invest millions of dollars each year to ensure that voltage
supplied to their customers is as close as possible to a sinusoidal wave-
form. If the power user connects loads to the system which are resistive,
such as an incandescent light bulb, the resulting current waveform will
also be sinusoidal. However, if the loads are nonlinear, which is typically
the case, the current is drawn in short pulses and the current waveform
will be distorted. Total current that is then drawn by the nonlinear load
would be the fundamental as well as all the harmonics.
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Harmonic distortion can cause serious problems for the users of electric
power, from inadvertent tripping of circuit breakers to dangerous overheat-
ing of transformers and neutral conductors, as well as heating in motors
and capacitor failure. Harmonics can cause problems that are easy to
recognize but difcult to diagnose.
It is becoming increasingly important to understand the fundamentals of
harmonics, and to be able to recognize and monitor the presence of dam-
aging harmonics. Harmonics within an electrical system vary greatly within
different parts of the same distribution system and are not limited simply

Harmonic Meter Model 721 15
to the supply of the harmonic-producing device. Harmonics can interact
within the system through direct system connections or even through
capacitive or inductive coupling.
A harmonic may be dened as an integer multiple of a fundamental fre-
quency. Harmonics are designated by their harmonic number. For our
discussion, we will focus on the 60 Hz power frequency. The second har-
monic would be two times the fundamental or 120 Hz. The third would be
three times the fundamental or 180 Hz, and so on.
Nonlinear equipment generates harmonic frequencies. The nonlinear
nature of a device draws current waveforms that do not follow the voltage
waveform. Electronic equipment is a good example. While this is a broad
category that encompasses many different types of equipment, most of
these devices have one characteristic in common: They rely on an internal
DC power source for their operation.
LOADS WHICH PRODUCE HARMONIC CURRENTS:
• Electronic lighting ballast • Adjustable speed drives
• Electric arc furnaces • Personal computers
• Electric welding equipment • Solid state rectiers
• Industrial process controls • UPS systems
• Saturated transformers • Solid state elevator controls
• Medical equipment
This is by no means an exhaustive list of equipment which generate har-
monics. Any electronic-based equipment should be suspected of produc-
ing harmonics.
Due to the ever increasing use of electronics, the percentage of equip-
ment which generates harmonic current has increased signicantly. The
harmonic problem manifests itself with proliferation of equipment using
diode-capacitor input power supplies. This type of equipment draws cur-
rent in a short pulse only during the Peak of the sine wave. The result of
this action, aside from improved efciency, is that high frequency harmon-
ics are superimposed onto the fundamental 60 Hz frequency.
The harmonics are produced by the diode-capacitor input section which
recties the AC signal into DC. The circuit draws current from the line only
during the peaks of the voltage waveform, thereby charging a capacitor to
the Peak of line voltage. The equipment DC requirements are fed from this
capacitor and as a result the current waveform becomes distorted.

16 Harmonic Meter Model 721
Harmonics in the electric power system combine with the fundamental
frequency to create distortion. The level of distortion is directly related to
the frequencies and amplitudes of the harmonic current. The contribution
of all harmonic frequency currents to the fundamental current is known as
“Total Harmonic Distortion”
or THD. This THD value is
expressed as a percentage
of the fundamental current.
THD values of over 10%
are reason for concern.
THD is calculated as the
square root of the sum of
the squares of all the har-
monics divided by the fun-
damental signal (50 or 60
Hz). This calculation arrives
at the value of distortion as a percentage of the fundamental.
Mathematically, %THD is the ratio of the root-mean-square (RMS) of the
harmonic content to the root-mean-square (RMS) value of the fundamen-
tal 50 or 60 Hz signal. THD is expressed as a percentage, and may be
greater than 100%.
Total Harmonic Distortion
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Wherever there are large numbers of nonlinear loads, there are sure to
be harmonics in the distribution system. Harmonic-producing equipment
is found in varied locations from administrative ofces to manufacturing
facilities. In the factory environment, electronic power converters such as
variable speed drives, SCR drives, etc., are the largest contributors to har-
monic distortion. It is not uncommon to have THD levels as high as 25%
within some industrial settings.
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Harmonic Meter Model 721 17
Most single-phase ofce equipment draws nonlinear current. While uo-
rescent lighting with electronic ballasts and many types of ofce equip-
ment contribute to creating harmonics, personal computer power supplies
are the largest contributor of harmonics within the ofce environment.
Although THD levels will be lower than in an industrial setting, the suscep-
tibility of ofce equipment to variations in power quality is extremely high.
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Computer Current Waveform
In the industrial environment, there can be many three-phase, nonlinear
loads drawing high levels of load current. The most prevalent harmonic
frequencies are the odd integer multiples of the 60 Hz frequency. The third
harmonic (180 Hz) is always the most prevalent and troublesome.
In general, even harmonics cancel out and are negligible. The largest
single current draw for ballasts is the third harmonic. Triplens (odd
multiples of the third harmonic) are typically the dominant harmonics and
are most common in single-phase, nonlinear loads. The fth and seventh
harmonics are dominant generally in motor drives.
Large commercial buildings have many different sizes and types of loads.
In most installations the power is distributed with 208/120 volt transform-
ers in a Delta-Wye conguration. When multiple loads are supplied, each
generates triplen harmonic currents on the neutral conductor which are
sent on to the transformer secondary and reected into the delta primary.
These currents circulate within the delta primary causing overheating and
shortened service life.





 




Delta Primary, Circulating Current

18 Harmonic Meter Model 721
Harmonics can cause a variety of problems to any electrical power user.
For large users, the problems can be intense. For electronic equipment
that relies on the zero crossing of the sinusoidal waveform, such as clock
timing devices, heavy harmonic content can cause a zero crossing point
offset.
Odd number harmonics (3rd, 5th, & 7th) cause the greatest concern in
the electrical distribution system. Because the harmonic waveform usu-
ally swings equally in both the positive and negative direction, the even
number harmonics are mitigated.
Heating effect causes the greatest problem in electrical equipment. Many
times, electrical distribution equipment has overheated and failed even
when operating well below the suggested rating requirements. Tempera-
ture increase is directly related to the increase in RMS current.
Because harmonic frequencies are always higher than the 60 Hz funda-
mental frequency, “skin effect” also becomes a factor. Skin effect is a phe-
nomenon where the higher frequency causes the electrons to ow toward
the outer sides of the conductor, effectively reducing the cross-sectional
diameter of the conductor and thereby reducing the ampacity rating of the
cable. This effect increases as the frequency and the amplitude increase.
As a result, higher harmonic frequencies cause a greater degree of heat-
ing in conductors.
On balanced three-phase systems with no harmonic content, the line cur-
rents are 120 degrees out-of-phase, canceling each other and resulting in
very little neutral current. However, when there is distortion in any one of
the phase currents, the harmonic currents increase and the cancellation
effect is lessened. The result is typically a neutral current that is signi-
cantly higher than planned. The triplen harmonics (odd multiples of three)
are additive in the neutral and can quickly cause dangerous overheating.
In theory, the maximum current that the neutral will carry is 1.73 times
the phase current. If not sized correctly, overheating will result. Higher
than normal neutral current will cause voltage drops between neutral and
ground which are well above normal. Readings above 4 volts indicate high
neutral current.
False tripping of circuit breakers is also a problem encountered with the
higher frequencies that harmonics produce. Peak sensing circuit breakers
often will trip even though the amperage value has not been exceeded.
Harmonic current Peak values can be many times higher than sinusoidal
waveforms.

Harmonic Meter Model 721 19
Power factor correction capacitor failure in many cases can be directly
attributed to harmonic content. Capacitors appear as extremely low imped-
ance values and are more susceptible to harmonics. Inductive reactance
varies directly with frequency (XL=2p). Parallel resonance between the
capacitor bank and the source impedance can cause system resonance
resulting in higher than normal currents and voltages. High harmonic cur-
rents have been known to overheat correction capacitors, causing prema-
ture failure and sometimes resulting in explosion.









Power Factor Capacitors at Resonant Frequency
Most harmonic problems result when the resonant frequency is close to
the 5th or 7th harmonic. These happen to be the largest harmonic ampli-
tude numbers that adjustable speed drives create. When this situation
arises, capacitor banks should be resized to shift the resonant point to
another frequency.
Another useful parameter is the Distortion Factor, or %DF. %DF is the
Total Harmonic Distortion referenced to the total RMS signal.
The Distortion Factor is expressed as a percentage, and may not be
greater than 100%. We provide this term because of the market need and
the requirement of this value under the international standard IEC-555.
Mathematically, %DF is the ratio of the root-mean-square(RMS) of the
harmonic content to the root-mean-square (RMS) value of the total signal,
and expressed as a percentage.