Power monic application notes chk power quality

CHK Power QualityPtyLtd Page 1
Address:Unit102, 25 Angas Street Telephone: +61 2 8283 6945
Meadowbank NSW 2114,Sydney Australia Fax: +61 2 8212 8105
Website:www.chkpowerquality.com.au ABN: 53 169 840 831
Electric Shock
Investigations
Introduction
Electric shocks can be of a minor nature or can be devastating,
resulting in severe injury or death. Technicians involved in the
investigation of electric shock incidents need to be well trained
and equipped with high quality test equipment so that the
incident is resolved quickly to prevent further incidents and in
case of litigation. A multimeter, fault loop impedance tester,
safety switch tester and a power quality logger may be some of
the requiredtestequipment. The PM45 is an excellent logger to
assistininvestigationsasithas an additional voltage channel for
logging shock voltages (see Figure 1).
Causes of Electric Shock
Electric shocks can occur for a variety of reasons such as:
 Raised neutral-earth voltages caused by:
 Poor or open circuit neutral connections in the
grid or within an electricity users installation;
 Long runs of neutral conductor in the grid or
within an electricity users installation;
 Reverse polarity connection of an installation or at another installation;
 Overloading of the neutral conductor because of unbalance loads;
 Faulty wiring or equipment that has not tripped circuit protection.
 Touching fallen powerlines;
 Live roofs where a nail or screw has punctured an energised electricity cable;
 Faulty wiring or equipment;
 Misuse of electrical equipment;
 Low energy shocks such as static, induced voltages or leakage through a high impedance path.
Effects of Electric Shock
Personsmayreceive a‘tingle’withlittleornolongterm physical or mental effects. More severe shocks
can have devastating health effects both mentally and physically for the victim.
Animalsmayalsobe affectedbyelectric shocks. Large animals such as cows and horses are affected by
stepvoltagesmuchmore thanpeople due tothe large distance betweenfrontandbacklegs.Dairy cows
may sufferfromnervousness,excessive defecationandurination,reducedmilk supply and may have an
elevated mastitis count even if only receiving very minor tingles.
The causes of electricshockproblems,as detailedabove,canalsodamage electrical equipment. A poor
or open circuit neutral connection or a long run of neutral often results in damaging low and/or high
volts being delivered to electrical equipment.
Figure 1 - A trained technician
installing a PM45 to log the
neutral-earth voltage. The remote
earth lead should be installed not
to create a trip or electrical hazard.

A reverse polarity of a multiphase installation can result in severe electric shocks and phase to phase
voltage beingappliedtophase toneutral equipment.Thisequipmentisgenerallydamaged severely and
may cause a fire that could also raze premises to the ground.
Required Standard
AS/NZS60479 detailsthe effectsof electriccurrentonhumanbeingsandlivestock. However,it does not
setacceptable levelsfortouchvoltages. IEC61200-413 provides curves with limits of touch voltage that
can be sustained indefinitely depending on normal or wet conditions. The levels provided by these
curves can result in a nasty shock and so many Australian distributors rely on a limit of 10 volts or less
for neutral-earth voltages.
Case Study
A customerinan urban situationhadbeenreceivingelectricshocksinthe shower for the last 2 months.
A trainedtechnician investigated and found minor voltages of up to 3 volts in the shower when all the
load in the installation was turned on. This level of voltage would not normally be of concern but the
customer was adamant that the problem had recently started.
Furtherinvestigationsfoundthata neutral connectioninthe street mains was open circuit. The neutral
currentwas forcedto take alternate paths back to the distribution transformer resulting in the voltage
on the neutral conductorbeingelevatedabove normal levels. This voltage is then transferred onto the
water pipes by the equipotential earthing bond.
A PM45 was connected to monitor the neutral-earth voltage at the customer’s installation to ensure
that all was backto normal (see Figure 1). The loggerwas removedaday lateranddownloaded.Figure2
showsthe resultsof that downloadwiththe neutral-earthvoltage peakingat0.52 voltswhichmeantthe
problem had been rectified. The customer also advised they were no longer receiving shocks in the
shower and everything was back to normal.
Figure 2 - PM45 neutral-earth voltage trace showing very minor voltage levels
Conclusions
Technicians involved in the investigation of electric shock need high quality equipment such as
multimeters,fault loop impedance testers, safety switch testers and power quality loggers e.g. PM45.
Thistestequipmentcanassistinidentifyingthe cause of the problem soa solution canbe implemented
to preventfurtherincidents.A faultyneutral connection will simply need to be replaced. A long run of
neutral conductor, that is causing an elevated voltage on the taps in a shower, may need to be re-
conductored with larger cable or a transformer installed closer to the load.

A power quality logger, such as the PM45, can log the supply voltages and load current, as well the
neutral to earth voltage and verify if the problem is related to the load. Supply voltages that vary
considerably may be caused by a floating neutral/open circuit or poor neutral connection.
All in all, the PM45 is an excellent tool to assist in the investigation and resolution of electric shock
problems.

Excessive Energy Usage
Introduction
Electricity costs are continually increasing and the need to minimise
climate change requiresthe reductioninenergyusage.Aspartof this,
manygovernments are also requiring energy conservation and more
stringent control and management of energy usage, particularly for
large energy users.
The PM45 issimple to use,accurate and an essential tool for those in
the energymanagementfieldtoassistinthe reductionof greenhouse
gases and electricity costs (Figure 1).
Causes of Excessive Costs
Excessive Usage
If electrical equipment is not turned on then it is not costing. This is a simple message but not easy to
manage for those with large numbers of electricity users in the premise and/or a larger premise.
However,electricityusage canbe recordedbya powerqualityorenergylogger to determine when and
where electricity is being used. This then allows an analysis of where energy can be saved.
Poor Power Factor
Poorpowerfactor ismostlycausedby inductionmotorswhere the currentlags the voltage. This results
inadditional wastedenergyandgreenhouse gases. There will be no reduction in electricity costs if the
premise isonlybeingchargedforkilowatthours and power factor correction equipment was installed.
But, there may be significant savings if the electricity tariff penalises for poor power factor e.g. a kVA
charge on top of kilowatt hours.
If there are no cost savings to be made, then the only benefits may be a release in capacity of the
supplying transformer and mains if power factor correction capacitors were installed. This may save
significant upgrade costs as well as reducing greenhouse gases.
Powerfactorstandardsare setby the National ElectricityRulesforabove 1kV andby local distributorfor
less than 1kV.
Wrong Tariff or Wrong Time of Use
The most suitable tariff for the premise can be determined by logging the electrical load. The logged
data isthenanalysedtodetermine the mostappropriate tariff. Changing tariffs can result in significant
savings and in one case resulted in an annual reduction from $20,000 to $14,000 – a saving of
$6000/year.
Figure 1 - A PM45 being
installed for an energy audit

Time of Use tariffscharge more for electrical usage whenthe electricityis used in peak periods than for
shoulderoroff-peakperiods.Careful analysisof PM45 graphsand an intimate knowledge of operations
may allow for movement of load from higher tariff periods to cheaper times of use, thus saving costs.
Case Study
A factorywas payingan annual electricityaccountthattheybelieved was excessive for the size of their
operations. An installed a PM45 recorded the electricity usage and power factor over one week.
The audit found that the considerable energy was being used at nights when only the cleaning crews
were on-site, attributed to the turning on all air conditioning at the facility. Discussions with cleaners
determined that most of the air conditioners could be left off at night except as required in each
location,as the cleaners moved from location to location, to maintain air quality. The factory’s energy
management system was programmed to prevent the use of all air conditioners at night.
The power factor at the site was extremely poor and down to about 0.65 lagging on one phase and
neverabove the required0.9standard on any phase at any time (Figure 2). Installation of power factor
correction capacitors saw a reduction in kVA demand, line losses and greenhouse gases. The power
factor correctionunitshowedareturnon assetswithinapproximately18 months. After this period, the
reductioninelectricitycostscontributedtoannual profitswhilstassistingingreenhouse gasabatement.
Figure 2 - Power Factor Graph for Factory
The audit alsodetermined that significant loads could be transferred to off-peak operation to provide
for betterplantutilisationandsignificantenergysavings.Unfortunately,awardpaymentsforstaff wages
offsetanysavingsandso the transferdidnotgo aheadat that stage.Awardnegotiations are continuing
with the union involved.

Conclusions
The PM45 can be an extremely valuable tool in reducing electricity costs and in the reduction of
greenhouse gases. The PM45 can be used to check when and where electricity is being used and at
what power factor.

Harmonic Pollution
Introduction
The quality of the electricity supply is a quite complex issue.
The focus of powerproblemsinyearsgone by has been more
on voltage quality than the more technical aspects of power
quality. This may still be the case in some power companies
where problems are referred to as voltage complaints.
The requirement for a higher quality electricity supply has
come with the proliferation of sensitive equipment which
generate more harmonics themselves.
The PM45 records levels of individual harmonics as well as
THD-f, which is Total Harmonic Distortion (THD) - a measure
of the effective valueof harmonicdistortion.More specifically
it is the ratio of the rms value of the harmonic content of an alternating voltage or current to the rms
value of the fundamental component of the voltage or current. Inter-harmonics can also be recorded
which are harmonic frequencies that are not an integer of the fundamental.
Causes of Harmonics
Harmonicsare sinusoidal voltagesorcurrentshavingfrequenciesthatare integermultiplesof the supply
frequency. Harmonicsare generallycausedbynon-linear loads i.e. equipment that has a capacitor and
a diode or diode type device (e.g. Silicon Controlled Rectifier). This type of combination is generally
foundin equipmentwithaswitchmode powersupply. Harmonicsare generallyatmuchhigherlevelsin
industrial premisesorcommercial premises which oftenhave variablespeeddrivesor many computers.
Inter-harmonicsare voltagesorcurrenthavingfrequencycomponents that are not integer multiples of
the supplyfrequency.The mainsourcesof inter-harmonicsare heavy industry equipment such as static
frequency converters, cyclo-converters, induction furnaces and arcing devices. Power-line-carrier
signals are regarded as inter-harmonics.
Effects of Harmonic Pollution
The effects of harmonics include:
• Eddy current heating in equipment
• Noise and torque oscillation in motors
• Vibration or noise in panels
• Nuisance tripping of breakers & fuses
• Metering errors
• Electronic equipment malfunctions
• Generator speed/frequency instability
• Telephone noise interference
• Data transfer errors

• Resonance causing large voltages &
currents
The effects of Inter-harmonics include:
• Distortion of power-line-carrier signals
• Flicker of fluorescent and arc lighting
• Flicker of computer display devices
Required Standard
Levels of harmonic
distortion should meet
the compatibility levels
of AS/NZS61000.3.6
(Figure 2).
The standard also allows
a distributor to record
harmonic levels before
and after the connection
of a new installation or
load to ensure the
customer does not
exceed the distributor’s
emmission limits.
Case Study
A plantwashaving problems in the early hours of the morning with circuit breakers tripping randomly
for nogood reason. Monitoring was carried out with a PM45 configured to record harmonic problems.
Voltage THD levelswere foundtobe nearing10% at timesand well above allowable compatibilitylevels
(Figure 3). It was believed that harmonics were causing the circuit breakers to trip.
A Variable Speed Drive (VSD) on the premise was controlling a quite large motor that was started at
around 2 am in the morning. The VSD was confirmed as the source of problems and the manufacturer
was contactedto solve the problem. Circuit breakers did not trip after the solution was implemented.
Figure 3 - Graph showing excessive harmonics at the circuit breaker panel
Figure 2: Compatibility levels for harmonic voltages (in percent of the nominal
voltage) in LV and MV power systems
Odd harmonics
non multiple of 3
Odd harmonics
multiple of 3
Even Harmonics
Order
h
Harmonic
voltage %
Order
H
Harmonic
voltage %
Order
H
Harmonic
voltage %
5
7
11
13
17
19
23
25
>25
6
5
3.5
3
2
1.5
1.5
1.5
0.2+
1.3 (25/h)
3
9
15
21
>21
5
1.5
0.3
0.2
0.2
2
4
8
10
12
>12
2
1
0.5
0.5
0.5
0.2
0.2
NOTE – Total harmonic distortion (THD): 8%

Conclusions
Harmonicsare causedby non-linearloadsandare oftena probleminindustrial and commercial supply.
The PM45 can be a valuable tool indeterminingif harmonics or inter-harmonics are at excessive levels
and in locating the source of the problem.

Monitoring Zone
Substations
Introduction
A PowerMonic (power quality loggers) may be installed at zone
substations, either for a short-term investigation or as a long-term
monitoringdevice.The zone substation may be either owned by the
power company or the electricity customer/user.
Remote communication with the PowerMonic may be important to
save travel time, particularly where permanently installed.
The PM45 provides a particularly good option for such situations as
it is robust, provides quality data and is easy to install (Figure 1).
Reasons for Installing Loggers at Zone Substations
The installation of a logger at a zone substation may occur for the
following reasons:
1. Compliance withregulatororstate code requirements –insome states the state regulator requires
that a power quality monitor be installed at each power company’s zone substations.
2. Power quality check before payment of claims – customers are increasingly claiming from power
companiesfordamagedelectrical orelectronicequipment.The zone substation graphs can be used
by the powercompany to verifythe qualityof the supplyleaving the zone substation at the time of
the incidentthatallegedlydamagedthe equipment. Checkingpowerqualitylogsmaybe part of the
investigationif aclaim is to be rejected by the power company or as justification for a claim by the
customerif the loggerwas installed. A disrupting event may cost a plant thousands or hundreds of
thousands of dollars, so it is important to have the detail to justify the claim.
3. Continual checking of zone substation capacity – zone substation loads are generally on the
increase. A power quality logger allows continual checking of the available capacity at the zone
substation. Thereby helping to ensure that overloads and loss of supply do not occur.
4. Newconnectionof alarge customerand providingpowerquality indices –. The collection of power
quality data can allow power quality indices to be collated that can be very beneficial to the new
customers,especiallyif theyare connecting directly from the zone substation. This allows the new
customer to determine the level of robustness of their plant and equipment, which is particularly
important when specifications for the plant and equipment are being developed.
5. Exceedancescapturedcanbe usedto checkthe operationof zone substationprotectionequipment
– Events can be captured by the power quality logger that can verify if protection equipment has
Figure 1 - A PM45 being installed
on a zone substation indoor
transformer panel to monitor
power quality on a temporary
basis.

performed as it should when a network problem occurs. An exceedance may show that a circuit
breaker did not work as intended and took an excessive time to open.
6. Check of frequency injection or ripple signal loads – frequency injection signals can cause large
jumps in load if the connection of the controllers is not adequately controlled.
Installation of the Logger
The loggerwill need tobe configuredtocapture the required data. Part of this set-up will be to set the
nominal voltage to the nominal output voltage of the voltage transformer (VT).
The powerqualityloggershouldbe connectedtothe zone substationoutputbusbar’sVTsupplyand the
powertransformer’scurrent transformers (CT). Alternatively, the logger can be connected to a feeder
circuit breaker CT’s. The connection to the CT’s is best performed using a GridSense Substation CT
Converter Kit which isolates the CT circuit from the PowerMonic to ensure integrity of the CT circuit.
The logger is now set-up and running. A land-line or cellular modem may be connected for the data
communication. A system needs to be established for data storage to ensure that the data is readily
available for the analysis of events or long-term trending of power quality indices.
Case Study
A powercompanywashavingcustomercomplaintsthatcorrelatedtoone zone substationthatsupplied
a large component of commerical load. The zone substation was supplied from a long transmission
network that supplied numerous zone substations.
A PM45 logger was installed at the zone substation on the output from the zone substation power
transformer.Figure 2showsthat the voltage outputfromthe zone substationwasdroopingatpeakload
times.The transformertapchangerwas suspectedof runningout of boost taps following an analysis of
the graph. Tap positioninformationwasanalysedfromthe dataaquistionsystematthe zone substation
and yes, the transformer was running out of boost taps.
The transmission campany was asked to include Line Drop Compensation settings on their supply, so
that supplyvoltage wasboostedatpeak times, as a short to medium term fix. This solved the problem
and a long-term fix was scheduled in the following year.

Figure 2 - Graph showing voltage drooping at peak load from a zone substation
Conclusions
A PowerMonic can be easily configured and installed in a zone substation for a short or long-term
investigation. The benefits for long-term monitoring are many and the costs are easily justified.

Steady-State Voltage
Problems
Introduction
Steady-state voltageproblemsrelateto long duration over and/or
undervoltage situations.Thisiswhere the voltage istypicallymore
than 10% above or below the nominal voltage for long durations,
typically longer than 1 minute. International standards require
logging equipment to be set at 10 minute averages when logging
for steady-state voltage problems.This is required if an electricity
customer was to have a dispute with the distribution company.
However, it may be more appropriate to record at much shorter
averages when trying to determine what is causing problems.
The PM45 can logat averagesdownto10 seconds.Figure 1 shows
a PM45, powerqualitylogger,beinginstalled in response to a voltage problem. The PM45 has memory
allocatedforsteadystate logging,orprofilingasitis sometimescalled,isindependent of logged events
and so the requiredprofilingperiodisassuredandcannotbe usedif excessive numberof eventswereto
occur.
Causes of Steady-State Voltage Problems
Overloading
Overloading of distribution cables and transformers or cabling within the installation often results in
longdurationunder-voltage problems. Overvoltageproblemscanalsooccur,but lessfrequently, where
a single phase is over loaded on a three phase system. This can offset the neutral point in a star three
phase systemandcause one of the phases to go above and the other phases to go below the standard.
Inappropriate Design
Networks or installations are occasionally installed with inappropriate sized conductors and hence an
overloadsituationcanoccurright fromthe outset.The PM45 can be usedto assist in determining if the
designer has designed less than ideally.
Load Switching
Switching on or off large loads can cause large variations in the voltage. Network automatic tap
changers(voltage adjustingequipment) cantake some minutestorespondandsolong duration voltage
variations can occur. Under-voltage can occur where large loads are switched on and over-voltage
where the large load has been switched off.
Figure 1 - A PM45 being installed at a
house where the stove is not cooking
effectively.

Faulty Regulating Equipment
Distribution companies have automatic regulator equipment as described above on their high and
mediumvoltage networks.Some are eveninstallingthemontheir low voltage distribution networks to
correct localised problems. This equipment can fail and is likely to cause over and/or under voltage
depending on what has occurred and the amount of load on the feeder/circuit.
Network Reconfiguration
Distribution companies need to reconfigure their networks for various reasons, including for
maintenance and repair which results in less than ideal supply voltage. This may be until regulating
equipment responds or for much longer durations until the network is returned to normal.
Effects of Steady-State Voltage Problems
The effects of steady-state voltage problems are divided into two categories as follows:
Sustained Over-voltage
 Lights globes reduced life span
 Electronic equipment life reduction
 Equipment destruction - high voltages
 Increased motor losses
 Overvoltage protection operation
Sustained Under-voltage
 Slowness with cooking
 Dullness in incandescent lighting
 Discharge lighting drop outs
 Contactor chatter and heating
 Increased motor losses
Required Standard
The required level of voltage to be supplied by a distributor in Australia is either set by the National
ElectricityRules,AS60038 and/orstate basedlegislation.Atlow voltage,the distributor should supply a
nominal voltage of 230 volts, plus 10% and minus 6% at the point of supply.
A voltage transformerwillbe requiredtomeasure voltagesathighvoltage anda GridSense PowerMonic
substationconverterkittoconnectto substation CTs(ApplicationNote –MonitoringZone Substations).
Case Study
A motherishavingproblemswithcookingthe eveningmeal andwithdull lights.A PM45 was installedat
the point of supply to determine if the incoming supply was up to standard.
Figure 2 showsthe resultsof the loggingwiththe voltage below the requiredstandard for unacceptable
periodsof time.The graphwas suppliedto the distribution company, who investigated and found that
the user had increased their load and overloaded the low voltage supply network.

Figure 2 - Graph showing long duration under voltage problem in the evening
Conclusions
The PM45 can be an extremely valuable tool in determining the cause of long duration under and/or
over voltage problems. The logger will need to be set to log for 10 minute averages if there is dispute
and maybe setat intervalsmuch less than 10 minutes to assist in locating the source of problems. The
PM45 can also be useful with other steady-state problems such as voltage unbalance and harmonics.

Voltage and Current
Unbalance
Introduction
Voltage unbalance occurs in a three-phase system where
there is a difference in the values of voltages or where the
phase separation is not 120 degrees. Current unbalance is
similar except the values are for current instead of voltage.
Large levels of current unbalance generally cause voltage
unbalance.
Voltage unbalance is normally calculated using two
methods.The firstiswhere the negative sequence voltage is
expressedasapercentage of the positive sequence voltage
(the method used in the PowerMonic). The second method
usesthe maximumdeviationfromthe meanof the three line
values expressed as a percentage of the mean of the three
line voltages. The values for this method can be obtained
from a PowerMonic using an export of the voltage data to a
spreadsheet and then calculated. Current unbalanced is calculated simile using values for current.
The PowerMonicisan excellentinstrumentforloggingvoltage and current unbalance. Figure 1 shows a
PM45 being installed where a motor is becoming overheated.
Causes of Voltage and Current Unbalance
Currentunbalance isthe primarycause of voltage unbalance, as described in the introduction. Current
unbalance may be caused by the following:
• Large and/or unequal distribution of single-phase load – this often occurs with overhead
networkswhere the linespersonconnectslow voltage single-phaseservicestothe closest phase
to the neutral (nicknamed“short-armedlinesman’ssyndrome”).The same problem can occur at
medium voltage levels where single-phase distribution transformers are all connected to the
easiest to reach conductors.
• Phase to phase loads – thisoccurs withsome equipmentthatsimplyrequiressingle phasebutat
line-to-line voltage e.g. 415 volt welder.
• Unbalancedthree phase loads –some three phase loadsare made up of single and three phase
equipment. It is important that these loads are balanced to meet the power company’s
requirements.
Figure 1 – A PM45, configured for voltage
unbalance, is being installed at a motor to
determine the cause of over heating - voltage
unbalance is suspected.

Unequal impedances of a three-phase transmission and distribution networks also causes voltage
unbalance – this occurs where the overhead transmission or distribution system does not have
adequate and regular transposition of the phases to balance the system impedance.
Effects of Voltage Unbalance
Resistive loadsare relativelyunaffected
by voltage unbalance. However, the
major problem with voltage unbalance
is that it causes additional
heating/losses with three-phase
motors. Motors may also be noisy due
to torque and speed variations caused
by the voltage unbalance and will have
less effective torque and speed than
normal. The voltage unbalance also
causesan increase incurrent unbalance
well in excess of the voltage unbalance
percentage. Figure 2 shows a standard that allows for de-rating motors based on the percentage of
voltage unbalance.
Variable speeddrives(VSD) maytripoff due toan increase inac line currentscausedby a compensation
for the voltage unbalance.Increasedthermalstress of VSD diodes and dc link capacitors and additional
triplen harmonics can also occur.
Required Standard
The National Electricity Rules sets the limits for voltage unbalance as per Figure 3.
Figure 3: Voltage Unbalance Limits
Nominal Supply Voltage Negative Sequence Voltage(% of Nominal Voltage)
Column 1 Column 2 Column 3 Column 4 Column 5
no contingency
event
credible
contingency
event
General Once per hour
30 minute
average
30 minute
average
10 minute
average
1 minute
average
>100kV 0.5% 0.7% 1.0% 2.0%
Figure 2 – De-rating Curve for Motors

Current balance requirements are also set by the National Electricity Rules, distributor or state based
Service Rules and in state based legislation. Check the requirements for the location being logged.
Measurement of Voltage Unbalance
Voltage unbalance shouldbe measuredwithline toline valuesof voltage.Gridsense’s 6-wire lead is the
only way of measuring this when using PowerMonics.
The logger should be set to 10-minute averages in case logs need to be compared with standards e.g.
where there isa dispute. Voltage unbalance is more a steady-state issue and so 10-minute averages is
oftensuffice.However, voltage or current unbalance protection may be tripping and shorter averages
may be better suited to assist in determining the cause.
Case Study
The motor inFigure 1 wasoverheatingandvoltage unbalance was suspected as the cause. A PM45 was
installedandthe graphinFigure 4 obtained.Itshowsexcessive voltage unbalance andthe likelycause of
the overheating.
Figure 4 - Graph showing excessive voltage unbalance to a motor
Conclusions
The major cause of currentunbalance isthe “short-armedlinesmen’s syndrome” that results in voltage
unbalance.The majoreffectof voltage unbalance isadditional heatingandlossesinthree-phasemotors.
Voltage and current unbalance can be easily tracked down using a PM45.
10kV to100kV 1.3% 1.3% 2.0% 2.5%
<10kV 2.0% 2.0% 2.5% 3.0%

Voltage Flicker
Introduction
Voltage fluctuations and flicker can be a real nuisance with the
source of the problem often difficult to locate. The PM45 is
arguably the best logger for locating the source of voltage
fluctuations, particularly where motor starting is a problem.
Figure 1 showsa PM45 beinginstalledtotrackdownthe source of
voltage fluctuations caused by a motor.
The PM 45 has shortand longterm flickermonitoringcapabilityas
well as event recording for rolling average voltage variations or
threshold settings.
The eventrecordingcomesintoits own when trying to locate the
motor that is causing voltage fluctuations or when determining
the best time to swap a motor from the start to run sequence. The PM45 has memory allocated for
events that is independent of steady state logging, or profiling as it is sometimes called, assuring that
profiling is not disrupted should significant numbers of events occur.
Causes of Voltage Fluctuations and Flicker
Motor Starting
Motor startingis a major source of complaintsregardingvoltage variations. A motor can draw up to ten
timesitsrunningcurrenton start up. This huge increase in current causes the voltage to sag due to the
source impedance. Reduced voltage starting seeks to limit the start-up current and hence limit the
voltage fluctuation during the start-up process.
Swappingamotor to run before ithasgottenup to full speedwill cause the currenttopeakmuchhigher
than it would if started when up to speed. The PM45 can capture the start up sequence if set
appropriately.Analysisof the eventrecordedfromthe startupsequence willshow whether the voltage
fluctuation complies with the required standard and if the controller, that swaps the motor to run, is
appropriately set. Generally a simple timer is used for the swap over process and it may be that this
timer needs to be more appropriately set (tweaked) to prevent the excessive voltage fluctuation.
Heavy Industry
Heavy industry is most often the cause of flicker. Electric arc furnaces, induction furnaces, static
frequency converters and cyclo-converters are some of the more common offending equipment.
Figure 1 - A PM45 being installed to
help locate a motor start issue. It is
arguably the best test instrument
for this task.

Loose Connections
Loose connectionscanalsocause voltage fluctuationsorflicker whether on the low or medium voltage
network.Heavilyloadedconnectionstendtoburnoutquickerbutlightlyloadedconnections may cause
fluctuations or flicker for long periods.
Effects of Voltage Fluctuations and Flicker
The most common effect of voltage fluctuations and flicker is to do with lighting and the human eye.
The incandescentlight globe is sensitive to voltage fluctuations and flicker. Fluorescent lighting is not
immune from such problems but is less prone to problems and tends to dampen voltage variations.
Required Standard
The flickercompatibilitylevel forLV andMV powersystemsisset by AS/NZS61000.3.7 at 1.0 for P-st and
0.8 for P-lt. AS/NZS61000.3.3, AS/NZS61000.3.5 and AS/NZS61000.3.7 set the limits for fluctuations.
Case Study
A customerina semi-rural situationwascomplainingtothe distribution company that their lights were
flickeringall day.A technicianwassentouttoinvestigate.The loggerwassettorecord flickerandrolling
voltage events set at 5%. The logger was down loaded a few days later and the Pst was continually
above the 1.0 limit. The logger failed to record any events outside the 5% rolling level.
The loggerwas reprogrammedwitha3% rollingvoltage setting.The resultsclearlyshowed that a motor
was startingapproximatelyeveryminuteandthe motorwasnot at the complainingcustomer’spremise
(Figure 2).There were twoneighbors,bothwithsingle phase supply, supplied from a common point of
supplyonpowerpole.One logger was installed with A phase C/T clipped over the active to one house
and B phase to the other house.
The results from this logging clearly showed that one house had a motor causing the problems.
Discussionswiththe customer revealed that the motor was on a pressure pump and the pressure tank
had lostitspressure.The customeralsohad a very leaky tap that was causing the pressure pump to cut
inand out, all day long. The customer replaced the valve in the pressure tank, and fixed the leaky tap.

Figure 2 - Graph showing a motor start. The starter was continually cutting in and out and causing a nuisance
Conclusions
The PM45 can be a valuable tool in determining the source of voltage fluctuations and flicker and is
arguably the best instrument on the market for locating motor starting problems and in assisting with
the settingof starters. Thisloggeris easyto set,obtainthe loggeddata and then to analyse the results.

Event Recording
Introduction
The PM45 notonlyprofiles/logssteady state issues such as voltage
and harmonic levels but can also record one off power quality
events.The memoryallocatedforeventsisindependentof profiling
to ensure thatprofilingisnotdisrupted should significant numbers
of events occur.
Events are divided into the following classes:
 Sag/Swell detection
 RMS capture;
 Transient capture (dV/dt).
Sag/Swell Detection
Sag/Swell detection is used where a list of sag and swell events is
requiredinatable formator where these eventsare required to be
plotted on a curve such as the ITIC curve. Table data includes the time, duration and the maximum or
minimum voltage of the event. Powerview automatically graphs the events on the ITIC curve when
selected.Plottingtoothercurves or manipulation of the data can be achieved by exporting the data to
Excel.
RMS Capture
RMS capture isideal to capture temporary (3 s – 1 min), momentary (30 cycles – 3 s) and instantaneous
(0.5 – 30 cycle) sag, swell and/or interruption events. It is an excellent tool to locate motor start
problemsandwhensettingthe changeover timer for motor starters. Voltage or current can be used to
setthe RMS capture.Interruptionscanbe clearlyseentodetermineif networkprotection equipment is
operating as it should. RMS capture allow comparison with customer logs to determine the cause of
equipment malfunctions or plant failures. Up to 30 seconds of 10 ms data points for 50 Hz supplies are
captured.
Waveformcapture can alsobe selectedwithRMScapture to allow directcorrelation with an RMS event
captured at the same time. This can be handy to see what happened at the onset of the RMS event in
more detail. 400ms of data points are captured at 98 micro-second intervals.
Transient Waveform Capture
Transient waveform capture allows the capture of low frequency oscillatory waveforms that would
occur as a result of the energisation of a capacitor bank and notching caused by the commutation of
electronic devices such as Silicon Controlled Rectifiers.
Setting the Logger
A detailedexplanationof settingthe loggertocapture eventdataandallocationof memory isprovided
inGridsense’sConfigurationGuidesavailable at www.gridsense.net
Figure 1 - A PM45 being installed
at a plastic plant to determine
the cause of plant shutdowns
(see Case Study).

Required Standard
The following provides a summary of the standards that apply to events captured by the PM45:
 Sags – no standard applies at this stage other than the input sags have on flicker and voltage
fluctuations;
 Swells – the National Electricity Rules Figure S5.1a.1;
 RMS voltage capture – voltage fluctuations are managed by AS/NZS61000.3.3, AS/NZS61000.3.5
and AS/NZS61000.3.7;
 RMS currentcapture – large swingsincurrentcause voltage fluctuations and so current capture
isgenerallymanagedthroughthe managementof voltage fluctuations though distributors may
have requirements in local service rules;
 Transient waveform capture – compatibility limits have not been applied for transients and
notchingat thisstage.ObsolescentstandardAS2270.2 providesguidance onthe managementof
notching and oscillatory transients should be managed through good industry practice.
Case Study
A plasticsfactorywashavingproblemswiththe plant’sVariable Speed Drive (VSD) equipment shutting
downrandomlyforno apparentreason.Unblockingof equipmentwas timing consuming and damaging
client relationships due to delays in the supply of their products.
Unseeneventswere suspectedasthe cause andso a PM45 was installedatthe mainswitchboardsetup
to logTransientWaveformcapture,aswell aslogging for RMS capture, voltage and harmonics. Figure 2
shows a low frequency oscillatory transient that was captured by the logger. This event related to a
major shutdown at the plant.
Figure 2 – A Transient Waveform event captured by a PM45 at the plasitcs plant
The networkpowercompanywascontactedto see if theywere switchingcapacitorsatthe time thatthe
oscillatorytransientoccurred.The powercompanyadmittedthatacapacitor bankhad beenswitchedat
the local zone substation at that time and that the bank did not have transient mitigation equipment.
The problemsatthe plasticsplantwasexplained and the power company agreed to stop switching the
capacitorswhenthe plantwas operatingandthat theywouldintroduce transientmitigation equipment
to the capacitor bank as soon as possibe.
Conclusions
The PM45 can be very useful in detecting event based power quality problems. The instrument will
record low frequency oscillatory transients and notching type events. Steady state profiling can be

carried out at the same time as event recording. This profiling will not affect the event logging as the
memory is partitioned and separate memory allocated for profiling and events.

Power monic application notes chk power quality

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