Function: Scope - Phasor
The Scope function provides a clear view of current and voltage waveform shapes.
Voltage waveforms in particular should be smooth and sinusoidal. If you see
voltage distortion on the waveform, check the harmonics display. The RMS
voltages and frequency should be close to their nominal values.
Waveform and Phasor display are also a useful way to verify that voltage leads
and current clamps are connected correctly. In the vector diagram, ensure that
the phase voltages and currents L1 (A), L2 (B), and L3 (C) appear in sequence
when observing them in clockwise direction.
To access, push the Scope button. Then, push F3 for Phasor
Voltage and frequency should be close to the applicable nominal values: 120 V,
230 V, 480 V, 60 Hz, or 50 Hz. For example: Check the voltages and currents in
the table to see if power applied to a three phase induction motor is in
balance. Each of the phase voltages should not differ more than 1 % from the
average of the three. Current unbalance should not exceed 10 %. Voltage
unbalance causes high unbalanced currents in stator windings, resulting in
overheating and reduced motor life. If unbalance is too high, use other
measuring modes to further analyze the power system. A Crest Factor close to 2.0
indicates high distortion. A pure sine wave would have a crest factor of 1.414.
Anything higher is a result of distortion.
To access, push the Menu button and select Volt/Amps/Hertz.
Function: Dips & Swells
Dips (Sags) and Swells may indicate a weak power distribution system. In a weak
system, voltage will change considerably when a big motor or a welding machine
is switched on or off. This may cause lights to flicker or even show visible
dimming. It can also cause reset and data loss in computer systems and process
controllers. By monitoring the voltage and current trend at the power service
entrance, you can determine if the cause of the voltage dip is inside or outside
the building. The cause is inside the building (downstream) when voltage drops
while current rises; it is outside (upstream) when both voltage and current
To measure dips and swells, push the Menu button and select Dips &
The harmonic number indicates the harmonic frequency: the first harmonic is the
fundamental frequency (60 or 50 Hz), the second harmonic is the component with
two times the fundamental frequency (120 or 100 Hz), and so on. The harmonics
sequence can be positive (+), zero (0), or negative (-).
Harmonic Frequencies and Sequences
As you can see, the sequence is + - 0 + - ….
Positive sequence harmonics try to make a motor run faster than the fundamental;
negative sequence harmonics try to make the motor run slower than the
fundamental. In both cases the motor loses torque and heats up. Harmonics can
also cause transformers to overheat. Even harmonics will disappear if waveforms
are symmetrical, i.e. as equally positive and negative. Zero sequence current
harmonics add in Neutral conductors. This can cause these conductors to
Current distortion is expected in a system with non-linear loads like DC
power supplies. When the current distortion starts to cause voltage distortion (THD)
of more than 5 %, this signals a potential problem.
K-factor indicates the amount of harmonic currents and can help in
selecting transformers. Use K-factor along with apparent power (kVA) to select a
replacement transformer to handle non-linear, harmonics-rich loads. K-factor is
a mathematically derived value that takes into account the effects of harmonics
on transformer loading and losses. A K-rated transformer is one that is
specifically designed to handle the effects associated with higher levels of
To measure Harmonics, push the Menu button and select Harmonics.
To measure K-factor, select Power & Energy
Function: Power & Energy
Power mode can be used to record apparent power (kVA) of a transformer
over several hours. Look at the Trend and watch for periods or peaks that exceed
the rating of the transformer. To mitigate the overload, transfer loads to other
transformers, stagger the timing of loads, or install a larger transformer.
Interpretation of Power Factor when measured at a device:
If you see negative power or power factor readings and you are connected to a
load, check to make sure the arrows on your current clamps are pointing towards
the load. Reactive power (VAR) is most often due to inductive loads such as
motors, inductors, and transformers. Installing correction capacitors can
correct for inductive VARs. Check with a qualified engineer before adding
PF-correction capacitors, especially if your system is already carrying current
- PF = 0 to 1: not all supplied power is consumed, a certain amount of
reactive power is present. Current leads (capacitive load) or lags
- PF = 1: all supplied power is consumed by the device. Voltage and current
are in phase.
- PF = -1: device generates power. Current and voltage are in phase.
- PF = -1 to 0: device is generating power. Current leads or lags.
To access power mode, push the Menu button and select Power &
Flicker refers to rapid change (to fast to see) in overhead lightning resulting
in human visual annoyance, headaches and eye-strain. From the Flicker
function, use the PF5 flicker trend and half-cycle voltage or current
trends to find the source of flicker. Press function key F1 to assign the
arrow keys to flicker, voltage, and current trends. Use a 10 minute (PST)
measuring period to eliminate the influence of random voltage variations and
detect interference from a single source with a long working cycle, such as
household appliances and heat pumps. A two hour measuring period (PLT) is useful
when facing more than one interference source with irregular working cycles and
for equipment such as welding machines and rolling mills.
To access, push the Menu button and select Flicker.
The voltages and currents in the Unbalance table can be used to check if applied
power is in balance; for example, on a three phase induction motor. Voltage
unbalance causes high unbalanced currents in stator windings, resulting in
overheating and reduced motor life. Each of the phase voltages should not differ
more than 1 % from the average of the three. Current unbalance should not exceed
10 %. If unbalance is too high, use other measuring modes to further analyze the
power system. Each phase voltage or current can be split into three components:
positive sequence, negative sequence, and zero sequence. The positive sequence
is the normal component present in balanced 3- phase systems. The negative
sequence results from unbalanced phase-to-phase currents and voltages. For
instance, this component causes a 'braking' effect in three phase motors,
resulting in overheating and life reduction. Zero sequence may appear in an
unbalanced load in 4 wire power systems and represents the current in the N
(Neutral) wire. Unbalance exceeding 2 % is considered too high.
To access, push the Menu button and select Unbalance.
Transients in a power distribution system can cause many types of equipment to
malfunction. Equipment subjected to repeated transients can eventually fail.
Events occur intermittently, making it necessary to monitor the system for a
period of time to locate them. Look for voltage transients when electronic power
supplies are failing repeatedly or if computers reset spontaneously. To isolate
the fault location, use the Transients function and monitor at several
points in the distribution. As you work your way down the line, eliminate
circuits that don't show events and follow the circuits that show the event in
sharper detail. The sharper the event, the closer you are to the load causing
the problem. Three phase monitoring also allows you to determine if it is a
single, dual or three phase load causing the problem, further reducing the
number of culprits.
To access, push the Menu button and select Transients.
Function: Inrush Currents
Inrush is the large spike most commonly caused by a motor load coming on-line.
As it first energizes, the motor utilizes a higher amount of current than when
runs at a constant speed. This large current draw frequently causes a large
enough voltage dip to send other equipment off-line or cause the lights to
blink. The Inrush function allows you to capture the inrush magnitude
along with the length of time it takes the motor to come up to speed: Start
recording, watch for inrush events and check the peak currents and their
duration. Use the Cursor for readout of momentary values. Check if fuses,
circuit breakers, and conductors in the power distribution system can withstand
the inrush current during this period. If the inrush exceeds the breaker
setting, it will trip. Measuring inrush current can help set appropriate breaker
trip levels. Also check whether phase voltages stay stable as a large inrush can
cause a voltage sag. Since the 434 Analyzer simultaneously captures inrush
current and voltage trends, you can use this measurement to check voltage
stability as large loads come on line.
To access, push the Menu button and select Inrush.
Monitor is a fully adjustable threshold driven feature. The Monitor screen
displays a bar chart as a Go-No-Go against the thresholds. Drill down into the
event to locate details for further investigation. By default, the meter is
programmed to use the EN50160 power standard. These values are fully adjustable
and can be set as desired. Use the Monitor function to quickly determine if a
manufacturer's specification is being met for a particular load or for doing
regular power audits against corporate defined limits. EN50160 is designed more
for the incoming utility and not necessarily a guarantee that all loads will
function within this standard.