PowerMonitor 5000 Family
Advanced Metering Functionality
Steve Lombardi, Rockwell Automation
The PowerMonitor™ 5000 is the new generation of
high-end electrical power metering products from Rockwell
Automation. This new family of power monitors provides
advanced technology, new functionality, and market
leading capabilities in response time and accuracy.
The PowerMonitor 5000 family provides three levels of functionality: the M5, M6, and M8. The 5000 M5 is the base model
and provides an extensive range of basic metering functions. The 5000 M6 and 5000 M8 add additional metering and power
quality capabilities. Rockwell publication 1426-WP001, “PowerMonitor 5000 – The Next Generation,” discusses the new,
underlying technologies in the PowerMonitor 5000 M5 and compares it to the technology in the PowerMonitor 3000 M5. This
publication focuses on the base functionality in the 5000 M5 and how the 5000 M6 expands the metering and power quality
capabilities.
PowerMonitor 5000 M5 Metering Functions
The PowerMonitor 5000 M5 provides the following metering functions:
• Frequency
• Phase rotation
• Voltage, per phase and average, line-to-line and line-to-neutral
• Voltage, neutral-to-ground
• Current, per phase and average
• Current, neutral or ground
• Power/energy/demand (real, reactive, and apparent), meets class 0.2% accuracy for both ANSI C12.20 and EN 62053-22
• Power factor, true and displacement
• Symmetrical component analysis values for both voltage and current
• Voltage and current unbalance
• Crest factor
• THD for both voltage and current
• K-factor
• Direct connect to 690V AC
• Data Logs (add logs supported)
• ADD (definition of increased volume for logs)
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The 5000 M5 metering functions are updated every line cycle. The fast, accurate readings
are excellent for monitoring power system conditions, monitoring energy usage, and
controlling industrial manufacturing systems based on the measured electrical data. In
addition to the real-time data, there are also numerous logs available to provide historical
information.
With the PowerMonitor 5000 M5, you can configure up to 10 setpoints to identify when
a measured parameter goes above or below a set threshold. Whenever a setpoint is
activated, the event time and the measured parameters pertinent to the event are
recorded in a log. The setpoint capability transitions a status bit and can be used to
actuate a relay output for control purposes or to identify an abnormal condition. In
addition to the user-configurable setpoints, the 5000 M5 provides status bits that identify
the occurrence of a voltage sag or swell condition.
The PowerMonitor 5000 uses an internal clock to time-stamp the metered
values, the occurrence of a setpoint event, and all data log entries. To
improve consistency between clocks in multiple power monitors or with
the utility, the clock can be sourced by an SNTP time source. For the
ultimate in clock synchronization, the PowerMonitor 5000 can use the
IEEE 1588 precision time protocol over Ethernet. This provides very precise
synchronization among all of the participating meters.
There are two time elements to consider when evaluating time protocol;
relative time accuracy and absolute time accuracy. Relative accuracy is the
time error between different devices on the network. Absolute accuracy
is the time error between a device on the network and a precision
reference clock such as a GPS clock. The IEEE 1588 precision time protocol
lets devices on the network determine the highest quality clock available
and to use that clock to source time to all participating devices.
A PowerMonitor 5000 can be used as the clock source if absolute accuracy is not required.
Excellent relative time accuracy between devices on a properly designed network results
by using the IEEE 1588 protocol. When synchronization is required between geographically
separate meters or with the utility, absolute accuracy depends on source clock quality.
A GPS clock source with IEEE 1588 capability provides very precise time to the power
monitors on the network for excellent relative accuracy and absolute accuracy. If neither
relative nor absolute time accuracy is required, use the PowerMonitor 5000 local clock.
PowerMonitor 5000 M6 Overview
The PowerMonitor 5000 M6 retains all functionality of the 5000 M5 plus the following:
• Additional setpoint capability
• User configurable voltage sag/swell settings
• A power quality log that details detected sag/swell events, oscillography, and harmonic
analysis
• IEEE 519 pass/fail capability
• Ability to synchronize detected events between multiple power monitors
If a user has a PowerMonitor 5000 M5 and wants the additional functionality of the 5000
M6, the M5 can be field upgraded to a M6 by purchasing a firmware upgrade.
PowerMonitor 5000 Family Advanced Metering Functionality | 3
PowerMonitor 5000 M6 New Setpoint Capabilities
The 5000 M6 improves how to identify and capture power system issues by increasing
the number of configurable setpoints from 10 to 20 so more conditions are identified and
more control options are provided. The 20 setpoints in the M6 includes two new types of
setpoints, relative setpoints and logical setpoints.
Relative setpoints are similar to standard setpoints except for the definition of the reference
value. A fixed reference value is specified when a standard setpoint is defined. For
example, a setpoint in a 480 VRMS system can be defined to activate when the measured
voltage is less than 90% or 432 VRMS. However, the nominal utility-supplied voltage
level can vary by the time of day due to power system loading changes. If you wish to
identify a reduction to 90% of the actual supplied voltage, then a fixed reference voltage
cannot provide the intended result; a relative setpoint must be used. In this example, a
rolling average of the utility-supplied voltage is computed over a sliding interval with user
configured duration. The rolling average value is now used as the reference value for the
setpoint. If the rolling average of the actual supplied voltage falls to 460 VRMS the 90%
value now becomes 414 VRMS. The choice between a fixed setpoint and a relative setpoint
gives you the ability to identify when the system hits a “critical” value or to identify when
an unexpected change in the system occurs.
The PowerMonitor 5000 M6 also sets logical setpoints, which use the results of other user
configured standard or relative setpoints as inputs. The configuration uses one level of
logic with up to four inputs. The logic supports AND, NAND, OR, NOR, XOR, and XNOR
logic functions. The output of the logic function is a setpoint result that can be used in
the same manner as other setpoint results. Logical setpoints allow users to create a more
complex condition for creating a setpoint action.
Power Quality Phenomena per IEEE 1159
The PowerMonitor 5000 M5 provides a considerable amount of metering data so you
can monitor the operating condition of their facility’s power distribution system and
thus manage their energy costs and consumption. To further increase the efficiency and
robustness of the power system and the reliability of the control systems connected
to it, monitor the system should also be monitored for power quality issues. A good
reference for defining and categorizing power quality phenomena is IEEE 1159-2009, IEEE
Recommended Practice for Monitoring Electric Power Quality. This document categorizes
power quality events and conditions into seven different types with various sub-types
where appropriate. The main categories are:
• Transients
• Root-mean-square (RMS) variations (short duration or long duration)
• Imbalance
• Waveform distortion
• Voltage fluctuation
• Power frequency variation
A transient is a very short event with a typical duration between 5 micro-seconds and 50
milliseconds. Transients are usually characterized by either rise time or frequency, and they
are either impulsive or oscillatory. Transients are typically the result of lightning strikes,
system switching events, fault conditions, or intermittent connections.
4 | PowerMonitor 5000 Family Advanced Metering Functionality
Short duration RMS variations are events characterized by voltage magnitude changes
between 10 percent and 180 percent of their nominal value. Changes that result in a
voltage less than normal are defined as “sags” and changes that result in a voltage greater
than normal are defined as “swells.” Typical duration is between one-half cycle and one
minute. Voltage sags in a power system can be caused by a variety of conditions such
as: a fault to ground or another phase either directly or through some impedance, circuit
breaker/re-closer operation, a blown fuse, the energization of a large load, the removal
of power factor correction capacitors, an overloaded conductor, or a poor connection.
Voltage sags that result in a level less than 10 percent of normal are referred to as
interruptions. Voltage swell events are typically the result of a fault to ground or another
phase either directly or through some impedance, a blown fuse, the de-energization of
a large load, the addition of power factor correction capacitors, or a poor connection.
Voltage level changes that have similar magnitude changes but last longer than one
minute are referred to as sustained interruptions, over-voltages, or under-voltages.
In addition to these power quality issues, IEEE 1159 also defines “steady state” power quality
concerns. The presence of an unbalance condition, voltage or current, is one of these
concerns. This condition is only defined for three-phase systems and occurs when the
voltage magnitudes and phase angles for each of the phases are not equal. The imbalance
percentages represent the ratio of the negative sequence component to the positive
sequence component as derived through symmetrical component analysis. Voltage and
current imbalance are usually the result of uneven distribution of single-phase loads on a
three-phase system or a blown fuse. Imbalance conditions adversely affect AC induction
motors by producing excess heat in the rotor winding and causing premature failure,
by creating unwanted torque oscillations causing possible motor bearing failure, and a
reduction in full-load torque capability. Imbalance conditions also create excess current in
the neutral conductor of a three-phase wye system.
Waveform distortion is comprised of any DC offset that can be present, such as harmonics
or inter-harmonics, line notching, and broadband noise. DC offset is a concern because
it results in magnetic saturation and unwanted heating of motors and transformers. The
causes of DC offset are half-wave rectification and geomagnetic interference. Harmonic
AC voltages or currents have a frequency that is an integer multiple of the fundamental
frequency. Harmonic currents are caused by non-linear loads on the power system. These
are typically variable frequency drives, switched-mode power supplies, or other power
electronic switching devices. Harmonic voltages result from harmonic currents flowing
through system impedances. The effects of the harmonic current can be transferred to
other parts of the power distribution system and the loads connected to it by the resulting
harmonic voltage. Inter-harmonics are voltages or currents at frequencies that are not
integer multiples of the fundamental frequency. Inter-harmonics are caused by static
frequency converters, cyclo-converters, induction furnaces, arc furnaces, and arc welders.
Both harmonics and inter-harmonics result in the overheating of conductors, power
factor correction capacitors, AC induction motors, chokes, and transformers. Extra care
must be exercised when power factor correction capacitors are present. The interaction
of the system inductance, capacitance, and one of the frequency components can create
a resonant condition with uncontrolled voltage and current oscillations that can damage
equipment and shut down the power distribution system.
The presence of harmonics and/or inter-harmonics can also disrupt communications and
control information. An additional voltage waveform distortion issue is line-notching.
Notching occurs due to line commutation of SCRs used in three-phase to DC converters.
When the current through the SCR commutates to zero, there is a short instant of time
where a line-to-line short occurs. The depth and duration of the notch is a function of the
actual commutation time and the system impedance. The Total Harmonic Distortion (THD)
calculation is one method used to detect the presence of line notching. However, this
is not completely reliable because the harmonics in the system can be created by other
PowerMonitor 5000 Family Advanced Metering Functionality | 5
factors besides notching. Line notching is also easily identified by inspection of the time
domain waveform.
Voltage fluctuation (also known as “flicker”) is either systematic or random changes
in voltage magnitude, which are typically in the range of ± 5% of the fundamental
magnitude and occur within a frequency range that goes from about two-thirds of the
fundamental frequency to just over DC. Then the voltage waveform usually appears as a
modulated fundamental frequency similar to an AM radio signal. Analogous to harmonic
voltage distortion, voltage fluctuations are caused by the resulting voltage drop from
load current passing through the system impedance. Any load that has significant current
variation can cause voltage fluctuation to occur. The voltage fluctuation is the actual
electromagnetic phenomena. Voltage fluctuation of this magnitude is of little concern
to the operation of the power system. However, the fluctuation can cause variation in
the light output of lamps energized by the power system. When the variation occurs at
an appropriate level and frequency, the variation in light output becomes perceptible
and irritating to people. It is this perceptible variation in light output that is called flicker.
When the flicker occurs at the right frequency, it can induce seizures in some individuals.
Because the variation of the light intensity is the real item of concern, voltage fluctuation is
only defined for the typical lighting circuit voltage of 120V or 230V AC. The most common
cause of voltage fluctuation is arc furnaces. Analysis of the voltage fluctuation involves
computing a human perceptibility index to indicate the level of human sensitivity. The
actual computation of the index is a fairly complicated procedure
that models the sensitivity of the human eye to how the light
output varies with voltage fluctuation.
The PowerMonitor 5000 M6
expands on the 5000 M5
capability by addressing the
most common power quality
events identified by IEEE 1159.
System power frequency is set by the rotational speed of the
generators supplying the system. As the load on the system
changes, small variation in generator speed can occur, which is
power frequency variation. These instantaneous changes occur
constantly but any changes that exceed the established limits are
usually caused by faults on the utility power transmission system,
a significant generation source going off-line, or a large block of
loads being disconnected from the system. Significant frequency
variation is rare in today’s interconnected power grid. Power
frequency variations are more common when a power distribution system is supplied by
local generation that is not connected to the grid (islanded).
New PowerMonitor 5000 M6 Power Quality Functions
The PowerMonitor 5000 M5 provides an alarm bit for when a voltage sag or voltage swell
occurs. The threshold is fixed at 90 % of configured nominal voltage for sag and 110% for
swell. When one of these events occurs, the associated alarm bit is set and maintains for
90 seconds after the system voltage has returned to normal. No other data is available
regarding the event. The 5000 M6 model expands on this capability by addressing the
most common power quality events identified by IEEE 1159. The 5000 M6 provides five
configurable threshold values for voltage sags and four values for voltage swells. The
following are recorded in the Power Quality Log when a sag or swell is detected:
• The event time
• The event duration
• The configured threshold
• The minimum sag value or the maximum swell value
6 | PowerMonitor 5000 Family Advanced Metering Functionality
The additional data helps you to more fully understand the event that affected the
power system and if any action is needed to minimize the effect of a similar event in the
future. The data also provides sufficient information to classify the event per the IEEE 1159
recommended practice discussed above.
The PowerMonitor 5000 can implement the IEEE 1588 Precision Time Protocol over its
EtherNet I/P network connection. With an appropriately designed network, the metering
results from multiple meters can be precisely aligned in time. This capability lets you
determine a very precise sequence of events to see how a power quality event propagates
through the power distribution system. The meters can be in a local facility or they can
be dispersed across multiple geographic locations. For dispersed meters GPS satellite
receivers are used to supply the time clock. The ability to provide precisely aligned
measurements is further enhanced by a unique feature of the PowerMonitor 5000 M6.
The monitors can be configured to alert other monitors in the system whenever a power
quality event is triggered. Upon receipt of the alert the other monitors use the embedded
time stamp to capture their local conditions at that point in time. The data is stored in each
monitor’s power quality log and waveform capture log even if the local magnitude of the
event was not sufficient to activate the locally configured trigger. This ensures that when
an event occurs, a complete “system” picture is captured and an enhanced view of system
performance is obtained.
The parameters recorded during a power quality event are useful for
quantifying, categorizing and analyzing the event. However, a visual
image of the waveforms before, during, and after the event provides
valuable additional information. The waveform shape and its relation
to the other waveforms at a particular device and across the power
distribution system provides additional diagnostic information to help
you analyze an event to determine what caused it and how to prevent
it in the future. When a short or long duration RMS voltage variation
occurs or when a manual waveform capture command is issued,
the PowerMonitor 5000 M6 automatically records the waveforms
for the three phase current inputs, the neutral or ground current
input, the three phase voltages, and the neutral to ground voltage. The number of cycles
captured before and after the event is user configurable. The complete duration of the
event is recorded unless the detected event lasts longer than one minute. In that case, it is
considered a steady-state condition and the waveform can stop recording. However, the
end of the event can still be recorded in the power quality log.
A waveform record can consist of multiple events. For example, a sag event where
the voltage decreased to 90% of nominal triggers a power quality event and starts a
waveform capture. Before the event ends, a second sag event occurs where the voltage
decreased to 80% of nominal. The second sag is considered to be part of the same event
and the waveform capture can contain both events. Whenever a waveform capture is
in process, it can be extended to include subsequent events as long as the subsequent
events occur before completion of the post-event capture or the one minute limit has
not been reached, whichever occurs first. In addition to short or long duration RMS
voltage variations, a waveform record can also be trigger by receiving an alert from
another PowerMonitor 5000 in the system. This capability is used to obtain a system wide
waveform capture from every monitor in the system, regardless of whether or not a trigger
threshold occurred at every location, when an event occurs at one or more locations in
the distribution system. To take advantage of this capability, the Precision Time Protocol
mentioned earlier must be configured and operating.
PowerMonitor 5000 Family Advanced Metering Functionality | 7
The PowerMonitor 5000 is capable of recording a large number of waveforms. The exact
number of waveforms varies based on the cumulative duration of the events recorded.
Additionally, when Rockwell Automation’s FactoryTalk® EnergyMetrix™ software is used
to configure and extract data from the monitors, it automatically detects when there are
waveform records available and download them from the monitors. This lets individual
monitors maximize their waveform capture capabilities and create virtual infinite storage
ability. Factory Talk EnergyMetrix software acquires all waveform information from
different monitors, properly align the waveforms, and provide a unified display of them.
The software can also be used to create various types of reports, such as monthly/annual
consumption or power quality reports.
Percent of Fundamental
The PowerMonitor 5000 M6 also measures the harmonic content of the voltage and current
inputs up through the 63rd harmonic. This measurement is computed and updated every
line cycle. The measurement data provides both the magnitude and angle for each of the
Harmonic Number
harmonics, the total harmonic distortion (THD), and the power flow at each harmonic.
This lets you analyze the harmonic content to determine what harmonics are present and
whether or not they are of sufficient magnitude to cause issues in your power distribution
system. If action is warranted, you can install filters or other mitigating technologies to
reduce the problematic harmonics and then verify the effectiveness of the solution.
The harmonic information is also used to measure compliance to the requirements of IEEE
519, Recommended Practices and Requirements for Harmonic Control in Electrical Power
Systems. The intent of IEEE 519 is to provide recommended limits for the level of harmonic
current injection due to loads at your facility and to provide recommended limits for the
level of harmonic content present in the voltage supplied by the utility. The measurement
of these two quantities is to be made at the point of common coupling (PCC) between the
utility and you. The PCC is usually defined as the location in the power distribution system
where the utility meters are connected.
IEEE 519 is not intended to be applied to individual loads or groups of loads in your
facility. Rather, IEEE 519 provides limits to the total amount of harmonic content and to the
magnitude of individual harmonics. There are different limits for short term and long term
intervals. When properly configured, the PowerMonitor 5000 uses the measured harmonics
to provide a pass/fail indication for the limits in IEEE 519. The monitor also provides detailed
information so you can precisely determine the limits that are being exceeded.
PowerMonitor 5000 M8 Overview
When available, the PowerMonitor 5000 M8 includes all functionality of the M5 and M6 models, and also implements metering
and power quality capabilities as defined in EN 61000-4-30, EN 61000-4-7, EN 61000-4-15, and EN 50160. These new capabilities
provide a standardized method for measuring and reporting system harmonics as well as measuring both inter-harmonics and
sub-harmonics in the power system. The 5000 M8 also measures and reports system voltage fluctuation (flicker). It can also
detect and capture sub-cycle transient events.
Allen-Bradley, EnergyMatrix, FactoryTalk, LISTEN. THINK. SOLVE., PowerMonitor, Rockwell, Rockwell Automation, and Rockwell Software are trademarks of Rockwell Automation, Inc.
Trademarks not belonging to Rockwell Automation are property of their respective companies.
Publication 1426-WP002A-EN-P – October 2013
Supersedes Publication XXX-XXXXXX-XX-X – Month 201X
Copyright © 2013 Rockwell Automation, Inc. All Rights Reserved. Printed in the U.S.A.