Johnson Controls EM-4000 Series Operation Manual
Code No. LIT-12011946
Issued July 29, 2014
EM-4000 Series Meters
Installation and Operation Manual
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EM-4000 Series Meters Installation and Operation Manual
Published by:
Johnson Controls, Inc.
Building Efficiency
507 E. Michigan Street, Milwaukee, WI 53202
All rights reserved. No part of this publication may be reproduced or transmitted in
any form or by any means, electronic or mechanical, including photocopying, recording, or information storage or retrieval systems or any future forms of duplication, for
any purpose other than the purchaser's use, without the expressed written permission
of Johnson Controls, Inc.
Metasys® and Johnson Controls® are registered trademarks of Johnson Controls,
Inc. All other marks herein are the marks of their respective owners.
© 2014 Johnson Controls, Inc.
Modbus® is a registered trademark of Schneider Electric, licensed to the Modbus
Organization, Inc.
EM-4000 Series Meters Installation and Operation Manual i
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EM-4000 Series Meters Installation and Operation Manual ii
Use of Product for Protection
Our products are not to be used for primary over-current protection. Any protection
feature in our products is to be used for alarm or secondary protection only.
Statement of Calibration
Our instruments are inspected and tested in accordance with specifications published
by Johnson Controls, Inc. The accuracy and a calibration of our instruments are traceable to the National Institute of Standards and Technology through equipment that is
calibrated at planned intervals by comparison to certified standards. For optimal
performance, Johnson Controls, Inc. recommends that any meter be verified for
accuracy on a yearly interval using NIST traceable accuracy standards.
Disclaimer
The information presented in this publication has been carefully checked for
reliability; however, no responsibility is assumed for inaccuracies. The information
contained in this document is subject to change without notice.
This symbol indicates that the operator must refer to an explanation in
the operating instructions. Please see Chapter 4 for important safety
information regarding installation and hookup of the EM-4000 meter.
Dans ce manuel, ce symbole indique que l’opérateur doit se référer à un important
AVERTISSEMENT ou une MISE EN GARDE dans les instructions opérationnelles. Veuillez consulter le chapitre 4 pour des informations importantes relatives à l’installation
et branchement du compteur.
The following safety symbols may be used on the meter itself:
Les symboles de sécurité suivante peuvent être utilisés sur le compteur même:
This symbol alerts you to the presence of high voltage, which can
cause dangerous electrical shock.
Ce symbole vous indique la présence d’une haute tension qui peut
provoquer une décharge électrique dangereuse.
This symbol indicates the field wiring terminal that must be connected
to earth ground before operating the meter, which protects against
electrical shock in case of a fault condition.
Ce symbole indique que la borne de pose des canalisations in-situ qui doit être
EM-4000 Series Meters Installation and Operation Manual iii
branchée dans la mise à terre avant de faire fonctionner le compteur qui est protégé
contre une décharge électrique ou un état défectueux.
This symbol indicates that the user must refer to this manual for
specific WARNING or CAUTION information to avoid personal injury or
damage to the product.
Ce symbole indique que l'utilisateur doit se référer à ce manuel pour AVERTISSEMENT
ou MISE EN GARDE l'information pour éviter toute blessure ou tout endommagement
du produit.
EM-4000 Series Meters Installation and Operation Manual iv
Table of Contents
Use of Product for Protection iii
Statement of Calibration iii
Disclaimer iii
1: Three-Phase Power Measurement 1-1
1.1: Three-Phase System Configurations 1-1
1.1.1: Wye Connection 1-1
1.1.2: Delta Connection 1-4
1.1.3: Blondel’s Theorem and Three Phase Measurement 1-6
Table of Contents
1.2: Power, Energy and Demand 1-8
1.3: Reactive Energy and Power Factor 1-12
1.4: Harmonic Distortion 1-14
1.5: Power Quality 1-17
2: Meter Overview and Specifications 2-1
2.1: EM-4000 Meter Overview 2-1
2.1.1: Voltage and Current Inputs 2-2
2.1.2: Ordering Information 2-3
2.1.4: Measured Values 2-5
2.1.5: Utility Peak Demand 2-6
2.2: Specifications 2-7
2.3: Compliance 2-12
2.4: Accuracy 2-13
3: Mechanical Installation 3-1
EM-4000 Series Meters Installation and Operation Manual TOC - 1
Table of Contents
3.1: Introduction 3-1
3.2: ANSI Installation Steps 3-3
3.3: DIN Installation Steps 3-4
4: Electrical Installation 4-1
4.1: Considerations When Installing Meters 4-1
4.2: CT Leads Terminated to Meter 4-4
4.3: CT Leads Pass Through (No Meter Termination) 4-6
4.4: Quick Connect Crimp-on Terminations 4-7
4.5: Voltage and Power Supply Connections 4-8
4.6: Ground Connections 4-8
4.7: Voltage Fuses 4-9
4.8: Electrical Connection Diagrams 4-10
5: Communication Installation 5-1
5.1: EM-4000 Series Meter Communication 5-1
5.1.1: IrDA Port (Com 1) 5-1
5.1.2: RS485 / KYZ Output (Com 2) 5-1
6: Using the EM-4000 Meter 6-1
6.1: Introduction 6-1
6.1.1: Understanding Meter Face Elements 6-1
6.1.2: Understanding Meter Face Buttons 6-2
6.2: Using the Front Panel 6-3
6.2.1: Understanding Startup and Default Displays 6-3
6.2.2: Using the Main Menu 6-4
EM-4000 Series Meters Installation and Operation Manual TOC - 2
Table of Contents
6.2.3: Using Reset Mode 6-5
6.2.4: Entering a Password 6-6
6.2.5: Using Configuration Mode 6-7
6.2.5.1: Configuring the Scroll Feature 6-9
6.2.5.2: Configuring CT Setting 6-10
6.2.5.3: Configuring PT Setting 6-11
6.2.5.4: Configuring Connection Setting 6-13
6.2.5.5: Configuring Communication Port Setting 6-13
6.2.6: Using Operating Mode 6-15
6.3: Understanding the % of Load Bar 6-16
6.4: Performing Watt-Hour Accuracy Testing (Verification) 6-17
7: Data Logging 7-1
7.1: Overview 7-1
7.2: Available Logs 7-1
A: EM-4000 Meter Navigation Maps A-1
A.1: Introduction A-1
A.2: Navigation Maps (Sheets 1 to 4) A-1
B: Modbus® Map and Retrieving Logs B-1
B.1: Introduction B-1
B.2: Modbus® Register Map Sections B-1
B.3: Data Formats B-1
B.4: Floating Point Values B-2
B.5: Important Note Concerning the EM-4000 Meter's
Modbus® Map B-3
EM-4000 Series Meters Installation and Operation Manual TOC - 3
Table of Contents
B.5.1: Hex Representation B-3
B.6: Modbus® Register Map (MM-1 to MM-37) B-3
C: Using the USB to IrDA Adapter (CAB6490) C-1
C.1: Introduction C-1
C.2: Installation Procedures C-1
EM-4000 Series Meters Installation and Operation Manual TOC - 4
1: Three-Phase Power Measurement
1: Three-Phase Power Measurement
This introduction to three-phase power and power measurement is intended to
provide only a brief overview of the subject. The professional meter engineer or meter
technician should refer to more advanced documents such as the EEI Handbook for
Electricity Metering and the application standards for more in-depth and technical
coverage of the subject.
1.1: Three-Phase System Configurations
Three-phase power is most commonly used in situations where large amounts of
power will be used because it is a more effective way to transmit the power and
because it provides a smoother delivery of power to the end load. There are two
commonly used connections for three-phase power, a wye connection or a delta
connection. Each connection has several different manifestations in actual use.
When attempting to determine the type of connection in use, it is a good practice to
follow the circuit back to the transformer that is serving the circuit. It is often not
possible to conclusively determine the correct circuit connection simply by counting
the wires in the service or checking voltages. Checking the transformer connection
will provide conclusive evidence of the circuit connection and the relationships
between the phase voltages and ground.
1.1.1: Wye Connection
The wye connection is so called because when you look at the phase relationships and
the winding relationships between the phases it looks like a Y. Figure 1.1 depicts the
winding relationships for a wye-connected service. In a wye service the neutral (or
center point of the wye) is typically grounded. This leads to common voltages of 208/
120 and 480/277 (where the first number represents the phase-to-phase voltage and
the second number represents the phase-to-ground voltage).
EM-4000 Series Meters Installation and Operation Manual 1-1
1: Three-Phase Power Measurement
V
A
Phase 3
Phase 2
V
B
Figure 1.1: Three-phase Wye Winding
The three voltages are separated by 120o electrically. Under balanced load conditions
the currents are also separated by 120
conditions can cause the currents to depart from the ideal 120
V
C
N
Phase 1
o
. However, unbalanced loads and other
V
A
o
separation. Threephase voltages and currents are usually represented with a phasor diagram. A phasor
diagram for the typical connected voltages and currents is shown in Figure 1.2.
V
C
I
C
N
I
A
I
V
B
Figure 1.2: Phasor Diagram Showing Three-phase Voltages and Currents
B
EM-4000 Series Meters Installation and Operation Manual 1-2
1: Three-Phase Power Measurement
The phasor diagram shows the 120o angular separation between the phase voltages.
The phase-to-phase voltage in a balanced three-phase wye system is 1.732 times the
phase-to-neutral voltage. The center point of the wye is tied together and is typically
grounded. Table 1.1 shows the common voltages used in the United States for wyeconnected systems.
Phase to Ground Voltage Phase to Phase Voltage
120 volts 208 volts
277 volts 480 volts
2,400 volts 4,160 volts
7,200 volts 12,470 volts
7,620 volts 13,200 volts
Table 1: Common Phase Voltages on Wye Services
Usually a wye-connected service will have four wires: three wires for the phases and
one for the neutral. The three-phase wires connect to the three phases (as shown in
Figure 1.1). The neutral wire is typically tied to the ground or center point of the wye.
In many industrial applications the facility will be fed with a four-wire wye service but
only three wires will be run to individual loads. The load is then often referred to as a
delta-connected load but the service to the facility is still a wye service; it contains
four wires if you trace the circuit back to its source (usually a transformer). In this
type of connection the phase to ground voltage will be the phase-to-ground voltage
indicated in Table 1, even though a neutral or ground wire is not physically present at
the load. The transformer is the best place to determine the circuit connection type
because this is a location where the voltage reference to ground can be conclusively
identified.
EM-4000 Series Meters Installation and Operation Manual 1-3
1.1.2: Delta Connection
V
A
V
B
Delta-connected services may be fed with either three wires or four wires. In a threephase delta service the load windings are connected from phase-to-phase rather than
from phase-to-ground. Figure 1.3 shows the physical load connections for a delta
service.
V
1: Three-Phase Power Measurement
C
Phase 2
Phase 1
Figure 1.3: Three-phase Delta Winding Relationship
In this example of a delta service, three wires will transmit the power to the load. In a
true delta service, the phase-to-ground voltage will usually not be balanced because
the ground is not at the center of the delta.
Figure 1.4 shows the phasor relationships between voltage and current on a threephase delta circuit.
In many delta services, one corner of the delta is grounded. This means the phase to
ground voltage will be zero for one phase and will be full phase-to-phase voltage for
Phase 3
the other two phases. This is done for protective purposes.
EM-4000 Series Meters Installation and Operation Manual 1-4
1: Three-Phase Power Measurement
V
A
V
BC
Figure 1.4: Phasor Diagram, Three-Phase Voltages and Currents, Delta-Connected
Another common delta connection is the four-wire, grounded delta used for lighting
loads. In this connection the center point of one winding is grounded. On a 120/240
volt, four-wire, grounded delta service the phase-to-ground voltage would be 120
volts on two phases and 208 volts on the third phase. Figure 1.5 shows the phasor
diagram for the voltages in a three-phase, four-wire delta system.
V
I
C
I
B
V
AB
C
V
CA
I
A
V
CA
V
BC
Figure 1.5: Phasor Diagram Showing Three-phase Four-Wire Delta-Connected System
N
V
AB
V
B
EM-4000 Series Meters Installation and Operation Manual 1-5
1: Three-Phase Power Measurement
1.1.3: Blondel’s Theorem and Three Phase Measurement
In 1893 an engineer and mathematician named Andre E. Blondel set forth the first
scientific basis for polyphase metering. His theorem states:
If energy is supplied to any system of conductors through N wires, the total power in
the system is given by the algebraic sum of the readings of N wattmeters so arranged
that each of the N wires contains one current coil, the corresponding potential coil
being connected between that wire and some common point. If this common point is
on one of the N wires, the measurement may be made by the use of N-1 Wattmeters.
The theorem may be stated more simply, in modern language:
In a system of N conductors, N-1 meter elements will measure the power or energy
taken provided that all the potential coils have a common tie to the conductor in
which there is no current coil.
Three-phase power measurement is accomplished by measuring the three individual
phases and adding them together to obtain the total three phase value. In older analog meters, this measurement was accomplished using up to three separate elements.
Each element combined the single-phase voltage and current to produce a torque on
the meter disk. All three elements were arranged around the disk so that the disk was
subjected to the combined torque of the three elements. As a result the disk would
turn at a higher speed and register power supplied by each of the three wires.
According to Blondel's Theorem, it was possible to reduce the number of elements
under certain conditions. For example, a three-phase, three-wire delta system could
be correctly measured with two elements (two potential coils and two current coils) if
the potential coils were connected between the three phases with one phase in common.
In a three-phase, four-wire wye system it is necessary to use three elements. Three
voltage coils are connected between the three phases and the common neutral conductor. A current coil is required in each of the three phases.
In modern digital meters, Blondel's Theorem is still applied to obtain proper metering.
The difference in modern meters is that the digital meter measures each phase voltage and current and calculates the single-phase power for each phase. The meter
then sums the three phase powers to a single three-phase reading.
EM-4000 Series Meters Installation and Operation Manual 1-6
1: Three-Phase Power Measurement
Phase B
Phase C
Phase A
A
B
C
N
Node "n"
Some digital meters measure the individual phase power values one phase at a time.
This means the meter samples the voltage and current on one phase and calculates a
power value. Then it samples the second phase and calculates the power for the second phase. Finally, it samples the third phase and calculates that phase power. After
sampling all three phases, the meter adds the three readings to create the equivalent
three-phase power value. Using mathematical averaging techniques, this method can
derive a quite accurate measurement of three-phase power.
More advanced meters actually sample all three phases of voltage and current
simultaneously and calculate the individual phase and three-phase power values. The
advantage of simultaneous sampling is the reduction of error introduced due to the
difference in time when the samples were taken.
Figure 1.6: Three-Phase Wye Load Illustrating Kirchhoff’s Law and Blondel’s Theorem
Blondel's Theorem is a derivation that results from Kirchhoff's Law. Kirchhoff's Law
states that the sum of the currents into a node is zero. Another way of stating the
same thing is that the current into a node (connection point) must equal the current
out of the node. The law can be applied to measuring three-phase loads. Figure 1.6
shows a typical connection of a three-phase load applied to a three-phase, four-wire
service. Kirchhoff's Law holds that the sum of currents A, B, C and N must equal zero
or that the sum of currents into Node "n" must equal zero.
If we measure the currents in wires A, B and C, we then know the current in wire N by
Kirchhoff's Law and it is not necessary to measure it. This fact leads us to the
conclusion of Blondel's Theorem- that we only need to measure the power in three of
EM-4000 Series Meters Installation and Operation Manual 1-7
the four wires if they are connected by a common node. In the circuit of Figure 1.6 we
must measure the power flow in three wires. This will require three voltage coils and
three current coils (a three-element meter). Similar figures and conclusions could be
reached for other circuit configurations involving Delta-connected loads.
1.2: Power, Energy and Demand
It is quite common to exchange power, energy and demand without differentiating
between the three. Because this practice can lead to confusion, the differences
between these three measurements will be discussed.
Power is an instantaneous reading. The power reading provided by a meter is the
present flow of watts. Power is measured immediately just like current. In many
digital meters, the power value is actually measured and calculated over a one second
interval because it takes some amount of time to calculate the RMS values of voltage
1: Three-Phase Power Measurement
and current. But this time interval is kept small to preserve the instantaneous nature
of power.
Energy is always based on some time increment; it is the integration of power over a
defined time increment. Energy is an important value because almost all electric bills
are based, in part, on the amount of energy used.
Typically, electrical energy is measured in units of kilowatt-hours (kWh). A kilowatthour represents a constant load of one thousand watts (one kilowatt) for one hour.
Stated another way, if the power delivered (instantaneous watts) is measured as
1,000 watts and the load was served for a one hour time interval then the load would
have absorbed one kilowatt-hour of energy. A different load may have a constant
power requirement of 4,000 watts. If the load were served for one hour it would
absorb four kWh. If the load were served for 15 minutes it would absorb ¼ of that
total or one kWh.
Figure 1.7 shows a graph of power and the resulting energy that would be transmitted
as a result of the illustrated power values. For this illustration, it is assumed that the
power level is held constant for each minute when a measurement is taken. Each bar
in the graph will represent the power load for the one-minute increment of time. In
real life the power value moves almost constantly.
The data from Figure 1.7 is reproduced in Table 2 to illustrate the calculation of
energy. Since the time increment of the measurement is one minute and since we
EM-4000 Series Meters Installation and Operation Manual 1-8
1: Three-Phase Power Measurement
0
10
20
30
40
50
60
70
80
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Time (minutes)
sttawolik
specified that the load is constant over that minute, we can convert the power reading
to an equivalent consumed energy reading by multiplying the power reading times 1/
60 (converting the time base from minutes to hours).
Figure 1.7: Power Use over Time
EM-4000 Series Meters Installation and Operation Manual 1-9
1: Three-Phase Power Measurement
Time
Interval
(minute)
Power
(kW)
Energy
(kWh)
Accumulated
1 30 0.50 0.50
2 50 0.83 1.33
3 40 0.67 2.00
4 55 0.92 2.92
5 60 1.00 3.92
6 60 1.00 4.92
7 70 1.17 6.09
8 70 1.17 7.26
9 60 1.00 8.26
10 70 1.17 9.43
11 80 1.33 10.76
12 50 0.83 12.42
13 50 0.83 12.42
Energy
(kWh)
14 70 1.17 13.59
15 80 1.33 14.92
Table 1.2: Power and Energy Relationship over Time
As in Table 1.2, the accumulated energy for the power load profile of Figure 1.7 is
14.92 kWh.
Demand is also a time-based value. The demand is the average rate of energy use
over time. The actual label for demand is kilowatt-hours/hour but this is normally
reduced to kilowatts. This makes it easy to confuse demand with power, but demand
is not an instantaneous value. To calculate demand it is necessary to accumulate the
energy readings (as illustrated in Figure 1.7) and adjust the energy reading to an
hourly value that constitutes the demand.
In the example, the accumulated energy is 14.92 kWh. But this measurement was
made over a 15-minute interval. To convert the reading to a demand value, it must be
normalized to a 60-minute interval. If the pattern were repeated for an additional
three 15-minute intervals the total energy would be four times the measured value or
EM-4000 Series Meters Installation and Operation Manual 1-10
1: Three-Phase Power Measurement
0
20
40
60
80
100
12345678
Intervals (15 mins.)
sruoh-ttawolik
59.68 kWh. The same process is applied to calculate the 15-minute demand value.
The demand value associated with the example load is 59.68 kWh/hr or 59.68 kWd.
Note that the peak instantaneous value of power is 80 kW, significantly more than the
demand value.
Figure 1.8 shows another example of energy and demand. In this case, each bar represents the energy consumed in a 15-minute interval. The energy use in each interval
typically falls between 50 and 70 kWh. However, during two intervals the energy rises
sharply and peaks at 100 kWh in interval number 7. This peak of usage will result in
setting a high demand reading. For each interval shown the demand value would be
four times the indicated energy reading. So interval 1 would have an associated
demand of 240 kWh/hr. Interval 7 will have a demand value of 400 kWh/hr. In the
data shown, this is the peak demand value and would be the number that would set
the demand charge on the utility bill.
As can be seen from this example, it is important to recognize the relationships
between power, energy and demand in order to control loads effectively or to monitor
use correctly.
EM-4000 Series Meters Installation and Operation Manual 1-11
Figure 1.8: Energy Use and Demand
1.3: Reactive Energy and Power Factor
V
I
I
R
I
X
0
The real power and energy measurements discussed in the previous section relate to
the quantities that are most used in electrical systems. But it is often not sufficient to
only measure real power and energy. Reactive power is a critical component of the
total power picture because almost all real-life applications have an impact on reactive power. Reactive power and power factor concepts relate to both load and generation applications. However, this discussion will be limited to analysis of reactive power
and power factor as they relate to loads. To simplify the discussion, generation will
not be considered.
Real power (and energy) is the component of power that is the combination of the
voltage and the value of corresponding current that is directly in phase with the voltage. However, in actual practice the total current is almost never in phase with the
voltage. Since the current is not in phase with the voltage, it is necessary to consider
1: Three-Phase Power Measurement
both the inphase component and the component that is at quadrature (angularly
rotated 90
o
or perpendicular) to the voltage. Figure 1.9 shows a single-phase voltage
and current and breaks the current into its in-phase and quadrature components.
Figure 1.9: Voltage and Complex Current
The voltage (V) and the total current (I) can be combined to calculate the apparent
power or VA. The voltage and the in-phase current (I
real power or watts. The voltage and the quadrature current (I
) are combined to produce the
R
) are combined to cal-
X
culate the reactive power.
The quadrature current may be lagging the voltage (as shown in Figure 1.9) or it may
lead the voltage. When the quadrature current lags the voltage the load is requiring
both real power (watts) and reactive power (VARs). When the quadrature current
EM-4000 Series Meters Installation and Operation Manual 1-12
1: Three-Phase Power Measurement
Displacement PF cos=
leads the voltage the load is requiring real power (watts) but is delivering reactive
power (VARs) back into the system; that is VARs are flowing in the opposite direction
of the real power flow.
Reactive power (VARs) is required in all power systems. Any equipment that uses
magnetization to operate requires VARs. Usually the magnitude of VARs is relatively
low compared to the real power quantities. Utilities have an interest in maintaining
VAR requirements at the customer to a low value in order to maximize the return on
plant invested to deliver energy. When lines are carrying VARs, they cannot carry as
many watts. So keeping the VAR content low allows a line to carry its full capacity of
watts. In order to encourage customers to keep VAR requirements low, some utilities
impose a penalty if the VAR content of the load rises above a specified value.
A common method of measuring reactive power requirements is power factor. Power
factor can be defined in two different ways. The more common method of calculating
power factor is the ratio of the real power to the apparent power. This relationship is
expressed in the following formula:
Total PF = real power / apparent power = watts/VA
This formula calculates a power factor quantity known as Total Power Factor. It is
called Total PF because it is based on the ratios of the power delivered. The delivered
power quantities will include the impacts of any existing harmonic content. If the voltage or current includes high levels of harmonic distortion the power values will be
affected. By calculating power factor from the power values, the power factor will
include the impact of harmonic distortion. In many cases this is the preferred method
of calculation because the entire impact of the actual voltage and current are
included.
A second type of power factor is Displacement Power Factor. Displacement PF is based
on the angular relationship between the voltage and current. Displacement power factor does not consider the magnitudes of voltage, current or power. It is solely based
on the phase angle differences. As a result, it does not include the impact of harmonic
distortion. Displacement power factor is calculated using the following equation:
EM-4000 Series Meters Installation and Operation Manual 1-13
where is the angle between the voltage and the current (see Fig. 1.9).
Time
Amps
– 1000
– 500
0
500
1000
In applications where the voltage and current are not distorted, the Total Power Factor
will equal the Displacement Power Factor. But if harmonic distortion is present, the
two power factors will not be equal.
1.4: Harmonic Distortion
Harmonic distortion is primarily the result of high concentrations of non-linear loads.
Devices such as computer power supplies, variable speed drives and fluorescent light
ballasts make current demands that do not match the sinusoidal waveform of AC
electricity. As a result, the current waveform feeding these loads is periodic but not
sinusoidal. Figure 1.10 shows a normal, sinusoidal current waveform. This example
has no distortion.
1: Three-Phase Power Measurement
Figure 1.10: Nondistorted Current Waveform
Figure 1.11 shows a current waveform with a slight amount of harmonic distortion.
The waveform is still periodic and is fluctuating at the normal 60 Hz frequency.
However, the waveform is not a smooth sinusoidal form as seen in Figure 1.10.
EM-4000 Series Meters Installation and Operation Manual 1-14
1: Three-Phase Power Measurement
–1000
–500
0
500
1000
t
)spma( tnerruC
a
2a
–1500
1500
Time
Amps
3rd harmonic
5th harmonic
7th harmonic
Total
fundamental
– 500
0
500
1000
Figure 1.11: Distorted Current Waveform
The distortion observed in Figure 1.11 can be modeled as the sum of several sinusoidal waveforms of frequencies that are multiples of the fundamental 60 Hz frequency.
This modeling is performed by mathematically disassembling the distorted waveform
into a collection of higher frequency waveforms.
These higher frequency waveforms are referred to as harmonics. Figure 1.12 shows
the content of the harmonic frequencies that make up the distortion portion of the
waveform in Figure 1.11.
Figure 1.12: Waveforms of the Harmonics
EM-4000 Series Meters Installation and Operation Manual 1-15
1: Three-Phase Power Measurement
The waveforms shown in Figure 1.12 are not smoothed but do provide an indication of
the impact of combining multiple harmonic frequencies together.
When harmonics are present it is important to remember that these quantities are
operating at higher frequencies. Therefore, they do not always respond in the same
manner as 60 Hz values.
Inductive and capacitive impedance are present in all power systems. We are accustomed to thinking about these impedances as they perform at 60 Hz. However, these
impedances are subject to frequency variation.
X
= jL and
L
= 1/jC
X
C
At 60 Hz, = 377; but at 300 Hz (5th harmonic) = 1,885. As frequency changes
impedance changes and system impedance characteristics that are normal at 60 Hz
may behave entirely differently in the presence of higher order harmonic waveforms.
Traditionally, the most common harmonics have been the low order, odd frequencies,
such as the 3rd, 5th, 7th, and 9th. However newer, non-linear loads are introducing
significant quantities of higher order harmonics.
Since much voltage monitoring and almost all current monitoring is performed using
instrument transformers, the higher order harmonics are often not visible. Instrument
transformers are designed to pass 60 Hz quantities with high accuracy. These devices,
when designed for accuracy at low frequency, do not pass high frequencies with high
accuracy; at frequencies above about 1200 Hz they pass almost no information. So
when instrument transformers are used, they effectively filter out higher frequency
harmonic distortion making it impossible to see.
However, when monitors can be connected directly to the measured circuit (such as
direct connection to a 480 volt bus) the user may often see higher order harmonic
distortion. An important rule in any harmonics study is to evaluate the type of equipment and connections before drawing a conclusion. Not being able to see harmonic
distortion is not the same as not having harmonic distortion.
It is common in advanced meters to perform a function commonly referred to as
waveform capture. Waveform capture is the ability of a meter to capture a present
picture of the voltage or current waveform for viewing and harmonic analysis.
EM-4000 Series Meters Installation and Operation Manual 1-16
Typically a waveform capture will be one or two cycles in duration and can be viewed
as the actual waveform, as a spectral view of the harmonic content, or a tabular view
showing the magnitude and phase shift of each harmonic value. Data collected with
waveform capture is typically not saved to memory. Waveform capture is a real-time
data collection event.
Waveform capture should not be confused with waveform recording that is used to
record multiple cycles of all voltage and current waveforms in response to a transient
condition.
1.5: Power Quality
Power quality can mean several different things. The terms "power quality" and
"power quality problem" have been applied to all types of conditions. A simple definition of "power quality problem" is any voltage, current or frequency deviation that
1: Three-Phase Power Measurement
results in mis-operation or failure of customer equipment or systems. The causes of
power quality problems vary widely and may originate in the customer equipment, in
an adjacent customer facility or with the utility.
In his book Power Quality Primer, Barry Kennedy provided information on different
types of power quality problems. Some of that information is summarized in Table
1.3.
EM-4000 Series Meters Installation and Operation Manual 1-17
1: Three-Phase Power Measurement
Cause Disturbance Type Source
Impulse transient Transient voltage disturbance,
sub-cycle duration
Oscillatory
transient with decay
Transient voltage, sub-cycle
duration
Sag/swell RMS voltage, multiple cycle
duration
Interruptions RMS voltage, multiple
seconds or longer duration
Under voltage/over voltage RMS voltage, steady state,
multiple seconds or longer
duration
Voltage flicker RMS voltage, steady state,
repetitive condition
Harmonic distortion Steady state current or volt-
age, long-term duration
Lightning
Electrostatic discharge
Load switching
Capacitor switching
Line/cable switching
Capacitor switching
Load switching
Remote system faults
System protection
Circuit breakers
Fuses
Maintenance
Motor starting
Load variations
Load dropping
Intermittent loads
Motor starting
Arc furnaces
Non-linear loads
System resonance
Table 1.3: Typical Power Quality Problems and Sources
It is often assumed that power quality problems originate with the utility. While it is
true that many power quality problems can originate with the utility system, many
problems originate with customer equipment. Customer-caused problems may manifest themselves inside the customer location or they may be transported by the utility
system to another adjacent customer. Often, equipment that is sensitive to power
quality problems may in fact also be the cause of the problem.
If a power quality problem is suspected, it is generally wise to consult a power quality
professional for assistance in defining the cause and possible solutions to the
problem.
EM-4000 Series Meters Installation and Operation Manual 1-18
2: Meter Overview and Specifications
2: Meter Overview and Specifications
2.1: EM-4000 Meter Overview
The EM-4000 meter is a multifunction, data
logging, power and energy meter with waveform recording capability, designed to be
used in electrical substations, panel boards,
as a power meter for OEM equipment, and as
a primary revenue meter, due to its high performance measurement capability. The unit
provides multifunction measurement of all
electrical parameters and makes the data
available in multiple formats via display and
communication systems. The unit also has
data logging and load profiling to provide
historical data analysis.
The EM-4000 meter offers 2 MegaBytes of Flash memory. (Because the memory is
flash-based rather than NVRAM (non-volatile random-access memory), some sectors
are reserved for overhead, erase procedures, and spare sectors for long-term wear
reduction.) The unit provides you with up to four logs: three historical logs and a
sequence of events log.
The purposes of these features include historical load profiling, voltage analysis, and
recording power factor distribution. The EM-4000 meter’s real-time clock allows all
events to be time stamped.
The EM-4000 meter is designed with advanced measurement capabilities, allowing it
to achieve high performance accuracy. It is specified as a 0.2% class energy meter for
billing applications as well as a highly accurate panel indication meter. It supplies
0.001 Hz Frequency measurement which meets generating stations’ requirements.
The EM-4000 meter provides additional capabilities, including standard RS485,
Figure 2.1: EM-4000 meter
Modbus® protocol support, and an IrDA port for remote interrogation.
Features of the EM-4000 meter include:
• 0.2% Class revenue certifiable energy and demand metering
• Meets ANSI C12.20 (0.2%) and IEC 62053-22 (0.2%) classes
EM-4000 Series Meters Installation and Operation Manual
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2: Meter Overview and Specifications
• Multifunction measurement including voltage, current, power, frequency, energy,
etc.
• Optional secondary Voltage display (see the EM Series Communicator Software
User Manual for instructions on setting up this feature)
• Percentage of Load bar for analog meter reading
• 0.001% Frequency measurement for Generating stations
• Interval energy logging
• Line frequency time synchronization
• Easy to use faceplate programming
• IrDA port for laptop PC remote read
• RS485 communication
• Transformer/Line Loss compensation (see the EM Series Communicator Software
User Manual for instructions on using this feature)
• CT/PT compensation (see the EM Series Communicator Software
instructions on using this feature)
2.1.1: Voltage and Current Inputs
Universal Voltage Inputs
Voltage inputs allow measurement up to Nominal 576VAC (Phase to Reference) and
721VAC (Phase to Phase). This insures proper meter safety when wiring directly to
high Voltage systems. The unit will perform to specification on 69 Volt, 120 Volt, 230
Volt, 277 Volt, and 347 Volt power systems.
NOTE: Higher Voltages require the use of potential transformers (PTs).
User Manual for
Current Inputs
The unit supports a 5 Amp secondary for current measurements.
The current inputs are only to be connected to external current transformers.
EM-4000 Series Meters Installation and Operation Manual
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