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MEgA – Měřící Energetické Aparáty, a.s.MEgA – Měřící Energetické Aparáty, a.s.
664 31 Česká 390664 31 Česká 390
Czech RepublicCzech Republic
Universal Energy Meter
MEg40
+
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3
Universal Energy Meter MEg40
+
Universal energy meter MEg40
+
1/ PURPOSE AND DESCRIPTION
e universal energy meter MEg40+ works as an energy meter and a monitor at the same
time. In the function of the energy meter, it has a set of six energy registers for each phase.
In the function of the monitor, it records long-term voltage, current and power curves
and according to the voltage quality standard ČSN EN 50160 ed. 3, it registers voltage
deviations in class S. e values of energies and recorded quantities are shown on the
display. e instrument MEg40+ is designed for LV, MV and HV measurements.
For LV measurements, it is possible to use both the basic version and the version
MEg40+/S1, which uses split core instrument transformers SMART PTD to indirectly
measure currents. e version MEg40
+
/S3 uses exible current sensors AMOSm to measure
currents; this version can be installed in uninterrupted power supply technology PPN (liveline working).
1)
e universal energy meter MEg40+ is an instrument of the measurement category IV,
it is designed for installation in unprotected circuits of LV stations and substitutes classic
pointer registering instruments and also four-quadrant energy meters.
MEg40
+
stores all measured data in the Flash data memory for further processing in PC
or PDA and archiving in database tools. e internal 4 MB data memory can be replaced
by a removable 16 MB memory card of special design that enables fast and on personnel
and technical means undemanding data transfer into information systems. e standard
communication interface of the instrument MEg40+ is USB 2.0. It is made also in versions
with the RS232 / RS485 interface that are used to integrate the instrument MEg40+ into
measuring systems. e USBhost / RS485 converter can be also additionally connected to
the instrument MEg40+ made with USB 2.0 interface.
e measuring modes and conversion constants of components of the measurement chain
can be programmed from the keyboard of the instrument or more comfortably using PC.
e user program of the instrument MEg40
+
evaluates data of one instrument in PC. Data
measured by more instruments MEg40+ and archived in a database can be processed using
the system software WebDatOr. e user SW is described in the User manual MEg40+.
1)
e versions of MEg40+/S1 and MEg40+/S3 are described in separate manuals.
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Měřící Energetické Aparáty
4
2/ TECHNICAL PARAMETERS
Reference conditions: U
supply
= 230 V / 50,0 Hz
ambient temperature = 20 °C, relative humidity = 40 % to 70 %.
Measured voltages and currents have a frequency identical with U
supply
and make
athree-phase system.
Measured
quantity
Rated value
Range of
measurement
Accuracy
[% of range]
Note
TRMS voltage
U
nom
= 230 V 0 V to 290 V 0.2 % ± 1 digit
1), 2)
U
nom
= 57.73 V 0 V to 125 V 0.2 % ± 1 digit
TRMS current
I
nom
=1 A 0 A to 1.2 A 0.2 % ± 1 digit
1), 2),
3)
I
nom
=5 A 0 A to 6 A 0.2 % ± 1 digit
Power factor PF
U > 0.8 U
nom
I > 0.1 I
nom
PF > 0.1 0.5 % ± 1 digit 4)
Active power 230 V / 5 A, 1 A PF > 0.4 0.5 % ± 1 digit 4)
Reactive power 230 V / 5 A, 1 A PF < 0.6 0.5 % ± 1 digit 4)
Active energy 230 V / 5 A
U ≥ 0.8 U
nom
I > 0
Cos ϕ L > 0.5
Cos ϕ C > 0.8
Class B
according to
TPM 2440-08
ČMI
Voltage events U
nom
0.05 Ujm to 1.20 U
nom
T ≤ 1 sec
1.0 % U
nom
20 msec
5), 6)
Notes:
¹ Only the range is to be specied in the order.
² e rated value of the primary quantity is to be entered using PC or from the
keyboard.
³ Only indirect current measurement through measuring current transformers. In
LV and MV networks, special measuring current split core transformers PTD with
the rated currents 100 A, 200 A, 300 A, 400 A, 500 A, 600 A and 900 A can be used.
It measures in 4 quadrants.
It evaluates events according to the voltage U
rms1/2
specied in ČSN
EN 61000-4-30, ed. 2 with characteristics in ČSN EN 50160, ed. 3, i.e. with the
residual voltage and event duration.
With an external uninterruptible power supply unit, e. g. MEg102, it can measure
longer voltage events.
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Universal Energy Meter MEg40
+
Frequency range of phase lock loop: 47.4 Hz to 52.9 Hz
Input impedance in 230 V range: 1.8 MΩ
in 57.7 V range: 0.9 MΩ
Maximum input phase voltage
in 230 V range: 295 V
ef
in 57.7 V range: 150 V
ef
Maximum voltage on current inputs at I
nom
in 5 A range: 0.16 V
ef
in 1 A range: 0.8 V
ef
Overload capacity of current inputs: 1 min – 2 × I
nom
1 sec – 30 × I
nom
Allowable voltage between current inputs: 50 V
ef
Supply voltage U
AC supply
: 230 V +10 %, –30 %
Spotřeba při U
AC supply
= 230 V: 5,0 VA
Quantities measured in MEg40
+
:
Phase voltage Active energy at consumption
Delta voltages Active energy at delivery
Phase currents Reactive energy L at consumption
Active and reactive powers Reactive energy L at delivery
U and I events Reactive energy C at consumption
Maximum currents Reactive energy C at delivery
Quantities calculated in PC : Quantities displayed on MEg40
+
:
True power factors - PF Phase/delta voltages
Daily current diagrams Phase currents
Statistics of events Active powers
General data
Flash data memory: 4 MB
1)
Data memory organisation: linear or circular
Serial communication: USB2.0 / RS232 / RS485
2)
Speed of serial communication (USB 2.0, RS485 and RS232):
115,2 kBd (default), 256 kBd when the measurement is stopped (USB 2.0 only)
Internal time: 1,0 sec / 24 hr., T
network
± 1 sec at f
network
synchronization
Notes:
1)
16 MB when 16 MB memory card is used
2)
One type of communication as ordered.
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Měřící Energetické Aparáty
6
Construction
Dimensions body: 90 × 90 × 90 mm
frame: 95 × 95 mm
Weight: 0.6 kg
Terminal block: max of wires 3.0 mm
Panel attachment: 2 pcs of removable eccentrics
Operating data
Working temperature: -25 °C to +55 °C
Storage temperature: -25 °C to +85 °C
Relative humidity: 20 % to 90 % at 40 °C
Ingress protection rating (IEC 60529): front panel IP40, other parts IP20
Pollution degree: 2
Measurement category: IV, U
nom
= 230 V
Battery type for internal time: Li battery CR ½ AA CD
Electromagnetic compatibility
Electrostatic discharge immunity: conforming to IEC 61000-4-2
(4 kV / 15 kV)
Immunity to radiated radio-frequency elds: conforming to IEC 61000-4-3
(10 V/m, 80 MHz - 2000 MHz)
Immunity to fast transients: conforming to IEC 61000-4-4 (2 kV)
Surge immunity: conforming to IEC 61000-4-5 (4 kV)
Immunity to induced voltages: conforming to IEC 61000-4-6 (3 V)
Immunity to dips, short interruptions: conforming to EN 61000-4-11
(1 period / 100 %)
Interference voltages conducted: conforming to EN 55011
Radiated emissions in the range 30-1000 MHz: conforming to EN 55011
Harmonic current emissions: conforming to EN 61000-3-2
Voltage changes, voltage and icker uctuations: conforming to EN 61000-3-3
Magnetic elds with f = 50
Hz, 0,5 mT: conforming to IEC 1036
External electric eld 50 Hz / 10 kV/m: conforming
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Universal Energy Meter MEg40
+
3/ FUNCTION DESCRIPTION
Compared with the original universal monitor MEg40, the universal energy meter
MEg40
+
oers extended functions to measure electrical energy. When measuring energies,
it stores measured values into non-destructive registers and allows also additional creation
of tari bands and load proles, without limitation of their number and time. anks
to the possibility of subsequent analysis, MEg40+ can be used in locations with a set of
functionally independent consumptions unspecied in advance, e.g. in manufacturing
and commercial complexes.
e instrument MEg40+ has a set of six energy registers for each phase according to
standard IEC 62053-23, see Fig. 1. ey are the following registers:
OBIS: 1.1.1.8.0 EP+ - active energy, consumption
OBIS: 1.1.2.8.0 EP- - active energy, delivery
OBIS: 1.1.5.8.0 E
QL/P+
- reactive energy inductive at consumption
OBIS: 1.1.7.8.0 E
QL/P-
- reactive energy inductive at delivery
OBIS: 1.1.8.8.0 E
QC/P+
- reactive energy capacitive at consumption
OBIS: 1.1.6.8.0 E
QC/P-
- reactive energy capacitive at delivery
e set of six registers for an outlet is located in the basic non-destructive memory of the
instrument and the set of six distributed registers of the individual phases is located in the
data ash memory that can be realized as a memory card.
Fig. 1: Denition of quadrants of active and reactive energy according to IEC 62053-23
half-plane delivery half-plane consumption
Quadrant II Quadrant I
Quadrant III Quadrant IV
Q+
P-
P+
Q-
U
E
S
QC/P-
EQL/P+
E QL/P- E QC/P+
E P- E P+
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Měřící Energetické Aparáty
8
e display of the instrument MEg40+ shows total registers for the three-phase outlet.
e set of six registers for the individual phases are read by the user program. e phase
energy measurement is unimportant when it is measured in compensated MV networks
(MVL). Also in the recorder mode, only basic voltage, current, active power and voltage
event data and other user information appear on the display.
e basic measurement time is 10 periods. True RMS voltage, current, power and energy
values are measured continuously thanks to the phase lock look. As well, intervals to
record into the data memory are multiples of 10 periods. In this case, the sampling rate of
the measured voltages and currents is controlled by the phase locked loop derived from
the L1 phase voltage. e phase locked loop is active in the frequency range from 47.4 Hz
to 52.9 Hz. If the frequency of the L1 phase voltage is outside the frequency interval, the
sampling rate is set at 50.00 Hz.
Apparent powers, reactive powers and true power factors - PFs are calculated in MEg40
+
from true RMS voltages and currents and from active powers recorded during the
recording interval into the Flash data memory. e reactive power includes a deformation
power component. e universal energy meter MEg40+ is designed for system, longterm measurements. For this use, it has both usual synchronization of the internal time
through the oscillator frequency and synchronization of the internal time through the
network voltage frequency. is allows a unied analysis of events in the course and
also of long-term measurement campaigns. During a mains failure when internal time
synchronization through the network frequency is selected, the time is synchronized by
the internal oscillator with f = 50.00 Hz.
In the function of time course recording, the interval to record the measured values
can be set from 1.0 sec to 1 hour. Besides average values for the recording interval, it
is also possible to store maximum and minimum values of 0.2 sec (10 periods) in the
memory, which occurred in the recording interval. It is also possible to record RMS
values measured in the time when the recording interval is nished.
In order to protect the data memory from lling with clusters of numerous unimportant
events, e.g. in case of voltage oscillations near the specied limits, it is possible to record
events on a new page only after it is opened. It does not occur prior to the time dened
after the previous page is opened. It allows suppressing the possibility to ll the entire
data memory with unimportant data in case of clusters of events.
e standard size of the data memory of the instrument MEg40
+
is 4 MB. When average
values of all voltages, currents, active and reactive powers, and energies in the summary
set of six registers, and up to 50 events per 27 hr 05 min are recorded, it is possible to store
data for the time period of 577.3 days in the 4 MB memory with the recording interval
of 10 minutes. When the 16 MB memory card is used and the recording is selected for
all average values of measured quantities, maximum and minimum voltages, maximum
currents and active powers, energies in the set of six registers in the individual phases in
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Universal Energy Meter MEg40
+
5-minute intervals and for up to 30 events during every 6 hr 45 min, the minimum time
of measurement is 573.6 days.
en both 10-minute voltage quality evaluations and 15-minute energy evaluations can
be made from 5-minute intervals.
e organisation of the internal data memory of MEg40
+
and the memory card can be
circular or linear. When the measured data are stored into the circular data memory,
after the memory is full, the oldest data in the range of one page are deleted and new
data are recorded on their place. When the measured data are stored into the linear
data memory, after the memory is full, the new measured data are not recorded into
the memory and the data measured after the measurement is started are stored in the
memory permanently. Cooperation of the internal data memory and the memory card is
included in the following description of the 16 MB memory card.
An event is registered when the voltage U
rms(1/2)
of any phase gets out of the preset limits;
according to ČSN EN 50160, ed. 3 it is 90 % U
nom
and 110 % U
nom
. e beginning and
ending time of an event can be recorded with the max. inaccuracy 10 msec. During
an event, minimum and maximum voltages U
rms(1/2)
are evaluated, or also currents of
all phases. e event ends when all of the voltages return in accordance with ČSN
EN 50160 into the allowable tolerance band narrowed by the hysteresis of 2 % U
nom
. E.g.
if the limits of 90 % U
nom
and 110 % U
nom
are selected, then the limits to end an event are
92 % U
nom
and 108 % U
nom
. Beside the time when an event occurred, also the duration
of the event is recorded. As an event, it is also recorded a measurement failure due to
a supply voltage loss, and it is recorded the beginning and ending time of the failure.
e universal energy meter measures for 1 sec also in case of a supply voltage failure.
Duration of longer failures is measured using the internal backup clock with the time
resolution of 1 sec. After the failure ends and the supply voltage is restored, the HW of the
instrument MEg40+ is checked for about 1 sec and then the measurement is restored. e
duration, during which the measurement is interrupted in case of a longer power failure,
is extended by about 1 sec.
When it is required so that the instrument measures also during supply voltage failures,
see ČSN EN 61000-4-30, ed. 2, it is possible to order also the uninterruptible power
supply MEg102 together with the instrument MEg40
+
, which can supply the instrument
MEg40+ during up to four subsequent supply voltage failures always for the required time
of 3 minutes.
In the function of measurement and registration of maximum currents, the maximum
currents are searched in the instrument MEg40+ among values measured during the
preset measurement interval for each phase and the whole outlet from the beginning of
the measurement, which appear only on the display of the instrument together with the
time of occurrence.
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Měřící Energetické Aparáty
10
e user software evaluates maximums for selected recording intervals on the individual
phases and also for the whole outlet for the recording interval and 1/4hr maximums.
Besides, daily diagrams of average currents are determined for any selected day.
e basic version of the instrument MEg40
+
has a bidirectional serial communication
USB 2.0. When measurement is stopped and the communication speed increases
to 256 kbit/sec, the 4 MB data memory is read within 7 minutes. Measured data are
transmitted from the 16 MB memory card to PC using a memory card reader within
4 minutes. For remote communication, optional communication RS232 or RS485 is
available. e communication interface USB 2.0 can be converted to the interface RS485
additionally using the USBhost /RS485 converter.
e function of the user program MEg40+ is described in a separate user manual.
4/ DESCRIPTION OF CONTROLS AND DISPLAY
e front panel of the instrument MEg40
+
includes a large-area graphic backlit display
with 64 × 128 pixels and four environment-resistant foil keys with mechanical response.
e function of the keys is preset by the control program of the instrument. ere is also
a connector of the serial interface USB 2.0 and a covered two-row connector of the 16 MB
memory card. e serial number of the instrument and prescribed data are specied on
the front panel.
e rear panel includes vents, two rows of terminal blocks with marked individual
terminals, rated current and rated voltage data and safety information.
After the supply voltage is applied and the HW function of the instrument is successfully
checked, basic data about the control program appear on the display temporarily. en
according to the settings made before the power supply was interrupted, rotating energy
registers of the function Energy meter or selected measured values of the function
Monitor are displayed. e display returns to the preset mode always automatically when
no of the instrument buttons is activated for 1 minute
e universal energy meter MEg40+ is set by the manufacturer so that after the power is
on, values of all energies of all of six registers for the whole outlet can rotate gradually on
the display from EP+ to E
QC/P-
. e energy values appear on the display in the format with
eight digits before the decimal point and three smaller decimal digits after the decimal
point. e type and unit of the measured energy is given above the energy value, and the
energy code is displayed under the energy value according to OBIS standard. To stop the
rotation of register values, use the left outside button Stop. You can browse through the
registers manually using the other two buttons with up and down arrows (↑ ↓). After
the required register is found, the value of the selected register appears on the display for
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Universal Energy Meter MEg40
+
1 minute. en the rotation of the registry values is restored. e rotation can be restored
using the button Start. When the button Menu is enabled, the item Energy meter and
the item Monitor appear. By turning to the item Energy meter (inverse display) and
pressing the button Select, you display the items Displ. interval, Cycle type and Higher
resolution. By selecting the item Displ. interval you can change the speed of rotation
of the displayed register values after 5 s, 10 s, 15 s, 20 s, 30 s, by selecting the item Cycle
type you can change rotation of all six registers for Consumption + delivery or only
three registers for Consumption or Delivery. By selecting the item Higher resolution
and yes, the frozen register values appear for 1 minute with 1 000 times higher resolution,
which results also in changes of displayed units. e default resolution is always basic, not
increased. In case of the higher resolution, three highest orders are cut o.
After the item Monitor is enabled, the items Measuring instrument, Maximum
currents, Recorder and Check of wiring are displayed and the buttons have assigned
the meanings End, ↑ - setting one line up, ↓ - setting one line down and Selection. Press
the button End to complete the preset selection and return the program to the previous
selection, i.e. in this case to the display mode of the function Monitor. Press the buttons
↑ or ↓ to set the corresponding inversely displayed line and press the button Select to
select the item on the set line.
After the main item Measuring instrument is selected, the following four items
appear on the display: View parameters, Voltage measurement parameters, Current
measurement parameters and Instrument parameters.
By selecting the item Display parameters you can display the items Type, Interval
and Method. After selecting the item Type you can use the buttons ↑ and ↓ to select
the display by quantities, by phases or simultaneous display of all outlet quantities. e
selected display type is to be conrmed by pressing the button End.
When displaying the item Quantity and returning to the basic display, you can use the
button U to continuously display phase or delta values, or the button I to display phase
currents, and the button P to display phase active powers. When measuring in a MV
network with a compensation coil MVL (vnL), the outlet power marked ∑P is displayed
instead of phase powers.
By simultaneous pressing more buttons, you display the selected quantities alternately
with the preset time of display.
When the item Phase is selected, use the dark button of the selected phase to display
the voltage, current and active power. According to the pre-selection, phase and delta
voltages, phase currents and active powers of the selected phases are displayed. As well in
this case, by simultaneous pressing more buttons you can display corresponding phases
alternately.
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Měřící Energetické Aparáty
12
When the item Outlet is selected, all three voltages, three currents and three phases or
active powers are displayed simultaneously, or the total active power of the outlet.
By selecting the item Interval you can select the repeat interval to display new values
in seven steps from 0.2 sec to 12.8 sec. By selecting the item Method, you can select the
display in absolute units or in % of the rated value.
After you select the items Voltage measurement parameters and Current measurement
parameters for the rst time, the item Password appears to prevent from unauthorized
intervention into the setting or displaying of parameters of the voltage and current
measuring chain.
e password is four-digit and is set in the form of 3355. Each of the password digits can
be selected separately using the buttons ↑ and ↓ and is conrmed by the button Select.
After entering all of the four password digits, complete the entry by pressing the button
End. e password can be changed and read by the PC program. Even if the password
is not entered correctly, you can browse parameters of the current and voltage chain but
possible changes are not realized after you press the button Select.
By selecting the item Voltage measurement parameters, you display the items Level,
Voltage and U
nom
. To select the line with the required item, use the buttons ↑ and ↓.
After selecting the item Level you can use the buttons ↑ and ↓ to set the LV, MV, MVL
and HV level. After you press the button Level selection, the instrument made for the
rated voltage 57.7 V will accept MV, MVL or HV levels and the instrument made for the
rated voltage of 230 V will accept only the LV level. By selecting the item Voltage you can
set and select the display of phase or delta voltages. By selecting the item U
nom
you can set
only the value of 230 V for the LV level, delta voltages of 3 kV, 6 kV, 10 kV, 20 kVA, 22 kV
and 35 kV for the MV level and delta voltages of 110 kV, 220 kV and 400 kV for the HV
level. e non-standard MV voltage 20 kV can be substituted by any other non-standard
real value by changing the program.
By selecting the item Current measurement parameters you display the items I
prim
and I
sec
. In the item I
prim
you can set one of the standard values of primary currents
of the measuring current transformers: 1 A, 5 A, 10 A, 12,5 A, 15 A, 20 A, 25 A, 30 A,
40 A, 50 A, 60 A, 75 A, 100 A, 125 A, 150 A, 200 A, 250 A, 300 A, 400 A, 500 A, 600 A,
750 A, 1000 A, 1250 A, 1500 A, 2000 A, 2500 A. You can also set a non-standard value
of the primary current of the current transformer User. e item I
sec
displays the size of
secondary input of the measuring current transformer, for which input current circuits
of MEg40+ are prepared. e default values are 1 A or 5 A. When a measuring current
split core transformer PTD is used and current inputs of the instrument MEg40+/S1 are
connected in the corresponding way, the character S1 is displayed. e designation S3 is
for the use of exible sensors AMOSm. When S1 is selected, rated primary currents of
transformers PTD can be set at 100 A, 200 A, 300 A, 400 A, 500 A, 600 A a900 A. When
S3 is selected, rated primary currents of sensors AMOSm can be set at 250 A, 500 A,
1000 A a 2000 A.
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Universal Energy Meter MEg40
+
When you select the item Instrument parameters, the instrument MEg40+ displays
the basic information about the instrument, i.e. serial number, control program version
- FW, date and time of the internal clock and capacity of the Flash data memory of
the instrument. When the 16 MB memory card is inserted, the capacity of this card is
displayed. To return to the previous selection, use the button End.
When you set and select the main item Maximum currents, the instrument MEg40
+
displays maximum currents for the measurement interval for each phase and maximum
value of the sum of phase currents measured by the instrument from the programmed
start. As well times and dates are displayed, when the individual maximums occurred.
After the item Recorder is selected, information about the course of function is displayed.
When the record is not active, the message Record completed will appear on the line
Status or the message Recording when the function Recorder is set. When the function
Recorder is programmed, also additional lines appear on the display including the
recording start time, i.e. hour, minute, second and date, and information that measured
data are stored in the memory, i.e. linear or circular memory, including information
about the interval when the measured data are stored into the memory.
After you select the item Check of wiring, four functions run automatically to check the
wiring of connected measuring circuits for correctness. ey are the following functions:
• voltage connection check,
• phase sequence check,
• current connection check,
• phase assignment check..
e used checking procedure may not detect double and multiple errors in the wiring
and may not be eective even when the wiring is correct, if there is a big voltage or
current unbalance or power factors and currents are small. e correct result of the
checking function is indicated by OK. In case of an ambiguous result, the quantities will
be displayed, because of which it was impossible to decide about the correct wiring, and
after the button TEST is enabled, the result is marked with the question mark. A wiring
error is indicated by the word Error.
To check voltage connections, phase and delta voltages are checked. is function
assumes phase voltages higher than 0.75 Unom. If it is found out that one, two or all
three voltages are not connected, the message „Voltage connection error“ will be displayed
and the evaluated delta voltages, from which the disconnected voltage can be derived. e
Voltage connection checking function may not be eective to check the common wire
for connection.
e following function checks the phase sequence. e check result is the message Phase
sequence 123 (clockwise) or Phase sequence 132 (counter-clockwise).
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Měřící Energetické Aparáty
14
e Current connection function checks currents for correct ow through individual
circuits of the instrument MEg40+ and for correct direction, which must be in phase with
the voltage corresponding to the voltage input. e allowable phase shift is ± 80°. If no
current ows through the current input or its direction is turned relative to the voltage,
then the message Current connection error and active powers of the individual phases
will be displayed. According to the sign and size of the active power, you can determine
the error in the connection of the corresponding current. is function assumes a phase
current more than 3 % I
nom
at the rated voltage.
e last function checks voltages and currents of the individual phases for correct
assignment. If the voltage and current assignment is incorrect, the message Current
assignment error and phase shifts between U1-I1, U2-I2 and U3-I3 will be displayed.
e phase shifts in the realized wiring are expressed in degrees. is check is eective
when the power factor is higher than 0.65.
5/ INSTALLATION
e universal energy meter MEg40
+
shall be installed into a square hole of the panel
with the dimensions of 92 × 92 mm ± 1 mm to ensure access from both sides to the screwon terminals and a free space above and below the instrument to remove heat from the
instrument and install eccentrics, which attach the instrument to the panel mechanically.
White eccentrics are to be inserted into proled holes in the top and bottom of the black
housing of the instrument and turned towards the panel. To take out the eccentrics when
disassembling the instrument, turn the eccentrics backwards and remove from the holes.
e voltage inputs of the instrument MEg40+ meet requirements of the measurement
category IV according to ČSN EN 61010-2-30 and can be connected directly to LV
collectors of the transformer station. In cases where the station includes a voltage circuit
protection or in cases where it is expected that voltage circuit protection will be realized
for other measuring instruments, the manufacturer recommends you to connect also
voltage inputs of the instrument MEg40+ to the protected circuits. e measured voltages
U1, U2 and U3 in LV networks are to be connected through xed or exible wires with
the minimum cross-section of 0.75 mm2 with double insulation.
Also in MV networks with resistance and compensated networks (MVL) and HV
networks, indirectly measured voltages U1, U2 and U3 are always connected to the phase
conductors and the measuring instrument measures phase or delta voltages according to
the programmed requirement. To the terminal Nm in MV, MVL and HV networks, the
ground is always applied. In LW networks, the central conductor is to be connected to
the terminal Nm.
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Universal Energy Meter MEg40
+
Current inputs of the instrument MEg40+ shall be always connected indirectly to
secondary circuits of the measuring current transformers through xed or exible wires
with the cross-section of 3 mm2 with double insulation. It is recommended to connect
them through a terminal block with the possibility to short-circuit secondary currents
of the measuring current transformers. e secondary current of the measuring current
transformer of the phase L1 is brought to the input terminal I1K of the instrument
MEg40+ and goes out from its output terminal I1L. e secondary current of the
measuring current transformer of the phase L2 is brought to the input terminal I2K
of the instrument MEg40+ and goes out from its output terminal I2L. e secondary
current of the measuring current transformer of the phase L3 is brought to the input
terminal I3K of the instrument MEg40+ and goes out from its output terminal I3L.
e current circuits inside the instrument MEg40+ are not galvanically connected, the
maximum allowable voltage between the current circuits is 50 V.
When it is measured in LV and MV networks, where measuring current transformers are
not installed, measuring split core instrument transformers PTD can be used to measure
currents - made according to the pat. No. 286255, with the rated current from 100 A to
900 A and a window size of 68 × 68 mm. en the universal energy meter is in the version
MEg40+/S1.
When it is measured in a LV network, the voltage of 230 V is not allowed to be connected
to the current terminals of the instrument in the version MEg40+. Direct current
measurement is impossible.
e supply network voltage 230 V / 50 Hz or uninterruptible voltage 230 V / 50 Hz is
applied to the terminals Network 230 V of the instrument; the position of the phase and
central conductor is unimportant. It is also recommended to install a protection element.
After all of the measuring and supply circuits are connected, it is possible to check them
for correct connection by activating the function Check of wiring, which is described in
the previous chapter.
e instrument MEg40+ can be delivered with the inserted 16 MB memory card. In
this case, it is not allowed to take out or handle the memory card during installation.
erefore the card is covered with a sticker by the manufacturer, which shall be removed
after the measurements are programmed. If the instrument MEg40+ is not delivered
with the memory card, the card slot is covered with a plastic cover. e memory card is
described in a separate chapter.
Warning!
When the instrument MEg40+ is used in a dierent way than it is specied
by the manufacturer, the protection provided by the instrument MEg40+ can
be impaired.
Page 16
Měřící Energetické Aparáty
16
5.1 Installation of the instrument with the serial communication
RS485, RS232
e universal energy meter MEg40
+
can be installed also into networks with communication interface RS485 or RS232. e required communication interfaces must be
specied in the order.
e modulation rate of the communication interfaces RS485 and RS232 is 115.2 kBd.
No data transfer is possible at an increased rate with interruption of the measurement.
To interconnect, it is recommended to use a shielded twisted pair. e connection of
terminals for RS485 and RS232 communication is as follows:
INSTRUMENT MEg40
+
(direction from the instrument)
INTERFACE
RS485
INTERFACE
RS232
TxD (output) Rx+ or RxTx+ TxD
RxD (input) Rx− or RxTx− RxD
⊥
shielding
⊥
If it is necessary to additionally ensure remote communication with the instrument
MEg40
+
equipped with the USB 2.0 interface, it is possible to use the USBhost / RS485
converter to convert the USB 2.0 interface to the RS485 interface.
6/ OPERATION OF THE INSTRUMENT MEG40
+
Operation of the instrument MEg40+ in the basic version includes programming the
measurement, reading the measured data of USB 2.0 communications, and taking out
the memory card with measured data and inserting an empty card if 16 MB memory
card is used.
e measurement is programmed in the instrument MEg40
+
using PC or PDA with the
running user program MEg40+ when the PC or PDA are connected to the instrument
MEg40+ through the communication cable MEg40+-PC, 1.8 m or 5 m long, with ferrite
absorbers. e procedure how to program measurements is included in the description of
the program MEg40+. After the function Recorder is programmed, the letter Z appears
permanently in the top R.H. corner, and after the function Registration of events is
programmed, the letter U appears permanently in the top R.H. corner of the display of
the instrument MEg40+.
It is possible to read the measured data through the serial communication USB 2.0 without
interrupting the measurement when the data are read into a data le in PC at the speed
of 115.2 kbit/sec. e measured data can be read into the data le also with interruption
of the running measurement, then the communication speed increases automatically to
256 kbit/sec and the communication is not interrupted due to the running measurement.
Page 17
17
Universal Energy Meter MEg40
+
us, the data reading time can be signicantly reduced, however the new measured data
will be saved into a new data le after the data transfer is completed.
After communication is nished with interruption of measurement, the new
measurement must be programmed. rough the serial communication, the measured
data can be read both from the internal data memory (4 MB) and from the 16 MB
memory card.
However, the data transfer from the 16 MB memory card is more ecient, when the
16 MB memory card is taken out from the instrument MEg40
+
and inserted into the
memory card reader connected to PC with the active reader control program. en the
data are read at the speed of 921.6 kbit/sec and the full card is read out within 4 minutes.
During one reading, you can read gradually up to eight memory cards. e operator
does not need PC to take out the 16 MB memory card with the measured data from the
instrument MEg40+ and insert the new empty 16 MB memory card into the instrument
MEg40+. en the operator hands on the 16 MB memory cards with the measured data
for reading and deleting. A detailed description of the data reading from the 16 MB
memory card is given in a separate chapter of this manual.
7/ MAINTENANCE INSTRUCTIONS
e universal energy meter MEg40
+
does not include any movable parts, and therefore
it does not require any mechanical maintenance other than common cleaning of the
panel. To clean, you can only use soft materials and non-aggressive solutions, preferably
water with a detergent. It is necessary to ensure that the vents in the rear panel of the
instruments are open through.
In demanding climatic and operating conditions, the manufacturer recommends you
to check the accuracy of measurements in the interval from 4 to 8 years of operation,
depending on the importance of the place of measurement. Accuracy of measurement is
checked using a multimeter with accuracy of voltage and current measurement at least
one class higher than the accuracy of the instrument MEg40
+
. e manufacturer of
the instrument MEg40+ recommends e.g. multimeter Agilent 34401A. If you detect an
error bigger than corresponding to the specication of the instrument, MEg40+ must be
recalibrated. You can order the measurement accuracy check and calibration also at the
manufacturer of the instrument MEg40+.
8/ CONTENTS OF THE SET
e set of the universal energy meter MEg40
+
includes:
• 1 instrument MEg40
+
,
• 2 eccentrics,
Page 18
Měřící Energetické Aparáty
18
• certicate of guarantee and delivery note,
• CD with the basic user program and manual..
Optional available accessories:
• communication cable MEg40
+
-PC / 1.8 m or 5 m,
• 16 MB memory card,
• reader of 8 memory cards,
• uninterruptible power supply MEg102,
• USBhost / RS485 converter with cable long 1 m.
e following versions are available for ordering beside the version MEg40
+
with
USB 2.0 interface:
• version MEg40
+
with interface RS485,
• version MEg40
+
with interface RS232.
9/ DELIVERY
e place of delivery unless otherwise specied is the seat of the manufacturer. e set
of the instrument MEg40
+
is delivered in the multilayer cardboard box with a delivery
note and a certicate of guarantee. e serial number of the instrument MEg40+ packed
inside, its measuring ranges and list of delivered accessories are specied on the packaging.
For transport, it is necessary to protect the front panel of the instrument with the display
and inserted memory card against mechanical damage using a multilayer cardboard
insert.
10/ GUARANTEE
Two-year standard guarantee is provided for the universal energy meter MEg40
+
and its
accessories from the date of its sale. Defects incurred during this period due to provably
defective construction, defective design or improper materials will be repaired free of
charge by the manufacturer; the place of performance of the guarantee is the seat of the
manufacturer of the instrument MEg40+.
e guarantee becomes invalid if the user carries out unauthorized modications
or changes on the instrument MEg40+ or its accessories, or connects the instrument
incorrectly, mechanical wearing of the instrument is inadequate or the instrument
MEg40+ or its accessories was operated contrary to the technical specication.
Page 19
19
Universal Energy Meter MEg40
+
Defects of the instrument MEg40+ and its accessories incurred during the guarantee
period shall be claimed by the user to the manufacturers of the instrument MEg40+.
Claims without the enclosed certicate of guarantee shall not be admitted.
e manufacturer shall not bear any responsibility for consequential damages caused
by the use of the instrument MEg40+ and its accessories. No responsibility of the
manufacturer follows from this guarantee that would exceed the price of the instrument
MEg40+.
11/ ORDERING
e order should indicate a number of pieces of the universal instruments MEg40
+
with
one of the possible parameters:
• voltage range: 57.73 V, 230 V,
• current range: 1 A, 5 A,
• serial communication type: USB 2.0, RS485, RS232
You can order only one type of the serial communication.
Specify extra:
• requirement for memory CARD 16 MB
• requirement for extended SW,
• number of memory card readers,
• number and length of communication cables MEg40
+
-PC
• number of uninterruptible power supplies MEg102,
• number of USBhost / RS485 converters.
Note
In the order, you can dene the voltage level, rated primary voltages and currents or
wiring type in the place of installation of the instrument. e manufacturer will program
these data into the instruments before dispatching them. e given data can also be
programmed by the orderer during installation of the instrument. You can order also a
four-digit password dierent from the password dened by the manufacturer. (3355). e
password can be changed after installation of the instrument either by means of software
or from the keyboard. A changed or forgotten password can be read out only using the
user program MEg40
+
.
12/ MANUFACTURER
MEgA – Měřící Energetické Aparáty, a.s., 664 31 Česká 390, Czech Republic,
tel: +420 545 214 988 • mail: mega@e-mega.cz • web: http://www.e-mega.cz
Page 20
Měřící Energetické Aparáty
20
L1
L2
L3
N
I2K
I2L
I3K
I3L
I1K
I1L
U1
U2
U3
Nm
SIŤ
MEg40
MTP
MTP
MTP typ
e MBS ASK 51.4
230V,5A/1A
connection terminal WKS 1/2
type WTL 6/3 STB type WTL 6/3 STB
OPV 10/3
PV 10 6A gG
SIŤ
+
SISISISI SISI
SUSU SUSU
SISI
SUSU SUSU
SISISISI
Fig. 2: Wiring of the instrument MEg40+ in LV network without uninterruptible power
supply
Fig. 3: Wiring of the instrument MEg40
+
in a LV network with uninterruptible power
supply
MTP
MTP
MTP typ
e MBS ASK 51.4
OPV 10/3
PV 10 6A gG
connection terminal WKS 1/2
type WTL 6/3 STB
L1
L2
L3
N
type WTL 6/3 STB
uninterruptible power supply
230V, 50Hz, 8VA
230V,5A/1A
SIŤ
I2K
I2L
I3K
I3L
I1K
I1L
U1
U2
U3
Nm
SIŤ
MEg40
+
SUSU
SISISISISISISISISISISISI
SUSUSUSUSUSUSUSU
PE
PE
Page 21
21
Universal Energy Meter MEg40
+
Fig. 4: Dimensions of the instrument unit MEG40
+
Profile 96 x 96 mm / body 90.5 x 90.5 mm
Hole in front panel 92 x 92mm
Fig 5: Rear panel of the instrument MEg40+
left: version with USB 2.0 communication
right: version with RS485/RS232 communication
I1k
I1l
I2k
I2l
I3k
I3l
U2
U3
N
m
U1
MEg 40
!
POWER
230V
50Hz
8VA
CAT
IV
U
=
max
290V
ef
I =
n
U
=
n
A
V
ef
+
POWER
230V
50Hz
8VA
+
I =
n
U
=
n
A
V
ef
MEg40 S USB MEg40 S ROZHRANÍM
Page 22
Měřící Energetické Aparáty
22
Menu
Electricity meter
Monitor
Interval
display
Cycle
type
Higher
resolution
5s
10s
15s
20s
30s
40s
50s
60s
consumption
+delivery
Consumption No
Delivery
Yes
Measuring instrument
Checking the connection Recorder Maximum values of currents
Parameters of display
Paramet
ers of voltage
Parameters of current Instrument
measurement (password
) measurement (password) parameters
Type
Interval Manner
Quantity
Phase
Feeder
Value
Value in %
200ms
400ms
800ms
1,6s
3,2s
6,4s
12,8s
Level Voltage Unom
LV
MV
230V
MVL
3kV,6kV,10kV
Phase
Phase-to-phase
HV
20kV,22kV,35kV
110kV,220kV
400kV
Recorder
State: recording in action
Recording since: dd:mm:yy
Memory: circular/linear
Interval of recording: mm.ss
Maximum values of currents
Instantaneous values
I1 nnnA
I2 nnnA
I3 nnnA
Connection of voltage
Sequence of phases
Connection of currents
Assignation of phases
Checking the connection
Fig. 6: Function of the control panel of the universal energy meter MEg40
+
Page 23
23
Universal Energy Meter MEg40
+
Monitor
Recorder Maximum values of currents
rs of voltage
Parameters of current Instrument
) measurement (password) parameters
230V
3kV,6kV,10kV
20kV,22kV,35kV
110kV,220kV
400kV
I prim I sec
1A,5A,S1,S2,S3
Serial number
Version of FW
Memory capacity
Date and time
1A,5A,10A,12.5A
15A,20A,25A,30A
40A,50A,60A,75A
100A,125A,150A
200A,250A,300A
400A,500A,600A
750A.1000A,1250A
1500A,2000A,User
Maximum values of currents
values
I1 nnnA
Maximum values Maximum of feeders
I1+I2+I3 vvvA
Time: hh:mm
Date: dd:mm:rr
I2 nnnA
I3 nnnA
I1 mmmA
I2 mmmA
I3 mmmA
Page 24
Měřící Energetické Aparáty
24
Accessories of the universal instrument MEg40
+
16 MB memory card and memory card reader
Page 25
25
16MB memory card and memory card reader
1/ PURPOSE AND USE
Easy, on time, personnel and technical means undemanding collection of data measured
by the instrument MEg40
+
is allowed by a special 16 MB memory card with Flash
memory and a reader for eight memory cards.
e use of the 16MB memory card allows you to record Uav, U
max
, U
min
, Iav, I
max
, Pav, P
max
,
Qav of all three phases and store energies in the set of six registers with the recording
interval of 5 min, register 30 voltage events and record extreme currents in each interval
with the length of 9 hr 20 min for the time period longer than 795 days, i.e. longer than
2 years and 2 months.
e universal energy meter MEg40+ will start writing only into a completely deleted
16 MB memory card, onto which at rst the measurement head is written. Only this
instrument MEg40+ can write down into such a marked memory card. Other instruments
detect any discrepancy of measurement heads and report them on the display. After the
data are read out from the memory card by the reader and transferred into PC, it is
possible to delete the data recorded on the card using a special conrmed command.
en the card can be used to record data in any instrument MEg40+.
2/ OPERATING CONDITIONS OF THE INSTRUMENT MEG40
+
WITH 16MB MEMORY CARD
2.1 Programming and start of measurement of the instrument MEg40+
with memory card
e programming and start of the measurement of the instrument MEg40+ equipped with
the memory card does not dier from the programming and start of the measurement
of the instrument MEg40+ without the memory card. e dierence consists in the time
during which the memory is deleted; the deletion time of the (16 MB) memory card and
the (4 MB) internal data memory MEg40+ increases from the original 20 sec to about
100 sec. We can assume that when the instrument MEg40+ with the memory card is
programmed, a wider range of recorded parameters and higher recording frequency will
be selected.
2.2 End of measurement of the instrument MEg40+ with memory card
In the linear recording mode, the record is ended after the memory card capacity is
used up (the internal data memory capacity is not used) or after the measurement end is
instructed by means of the control program from PC.
Page 26
Měřící Energetické Aparáty
26
In the circular recording mode, measured data are permanently recorded only into the
memory card and the oldest data pages are overwritten. e measurement is ended after
the measurement is ended from PC.
2.3 Data transmission from the instrument MEg40
+
with memory card
e data transmission from the instrument MEg40
+
equipped with the memory card to
PC can be realized through a serial USB interface similarly as in case of the instrument
without a memory card. is method is time consuming and lasts tens of minutes even if
the running measurement is stopped.
e procedure used in practise to transmit data measured by the instrument MEg40
+
and stored on the 16 MB memory card includes taking out the card and subsequent
inserting another deleted memory card. en the memory card with the measured data
is to be inserted into a reader connected via the serial USB interface to PC. e reader is
supplied from the computer. After the utility of the memory card reader is enabled, the
card content is transmitted to PC. is can run in a time independent of the time when
the memory card was taken out from MEg40+.
Up to eight memory card can be inserted in the card reader simultaneously, their data are
automatically gradually read out into the memory of the computer. Before the data are
read out, the conguration of the inserted cards is read out and it is possible to view heads
of the measured data les on the individual memory card in detail. After the measured
data are read out from the memory cards into the computer, you can require verication
of the measured data transferred into your computer and data stored on the memory
cards and only then using the corresponding conrmed command, you can delete the
data and their heads recorded on the individual cards.
2.4 First insertion of 16 MB memory card into the instrument MEg40
+
e measured data written into the data memory of the instrument MEg40+ must be read out
before the memory card is inserted.
e deleted 16MB memory card can be inserted into the programmed meter MEg40
+
any time. From the time when the card was inserted and the measurement head brought
on the card, the measured data are stored only on the memory card. After the 16 MB
memory card is inserted, the following message appears on the display of the instrument
MEg40+ for 1.5 sec: „Memory module inserted / Start of recording“.
If a memory card was inserted into the instrument MEg40
+
that was marked by another
instrument and contains a dierent measurement head, the instrument detects this
discrepancy and displays alternately: „Memory module inserted. Module not deleted“.
en the instrument keeps displaying measured quantities alternately, however they are
not stored either into the instrument memory or onto the memory card. e modes
Recorder and Events may not be evaluated correctly on the display
Page 27
27
16MB memory card and memory card reader
2.5 Replacement of 16 MB memory cards in the measuring instrument MEg40
+
After the 16 MB memory card is taken out from the measuring instrument MEg40+, the
measured data recording is interrupted and this status is displayed alternately with the
measured data on the display MEg40
+
with the message „Memory module taken out“.
en a new deleted memory card can be inserted, which will be marked by the
instrument (with the head of the running measurement) and the instrument shows the
message „Memory module inserted. Start of recording“ on the display for 1.5 sec. en it
continues storing the measured data onto this card.
It is also possible to insert a not deleted card, which is marked by another instrument.
is wrong situation is alternately reported with the message „Memory module inserted.
Module not deleted“ and measured data are being lost until a deleted card is inserted.
Also repeated insertion of the memory card can be assumed, onto which measured data
were recorded before. In this case, the display shows the message „Memory module
inserted. Recording restored“ and the instrument continues recording the measured data
onto the repeatedly inserted memory card. e data measured during the time when the
card was not inserted will be lost.
3/ MANUFACTURER
MEgA – Měřící Energetické Aparáty, a.s.
664 31 Česká 390, Czech Republic
tel: +420 545 214 988 • mail: mega@e-mega.cz • web: http://www.e-mega.cz
Page 28
Měřící Energetické Aparáty
28
Uninterruptible power supply MEg102
1/ PURPOSE
e uninterruptible power supply MEg102 serves for short-term power supply of the
instrument MEg40+ in case of supply voltage interruptions or drops. In accordance with
ČSN EN 61000-4-30 ed. 2, its use is necessary for registration of short-term voltage events
up to 3 min.
2/ FUNCTION DESCRIPTION
e power supply MEg102 generates rectangular output voltage with a frequency equal
to the frequency of the network or with a lower frequency in case of an input voltage
failure. e accumulator and its keeping in charged condition is a part of the power
supply unit MEg102. e input and output voltages of the power supply unit MEg102
Page 29
29
Uninterruptible power supply MEg102
are galvanically isolated by transformers, they are to be connected to the power supply
unit using screw-on terminals. ere is a button on the outside of the plastic cover to stop
the battery operation.
e principle of the uninterruptible power supply MEg102 is represented by the group
diagram in Fig. 1. e input voltage U
inp
applied to the terminals IN is converted by
the transformer T1 and the subsequent rectier to the DC voltage, which is converted
by means of a synchronized generator and output switches to the AC pulse voltage and
transformed to U
outp
by the transformer T2 to power supply the instrument. e voltage
U
outp
is on the terminals of the power supply unit MEg102.
e U
inp
voltage drop below the lower limit indicates with the SitOK signal to the control
circuits of the accumulator to change over the battery supply. e battery operation is
nished when U
inp
returns above the lower limit plus necessary hysteresis or when the
period set by the internal generator expires (default 180 sec) or when the external button
Battery stop is pressed for about 2 seconds.
Fig. 1: Group wiring diagram of uninterruptible power supply MEg102.
Battery control
Output
switches
SitOK Upom
UpomSync
Control signal generator
Uinp Uoutp
T1T1
+
Bat+Battery
T2T2
Page 30
Měřící Energetické Aparáty
30
3/ TECHNICAL PARAMETERS
Input voltage: U
inp nom
= 230 V / 50 Hz
Maximum input voltage: 253 V
Change to battery operation: U
inp
= 180 V
Return to network operation: U
inp
= 195 V
Output voltage: 170 Vef, rectangular course,
mark-to-space ratio 1:4 in both polarities,
U
peak-peak
≈ 450 V
Maximum output power: 1.5 VA
Maximum input power: 10 VA
Accumulator: NiMH,
U
nom
= 10.5 V / 110 mAh
3 × 3H110BC (Vinic), or V150H (Varta)
Min. charging current: about 5 mA
Battery operation time: 4 × 180 s, for MEg40
+
Frequency synchronization with the network: for U
inp
≥ 100 V
Working conditions
Temperature: -25 °C to +50 °C
Relative humidity: 5 % to 95 %
Safety: ČSN EN 61010
Dimensions: 115 × 65 × 40 mm
Weight: 0,4 kg
Ingress protection rating: IP20
Max. cross-section of input and output wires: 3,0 mm
4/ INSTALLATION INSTRUCTIONS
e supply voltage 230 V ± 10 % with the rated frequency of 50 Hz must be brought to the
power supply MEg102 through a 200 mA fuse. e phase conductor is to be connected
to the terminal 1 of the double terminal IN and the central conductor to the terminal 2.
e output AC voltage of 170 V
ef
is on the terminals 3 and 4 of the double terminal OUT.
It is galvanically isolated from the network circuits and shall be connected to the power
supply system of the instrument MEg40+.
e maximum cross-section of the conductors is 3 mm. e conductors shall be with
double insulation.
Page 31
31
Uninterruptible power supply MEg102
Mechanically, the power supply unit MEg102 is to be placed close to the measuring
instrument mounted on the DIN rail TC 35 using a clip. e power supply unit can be
also just put on the horizontal surface.
e vents of the unit MEg102 are not allowed to be covered. During installation, it is
necessary to respect IP20 protection.
When the uninterruptible power supply MEg102 is used in a dierent way
than it is specied by the manufacturer, the protection provided by the power
supply unit MEg102 can be impaired.
5/ MAINTENANCE INSTRUCTIONS
e uninterruptible power supply units MEg102 do not contain any movable parts, and
therefore do not require any mechanical maintenance other than common cleaning. To
clean you can only use soft materials and non-aggressive solutions. In rough industrial
conditions, it is necessary to check that the vents are open through. e instrument
includes maintenance-free accumulator NiMH batteries that shall be replaced after
10years of operation as recommended by the manufacturer and then the power supply
unit checked for correct operation.
6/ MANUFACTURER
MEgA – Měřící Energetické Aparáty, a.s.
664 31 Česká 390, Czech Republic
tel: +420 545 214 988 • mail: mega@e-mega.cz • web: http://www.e-mega.cz
Page 32
Měřící Energetické Aparáty
32
USBhost / RS485 converter
1/ PURPOSE
e USBhost / RS485 converter is designed to connect a USB slave unit to the RS485
serial line.
e USBhost / RS485 converter allows you to connect the instrument MEg40+ with
the USB interface to the RS485 serial bus. It also supplies the USB interface from the
instrument MEg40+. e RS485 bus is dimensioned for connecting up to 31 units. e
maximum bus length is up to 1200 m when the cabling system is correctly designed and
has a suitable impedance end.
2/ TECHNICAL PARAMETERS
Power supply
voltage: +6 V to +16 V
current (MEg40
+
not connected) : 20 mA
current (MEg40+ connected): 60 mA
RS485 interface
max. rate: 1 Mb/s
max. number of connected units 31 (according to RS485 standard)
Connector
screw-on terminal block, with four terminals
USBhost interface
specication: USB 1.1
USB 2.0 compatible
connector: type B (M)
power supply slave through USB: 5 V / 300 mA
Construction dimensions
length × width × height: 45 × 28 × 18 mm
USB cable length: 1 m
Terminal block, max. of wire: 1.5 mm2
Temperature range: -40 °C to +85 °C
Page 33
33
USBhost / RS485 converter
3/ CONSTRUCTION
e USBhost/RS485 converter according to Fig. 1 with the panel Fig. 2 is installed in
aplastic box designed for spaces with the maximum voltage of 50 V
AC
. ere is a 1 m long
USB cable with USB B (M) connector running out from the left side. ere are 4 screwon terminals on the right side, 2 for the RS485 serial interface and 2 for the power supply
(see Tab. 1). e max. cross-section of connected conductors is 1.5 mm2.
Tab. 1: Table of USBhost/RS485 converter terminals
Terminals Description
A (RxTx+) bidirectional data
B (RxTx−) bidirectional data
+12 V supply voltage from + 6 to + 16 V
⊥ signal ground
4/ INSTALLATION
Before installation, FW must be installed in MEg40
+
allowing the addressing. By default,
MEg40+ with the USB interface includes FW, for which no addressing is assumed.
e schematic diagram of converter in communication chain
MEg40+ → USBhost / RS485 → MEg202.2 is shown in Fig.3. USB cable with connector
B (M) is shown in Fig. 2. e USB cable with the connector B (M) is intended to
be connected into the universal instrument MEg40+. rough this connector, the USB
interface of the instrument MEg40+ is also supplied as specied by the USB interface
standard. rough screw-on terminals, the converter is connected to terminals of the
communication unit MEg202.2; for interconnection of the terminals see Table 2.
Tab. 2: Interconnection of USBhost/RS485 converter and communication unit MEg202.2
USBhost / RS485
converter
MEg202.2
Chan1 Chan2
A 3 7
B 4 8
+12 V 1 5
⊥ 2 6
Page 34
Měřící Energetické Aparáty
34
Fig. 1: USBhost/RS485 converter in version for MEg40+ and MEg202.2
Fig. 2: Detail of type plate of USBhost/RS485 converter
and communication unit MEg202.2
USB host / RS485
konvertor
SN:
A
B
+12V
USB host / RS485
konvertor
SN:
A
B
+12V
Page 35
35
USBhost / RS485 converter
Fig. 3: Interconnection of USBhost/RS485 converter and instrument MEg40
+
and communication unit MEg202.2
Universal Energy Meter MEg40
+
USB
USB host/RS485
+12V
B
A
T
CHAN1 CHAN2
USB host/RS485
+12V
B
A
T
USB slave
1 2 3 4 5 6 7 8
communication unit
GPRS MEg202.2
Page 36
Měřící Energetické Aparáty
36
Appendix No. 1
Methodology of measurement using the monitor MEg40
+
Appendix made by prof. Ing. Vladislav Matyáš, CSc. We understand it not only as a universal
denition of algorithms of the universal monitors of MEg40+ series but also as a generally
valid description of digital measurements.
e monitor MEg40+ performs four dierent functions simultaneously. All of them are
based on measurement of three voltages and three currents in a three-phase system. e
basis is numerical measurement of instantaneous values of these voltages and currents in
regular time intervals given by the sampling rate that is an integer multiple of the mains
frequency. e data sequence u(k) representing instantaneous values of this voltage is
derived by sampling and digitalizing from the voltage waveform u(t); where k = 0, 1, 2, …
is a serial number. e sequence of instantaneous values i(k) is derived from the current
waveform i(t) in the same way.
For three of the monitor functions, the sampling rate is used that is 32-multiple of the
mains frequency, and therefore every network period T
s
receives 32 data for each voltage
and current referring its instantaneous values. e RMS values are calculated from data
sequences. So for the voltage from the data sequences u(k) with K data with the serial
numbers k = 0, 1, 2, …, K – 1, the RMS value is calculated using the following formula
(1)
e formula is gradually used for all three voltages. If instantaneous values u
1
(k) of the
voltage of phase 1 are used instead of u(k) in the formula, you receive the RMS value
U1 of this voltage that applies to the K given data group. Similarly, from the group of
instantaneous values u2(k) of the voltage in phase 2, you get its RMS value U2 and from
the group of instantaneous values u3(k) of the voltage in phase 3 you get its RMS value
U3.
It is also possible to evaluate delta voltages instead of phase voltages. When you substitute
u12(k) = u1(k) – u2(k) in the formula (1) instead of u(k), you can calculate the RMS value
U
12
of the voltage between phases 1 and 2. Similarly, from the instantaneous values u23(k)
= u2(k) – u3(k) you get the RMS value U23 of the voltage between phases 2 and 3 and from
the instantaneous values u31(k) = u3(k) – u1(k) you get the RMS value U31 of the voltage
between the phase 3 and 1.
( )
ku
K
U
K
k
∑
−
=
=
1
0
2
1
Page 37
Měřící Energetické Aparáty
37
A similar relation as for voltages applies to currents. From the instantaneous current
values i(k) with the serial numbers k = 0, 1, 2, …, K – 1, the RMS current value is
calculated according to the formula
(2)
Using this formula, you calculate the RMS value I
1
of the current in phase 1 from the
group of instantaneous values i1(k) of the current in phase 1, the RMS value I2 of the
current in phase 2 from the group of instantaneous values i2(k) of the current in phase 2
and the RMS value I3 of the current in phase 3 from the group of instantaneous values
i3(k) of the current in phase 3.
DETECTION OF EVENTS
In case of this function, RMS values of all three voltages are used, always in the range
of the network period T
s
, and the interval Ts gradually moves by 0.5 Ts. Because the used
sampling rate is 32 times higher than the mains frequency, every interval Ts contains 32
instantaneous values. For calculation, the formula (1) is used where K = 32. e obtained
RMS values of all three voltages are compared with the preset thresholds. If it is found
out that there is a voltage dip, swell or interruption, the extreme voltage value, duration
and time of occurrence are recorded.
DETERMINATION OF VOLTAGES, CURRENTS AND POWERS
Voltages and currents in a three-phase system are evaluated according to their RMS
values in measuring time intervals T
m
lasting 10 network periods, i.e. T
m
= 10Ts.
ese intervals follow immediately one by one but they do not overlap. e sampling runs
continuously with a frequency, which is 32 times higher than the network frequency.
erefore 320 instantaneous values fall into each of the measuring time intervals Tm for
each of the voltages and currents. To calculate the RMS voltage values, the formula (1)
is used where K = 320. So the RMS values of phase voltages U1, U2, U3 or delta voltages
U12, U23, U
31
are obtained.
To calculate the RMS phase current values, the formula (2) is used where K = 320 to
receive RMS phase current values I1, I2, I3.
( )
ki
K
I
K
k
∑
−
=
=
1
0
2
1
Page 38
Měřící Energetické Aparáty
38
As well, powers are evaluated in each of the measuring time intervals Tm. e following
formula is applied to compute the active power:
(3)
where K = 320. From the values u1(k) and i1(k), the active power P1 in phase 1 is obtained,
from the values u2(k) and i2(k) the active power P2 in phase 2 is obtained, from the values
u3(k) and i3(k), the active power P3 in phase 3 is obtained.
From the RMS phase voltage value U and from the RMS current value I in the same
phase and the same measuring time interval Tm, the apparent power is evaluated.
S = U I (4)
Particularly S1 = U1 I1, S2 = U2 I2, S3 = U3 I3.
e reactive power (including the deformation one) in each phase and in the same
measuring time interval Tm is determined according to the formula
(5)
So Q
1
is obtained from S1 and P1, Q2 from S2 and P2, Q3 from S3 and P3.
To assess the electrical power eciency in each phase, the coecient of performance (true
power factor) is used:
(6)
particularly η
1
, η2, η3.
e total outlet powers result from the powers in the individual phases.
In case of long-term measurements, a high number of data is obtained in the followup measuring time intervals T
m
for each voltage and current. Recording of all of these
data would be demanding on the monitor memory and would not provide any general
overview of measurement results. erefore, time aggregation of the mentioned data is
used. e recording interval Tz is selected, containing L measuring time intervals Tm,
i.e. T
z
= L Tm, where L is a natural number. From data measured in the measuring time
intervals Tm for the individual voltages, currents and powers, simple data are derived
characterizing voltage, current and power values in the individual recording intervals Tz.
If for the given voltage, the RMS values U(l) were obtained in the measuring intervals T
m
and with the serial numbers l = 1, 2, … L, the following total RMS value is corresponding
in the recording intervals Tz.
22
PSQ −=
SP /=
η
( ) ( )
kiku
K
P
K
k
∑
−
=
=
1
0
1
Page 39
Měřící Energetické Aparáty
39
(7a)
e average eective value is sometimes used instead of the RMS value.
(7b)
Under normal circumstances, the values U
zc
and Uzp are almost the same. In addition to
the total (or average) RMS value, for each value in the range of the recording interval
between the values U(l), the minimum and maximum values are searched
(8)
ese data are obtained for each voltage.
Similarly, for the recording intervals T
z
, characteristic phase current values are obtained.
From the RMS current values I(l) obtained in the measuring time intervals Tm with the
serial numbers l = 1, 2, … L, for the recording interval Tz, the total RMS current value is
calculated according to the formula
(9)
or the average RMS current value according to the formula
(10)
e values I
zc
and Izp can dier considerably. Besides, the minimum and maximum
current values are determined
(11)
in the recording intervals T
z
( )
lU
L
U
L
l
zc
∑
==1
2
1
( )
∑
=
=
L
l
zc
lI
L
I
1
2
1
( )
∑
=
=
L
l
zp
lU
L
U
1
1
( )
lUU
l
z
min
min
=
( )
lUU
l
z
max
max
=
( )
∑
=
=
L
l
zp
lI
L
I
1
1
( )
lII
l
z
min
min
=
( )
lII
l
z
max
max
=
Page 40
Měřící Energetické Aparáty
40
From the active power values P(l) found out in the individual measuring time intervals
Tm with the serial numbers l = 1, 2, … L, the average active power is obtained for each of
the recording intervals T
z
(12)
and the minimum and maximum active power
(13)
From the reactive power Q(l) in the measuring intervals T
m
, the average reactive power is
determined from each of the recording intervals Tz
(14)
and the minimum maximum reactive power values.
During the recording interval T, the active energy
E
PZ
= TZ PZ (15)
and the reactive energy
EQZ = TZ QZ (16)
was transmitted.
e above data characteristic for the recording intervals are obtained for all three phases.
DETERMINATION OF THE QUARTER-HOUR MAXIMUM CURRENTS
e algorithm used in the universal monitor MEg40
+
with 16 MB memory card in the
version with FW and SW 2008 is modied to allow equivalent evaluation of the quarterhour maximum currents and daily diagrams on the day of occurrence of the quarter-hour
maximum current for any selected evaluation period, and besides, the daily diagram
evaluation is also possible in any selected day.
( )
∑
=
=
L
l
z
lP
L
P
1
1
( )
∑
=
=
L
l
z
lQ
L
Q
1
1
( )
lPP
l
z
min
min
=
( )
lPP
l
z
max
max
=
Page 41
Měřící Energetické Aparáty
41
DISPLAY AND EVALUATION USING A PERSONAL COMPUTER
e data obtained during operation of the monitor and stored in its memory for further
use are transmitted into a personal computer. e simplest operations with the transmitted
data include statements. For each of the detected events, place (phase), type, size, time
duration and time of occurrence is specied. Another example can be a statement of
quarter-hour maximum phase currents with the times of occurrence.
e displayed time courses provide wide application. ey include a display of
characteristic data obtained gradually in the follow-up recording intervals. For voltages
and currents in the individual phases, such data include total or average RMS values,
minimum RMS value and maximum RMS value. For the active, reactive and apparent
power, they are average, minimum and maximum values, similarly for the coecient of
performance (true power factor). It is also useful to display time curves of the average,
minimum and maximum values of the total harmonic distortion and selected harmonics.
Statistical evaluation with subsequent displaying of results in the form of histograms and
cumulative diagrams is also considered. is applies to the above mentioned quantities
but without their time curves. Simple numerical expression is often sucient, e.g. what
percentage of supply voltages detected in ten minute intervals is outside ± 10 % of the
rated value.
e personal computer allows additional processing of displayed data. It is also possible
to make additional time aggregation. e period T
v
is determined as an M-multiple of
the recording interval, i.e. T
v
= M Tz. From the data collected for the recording intervals
during the period Tv, the corresponding data are evaluated for the period Tv. en if
Uzc(m) are total RMS voltage values belonging in the recording interval with the serial
numbers m = 1, 2, … M during the time Tv, the voltage during the time Tv has the total
RMS value
(17)
minimum and maximum value
(18)
e same procedure is used for currents. e average active power in the time T
v
is
(19)
and the minimum and maximum active power is also computed.
( )
mU
M
U
M
m
zcvc
∑
==1
2
1
minmin
min
z
m
v
UU =
maxmax
max
z
m
v
UU =
( )
∑
=
=
M
m
zv
mP
M
P
1
1
Page 42
Měřící Energetické Aparáty
42
Similar formulas apply to the idle power.
e active energy transmitted during the time T
v
is
EPV = TV PV (20)
and the reactive energy similarly.
Data from the time interval T
v
, can be displayed depending on time and evaluated
statistically. It is also possible to use more times Tv for aggregation, with a dierent
position and duration.
Page 43
Měřící Energetické Aparáty
43
Page 44
MEgA – Měřící Energetické Aparáty, a.s.
664 31 Česká 390
Czech Republic
www.e-mega.cz
Edition: 03/2014
Universal Energy Meter
MEg40
+
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