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IOMod Meter User Manual

1. Introduction

IOMod Meter is a compact-sized, stand-alone power meter for measuring analog AC input signals from low-power current and voltage sensors. It measures three phases of AC voltage and current amplitudes and phase shifts. Unlike IOMod 4Cs4Vs IOMod Meter only has three inputs for each phase current and voltage measurements. The measured and calculated values are transmitted to the host system via the communication protocol Modbus RTU, IEC 60870-5-101 or IEC 60870-5-103. 

1.1 Features

  • 3 AC current sensor inputs according to IEC 60044-8 (nominal value 225 mV);
  • 3 AC voltage sensor inputs according to IEC 60044-7 (nominal value 3.25/√3 V);
  • 32 samples per cycle;
  • FFT-based calculation with harmonic information;
  • Additional measurements of:
    • Frequency (Nominal frequencies: 50 and 60 Hz; Frequency range: 45–65 Hz);
    • Active, reactive, and apparent power;
    • Neutral voltage, neutral current;
    • Power factor;
    • Phase angle;
  • Firmware upgrade over USB, RS485;
  • Configurable using the IOMOD Utility app for user-friendly setup;
  • RS-485 interface with a switchable terminating resistor;
  • Compact case with a removable transparent front panel;
  • DIN rail mounting for seamless integration into industrial systems;

1.2 Block diagram

image-1740038444975.drawio.png

Fig. 1.2.1. IOMOD Meter internal structure and block diagram

2. Hardware data

2.1 Mechanical drawings

image-1738838645151.png

Fig. 2.1.1. IOMod Meter side view with dimensions and terminal description. 1 – current measurement inputs; 2 – voltage measurement inputs; 3 – ground input for analogue measurements; 4 - RS485 interface; 5 - power supply input

image-1738838959320.png

Fig. 2.1.2 IOMOD Meter front view with measurements

2.2 Terminal Connections

IOMod Meter has 18 terminals, which are depicted below:

image-1738841460195.png

Fig. 2.2.1 IOMod Meter terminal diagram

The description of each terminal can be found in the table below:

Table 2.2.1 Terminal Specifications

Terminal number

Terminal name

Description

1

Ia

Phase current 1

2

N

3

Ib

Phase current 2 or neutral current in case of I0 metered mode

4

N

5

Ic

Phase current 3

6

N

7

Ua

Phase voltage 1 or phase current 1 in case of 3I3I connection mode

8

N

9

Ub

Phase voltage 2 or phase current 2 in case of 3I3I connection mode, or neutral current in case of 3I3I connection mode, along with I0 metered mode

10

N

11

Uc

Phase voltage 3 or phase current 3 in case of 3I3I connection mode

12

N

13

COM

Analogue measurements common neutral terminals

14

COM

15

A

RS-485 interface port

16

B̄

17

V-

 Power source inputs

18

V+

2.3 Status indication

IOMod Meter have 2 LEDs (Fig. 2.3.1), which indicate communication and power statuses. 

image-1738841815390.png

Fig. 2.3.1. IOMod Meter LEDs physical location

The description of each IOMod Meter LED can be found in the table below:

Table 2.3.1. Description of LEDs.

Name

LED color

Description

RX/TX

🟢 (green)

A blinking green light indicates active communication via the RS-485 interface.

STAT

🟢 (green)

The power source is connected to the power supply input.

🔵 (blue)

IOMod Meter is connected to an external device via a USB mini cable.

3. Technical information

Table 3.1. Technical specifications.

System

Dimension 101 x 119 x 17.5 mm
Case ABS, black
Working environment Indoor
Operating temperature -40°C ... +85°C
Recommended operating conditions  5–60°C and 20–80%RH;
Configuration

USB, RS485
Firmware upgrade USB, RS485
Electrical specifications

Inputs

Resolution

16 bits

Input resistance

~1 MΩ

Input capacitance

< 170 pF

Input ranges

±10 V (amplitude)

Nominal values

Current input: 225 mV (rms)

Voltage input: 1.876 V (rms)

Overvoltage protection for all inputs

up to ±20 V (amplitude)
Power

Power Supply 9–33 VDC (full range)
Current consumption 40 mA @ 12 VDC, 20 mA @ 24 VDC

4. Mounting and Installation

4.1  Connection Diagrams

In this chapter the various options of connecting the device to medium-voltage systems are discussed.

4.1.1  3 Low-Power Current Sensor, 3 Low-Power Voltage Sensors

In the case of 3I3U connection mode, IOMod Meter can be connected to a medium-voltage system by using low-power current and low-power voltage sensors (Fig. 4.1.1.1). In this scenario, the neutral current I0 and the neutral voltage U0 are calculated by taking a vector sum of appropriate measurements. IOMod Meter GND inputs are not required to be connected to the neutral line because they are interconnected with signal neutral inputs (Fig. 1.2.1).

image-1740043377566.png

Fig. 4.1.1.1. Connection diagram with 3 low-power current and 3 low-power voltage sensors 

4.1.2 Fault Passage Indicator for two feeders

The special feature of IOMod Meter is the ability to perform the metering of two feeders (Fig. 4.1.2.1). In this case, 3I3I connection mode needs to be enabled in the IOMod Utility (Fig. 4.1.2.2).

image-1740043505158.png

Fig. 4.1.2.1. IOMod Meter connection diagram for two feeders

image-1738845605650.png

Fig. 4.1.2.2. IOMod Utility General settings tab with Connection mode set to 3I3I

This mode allows us to use IOMod Meter voltage inputs for current measurements, so that the currents of both feeders are measured simultaneously. In the connection scheme above (Fig. 4.1.2.1), IOMod Meter, each input is connected to the pair of feeders via low-power current sensors.

4.1.3 3 Low-Power Voltage Sensor, 2 Phase Current, and Core Balance Current Transformer

IOMod Meter allows direct measurement of the neutral current. To use this feature, I0 current acquiring mode needs to be switched in IOMod Utility from calculated to metered (Fig. 4.1.3.1).

image-1738845968961.png

Fig. 4.1.3.1. IOMod Utility 3I3U settings view with I0 mode switched to metered

After enabling I0 metered mode IOMod Meter second phase input (Ib+/N) becomes neutral current input. Since neutral current measurements are performed directly instead of being calculated, it allows to achieve much higher precision and sensitivity. While neutral current is being metered directly, the second phase measurements are calculated by taking a vector sum of the measured currents. In the scheme below (Fig. 4.1.3.2), current and voltage measurements are taken by using low-power current and low-power voltage sensors. The second input (Ib+/N) is connected to a low-power current sensor, which is placed on the neutral line.

image-1740043531245.png

Fig. 4.1.3.2. IOMod Meter I0 metered mode connection diagram 

4.1.4 2-Phase Current and Core Balance Current Transformer for two feeders

IOMod Meter operating in I0 metered mode preserves the ability of monitoring the currents of two feeders (Fig. 4.1.4.1). In this case, 3I3I connection mode needs to be enabled in IOMod Utility (Fig. 4.1.4.2). 3I3I connection mode allows using voltage inputs as second channel current inputs.

image-1740043554234.png

Fig. 4.1.4.1. IOMod Meter connection diagram for two feeders
with both channels I0 metered mode

In the connection scheme above (Fig. 4.1.4.1), IOMod Meter current inputs are connected to the pair of feeders via low-power current sensors. Moreover, in IOMod Utility I0 mode of both current input channels needs to be changed from calculated to metered (Fig. 4.1.4.2). 

image-1738846533899.png

Fig. 4.1.4.2. IOMod Utility 3I3I settings view with I0 mode of both channels set to metered.

4.1.5 Conventional Current transformers (CT) connection via CT adapters.

IOMod Meter can take current measurements via a current transformer adapter (Fig. 4.1.5.1). Contrary to the current sensors, current transformers are usually intended for transforming priorly lowered currents from secondary distribution networks.

image-1740043573316.png

Fig. 4.1.5.1. IOMod Meter connection diagram with current transformer adapter
and low-power voltage sensors

4.1.6 Conventional Voltage transformers (VT) connection via VT adapters.

IOMod Meter can take voltage measurements via a voltage transformer adapter (Fig. 4.1.6.1). Contrary to the voltage sensors, voltage transformers are usually intended for transforming priorly lowered voltages from secondary distribution networks.

image-1740043586442.png

Fig. 4.1.6.1. IOMod Meter connection diagram with low-power current sensors
and voltage transformer adapter

4.2 RS485 Interface 

IOMod Meter has an integrated 120 Ω termination resistor, which can be enabled or disabled via the configuration terminal. It is recommended that termination be used at each end of the RS-485 cable. IOMod Meter has a 1/8 Unit load receiver, allowing up to 255 units on a single line (compared to the standard 32 units). To reduce reflections, keep the stubs (cable distance from the main RS485 bus line) as short as possible.

4.3 Power Supply

IOMod Meter need to be powered by a 9–33 V power source. IOMOD Meter power supply inputs are located next to RS485 interface inputs (Fig. 4.3.1).

image-1738847702757.png

Fig. 4.3.1. Power supply inputs physical location

4.4 USB Connection

IOMod Meter device has a USB mini connection port. Its primary function is the physical connection establishment between the IOMod and a PC. By selecting the USB interface and correct communication port in IOMod Utility (Fig. 4.4.1), a user can connect to the IOMod to control its parameters and monitor its measured data and the status of fault detection functions. Also, this connection can be used for powering the module. 

Fig. 4.4.1. IOMOD Utility interface and communication port parameters

image-1738849420377.png

Fig. 4.4.2. IOMOD Meter USB connection port physical location

5. Parametrization

In this section, the IOMod Meter settings configuration is described. IOMod Meter configuration is performed via IOMod Utility (the manual can be accessed here). All IOMod-related settings can be found in the "Iomod settings" tab (Fig. 5.1).

Fig. 5.1. IOMod settings tab

5.1 General Parameters

To configure IOMod Meter general settings, open the "Iomod settings" tab in IOMod Utility. After clicking on "Iomod settings", the "General" section opens (Fig. 5.1.1).

image-1738849875787.png

Fig. 5.1.1. IOMod Utility with IOMod Meter general settings window opened.

The general settings consist of two parameters, which apply to all communication protocols (Table 5.1.1). "Measurands set" and "Scale factor" are defined only in the context of the IEC 60870-5-103 communication protocol. The last parameter, "Value update time (ms)", is defined only in the context of IEC 60870-5-101 and IEC 60870-5-103 communication protocols.

Table 5.1.1. IOMOD Meter general parameter ranges and default values.

Parameter

Range

Default value

Connection mode

3I3I, 3I3U

3I3U

Frequency 

50 Hz, 60 Hz

50 Hz

Value update time (ms) *

20-60000

500

Measurands set **

1-4

1

Scale factor **

1.2, 1.4

1.2

*The parameter is defined only for IEC 60870-5-101 and IEC 60870-5-103 communication protocols.

** The parameters are defined only for the IEC 60870-5-103 communication protocol.

The first parameter "Connection mode" allows us to define how the values measured with voltage inputs (terminals 7–12, see Fig. 2.2.1) are supposed to be interpreted. The values are interpreted as voltage measurements by default. This connection mode is denoted by the 3I3U designation. 3I3U designation means "3 currents and 3 voltages", meaning that both current and voltage measurements are being taken from a feeder. 3I3U connection mode parameters can be found in a separate settings section, which is labelled with the communication mode designation (connection mode settings are described in the next section).

Selecting 3I3I connection mode in IOMod Utility changes IOMod Setting sections – 3I3U changes to 3I3I. IOMod Meter, in 3I3I connection mode, interprets the values measured with voltage inputs (terminals 7–12, see Fig. 2.2.1) as current measurements. 3I3I designation means – "3 currents and 3 currents", meaning that the voltage inputs become the second channel current inputs. The 3I3I settings section allows us to modify connection mode parameters (described in the next section). 

The "Frequency" parameter allows us to set the nominal frequency of the power line to which the IOMod Meter is connected.

If the IEC 60870-5-103 communication protocol is selected, the "Measurands set" parameter sets one of the lists of measurements (Table 6.3.2, Table 6.3.3), which is going to be sent to a master device.

If the IEC 60870-5-103 communication protocol is selected, the "Scale factor" parameter sets a value by which all measurements are going to be multiplied.

The value update time (ms) parameter defines how frequently the updated values are going to be sent to a controlling station via IEC 60870-5-101 or IEC 60870-5-103 communication protocols.

5.2 Connection mode settings

As was described earlier IOMod Meter supports two connection modes – 3I3U and 3I3I. After selecting one of them in General settings (Fig. 5.1.1), a new respectively named section appears. In this subsection, the parameters of a specific connection mode are going to be described.

5.2.1 3I3U connection mode parameters

The 3I3U connection mode parameters section has six parameters (Table 5.2), which are going to be described below.

Table 5.2.1.1 3I3U connection mode parameters.

Parameter

Range

Default value

Primary current (A)

1–2000

100

Primary voltage (kV)

0.2–60.0

10.0

Current sensor (mV)

100–300

225

Voltage sensor (V)

1.0–3.0

1.876

I0 mode

Calculated, Metered

Calculated

Primary current I0

1–2000

100
  • The "Primary current (A)" parameter defines the nominal input current of a current sensor or a current transformer.
  • The "Primary voltage (kV)" parameter sets the nominal input line voltage of a voltage sensor or a voltage transformer. If instead of the line voltage, the sensor or adapter converts the phase voltage, still, the value of the line voltage must be used. For example, if a voltage sensor declares the primary voltage of 10/√3 kV, then 10 kV must be used for the "Primary voltage (kV)" parameter, for it is the line voltage of the network.
  • The "Current sensor (mV)" parameter defines the nominal output voltage of a current sensor or a current transformer.
  • The "Voltage sensor (V)" parameter defines the nominal output phase voltage of a voltage sensor or a voltage transformer. Contrary to the Primary Voltage, the phase voltage must be used for this parameter. For example, if a voltage sensor declares the secondary voltage of 3.25/√3 V, then the approximate phase voltage value must be used. It means, that the given expression must be evaluated (3.25/√3 ≈ 1.876 V) and the result must be entered into the "Voltage sensor (V)" parameter (1.876 V).
  • The "I0 mode" parameter defines the way of obtaining the neutral current values. The default parameter value is "Calculated", meaning that the value of the neutral current is going to be calculated by taking the phase current measurements. If "Metered" is selected, then the neutral current values are expected to be measured directly.
  • The "Primary current I0" parameter defines the nominal input neutral current which is being measured by a Core Balance Current Transformer.
5.2.2 3I3I connection mode parameters

The 3I3I connection mode parameters section has eight parameters (Table 5.3), which are going to be described below.

Table 5.2.2.1 3I3I connection mode parameters.

Parameter

Range

Default value

Primary current ch1 (A)

1–2000

100

Primary current ch2 (A)

1–2000

100

Current sensor ch1 (mV)

100–300

225

Current sensor ch2 (mV)

100–300

225

I0 mode ch1

Calculated, Metered

Calculated

I0 mode ch2

Calculated, Metered

Calculated

Primary current I0 ch1

1–2000

100

Primary current I0 ch2

1–2000

100
  • The "Primary current ch1 (A)" parameter sets the nominal input current of a current sensor or a current transformer which is connected to the first channel current inputs.
  • The "Primary current ch2 (A)" parameter sets the nominal input current of a current sensor or a current transformer which is connected to the second channel current inputs.
  • The "Current sensor ch1 (mV)" parameter defines the nominal output voltage of a current sensor or a current transformer which is connected to the first channel current inputs.
  • The "Current sensor ch2 (mV)" parameter defines the nominal output voltage of a current sensor or a current transformer which is connected to the second channel current inputs.
  • The "I0 mode ch1" parameter defines the way of obtaining the neutral current values with the first channel current inputs. The default parameter value is "Calculated", meaning that the value of the neutral current is going to be calculated by taking the phase current measurements. If "Metered" is selected, then the neutral current values are expected to be measured directly.
  • The "I0 mode ch2" parameter defines the way of obtaining the neutral current values with the second channel current inputs. The default parameter value is "Calculated", meaning that the value of the neutral current is going to be calculated by taking the phase current measurements. If "Metered" is selected, then the neutral current values are expected to be measured directly.
  • The "Primary current I0 ch1" parameter defines the nominal input neutral current which is being measured by a Core Balance Current Transformer connected to the first channel current inputs.
  • The "Primary current I0 ch2" parameter defines the nominal input neutral current which is being measured by a Core Balance Current Transformer connected to the second channel current inputs.

5.3 Data Select

The data select tab (Fig. 5.3.1) is the last IOMod settings section, which provides a way to control the data being sent via the IEC 60870-5-101 communication protocol. The IOA (Information Object Address) of each data unit is specified in the brackets to the right of a parameter's name. To include a parameter to a set of parameters which are sent via IEC 60870-5-101 communication protocol a checkbox to the right of a parameter's name needs to be checked.

image-1738917577097.png

Fig. 5.3.1. IOMOD Meter Data select tab view

5.4 Diagnostics

The IOMod Utility Diagnostics tab allows real-time monitoring of IOMod Meter measurements and harmonics statuses. The diagnostics mode of both measurements and harmonics is turned off by default. This is indicated by the red "Offline" word designation and by the unchanging black circle (Fig. 5.4.1, Fig. 5.4.2).

image-1738918161285.png

Fig. 5.4.1. IOMod Utility Diagnostics tab, Measurements section in offline mode

image-1738918112988.png

Fig. 5.4.2 IOMod Utility Diagnostics tab Harmonics section in offline mode

To turn on real-time monitoring of both Diagnostics sections, the "Connect" button to the left of the "Offline" word designation needs to be pressed. The button can be pressed in either the Diagnostics sections (Measurements or Harmonics). After pressing the "Connect" button, the word designation of Diagnostics mode changes to "Online", the black circle starts blinking, and the button name changes to "Disconnect". 

It is advisable to turn off Diagnostics mode before setting new IOMod Meter parameters. To turn off Diagnostics real-time monitoring mode, the "Disconnect" button needs to be pressed.

6. Communication Protocols

IOMod Meter supports three communication protocols: Modbus RTU, IEC 60870-5-101 and IEC 60870-5-103. Using these communication protocols, a user via a master device can read the measured data from the device. The communication protocol can be selected using the IOMod Utility (the IOMod Utility manual can be accessed here).

6.1 Modbus RTU operational information

When the Modbus RTU protocol is selected IOMod Meter acts as a slave device and waits for requests from the Modbus master. For reading the measurements, a master can send a Read Input Register (FC 04) request. A request with an unsupported function code or register number out of range will be answered with the corresponding exception. Measurement results in nominal values have an integer type, while results in primary values are 32-bit float type.

Table 6.1.1 Nominal values in integer format. The data can be read using a Modbus FC4 request.

Address

(Dec)

Description

Units

Data type 

Access

0

Phase L1 current

% x10

UINT16

R

1

Phase L2 current

% x10

UINT16

R

2

Phase L3 current

% x10

UINT16

R

3

Calculated neutral current

% x10

UINT16

R

4

Calculated line voltage U12

% x10

UINT16

R

5

Calculated line voltage U23

% x10

UINT16

R

6

Calculated line voltage U31

% x10

UINT16

R

7

Calculated zero sequence voltage

% x10

UINT16

R

8

Total 3-phase apparent power (S1+S2+S3)

% x10

UINT16

R

9

Total 3-phase active power (P1+P2+P3)

% x10

INT16

R

10

Total 3-phase reactive power (Q1+Q2+Q3)

% x10

INT16

R

11

Total 3-phase power factor

x1000

INT16

R

12

Total harmonic distortions of U1 voltage

UINT16

R

13

Total harmonic distortions of U2 voltage

UINT16

R

14

Total harmonic distortions of U3 voltage

UINT16

R

15

Total harmonic distortions of I1 current

UINT16

R

16

Total harmonic distortions of I2 current

UINT16

R

17

Total harmonic distortions of I3 current

UINT16

R

18

3rd harmonic level of the I1 current

%

UINT16

R

19

5th harmonic level of I1 current

%

UINT16

R

20

7th harmonic level of I1 current

%

UINT16

R

21

9th harmonic level of I1 current

%

UINT16

R

22

3rd harmonic level of the I2 current

%

UINT16

R

23

5th harmonic level of I2 current

%

UINT16

R

24

7th harmonic level of I2 current

%

UINT16

R

25

9th harmonic level of I2 current

%

UINT16

R

26

3rd harmonic level of the I3 current

%

UINT16

R

27

5th harmonic level of I3 current

%

UINT16

R

28

7th harmonic level of I3 current

%

UINT16

R

29

9th harmonic level of I3 current

%

UINT16

R

30

3rd harmonic level of U1 voltage

%

UINT16

R

31

5th harmonic level of U1 voltage

%

UINT16

R

32

7th harmonic level of U1 voltage

%

UINT16

R

33

9th harmonic level of U1 voltage

%

UINT16

R

34

3rd harmonic level of U2 voltage

%

UINT16

R

35

5th harmonic level of U2 voltage

%

UINT16

R

36

7th harmonic level of U2 voltage

%

UINT16

R

37

9th harmonic level of U2 voltage

%

UINT16

R

38

3rd harmonic level of U3 voltage

%

UINT16

R

39

5th harmonic level of U3 voltage

%

UINT16

R

40

7th harmonic level of U3 voltage

%

UINT16

R

41

9th harmonic level of U3 voltage

%

UINT16

R

42

Phase L1 active power

% x10

INT16

R

43

Phase L2 active power

% x10

INT16

R

44

Phase L3 active power

% x10

INT16

R

45

Phase L1 reactive power

% x10

INT16

R

46

Phase L2 reactive power

% x10

INT16

R

47

Phase L3 reactive power

% x10

INT16

R

48

The phase angle of U1 voltage

0.1 deg

INT16

R

49

The phase angle of U2 voltage

0.1 deg

INT16

R

50

The phase angle of U3 voltage

0.1 deg

INT16

R

51

Phase L1 voltage

% x10

UINT16

R

52

Phase L2 voltage

% x10

UINT16

R

53

Phase L3 voltage

% x10

UINT16

R

54

Frequency of phase L1 voltage

Hz x100

UINT16

R

55

Input I4 current

% x10

UINT16

R

56

Input U4 voltage

% x10

UINT16

R

57

S1 phase apparent power

% x10

INT16

R

58

S2 phase apparent power

% x10

INT16

R

59

S3 phase apparent power

% x10

INT16

R

60

L1 phase power factor

% x10

INT16

R

61

L2 phase power factor

% x10

INT16

R

62

L3 phase power factor

% x10

INT16

R

63

The angle of the I1 current

0.1 deg

INT16

R

64

The angle of the I2 current

0.1 deg

INT16

R

65

The angle of the I3 current

0.1 deg

INT16

R

66

Line voltage U12 angle

0.1 deg

INT16

R

67

Line voltage U23 angle

0.1 deg

INT16

R

68

Line voltage U31 angle

0.1 deg

INT16

R

69

Current positive sequence

Data * 10

UINT16

%

70

Current negative sequence

% x10

UINT16

R

71

Voltage positive sequence

%  x10

UINT16

R

72

Voltage negative sequence

% x10

UINT16

R

73

Current I0 angle

0.1 deg

UINT16

R

74

Current I4 angle

0.1 deg

UINT16

R

75

Voltage U0 angle

0.1 deg

UINT16

R

76

Voltage U4 angle

0.1 deg

UINT16

R

77

Current Ip angle

0.1 deg

UINT16

R

78

Current In angle

0.1 deg

UINT16

R

79

Current Up angle

0.1 deg

UINT16

R

80

Current Un angle

0.1 deg

UINT16

R

81

Current I1 2nd harmonic

% x10

UINT16

R

82

Current I2 2nd harmonic

% x10

UINT16

R

83

Current I3 2nd harmonic

% x10

UINT16

R

84

Current I1 channel 2

% x10

UINT16

R

85

Current I2 channel 2

% x10

UINT16

R

86

Current I3 channel 2

% x10

UINT16

R

87

Current I0 channel 2

% x10

UINT16

R

88

Current I4 channel 2

% x10

UINT16

R

89

Current Ip channel 2

% x10

UINT16

R

90

Current In channel 2

% x10

UINT16

R

91

Current I1 channel 2 angle

0.1 deg

UINT16

R

92

Current I2 channel 2 angle

0.1 deg

UINT16

R

93

Current I3 channel 2 angle

0.1 deg

UINT16

R

94

Current I0 channel 2 angle

0.1 deg

UINT16

R

95

Current I4 channel 2 angle

0.1 deg

UINT16

R

96

Current Ip channel 2 angle

0.1 deg

UINT16

R

97

Current In channel 2 angle

0.1 deg

UINT16

R

98

Current I1 2nd harmonic channel 2

0.1 deg

UINT16

R

99

Current I2 2nd harmonic channel 2

0.1 deg

UINT16

R

100

Current I3 2nd harmonic channel 2

0.1 deg

UINT16

R

101

THD of current I1 channel 2

UINT16

R

102

THD of current I2 channel 2

UINT16

R

103

THD of current I3 channel 2

UINT16

R

104

Current I1 3rd harmonic channel 2

%

UINT16

R

105

Current I1 5th harmonic channel 2

%

UINT16

R

106

Current I1 7th harmonic channel 2

%

UINT16

R

107

Current I1 9th harmonic channel 2

%

UINT16

R

108

Current I2 3rd harmonic channel 2

%

UINT16

R

109

Current I2 5th harmonic channel 2

%

UINT16

R

110

Current I2 7th hamonic channel 2

%

UINT16

R

111

Current I2 9th harmonic channel 2

%

UINT16

R

112

Current I3 3rd harmonic channel 2

%

UINT16

R

113

Current I3 5th harmonic channel 2

%

UINT16

R

114

Current I3 7th harmonic channel 2

%

UINT16

R

115

Current I3 9th harmonic channel 2

%

UINT16

R

116-117

Active import energy

kWh

UINT32

R

118-119

Active export energy

kWh

UINT32

R

120-121

Reactive import energy

kVArh

UINT32

R

122-123

Reactive export energy

kVArh

UINT32

R

Table 6.1.2 Primary values in float format. The data can be read using Modbus FC4.

Address (Dec)

Description

Units

Data type 

Access

200 - 201

Current I1

A

FLOAT

R

202 - 203

Current I2

A

FLOAT

R

204 - 205

Current I3

A

FLOAT

R

206 - 207

Current I0

A

FLOAT

R

208 - 209

Voltage U12

U

FLOAT

R

210 - 211

Voltage U23

U

FLOAT

R

212 - 213

Voltage U31

U

FLOAT

R

214 - 215

Voltage U1

U

FLOAT

R

216 - 217

Voltage U2

U

FLOAT

R

218 - 219

Voltage U3

U

FLOAT

R

220 - 221

Voltage U0

U

FLOAT

R

222 - 223

Voltage U1 angle

°

FLOAT

R

224 - 225

Voltage U2 angle

°

FLOAT

R

226 - 227

Voltage U3 angle

°

FLOAT

R

228 - 229

Apparent power Σ3 phase

VA

FLOAT

R

230 - 231

Active power Σ3 phase

W

FLOAT

R

232 - 233

Reactive power Σ3 phase

Var

FLOAT

R

234 - 235

Power factor Σ3 phase

FLOAT

R

236 - 237

Apparent power S1

VA

FLOAT

R

238 - 239

Apparent power S2

VA

FLOAT

R

240 - 241

Apparent power S3

VA

FLOAT

R

242 - 243

Active power P1

W

FLOAT

R

244 - 245

Active power P2

W

FLOAT

R

246 - 247

Active power P3

W

FLOAT

R

248 - 249

Reactive power Q1

Var

FLOAT

R

250 - 251

Reactive power Q2

Var

FLOAT

R

252 - 253

Reactive power Q3

Var

FLOAT

R

254 - 255

Power factor PF1

FLOAT

R

256 - 257

Power factor PF2

FLOAT

R

258 - 259

Power factor PF3

FLOAT

R

260 - 261

Frequency

Hz

FLOAT

R

262 - 263

THD Voltage U1

FLOAT

R

264 - 265

THD Voltage U2

FLOAT

R

266 - 267

THD Voltage U3

FLOAT

R

268 - 269

THD Current I1

FLOAT

R

270 - 271

THD Current I2

FLOAT

R

272 - 273

THD Current I3

FLOAT

R

274 - 275

Current I1 3rd harmonic

FLOAT

R

276 - 277

Current I1 5th harmonic

FLOAT

R

278 - 279

Current I1 7th harmonic

FLOAT

R

280 - 281

Current I1 9th harmonic

FLOAT

R

282 - 283

Current I2 3rd harmonic

FLOAT

R

284 - 285

Current I2 5th harmonic

FLOAT

R

286 - 287

Current I2 7th harmonic

FLOAT

R

288 - 289

Current I2 9th harmonic

FLOAT

R

290 - 291

Current I3 3rd harmonic

FLOAT

R

292 - 293

Current I3 5th harmonic

FLOAT

R

294 - 295

Current I3 7th harmonic

FLOAT

R

296 - 297

Current I3 9th harmonic

FLOAT

R

298 - 299

Voltage U1 3rd harmonic

FLOAT

R

300 - 301

Voltage U1 5th harmonic

FLOAT

R

302 - 303

Voltage U1 7th harmonic

FLOAT

R

304 - 305

Voltage U1 9th harmonic

FLOAT

R

306 - 307

Voltage U2 3rd harmonic

FLOAT

R

308 - 309

Voltage U2 5th harmonic

FLOAT

R

310 - 311

Voltage U2 7th harmonic

FLOAT

R

312 - 313

Voltage U2 9th harmonic

FLOAT

R

314 - 315

Voltage U3 3rd harmonic

FLOAT

R

316 - 317

Voltage U3 5th harmonic

FLOAT

R

318 - 319

Voltage U3 7th harmonic

FLOAT

R

320 - 321

Voltage U3 9th harmonic

FLOAT

R

322 - 323

Current I4

A

FLOAT

R

324 - 325

Voltage U4

U

FLOAT

R

326 - 327

Current I1 angle

°

FLOAT

R

328 - 329

Current I2 angle

°

FLOAT

R

330 - 331

Current I3 angle

°

FLOAT

R

332 - 333

Current I0 angle

°

FLOAT

R

334 - 335

Voltage U0 angle

°

FLOAT

R

336 - 337

Voltage U12 angle

°

FLOAT

R

338 - 339

Voltage U23 angle

°

FLOAT

R

340 - 341

Voltage U31 angle

°

FLOAT

R

342 - 343

Current I4 angle

°

FLOAT

R

344 - 345

Voltage U4 angle

°

FLOAT

R

346 - 347

Current positive seq Ip

A

FLOAT

R

348 - 349

Current negative seq In

A

FLOAT

R

350 - 351

Current Ip angle

°

FLOAT

R

352 - 353

Current In angle

°

FLOAT

R

354 - 355

Voltage positive seq Up

U

FLOAT

R

356 - 357

Voltage negative seq Un

U

FLOAT

R

358 - 359

Voltage Up angle

°

FLOAT

R

360 - 361

Voltage Un angle

°

FLOAT

R

362 - 363

Current I1 2nd harmonic

FLOAT

R

364 - 365

Current I2 2nd harmonic

FLOAT

R

366 - 367

Current I3 2nd harmonic

FLOAT

R

368 - 369

Current I1 channel 2

A

FLOAT

R

370 - 371

Current I2 channel 2

A

FLOAT

R

372 - 373

Current I3 channel 2

A

FLOAT

R

374 - 375

Current I0 channel 2

A

FLOAT

R

376 - 377

Current I4 channel 2

A

FLOAT

R

378 - 379

Current I1 channel 2 angle

°

FLOAT

R

380 - 381

Current I2 channel 2 angle

°

FLOAT

R

382 - 383

Current I3 channel 2 angle

°

FLOAT

R

384 - 385

Current I0 channel 2 angle

°

FLOAT

R

386 - 387

Current I4 channel 2 angle

°

FLOAT

R

388 - 389

Current Ip channel 2

A

FLOAT

R

390 - 391

Current In channel 2

A

FLOAT

R

392 - 393

Current Ip channel 2 angle

°

FLOAT

R

394 - 395

Current In channel 2 angle

°

FLOAT

R

396 - 397

Current I1 2nd harmonic ch2

FLOAT

R

398 - 399

Current I2 2nd harmonic ch2

FLOAT

R

400 - 401

Current I3 2nd harmonic ch2

FLOAT

R

402 - 403

THD Current I1 ch2

FLOAT

R

404 - 405

THD Current I2 ch2

FLOAT

R

406 - 407

THD Current I3 ch2

FLOAT

R

408 - 409

Current I1 3rd harmonic ch2

FLOAT

R

410 - 411

Current I1 5th harmonic ch2

FLOAT

R

412 - 413

Current I1 7th harmonic ch2

FLOAT

R

414 - 415

Current I1 9th harmonic ch2

FLOAT

R

416 - 417

Current I2 3rd harmonic ch2

FLOAT

R

418 - 419

Current I2 5th harmonic ch2

FLOAT

R

420 - 421

Current I2 7th harmonic ch2

FLOAT

R

422 - 423

Current I2 9th harmonic ch2

FLOAT

R

424 - 425

Current I3 3rd harmonic ch2

FLOAT

R

426 - 427

Current I3 5th harmonic ch2

FLOAT

R

428 - 429

Current I3 7th harmonic ch2

FLOAT

R

430 - 431

Current I3 9th harmonic ch2

FLOAT

R

6.2 IEC 60870-5-101 operational information

IEC 60870-5-101 (IEC101) is a communication protocol designed for telecontrol applications in power systems, enabling communication between a master station and slave devices (e.g., Remote Terminal Units or RTUs). The implementation of IEC101 protocol allows for a data transfer to be initiated only by a master (unbalanced mode).

IOMod Meter via IEC101 protocol transmits various measurement signals in a standardized format. These signals are predefined in the IOMod and mapped to corresponding Information Object Addresses (IOA).

Using IOMod devices along with WCC Lite allows sending broadcast time synchronization messages to multiple IOMod devices simultaneously.

The protocol distinguishes between Type Identifiers (TI), which, according to the standard, define the format, structure and type of the data being sent. The measurement signals are assigned to two different Type Identifiers, 7 and 13.

All the measurements are represented in absolute values without any scaling and using standard units. Almost every measurement can be sent using 13 ("measured value, short floating-point number"). The measurements which are sent with TI 13 signals are not marked with timestamps. This is because these signals are not intended for spontaneous transmission upon a change, but rather are to be polled by a controlling (master) station. All energy measurements are assigned to the signals with TI 7, which stands for "bitstring of 32 bits". The necessity for other data formats for the energy measurements comes from the fact that they are saved in a 32-bit unsigned integer data type. The usage of an integer type instead of a float ensures better precision.

Table 6.2.1 List of IEC101 measurement signals

IOA

Description

Units

TI

0

Current I1

A

13 (M_ME_NC_1)

1

Current I2

A

13 (M_ME_NC_1)

2

Current I3

A

13 (M_ME_NC_1)

3

Current I0

A

13 (M_ME_NC_1)

4

Voltage U12

U

13 (M_ME_NC_1)

5

Voltage U23

U

13 (M_ME_NC_1)

6

Voltage U31

U

13 (M_ME_NC_1)

7

Voltage U1

U

13 (M_ME_NC_1)

8

Voltage U2

U

13 (M_ME_NC_1)

9

Voltage U3

U

13 (M_ME_NC_1)

10

Voltage U0

U

13 (M_ME_NC_1)

11

Voltage U1 angle

°

13 (M_ME_NC_1)

12

Voltage U2 angle

°

13 (M_ME_NC_1)

13

Voltage U3 angle

°

13 (M_ME_NC_1)

14

Apparent power Σ 3-phase

VA

13 (M_ME_NC_1)

15

Active power Σ 3-phase

W

13 (M_ME_NC_1)

16

Reactive power Σ 3-phase

Var

13 (M_ME_NC_1)

17

Power factor Σ 3-phase

13 (M_ME_NC_1)

18

Apparent power S1

VA

13 (M_ME_NC_1)

19

Apparent power S2

VA

13 (M_ME_NC_1)

20

Apparent power S3

VA

13 (M_ME_NC_1)

21

Active power P1

W

13 (M_ME_NC_1)

22

Active power P2

W

13 (M_ME_NC_1)

23

Active power P3

W

13 (M_ME_NC_1)

24

Reactive power Q1

Var

13 (M_ME_NC_1)

25

Reactive power Q2

Var

13 (M_ME_NC_1)

26

Reactive power Q3

Var

13 (M_ME_NC_1)

27

Power factor PF1

13 (M_ME_NC_1)

28

Power factor PF2

13 (M_ME_NC_1)

29

Power factor PF3

13 (M_ME_NC_1)

30

Frequency

Hz

13 (M_ME_NC_1)

31

THD Voltage U1

13 (M_ME_NC_1)

32

THD Voltage U2

13 (M_ME_NC_1)

33

THD Voltage U3

13 (M_ME_NC_1)

34

THD Current I1

13 (M_ME_NC_1)

35

THD Current I2

13 (M_ME_NC_1)

36

THD Current I3

13 (M_ME_NC_1)

37

Current I1 3rd harmonic

13 (M_ME_NC_1)

38

Current I1 5th harmonic

13 (M_ME_NC_1)

39

Current I1 7th harmonic

13 (M_ME_NC_1)

40

Current I1 9th harmonic

13 (M_ME_NC_1)

41

Current I2 3rd harmonic

13 (M_ME_NC_1)

42

Current I2 5th harmonic

13 (M_ME_NC_1)

43

Current I2 7th harmonic

13 (M_ME_NC_1)

44

Current I2 9th harmonic

13 (M_ME_NC_1)

45

Current I3 3rd harmonic

13 (M_ME_NC_1)

46

Current I3 5th harmonic

13 (M_ME_NC_1)

47

Current I3 7th harmonic

13 (M_ME_NC_1)

48

Current I3 9th harmonic

13 (M_ME_NC_1)

49

Voltage U1 3rd harmonic

13 (M_ME_NC_1)

50

Voltage U1 5th harmonic

13 (M_ME_NC_1)

51

Voltage U1 7th harmonic

13 (M_ME_NC_1)

52

Voltage U1 9th harmonic

13 (M_ME_NC_1)

53

Voltage U2 3rd harmonic

13 (M_ME_NC_1)

54

Voltage U2 5th harmonic

13 (M_ME_NC_1)

55

Voltage U2 7th harmonic

13 (M_ME_NC_1)

56

Voltage U2 9th harmonic

13 (M_ME_NC_1)

57

Voltage U3 3rd harmonic

13 (M_ME_NC_1)

58

Voltage U3 5th harmonic

13 (M_ME_NC_1)

59

Voltage U3 7th harmonic

13 (M_ME_NC_1)

60

Voltage U3 9th harmonic

13 (M_ME_NC_1)

61

Current I4

A

13 (M_ME_NC_1)

62

Voltage U4

U

13 (M_ME_NC_1)

63

Current I1 angle

°

13 (M_ME_NC_1)

64

Current I2 angle

°

13 (M_ME_NC_1)

65

Current I3 angle

°

13 (M_ME_NC_1)

66

Current I0 angle

°

13 (M_ME_NC_1)

67

Voltage U0 angle

°

13 (M_ME_NC_1)

68

Voltage U12 angle

°

13 (M_ME_NC_1)

69

Voltage U23 angle

°

13 (M_ME_NC_1)

70

Voltage U31 angle

°

13 (M_ME_NC_1)

71

Current I4 angle

°

13 (M_ME_NC_1)

72

Voltage U4 angle

°

13 (M_ME_NC_1)

73

Current positive seq Ip

A

13 (M_ME_NC_1)

74

Current negative seq In

A

13 (M_ME_NC_1)

75

Current Ip angle

°

13 (M_ME_NC_1)

76

Current In angle

°

13 (M_ME_NC_1)

77

Voltage positive seq Up

U

13 (M_ME_NC_1)

78

Voltage negative seq Un

U

13 (M_ME_NC_1)

79

Voltage Up angle

°

13 (M_ME_NC_1)

80

Voltage Un angle

°

13 (M_ME_NC_1)

81

Current I1 2nd harmonic

13 (M_ME_NC_1)

82

Current I2 2nd harmonic

13 (M_ME_NC_1)

83

Current I3 2nd harmonic

13 (M_ME_NC_1)

84

Current I1 channel 2

A

13 (M_ME_NC_1)

85

Current I2 channel 2

A

13 (M_ME_NC_1)

86

Current I3 channel 2

A

13 (M_ME_NC_1)

87

Current I0 channel 2

A

13 (M_ME_NC_1)

88

Current I4 channel 2

A

13 (M_ME_NC_1)

89

Current I1 channel 2 angle

°

13 (M_ME_NC_1)

90

Current I2 channel 2 angle

°

13 (M_ME_NC_1)

91

Current I3 channel 2 angle

°

13 (M_ME_NC_1)

92

Current I0 channel 2 angle

°

13 (M_ME_NC_1)

93

Current I4 channel 2 angle

°

13 (M_ME_NC_1)

94

Current Ip channel 2

A

13 (M_ME_NC_1)

95

Current In channel 2

A

13 (M_ME_NC_1)

96

Current Ip channel 2 angle

°

13 (M_ME_NC_1)

97

Current In channel 2 angle

°

13 (M_ME_NC_1)

98

Current I1 2nd harmonic ch2

13 (M_ME_NC_1)

99

Current I2 2nd harmonic ch2

13 (M_ME_NC_1)

100

Current I3 2nd harmonic ch2

13 (M_ME_NC_1)

101

THD Current I1 ch2

13 (M_ME_NC_1)

102

THD Current I2 ch2

13 (M_ME_NC_1)

103

THD Current I3 ch2

13 (M_ME_NC_1)

104

Current I1 3rd harmonic ch2

13 (M_ME_NC_1)

105

Current I1 5th harmonic ch2

13 (M_ME_NC_1)

106

Current I1 7th harmonic ch2

13 (M_ME_NC_1)

107

Current I1 9th harmonic ch2

13 (M_ME_NC_1)

108

Current I2 3rd harmonic ch2

13 (M_ME_NC_1)

109

Current I2 5th harmonic ch2

13 (M_ME_NC_1)

110

Current I2 7th harmonic ch2

13 (M_ME_NC_1)

111

Current I2 9th harmonic ch2

13 (M_ME_NC_1)

112

Current I3 3rd harmonic ch2

13 (M_ME_NC_1)

113

Current I3 5th harmonic ch2

13 (M_ME_NC_1)

114

Current I3 7th harmonic ch2

13 (M_ME_NC_1)

115

Current I3 9th harmonic ch2

13 (M_ME_NC_1)

400

Active import energy

kWh

7 (M_BO_NA_1)

401

Active export energy

kWh

7 (M_BO_NA_1)

402

Reactive import energy

kVArh

7 (M_BO_NA_1)

403

Reactive export energy

kVArh

7 (M_BO_NA_1)

6.3 IEC 60870-5-103 operational information

When the IEC-60870-5-103 protocol is selected, IOMod Meter uses a standard communication scheme. Initiation, control messages, and queries are initiated by a master (controlling station), while the IOMod device (controlled station) only answers requests and sends values. The first message sent by the master should be RESET CU to restart communication. When an acknowledge (ACK) packet is sent from a slave device, a master may proceed with acquiring General Interrogation and sending Time synchronization packets.

When this initialization is complete, the master should poll the IOMod Meter with Class 1 and Class 2 requests. Class 2 is used when the master polls for cyclic data. The controlled device responds when spontaneous data exists and the master then sends a request for Class 1. The controlled station responds with a time-tagged message.

Time synchronization is critical for logging events. To synchronize time, the master sends a Time Sync command with function 0 and Cause of Transmission (COT) 8. According to the IEC 60870-5-103 protocol specification, time synchronization can be performed for multiple devices using broadcast messages. For broadcast time synchronization, the master device sends a periodic signal with a time stamp to synchronize the system time of slave devices. If synchronization fails, devices default to their local system time until they successfully resynchronize.

As IOMod Meter does not have any digital inputs, only analog ones, the general interrogation returns nothing. Values of measurements are returned cyclically as a response to Class 2 data requests.

Specific settings for the IEC 60870-5-103 protocol:

  1. Measurand set selection. A user can select which predefined measurand set will be transmitted to the host system. Available measurand sets are presented in Table 6.3.1.
  2. Scale factor. The communication protocol IEC 60870-5-103 only lets 13-bit signed values in the range of -1...+1. When an IEC 60870-5-103 measurand, for example, phase voltage, is scaled as 2.4, it means that the measurand value 1 corresponds to 2.4 multiplied by Un, the measurand value 0.5 corresponds to 1.2 multiplied by In, and so on. If the measurand value, in this case, exceeds 2.4 multiplied by Un, the IEC 60870-5-103 object value saturates at its maximum value, and an overflow flag is set in the IEC 60870-5-103 object transmission.
  3. Device function type. By default, IOMod has the IEC 60870-5-103 Function Type set to 253. If this Function type, for some reason, is not suitable, a user can define any other type

Table 6.3.1. Data sets for 3I3U connection mode

Set Nr.

TYPE

FUN*

INF

Qty of data

Information elements (measurands)

1

9

253

148

9

I1, I2, I3, U1, U2, U3, P, Q, f

2

9

253

149

23

I1, I2, I3, I4, U1, U2, U3, U4, P1, P2, P3, Q1, Q2, Q3, S1, S2, S3, PF1, PF2, PF3, U12(angle), U23(angle), U13(angle)

3

9

253

150

60

I1, I2, I3, IN, U1, U2, U3, UN, P1, P2, P3, Q1, Q2, Q3, S1, S2, S3, PF1, PF2, PF3, U12, U23, U13, f, THDU1, THDU2, THDU3, THDI1, THDI2, THDI3, I1(h2), I1(h3), I1(h5), I1(h7), I1(h9), I2(h2), I2(h3), I2(h5), I2(h7), I2(h9), I3(h2), I3(h3), I3(h5), I3(h7), I3(h9), U1(h2), U1(h3), U1(h5), U1(h7), U1(h9), U2(h2), U2(h3), U2(h5), U2(h7), U2(h9), U3(h2), U3(h3), U3(h5), U3(h7), U3(h9)

4

9

253

151

54

I1, I2, I3, IN, U12, U23, U13, UN, S, P, Q, PF, THDU1, THDU2, THDU3, THDI1, THDI2, THDI3, I1(h3), I1(h5), I1(h7), I1(h9), I2(h3), I2(h5), I2(h7), I2(h9), I3(h3), I3(h5), I3(h7), I3(h9), U1(h3), U1(h5), U1(h7), U1(h9), U2(h3), U2(h5), U2(h7), U2(h9), U3(h3), U3(h5), U3(h7), U3(h9), P1, P2, P3, Q1, Q2, Q3, U1(angle), U2(angle), U3(angle), U1, U2, U3


6.3.2 Data sets for 3I3I connection mode

Set Nr.

TYPE

FUN*

INF

Qty of data

Information elements (measurands)

1

9

253

148

7

I1(ch1), I2(ch1), I3(ch1), I1(ch2), I2(ch2), I3(ch2), f

2

9

253

149

8

I1(ch1), I2(ch1), I3(ch1), I4(ch1), I1(ch2), I2(ch2), I3(ch2), I4(ch2)

3

9

253

150

45

I1(ch1), I2(ch1), I3(ch1), I0(ch1), I1(ch2), I2(ch2), I3(ch2), I0(ch2), f, THDI1(ch1), THDI2(ch1), THDI3(ch1), I1(h3, ch1), I1(h5, ch1), I1(h7, ch1), I1(h9, ch1), I2(h3, ch1), I2(h5, ch1), I2(h7, ch1), I2(h9, ch1), I3(h3, ch1), I3(h5, ch1), I3(h7, ch1), I3(h9, ch1), THDI1(ch2), THDI2(ch2), THDI3(ch2), I1(h3, ch2), I1(h5, ch2), I1(h7, ch2), I1(h9, ch2), I2(h3, ch2), I2(h5, ch2), I2(h7, ch2), I2(h9, ch2), I3(h3, ch2), I3(h5, ch2), I3(h7, ch2), I3(h9, ch2)

A certain set of measurements can be configured in IOMod Utility General settings (see Table 5.1.1, Fig. 6.3.1).

image-1729167116205.png

Fig. 6.3.1. IOMod Utility General settings IEC 60870-5-103 protocol parameters

Type 9 signals allocate only 13 bits for measurement values, which is not enough for float values to be transferred. For that reason, all measurement data are being scaled. However, not all values are scaled the same. All currents, voltages and power measurements are scaled using the same algorithm. The range of the maximum and the minimum measurement values, which can be transferred with the IEC103 protocol, is calculated by multiplying the nominal value by the scale factor:

MMV = SF ⋅ NV     (6.3.1)

  • MMV – maximum measurement value;
  • NV – nominal value;
  • SF – scale factor;

The scale factor of most measurements can be selected in IOMod Utility General settings (Table 5.1.1, Fig. 6.3.1). The maximum measurement value (MMV) is only the upper limit of the allowed range. The full allowed range goes from -MMV up to +MMV. Since the first bit is used to denote the sign, the maximum absolute value, which can be sent via IEC 60870-5-103 communication protocol, is 212 = 4096. The MMV is mapped to this value, so that if the measured value is equal to the MMV, 4096 is going to be sent to a controlling station via IEC103 protocol. If a measurement value exceeds MMV, then the overflow is going to be indicated by the signal and 4096 is going to be sent. If a measured value is inside the allowed range, then the scaled value, which is going to be sent using the IEC103 signal, is calculated by multiplying it by 4096 and dividing it by the maximum measurement value:

SV = MV ⋅ 4096MMV, where -MMV ≤ MV ≤ +MMV     (6.3.2)

  • SV – scaled value, which is going to be sent using IEC103 protocol;
  • MV – measured value, which must be in the allowed range;
  • MMV – maximum measurement value;

In the special case where the measured value is equal to the nominal value, the scaled value formula can be simplified as:

SV = NV ⋅ 4096SF ⋅ NV = 4096SF       (6.3.3)

The scaled values of other measurands are calculated by using different scaling techniques. The scaled frequency is calculated by multiplying the measured frequency by 50. All angle measurements are scaled by a factor of 10.

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