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Load guard is a sensor that is installed in the building’s electric cabinet. It measures the electric current in the building’s installation and sends real-time measurements to the charging station.
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Figure 1: Etrel Load Guard
Benefits of Using Load Guard
Optimised energy consumption of existing infrastructure.
Reduced charging and operational costs.
Local consumption of renewable energy sources.
Future-proof and grid-friendly charging infrastructure.
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Figure 2: Load Guard preventing the fuses overload
Where to Use Load Guard
Load Guard sensor is especially important in situations, where charging stations do not have a dedicated power supply but rather share available power with other consumers in the building.
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Homes
Apartment buildings
Business fleets
Parking spaces
Commercial buildings
Prerequisites for Use
Load Guard connected to the mains and LAN.
A computer connected to the same LAN as the Load Guard.
Load guard configuration program (Load Guard Configurator).
INCH charging station (set up as a master) connected to the same LAN as Load Guard.
Distance
Normally, a UTP Cat 6 cable is sufficient to use for distances up to at least 100 m between Load Guard and charging station. However, for longer distances it may be necessary to use active equipment, e.g., repeaters or network switches.
LOAD GUARD
Load Guard is a device that measures the current and voltage across phases of a particular segment of the power grid, calculates power and sends all data to the master station.
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Figure 5: Load Guard with connected measuring current transformers
Technical Specifications
DIMENSIONS | 90.5 x 53.5 x 61.8 [mm] Width 3 TE on DIN rail |
WEIGHT | 0.23 - 0.70 [kg], packaging adds 0.10 [kg] |
CLAMP CABLE LENGTH | 70 cm |
CLAMP DIAMETER | Small 16 mm, large 24 mm |
CONNECTION | Single-phase or three-phase |
MAX. RATED CURRENT | 150 A or 400 A per phase |
OPERATING VOLTAGE | Up to 253 V AC phase voltage This limitation is set by the highest operational voltage of the charging station. |
FREQUENCY | 50 Hz or 60 Hz |
TEMPERATURE RANGE | Operation temperature range: -25°C to +60°C Storage temperature range: -30°C to +90°C |
COMMUNICATION | Ethernet |
CONFIGURATION AND MONITORING | Web interface |
Connecting the LOAD GUARD
Load Guard is installed in electrical cabinet, after the main counter. It measures currents of all phases and is sending the measurements to the charging station in real time to ensure that the overload of the fuses cannot happen.
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Load Guard should be protected against overload current and short-circuit current either with fuse or with MCB.
Figure 6: Load Guard installed in electrical cabinet
Load Guard Current transformers
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Figure 7: Dimensions of current transformers
Connecting the Current transformers
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Figure 8: Connecting the current transformers
Three-Phase Connection
For proper three-phase connection, current clamps must be placed on specific phase conductors.
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The following figure shows the current clamp cables connection for all three phases (L1, L2 in L3) from left to right. The phase conductors for powering the Load Guard must be connected in the same way (from right to left). Positions for PE (earthing conductor) and N (neutral conductor) are also indicated. If phases are not connected in correct sequence, the Load Guard power calculation will be wrong.
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Figure 12: Arrow pointing in the direction of energy flow
Single-Phase Connection
In case of single-phase connection, the measuring current transformer is set only on the phase conductor that is used, as shown on the following figure.
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Figure 14: Arrangement of input and output phases in case of single-phase connection
Production of Energy at the Location
If on location there is also production of electrical energy present (photovoltaic cells, batteries, ...), the measuring current transformers can be set on two conductors (production conductor and consumption conductor). In this case the Load Guard would be measuring the difference of consumption and production currents and would enable higher charging current in time of production.
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Figure 16: Example of production and consumption of energy at the location
Obtaining IP Adress of Computer and Charging Station
To enable configuration of the Load Guard and of the charging station, the computer, Load Guard and charging station need to be in the same network segment: 192.168.1.xxx. First three numbers must be the same and the fourth must be different among the devices.
Computer IP Address
To obtain IP address of the computer the Windows Command Prompt is used. Press Win+R on the keyboard and in the presented window type cmd and press Enter (or click OK).
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Options of wired interfaces are shown (ethernet). The part of the IP address that is inside of red rectangle must be the same as it is written in the Load Guard Configuration Software settings. If this is not true, the software could not find the Load Guard and even if Load Guard is found, the configuration is not possible.
Charging Station IP Address
If the IP address of the charging station is not known, press the reset key for 5 seconds (figure below).
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Figure 23: Display of network and state
Configuration
Software for Configuration
Configuration software Load Guard Configurator 1.4.zip can be downloaded from the following address:
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Figure 27: MAC is not shown – the computer is not in the same network
Configuration of the Load Guard
To configure Load Guard, the following is needed:
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Serial number of the charging station that is used to connect Load Guard to.
Load Guard Network Settings
Click on the white part of the screen (the line with Load Guard data) opens the configuration window.
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We are interested in the number: 18010000, which is a serial number of charging station.
Pairing
Pairing of Load Guard to Charging Station
When all the needed information are available, the configuration of Load Guard can continue. In IP address field the IP address of the charging station must be written, also in the Serial field, the serial number of the charging station must be written. Serial number of the charging station can be obtained from the web interface of the charging station.
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Figure 33: Setting the measurement report interval
Pairing of Charging Station with Load Guard
To connect to INCH charging station web interface use username: root@etrel.com and password: toor
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Most of the electric vehicles can not charge with charging current of less than 6 A. Because of this, in a case that the target current would be lowered to less than 6 A, the charging would be temporarily paused. Charging will continue when the Load Guard sends information that the total consumption is lower that the set limit for more than 6 A.
TROUBLESHOOTING
If the message Connection established can be seen in Load Guard Configuration software, then the configuration of the Load Guard and the connection to the master charging station was successful. Same message will be displayed in web interface of the master charging station.
Configuration Software Can Not Find the Load Guard
If the configuration software (Load Guard Configurator 1.4) cannot find the Load Guard in the network, the following should be checked:
Is Load Guard connected to the supply (Is PWR LED lit)?
Is Load Guard connected to the ethernet network (Are LEDs on the ethernet socket lit or blinking)?
Load Guard must be in the same LAN network as the computer that is used for the configuration and is the master charging station in the same network?
Are other connections on the computer enabled (e.g. Wi-Fi, other ethernet interface)? If there is another connection enabled in the computer, it must be disabled. All of the possible connections should be disabled, except the one used for the connection to the Load Guard.
No Connection Between Load Guard and Charging Station
If the connection is not successful, perform refresh of the web interface (Ctrl+F5). If this does not resolve the issue, perform reset of the charging station and reset the Load Guard as well. Sometimes click on the Sync device time helps. If the time on the Load Guard is not synchronized, the connection will not work correctly!
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If this does not work, check all steps of the procedure and start with the configuration procedure again.
Serial Number is Not Valid
If the Load Guard Configuration Software the message “Serial number is not valid” is shown, the correct serial number must be written in the web interface of charging station.
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Figure 39: Message that the serial number is not valid
Load Guard Does Not Measure Voltage
When Load Guard is connected only in single-phase connection and in the “Load Guard Configurator” windows, the voltage is not shown, or it is very low (~5 V) it means that the supply of phase and neutral conductors of Load Guard are switched.
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Figure 41: Display of measurement when the neutral and phase conductors are correctly connected
Negative Value of Active Power
If the Load Guard Configuration windows is showing negative active power this could mean the following:
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Figure 42: The value of measured power is negative
Displayed Power is Not Correct
If the displayed power of any phase is not correct, that would mean that the conductors are not set on the right phase conductors.
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