Transclinic Xi+ Installation Guide PV Array Performance Monitor with Modbus Interface
Revision History Contact details Version Date Version 1.0 12/2011 First release (Australian version) Weidmuller Pty Ltd 43 Huntingwood Drive Huntingwood NSW 2148 Australia Tel. +61 (0) 2 9671 9999 Fax +61 (0) 2 9671 9900 E-Mail info@weidmuller.com.au Internet www.weidmuller.com.
Contents Revision History ............................................................................................................................................... 2 Contact details .................................................................................................................................................. 2 Contents ............................................................................................................................. 3 1. Introduction ...................
. Surge protection ................................................................................................. 14 4.1 Best practice for PV Plants ............................................................................................................ 14 4.2 Common mode and differential voltages...................................................................................... 14 4.3 Types of surge protection devices .......................................................................
www.weidmueller.com 1. Introduction 1.1 General description Transclinic Xi+ modules provide very detailed monitoring, at the string box, of all the main plant variables, like string current, voltage and temperature.
1.2 Warnings and notices NOTICE This device is intended for use in applications as described in the operating instructions only. Any other form of usage is not permitted and can lead to accidents or destruction of the device. Using the device in non-approved applications will lead immediately to the expiry of all guarantee and warranty claims on the part of the operator against the manufacturer. Take the necessary precautions regarding electrostatic discharge while handling and mounting the device.
www.weidmueller.com 1.2.5 Recycling in accordance with WEEE Purchasing our product gives you the opportunity, free of charge, to return the Device to Weidmuller at the end of its lifecycle. The EU Directive 2002/96 EC (WEEE) regulates the return and recycling of waste electrical and electronics equipment. Manufacturers of electrical equipment are obliged as of 13/08/05 to take back and recycle free of charge electrical equipment sold after that date.
2. Installation 2.1 General Electrical installation must be carried out by qualified technical personnel in compliance with general electrical engineering regulations and current legislation. Specific regional standards must also be complied with. Be sure that there is no voltage applied to any part of the housing, and that the PV Array is disconnected before installing or removing the equipment. • Always use a screwdriver with the correct blade size.
www.weidmueller.com 2.
2.4 Power Board Connections 2.4.1 PV Array wiring (X1, X2, X4 and Busbars) There must be a switch or disconnection device to disconnect the PV Array in accordance with local regulations. This must be operated during installation to prevent electric shock (since PV Arrays typically operate at dangerous voltages). Additional hazards arise because circuits carrying DC currents arc when broken (unlike AC circuits).
www.weidmueller.com Voltage measurement (X2) Connect the positive pole from the PV string to the X2 connection. Normally the negative pole of the PV Array voltage measurement at X2 is already internally connected with the negative pole of the PV array; so no additional connection is required. If you only need to measure voltage from the PV string without connecting any current input or output, then connect the negative pole to the X2 connection.
2.5.3 Opto-coupled Digital inputs (X8) The digital inputs accept a digital voltage signal. They read as: • ON for voltages between 15V and 24V • OFF for voltages between 0V and 5V Physical connection specifications: • Cross sectional Area: With ferrules: from 0.2 to 2.5 mm² Without ferrules from 0.2 to4mm² • Tightening torque 0.4-0.5 Nm • Stripping length/blade size: 7 mm / 0.6 x 3.5 2.5.
www.weidmueller.com 3. Configuration 3.1.1 DIP Switches 3.1.2 SW1 – Modbus Address Use unique addresses: assign a unique Modbus slave address to each Modbus Slave device on the network. Although Modbus allows for Modbus slave addresses from 1 to 247, you can still only connect 32 unit loads (including the PV Plant PC). The following table specifies the MODBUS addresses.
4. Surge protection 4.1 Best practice for PV Plants Surge Protection Devices (SPDs) protect your equipment from various common fault conditions that occur in PV plants. Larger PV installations cover a considerable surface area, typically in a highly exposed location, and normally projected plant life spans are very large, so protection is essential.
www.weidmueller.com 4.3 Types of surge protection devices Although the power line is the most obvious source of high-voltage surges, any wire connection between your system and its environment can carry surges and stray voltages. Surges on data cables, for example, can bring down the entire network, this means loss of valuable power production while repairs are made to inverters and supporting equipment.
5. Data Communications 5.1 General This section is a guide for the proper installation of Transclinic RS485 networks in a photovoltaic installation. It should help, prevent possible installation errors and guarantee good communication. Most information is valid for any RS485 network since what is explained are concepts of the standard. Transclinic data communications strictly comply with both Modbus and RS485 standards. PV Plants are usually electrically noisy environments.
www.weidmueller.com Fig. 3: Example of RS485 communication In addition to the data bits, we have the start, parity and stop bits. Generally, one or several start bits are transmitted to indicate the start of data transmission. Next, the data bits themselves are transmitted. A parity bit can be included (used to detect errors in the reception of the frame) and finally the stop bits are sent. 5.2.
Fig. 6 Interconnection of the 3 wires in ‘2 wire’ RS485 communication Weidmuller’s Transclinics use a 3 wire system so connect all the devices using the three signal wires A (or +), B (or -) and GND (or ref) using internal cable conductors (do not use the cable shield for any of these connections). 5.2.2 Isolated vs Non-isolated Devices All RS485 device inputs have an internal 0V reference which is compared to the signals A and B when reading the signal data.
www.weidmueller.com ground reference. Transclinics equipment have a floating (isolated) RS485 inputs (in other words, not connected to earth), but other equipment might be connected to ground or they could induce residual voltages. Therefore recommend that the 485 communications line for Transclinics equipment be independent of other equipment to prevent problems arising from incompatibilities.
poorly terminated), which worsen the quality of the communications. The recommendation is to avoid these and if stubs are unavoidable, make them as short as possible (only for the inner panel). 5.2.7 Termination resistances To prevent reflections at the ends of the cable, it is recommended that a 120Ω termination resistor is installed at each end of the RS485 line. These resistances must be installed between the A and B data lines at each end of the network and at no other location in the network. Fig.
www.weidmueller.com 5.3 Rules for reliable RS485 networks Some simple rules must be followed for reliable communications using RS485: No more than 32 Loads: RS485 does not specify the maximum number of transceivers but allows for the connection of a maximum of 32 ‘unit loads’. A unit load is typically a single device although some transceivers are now available with ½ and ¼ unit load ratings. If you are unsure it is best to stick to 32 especially if you are using higher speeds.
6. Modbus 6.1 General Modbus is a simple and robust, polled, industrial communications protocol that has become the de-facto standard for industrial applications and is now among the most commonly used systems for transferring data between devices. Transclinic Modules use Modbus RTU serial communications via RS485 because the signals can be sent over long distances using cost effective, twisted pair cables. For a complete description of Modbus Protocols, please refer to the www.modbus.org website. 6.
www.weidmueller.com 6.3 Alternative communications methods 6.3.1 Modbus TCP (Ethernet) Modbus TCP is a version of Modbus for use over Ethernet networks. Except for the communication between devices it operates in a similar way to Modbus RTU (in that devices have documented memory maps that you can use to access and interpret data). Modbus RS485 can be converted to Modbus TCP by using a suitable Modbus Gateway like the SL-MODGW.
6.4 Modbus Maps Registers are addressed starting at zero. Therefore register numbered 1 is addressed as 0. 6.4.1 Calibration values (Holding Register Values) – for reference only This table is provided for reference only; the values are factory set and should not be changed. The exception is the Digital Output Value (Register 37). There is a DIP switch setting that controls writing of values to the unit. It should always be set to prevent changes to these calibration values.
www.weidmueller.com 6.5 Measurements (Input Register Values) REGISTER ID Reg. # DESCRIPTION MIN MAX UNITS DATA R/W Function INPUTS1 30001 Inputs INS1 0 3 (See description) UNSIG. INTEGER R 4 INST_CUR_STR01 30002 Current STR01 0 65535 mA UNSIG. INTEGER R 4 INST_CUR_STR02 30003 Current STR02 0 65535 mA UNSIG. INTEGER R 4 INST_CUR_STR03 30004 Current STR03 0 65535 mA UNSIG. INTEGER R 4 INST_CUR_STR04 30005 Current STR04 0 65535 mA UNSIG.
6.6 Register Values 6.6.
