INSTALLATION GUIDE SCXI™-1313 HIGH-VOLTAGE ATTENUATOR TERMINAL BLOCK This guide describes how to install and use the SCXI-1313 high-voltage attenuator terminal block with an SCXI-1125 module. Introduction The SCXI-1313 high-voltage attenuator terminal block is shielded and has screw terminals that connect to the SCXI-1125 input connector. Each SCXI-1313 channel has a precision 100:1 resistive voltage divider that you can use to measure voltages of up to 300 Vrms or ±300 VDC with the SCXI-1125. You can individually bypass these dividers for low-voltage measurement applications. The terminal block has 18 screw terminals for easy signal connection. One pair of screw terminals connects to the SCXI-1125 chassis ground. When used with the SCXI-1125, the remaining eight pairs of screw terminals connect signals to the eight analog inputs. Conventions The following conventions are used in this guide: » The » symbol leads you through nested menu items and dialog box options to a final action. The sequence File»Page Setup»Options directs you to pull down the File menu, select the Page Setup item, and select Options from the last dialog box. This icon denotes a note, which alerts you to important information. This icon denotes a caution, which advises you of precautions to take to avoid injury, data loss, or a system crash. bold Bold text denotes items that you must select or click on in the software, such as menu items and dialog box options. CVI ™, LabVIEW™, National Instruments™, ni.com™, NI-DAQ™, and SCXI ™ are trademarks of National Instruments Corporation. Product and company names mentioned herein are trademarks or trade names of their respective companies. 322853A-01 © Copyright 2000 National Instruments Corp. All rights reserved. October 2000 italic Italic text denotes variables, emphasis, a cross reference, or an introduction to a key concept. This font also denotes text that is a placeholder for a word or value that you must supply. monospace Text in this font denotes text or characters that you should enter from the keyboard, sections of code, programming examples, and syntax examples. This font is also used for the proper names of disk drives, paths, directories, programs, subprograms, subroutines, device names, functions, operations, variables, filenames and extensions, and code excerpts. What You Need to Get Started To set up and use your SCXI-1313 terminal block, you need the following items: ❑ SCXI-1313 high-voltage attenuator terminal block ❑ SCXI-1313 High-Voltage Attenuator Terminal Block Installation Guide ❑ SCXI chassis ❑ SCXI-1125 module ❑ Number 1 and 2 Phillips-head screwdrivers ❑ 1/8 in. flathead screwdriver ❑ Long-nose pliers ❑ Wire cutter ❑ Wire insulation stripper SCXI-1313 Installation Guide 2 ni.com Safety Information Cautions Do not operate the device in an explosive atmosphere or where there may be flammable gases or fumes. Keep away from live circuits. Do not remove equipment covers or shields unless you are trained to do so. If signal wires are connected to the device, hazardous voltages can exist even when the equipment is turned off. To avoid a shock hazard, do not perform procedures involving cover or shield removal unless you are qualified to do so and disconnect all field power prior to removing covers or shields. Do not operate damaged equipment. The safety protection features built into this device can become impaired if the device becomes damaged in any way. If the device is damaged, turn the device off and do not use it until service-trained personnel can check its safety. If necessary, return the device to National Instruments for service and repair to ensure that its safety is not compromised. Do not operate this equipment in a manner that contradicts the information specified in this document. Misuse of this equipment could result in a shock hazard. Do not substitute parts or modify equipment. Because of the danger of introducing additional hazards, do not install unauthorized parts or modify the device. Return the device to National Instruments for service and repair to ensure that its safety features are not compromised. You must insulate all of your signal connections to the highest voltage with which the SCXI-1125 can come in contact. When using the device with high common-mode voltages, you must insulate your signal wires for the highest input voltage. National Instruments is not liable for any damages or injuries resulting from inadequate signal wire insulation. Use only 26-14 AWG wire with a minimum voltage rating of 300 V and a temperature value of 60 °C for measuring up to 300 V. When connecting or disconnecting signal lines to the SCXI terminal block screw terminals, make sure the lines are powered off. Potential differences between the lines and the SCXI ground can create a shock hazard while you connect the lines. Connections, including power signals to ground and vice versa, that exceed any of the maximum signal ratings on the SCXI device can create a shock or fire hazard, or can damage any or all of the boards connected to the SCXI chassis, the host computer, and the SCXI device. National Instruments is not liable for any damages or injuries resulting from incorrect signal connections. If hazardous voltages (≥30 Vrms and 42.4 Vpeak or 60 VDC) are present, you must connect a safety earth-ground wire to the terminal block safety-ground lug, shown in Figure 1. This maintains compliance with UL-3111-1 and IEC-61010-1 and protects against electric shock when the terminal block is not connected to the chassis. To connect the safety earth ground to the safety-ground lug, run an earth-ground wire from the signal source to the © National Instruments Corporation 3 SCXI-1313 Installation Guide terminal block. National Instruments is not liable for any damages or injuries resulting from inadequate safety earth-ground connections. Do not loosen or re-orient the safety-ground lug hardware when connecting the safety ground wire; to do so reduces the safety isolation between the high voltage and safety ground. Clean the module and accessories by brushing off light dust with a soft non-metallic brush. Remove other contaminants with a stiff non-metallic brush. The unit must be completely dry and free from contaminants before returning it to service. The terminal block must be used with a UL-listed SCXI chassis. Configuring the High-Voltage Attenuator Each channel has a 100:1 high-voltage attenuator. To enable or disable the attenuator, either change the default configuration settings for the SCXI-1313 in Measurement & Automation Explorer or adjust the input limit ranges in your application. When using virtual channels, the input limits configured in the virtual channel configurator are used to set the attenuation circuitry appropriately. The SCXI-1313 is factory calibrated to the specifications listed in the Specifications section of this guide and is shipped with a calibration certificate. The calibration EEPROM on the SCXI-1313 stores calibration constants, which provide software correction values, that the application development software uses to correct your measurements for gain errors in the attenuation circuitry. Table 1. Input Signal Range Versus Gain Overall Gain SCXI-1313 Installation Guide Overall Voltage Range Module Gain Terminal Block Gain 0.01 300 Vrms or VDC 1 0.01 0.02 ±250 Vpeak or VDC 2 0.01 0.05 ±100 Vpeak or VDC 5 0.01 0.1 ±50 Vpeak or VDC 10 0.01 0.2 ±25 Vpeak or VDC 20 0.01 0.5 ±10 Vpeak or VDC 50 0.01 1 ±5 Vpeak or VDC 1 1 2 ±2.5 Vpeak or VDC 2 1 2.5 ±2.0 Vpeak or VDC 250 0.01 4 ni.com Table 1. Input Signal Range Versus Gain (Continued) Overall Gain Overall Voltage Range Module Gain Terminal Block Gain 5 ±1 Vpeak or VDC 5 1 10 ±500 mVpeak or VDC 10 1 20 ±250 mVpeak or VDC 20 1 50 ±100 mVpeak or VDC 50 1 100 ±50 mVpeak or VDC 100 1 200 ±25 mVpeak or VDC 200 1 250 ±20 mVpeak or VDC 250 1 500 ±10 mVpeak or VDC 500 1 1000 ±5 mVpeak or VDC 1000 1 2000 ±2.5 mVpeak or VDC 2000 1 Connecting Signals Refer to the Safety Information section before removing equipment covers or connecting or disconnecting any signal wires. Caution To connect the signal to the terminal block, perform the following steps, referring to Figures 1 and 2 as necessary: 1. Unscrew the top cover screws and remove the top cover. 2. Loosen the strain-relief screws and remove the strain-relief bar. © National Instruments Corporation 5 SCXI-1313 Installation Guide 3. Prepare your signal wire by stripping the insulation no more than 7 mm. 6 1 2 7 5 4 3 Front View Back View 1 2 Top Cover Screws Top Cover 3 4 Thumbscrew Mating Connector 5 6 Strain-Relief Bar Strain-Relief Screws 7 Safety-Ground Lug Figure 1. SCXI-1313 Parts Locator Diagram 4. Run the signal wires through the strain-relief opening. You can add insulation or padding if necessary. When connecting your signals to the SCXI-1313, follow the labeling on the SCXI-1313 for the appropriate module, as indicated in Figure 2. Note SCXI-1313 Installation Guide 6 ni.com 1 10 9 2 8 7 6 5 1 2 3 4 5 3 4 Voltage Dividers Product Name Chassis Ground Thermistor Assembly Number and Revision Letter 6 7 8 9 10 Serial Number Channel Labeling for SCXI-1123 Channel Labeling for SCXI-1125 Screw Terminals Relays to Enable or Bypass the Attenuator Figure 2. SCXI-1313 Signal Connections 5. Connect the signal wires to the screw terminals by inserting the stripped end of the wire fully into the terminal. No bare wire should extend past the screw terminal. Exposed wire increases the risk of short circuits and equipment failure. 6. Tighten the screws to a torque of 5–7 in.-lb. 7. Connect the safety earth ground to the safety-ground lug. Refer to the Safety Information section for connection information. 8. Reinstall the strain-relief bar and tighten the strain-relief screws. 9. Reinstall the top cover and tighten the top cover screws. 10. Connect the terminal block to the module front connector as explained in the Installing the Terminal Block section. © National Instruments Corporation 7 SCXI-1313 Installation Guide Installing the Terminal Block To connect the terminal block to the SCXI module front connector, perform the following steps: 1. Connect the module front connector to its mating connector on the terminal block. 2. Tighten the top and bottom thumbscrews on the back of the terminal block to hold it securely in place. For accurate cold-junction compensation, place the SCXI chassis away from an extreme temperature differential. Note Cleaning the Terminal Block Clean the terminal block by brushing off light dust with a soft, nonmetallic brush. Remove other contaminants with deionized water and a stiff nonmetallic brush. The unit must be completely dry and free from contaminants before returning it to service. Calibrating the Terminal Block For information on calibrating the SCXI-1313, see the SCXI-1313 High-Voltage Attenuator Terminal Block Calibration Procedure located online at ni.com/calibration and follow the link for Manual Calibration Procedures. Specifications All specifications are typical at 25 °C unless otherwise specified. Compatible module SCXI-1125.......................................8 input channels Input range SCXI-1125.......................................300 Vrms or VDC SCXI-1313 Installation Guide 8 ni.com Cold-junction sensor Sensor type...................................... Thermistor Accuracy1 ........................................ ±0.5 °C from 15 to 35 °C ±0.9 °C from 0 to 15 °C and 35 to 55 °C Repeatability ................................... ±0.2 °C from 15 to 35 °C Output ............................................. 1.91 to 0.65 V from 0 to 50 °C Maximum temperature gradient between sensor and any terminal .... ±0.4 °C (non-isothermal) High-voltage divider Accuracy ......................................... ±0.06% (for 100:1 setting) Drift................................................. 15 ppm/°C Resistance ....................................... 1 MΩ Attenuation ratio ............................. 100:1 or 1:1 on programmatic basis Common-mode isolation Channel to channel.......................... 300 Vrms or ±300 VDC Channel to ground........................... 300 Vrms or ±300 VDC Coupling.......................................... DC only Field-wiring connectors Screw terminals Signal terminals ....................... 16 (8 pairs) Functional ground terminals .... 2 Maximum wire gauge .............. 16 AWG Terminal spacing ..................... 0.5 cm (0.2 in.) center-to-center Dimensions of front entrance.......... 1.2 by 7.3 cm (0.47 by 2.87 in.) Solder pads for additional components .................... None Safety earth-ground lugs ................. 1 Strain relief ..................................... Strain-relief bar at terminal-block entrance 1 The temperature sensor accuracy includes tolerances in all component values, effects caused by temperature and loading, and self-heating. Errors caused by temperature gradients between terminals and the sensor are not included in this specification. © National Instruments Corporation 9 SCXI-1313 Installation Guide Mechanical Dimensions .............................................17.8 by 7.94 by 3.0 cm (7.0 by 3.125 by 1.2 in.) Weight ....................................................200 g (7 oz) Environment Operating temperature ............................0 to 50 °C Storage temperature ................................–20 to 70 °C Relative humidity ...................................10 to 90% noncondensing Safety Designed in accordance with IEC 61010-1, UL 3111-1, and CAN/CSA C22.2 No. 1010.1 for electrical measuring and test equipment. For use at altitudes up to 2000 meters. Installation category II1 Pollution degree 2 Electromagnetic Compatibility EMC/EMI ...............................................CE, C-Tick, and FCC Part 15 (Class A) Compliant Electrical emissions ................................EN 55011 Class A at 10 m FCC Part 15A above 1 GHz Electrical immunity ................................Evaluated to EN 61326:1998, Table 1 This device should only be operated with shielded cabling for full EMC and EMI compliance. See the Declaration of Conformity for this product for any additional regulatory compliance information. Note 1 Category II refers to local-level power distribution, such as that provided by a standard wall outlet. SCXI-1313 Installation Guide 10 ni.com Temperature Sensor Output and Accuracy The SCXI-1313 temperature sensor outputs 1.91 to 0.65 V from 0 to 50 °C. Converting a Thermistor Voltage to a Temperature National Instruments software can convert a thermistor voltage to the thermistor temperature for the circuit diagram shown in Figure 3. In LabVIEW, you can use the Convert Thermistor Reading VI found in the Data Acquisition»Signal Conditioning palette. If you are using CVI or NI-DAQ, use the Thermistor_Convert function. The VI takes the output voltage of the temperature sensor, the reference voltage, and the precision resistance and returns the thermistor temperature. Alternatively, you can use the following formulas: T(°C) = TK – 273.15 where TK is the temperature in Kelvin 1 T K = ------------------------------------------------------------3 [ a + b ( ln R T ) + c ( ln R T ) ] a = 1.295361 × 10 –3 b = 2.343159 × 10 –4 c = 1.018703 × 10 –7 RT = resistance of the thermistor in ohms V TEMPOUT R T = 5, 000 -------------------------------------- 2.5 – V TEMPOUT VTEMPOUT = output voltage of the temperature sensor [ T ( °C ) ]9 T ( °F ) = ----------------------- + 32 5 where T(°F) and T(°C) are the temperature readings in degrees Fahrenheit and degrees Celsius, respectively. Use an average of a large number of samples to obtain the most accurate reading. Noisy environments require more samples for greater accuracy. Note © National Instruments Corporation 11 SCXI-1313 Installation Guide Reading the Temperature Sensor in LabVIEW In LabVIEW, to read VTEMPOUT, use the address string: obx ! scy ! mdz ! cjtemp You can have this channel-address string in the same channel-string array as other channels on the same SCXI-1125 module and call it multiple times within the same channel-string array. For more information about channel-string arrays and the SCXI channel-addressing syntax, see the LabVIEW Measurements Manual. Temperature Sensor Circuit Diagram You do not need to read this section to operate the SCXI-1313. The circuit diagram in Figure 3 is optional information that you can use if you want more details about the SCXI-1313 temperature sensor. +5 V 4.7 k 1% 2.5 V LM 4040 2.5 V 0.1% 2 5k 0.1% 0.1 µF –t MTEMP o + 1 10 µF 5k o at 25 C 2 16 V 1 2 0.1 µF Figure 3. Temperature Sensor Circuit Diagram SCXI-1313 Installation Guide 12 ni.com Technical Support Resources NI Web Support National Instruments Web support is your first stop for help in solving installation, configuration, and application problems and questions. Online problem-solving and diagnostic resources include frequently asked questions, knowledge bases, product-specific troubleshooting wizards, manuals, drivers, software updates, and more. Web support is available through the Technical Support section of ni.com Worldwide Support National Instruments has offices located around the world to help address your support needs. You can access our branch office Web sites from the Worldwide Offices section of ni.com Branch office web sites provide up-to-date contact information, support phone numbers, e-mail addresses, and current events. 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