Vega VEGAPULS SR 68 Operating Instructions Manual

Also see for VEGAPULS 68: Operating instructions Safety manual Quick setup guide Quick setup guide Quick setup guide

Contents

Vega VEGAPULS SR 68 Operating Instructions Manual Manual pdf 30 page image

305 Connecting to power supplyVEGAPULS SR 68 • 4 … 20 mA/HART two-wire38294-EN-1306245 Connecting to power supply5.1 Preparing the connectionAlways keep in mind the following safety instructions:• Connect only in the complete absence of line voltage• If overvoltage surges are expected, overvoltage arresters shouldbe installedPower supply and current signal are carried on the same two-wirecable. The operating voltage can differ depending on the instrumentversion.The data for power supply are specified in chapter "Technical data".Provide a reliable separation between the supply circuit and themains circuits according to DIN EN 61140 VDE 0140-1.Keep in mind the following additional factors that influence the operat-ing voltage:• Lower output voltage of the power supply unit under nominal load(e.g. with a sensor current of 20.5 mA or 22 mA in case of faultmessage)• Influence of additional instruments in the circuit (see load values inchapter "Technical data")The instrument is connected with standard two-wire cable withoutscreen. If electromagnetic interference is expected which is above thetest values of EN 61326-1 for industrial areas, screened cable shouldbe used.For instruments with housing and cable gland, use cable with roundcross-section. A cable outer diameter of 5 … 9 mm (0.2 … 0.35 in)ensures the seal effect of the cable gland. If you are using cable witha different diameter, exchange the seal or use a suitable cable gland.We generally recommend the use of screened cable for HART multi-drop mode.With plastic housing, the NPT cable gland or the Conduit steel tubemust be screwed without grease into the threaded insert.Max. torque for all housings see chapter "Technical data".If screened cable is required, connect the cable screen on both endsto ground potential. In the sensor, the screen must be connecteddirectly to the internal ground terminal. The ground terminal on theoutside of the housing must be connected to the potential equalisa-tion (low impedance).If potential equalisation currents are expected, the connection on theprocessing side must be made via a ceramic capacitor (e. g. 1 nF,1500 V). The low-frequency potential equalisation currents are thussuppressed, but the protective effect against high frequency interfer-ence signals remains.Safety instructionsVoltage supplyConnection cableCable gland ½ NPTCable screening andgrounding