Vega VEGAPULS 61 Operating Instructions Manual

Contents

Vega VEGAPULS 61 Operating Instructions Manual Manual pdf 22 page image

225 Connecting to power supplyVEGAPULS 61 • Profibus PA28444-EN-1412155 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 voltage surges are expected, overvoltage arresters should beinstalled according to Profibus specificationsTip:We recommend VEGA overvoltage arrester B63-32.In hazardous areas you must take note of the respective regulations,conformity and type approval certificates of the sensors and powersupply units.Power is supplied via a Profibus DP/PA segment coupler or a VEGA-LOG 571 EP input card. The power supply range can differ dependingon the instrument version.The data for power supply are specified in chapter "Technical data".Connection is made with screened cable according to the Profibusspecification. Power supply and digital bus signal are carried over thesame two-wire connection cable.Use cable with round cross-section. A cable outer diameter of5 … 9 mm (0.2 … 0.35 in) ensures the seal effect of the cable gland.If you are using cable with a different diameter or cross-section,exchange the seal or use a suitable cable gland.Please make sure that your installation is carried out according to theProfibus specification. In particular, make sure that the termination ofthe bus is done with appropriate terminating resistors.On the instrument with cable entry ½ NPT and plastic housing there isa metallic ½" threaded insert moulded into the plastic housing.Caution:No grease should be used when screwing the NPT cable gland orsteel tube into the threaded insert. Standard grease can containadditives that corrode the connection between threaded insert andhousing. This would influence the stability of the connection and thetightness of the housing.In systems with potential equalisation, connect the cable screendirectly to ground potential at the power supply unit, in the connectionbox and at the sensor. The screen in the sensor must be connecteddirectly to the internal ground terminal. The ground terminal outsideon the housing must be connected to the potential equalisation (lowimpedance).In systems without potential equalisation, connect the cable screendirectly to ground potential at the power supply unit and at the sensor.In the connection box or T-distributor, the screen of the short stub tothe sensor must not be connected to ground potential or to anotherSafety instructionsVoltage supplyConnection cableCable gland ½ NPTCable screening andgrounding