Vega VEGACAL 65 Operating Instructions Manual

Also see for VEGACAL 65: Safety manual Operating instructions Operating instructions Operating instructions

Contents

155 Connecting to power supplyVEGACAL 65 • Foundation Fieldbus30035-EN-1309175 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 installed according to Foundation Fieldbus specificationTip: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.The instrument requires a operating voltage of 9 … 32 V DC. Operat-ing voltage and the digital bus signal are carried on the same two-wireconnection cable. Power is supplied via the H1 power supply.Connection is carried out with screened cable according to Fieldbusspecification.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.Make sure that the entire installation is carried out according to theFieldbus specification. In particular, make sure that the bus is termi-nated with suitable 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.With 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 anothercable screen. The cable screens to the power supply unit and to thenext distributor must be connected to each other and also connectedto ground potential via a ceramic capacitor (e.g. 1 nF, 1500 V). TheSafety instructionsVoltage supplyConnection cableCable gland ½ NPTCable screening andgrounding