ABB 2600T Series Operating Instruction

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ABB 2600T Series Operating Instruction Manual pdf 17 page image

- 17 -ELECTRICAL REQUIREMENTSThe transmitter operates on a minimum voltage of 10.5 Vdc toa maximum of 42 Vdc and is protected against polarityinversion.Note - The transmitter operates from 10.5 to 42 Vdcwith no load (additional load allows operation over 42Vdc). For Ex ia and intrinsically safe approval powersupply must not exceed 30 Vdc.In some countries the maximum power supply voltage islimited to a lower value.Installing optional devices the minimum voltage increases to:- 10.5 Vdc with no option- 10.7 Vdc with output analog indicator- 12.5 Vdc with LCD ProMeter- 12.3 Vdc with surge protection- 13.3 Vdc with LCD CoMeter- 15.3 Vdc with no link on output indicator plugThe total loop resistance is indicated in the expression below.The Smart 2600T Transmitter Specification Sheets provide allinformation concerning the Range and Span limits in relation tothe model and the sensor code.The terminology currently used to define the variousparameters is as follows:URL : Upper Range Limit of a specific sensor. The highestvalue of the measured value that the transmitter can beadjusted to measure.LRL : Lower Range Limit of a specific sensor. The lowest valueof the measured value that the transmitter can be adjusted tomeasure.URV : Upper Range Value. The highest value of the measuredvalue to which the transmitter is calibrated.LRV : Lower Range Value. The lowest value of the measuredvalue to which the transmitter is calibrated.SPAN : The algebric difference between the Upper and LowerRange Values. The minimum span is the minimum value thatcan be used without degradation of the specified performance.TURN DOWN RATIO : is the ratio between the maximum spanand the calibrated span.The transmitter can be calibrated with any range between theLRL and the URL with the following limitations:LRL ≤ LRV ≤ (URL - CAL SPAN)CAL SPAN ≥ MIN SPANURV ≤ URLRANGE AND SPAN CONSIDERATIONThe total loop resistance is the sum of the resistance of allelements of the loop, including wiring, conditioningresistor,safety barriers and additional indicators (excluding theequivalent resistance of the transmitter).Where a configuration device (HART), such as the Hand HeldCommunicator or a Modem is likely to be used, a resistance of250 ohm minimum should be present between the powersupply and the point of insertion of these devices, to allowcommunication.Several types of safety barriers, either passive or active, can besatisfactorily used in conjunction with the Smart 2600Ttransmitters. Nevertheless, in case of use of active barriers,check with the supplier if the model is suitable for use withsmart transmitters allowing the connection of the configurationdevices in the "safe" or non-hazardous area.TRANSMITTER OUTPUT SIGNALThe 2600T Safety transmitter provides both the analog 4÷20mA and the digital HART communication. HART signals do notaffect safety during trading operations. HART writings arepermitted only in maintenance (out of safety) condition.Analog SignalTwo-wire 4 to 20 mA dc, user-selectable for linear or squareroot output; power of 3/2 or 5/2, 5th order or two 2nd orderswitching point selectable programmable polynomial outputcan be also selected for version with HART communication.HART SignalDigital process variable (%, mA or engineering units)superimposed on the 4 to 20 mA signal, with protocol based onBell 202 FSK standard.Output current limits (to NAMUR standard)- Low saturation: 3.8 mA (field configurable from 3.5 to 4mA)- High saturation: 20.5 mA (field configurable from 20 to 22.5 mA)R (kΩ) = Supply voltage - min. operating voltage (Vdc)22.5Transmitter failure mode (compliant to NE 43 NAMURregulation)The output signal can be user-selected to a value of 3.7 or 22mA on gross transmitter failure contition, detected by self-diagnostics.WARNING - The transmitter may be used as asafety accessory (as defined by the Pressure EquipmentDirective 97/23/EC) i.e. as part of a shutdown system.In this case it is recommended to select the correct failsafe mode for the 4-20 mA signal (as per Namur NE43recommendation).See also the instructions relevant to fail safe selection(Up/Down scale mode) in the addendum to the instructionmanual on "Use of hardware links on the secondaryelectronics" .