Siemens 7ML19985AB01 Flow Velocity Input, Auxiliary Head Input, Voltage Input Current Input

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FLOW VELOCITY INPUT

In some applications, the flow calculation for the chosen primary element requires a velocity input. In this type of application, the transducer measurement is used to calculate the cross sectional area of the flow. By multiplying the area with the distance per time units of velocity, the volume per time units of flow are calculated. The calculated velocity can be viewed via D8.

The 0% and 100% limits of the velocity input must be scaled using parameters P8 and P9.

»select P8

»enter the voltage corresponding to zero velocity

»select P9

»enter the velocity corresponding to 5 V

e.g.	If the velocity sensor output is 1 V per m/sec and the output is
	scaled for 7 V at 100% velocity (7 m/sec), then enter 5 m/sec. If the
	output is scaled for 4 V at 100% velocity (4 m/sec), enter 5 m/sec.

P8 and P9 can only be accessed if P3 has been set for an option that requires the use of a velocity input. The input voltage level can be viewed via D12.

Voltage Input

Current Input

typical 1 - 5 V signal from	typical 4 - 20 mA signal from velocity sensor.
velocity sensor.	Add terminating resistor.
	e.g. 250 Ω for 1 - 5 V over 4 - 20 mA.

Signal must be positive with respect to ground.

Velocity Input (additional to Basic Wiring)

AUXILIARY HEAD INPUT

In some applications, the transducer input (TB1-1/2) is not used to provide a signal for head measurement. A typical example of this is an application which is beyond the 3 m (10 ft) range of the OCM-3. In such a case, the head could be derived from another Milltronics level monitor or other compatible device.

The method of head determination is set by P42. The OCM-3 simply substitutes the signal from the auxiliary device for the ultrasonic measurement provided by the transducer. The programming and consequent flow calculation are performed

as normal.

7ML19985AB01

OCM III

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Contents Open channel Unit Repair and Excluded Liability Contact Smpi Technical Publications at the following addressTable of Contents Start UP General Keypad Initial Start Up Fundamental ChecksOperation Maintenance Error Codes 100 Communications 101 7ML19985AB01 AppendicesOCM About this ShortIf you want to know about Read Product OCM Specifications » range 20 or 4-20 mA » resolution» 20 to 50 C -5 to 122 F IP65 enclosureProgrammer » CE *, FM, CSA NRTL/CTemperature Sensor TransducerCabling Communication Software Auxiliary InputOutput » Belden Installation Installing the OCM-3Outline and Mounting OCM-3 Layout System Diagram OCM-3Customer device Installing the Transducer Installing the Temperature SensorGround shield at OCM-3 only Basic Wiring Temperature Sensor Ground shield at OCM-3 onlyMA Output RelaysSynchronization Power Connections AC PowerDC Power Installing the Memory BACK-UP Battery Installing the ProgrammerDisconnect power before installing or replacing the battery Communicating VIA ComputerStart UP GeneralKeypad Initial Start UP OCM-3 is asking which language you prefer to communicateLanguage EnglishP0 language English P1 dimensional units Centimeters F13 auto zero calibration 160 Completed 7ML19985AB011141 24-hr. time114100 Enter new time F5 ddmmyyyy date October 12Fundamental Checks OCM Operation MemorySecurity UnitsFlow Calculation DisplayAbsolute vs. ratiometric = constantFor battery operation, set display lighting to off or auto DampingFor battery operation, have relays energizing on alarm Example For relay» 20 mA » P6 * flow rateFAIL-SAFE Flow Rate and TotalizingFlow rate Logging CapacityViewing the data log Temperature BlankingTime and Date Emulation Mode ResetFlow Velocity Input Auxiliary Head InputVoltage Input Current Input As normal 7ML19985AB01Diagnostic Aids DC Output100% head 4 m, enter 5 m Security access required ‘D’ Parameter ListingVelocity Nominal target rangeOCM Enter security code Emulation mode ‘F’ Parameter ListingKeypad to mA output OCM ‘P’ Parameter Listing Linear Velocity= centimetres Flowrate Volume = absolute = ratiometric Flow rate unitsGallons = imperial million gallons per dayOCM = 4-20 mA = 0-20 mA 7ML19985AB01 OCM OCM Fixed Variable conditionUnits OCM ‘U’ Parameters for P3 Primary Element OCM U0 = exponent U1 = k factor P4 = 0 only Reference= constant factor U1 = head Typical SHARP-CRESTED Weirs Typical Weir ProfilesKhafagi Venturi Typical Parshall Flume Typical Leopold Lagco ‘U’ parameters required ‘U’ parameters calculated BS-3680 Rectangular Flume = crest width = Cv = crest height = Cd = crest length = a BS-3680 Round Nose Horizontal Crest Weir Cv = velocity coefficient ¤ Refer to Operation \ Flow Calculation 7ML19985AB01BS-3680 Trapezoidal Flume BS-3680 U-Flume, P3 = BS-3680 U-FLUME = crest width = C = crest height = Cp = crest length = head H and p applied to CBS-3680 Finite Crest Weir = Ce x 2⁄3 ⎯⎯√2⎯g x be x he1.5 Where q = flow rate = approach width = Ce = crest width = K b = crest height= gravitational acceleration = crest width He = effective head h + Kh = head Kh = 1 mmBS-3680 Thin Plate Rectangular Weir U0 = notch angle Alpha U1 = Ce BS-3680 Thin Plate V-NOTCH Weir U0 = crest width b Rectangular Weir Contracted Based on the Manning Formula = hydraulic radius = slope of hydraulic gradientRound Pipe U0 = maximum flume width, hmax PALMER-BOWLUS Flume U0 = maximum listed head, hmax Flume Universal Head vs FLOW, P3 = U0 = number of data points n, 4 toFlow, point A13 Head, point A14 Flow, point A15 Head, point A16Flow, point A17 Head, point A18 Flow, point A19U0 = channel width B U1 = area h Rectangular Area X Velocity = head, cm = flow velocity, cm/sec Trapezoidal Area X Velocity = B b/d Where q = flow rate, l/s For h ≥ d= channel top width, cm = head, cm = channel base width, cm Modified Trapezoidal Area X Velocity U0 = base diameter D U1 = area h Channel Area x Velocity U0 = conduit diameter U1 = area h Circular Area X Velocity GULL-WING Area X VELOCITY, P3 = Gull Wing Area X Velocity EGG-SHAPED Area X VELOCITY, P3 = EGG-SHAPED Area X Velocity Universal Area X VELOCITY, P3 = Typical open channelUniversal Area X Velocity Area HeadA10 = OCM Maintenance Error Codes Customer’s ComputerSerial printer Protocol for the OCM-3 is as follows Baud rate 102DB-9 connector DB-25 connectorBipolar Current Refer to Cvcc InstructionDate P35 = 7, print interval set for 7 minutes104 Utilities Software Programmer Remote OCM-3 programming Remote OCM-3 display Local display105 106 Typical OCM-3 Display value00.000000 99.12399.123000 7ML19985AB01 107# = 0 through Content of P5 ResponseStart data log down load Stop data log down load109 DB-25 connector 7ML19985AB01 Standard modemCable Computer Telephone lines Remote modemEstablishing Communication Connect111 Ending Communication 112Rev