118_4416655_Rev06

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Average temperature measurement with MPT / RTD ___________________________________________________________________________ Refer to figures 4.1 and 4.2 Item Name Description W2= Protection level 2 Enter protection level 2 TD= Temperature dimension One character; either ‘C’ or ‘F’. Default set to C. C : degrees Celsius F : degrees Fahrenheit Both dimensions have the same format. MT= Element type Three ASCII characters. Selects the element type connected to the 762 VITO MRT Interface. For 1 – 3 RTD’s and MPT probe, set this item to: ‘ SPL ’ (Pt100 large); range : -200 ÷ +250 °C (-328 ÷ +482 °F) MN= Number of elements Two ASCII digits. This item specifies the number of elements of the MPT probe. • 01 through 03 means RTD spot in a 3 wire connection • 04 through 14 means an MPT probe. MO= Temperature element offset Format according to item LD. The offset represents the distance from the tank zero level to the lowest position of the MPT probe. In case of the RTD spots this item should be left at 0. Note: In case of ullage measurement, distance MO is taken from the upper reference point. J0 – JD= RTD element position. Format according to item LD. In case of the RTD spots items J0 .. J2 represent the distance from tank zero level to the RTD spot. In case of a MPT probe items J0 .. JD represent the distance from the bottom of the probe (nearest to tank zero level) to the RTD elements. Refer to the description above to obtain the values for J0 .. JD. Note: Only enter as much element positions as specified by the number of elements, starting from J0 (see item MN). MI= Switch hysteresis Format according to item LD. The distance MI is a hysteresis around the switching point of the temperature elements. MP= Product immersion depth Format according to item LD. The distance MP specifies the minimum required liquid level above a spot before it is selected for the average product temperature calculation MG= Gas immersion depth Format according to item LD. The distance MG specifies the minimum required distance below a spot before it is taken in the average gas temperature calculation TU= Temperature status conversion One character (default: ‘T’) This item is used to indicate the temperature status character in case of a reduced or not guaranteed temperature accuracy. This is the case when the temperature status is: • out of specified temperature range • last valid level used • manual level used • level below lowest temperature element If required, this item can be set to another character. EX Exit Exit protection level 2 Instruction manual VITO Page 30
Average temperature measurement with MPT / RTD ___________________________________________________________________________ 4.2.2 Additional settings for and 877 FDI Item Name Description W2= Protection level 2 Enter protection level 2 OB= Option board *) Three ASCII characters. This item informs the XPU what option board is installed. That can be: MPU : for HCU/ICU option board in MPU emulation mode HPU : for HCU/ICU option board in HPU emulation mode EG= Enable temperature One ASCII character; either ‘D’ or ‘E’. With this item can be transmission *) selected if the 877 FDI shall answer on a temperature request (C-record), addressed to the connected level gauge. E : transmission of temperature record enabled D : transmission of temperature record disabled Note: When item EG is set to ‘E’, make sure the related level gauge has no temperature option installed. TF= Temperature source One ASCII character; either ‘I’ or ‘E’. this item selects if there is Selection a temperature measurement inside the indicator (internal) or to be fetched from the Enraf field bus (external). E : Internal D : External EX Exit Exit protection level 2 *) This item is not implemented in the XPU-2. 4.2.3 Temperature verification MPT (Multiple Pt100 spots) probes After the settings described in section 4.2.1 and, if applicable in section 4.2.2, are entered the temperature measurement is operational. The following checks can be made to verify if the settings are made correct and the product temperature reading is correct. • Read item AP (Average Product temperature): This data item is preceded by four status characters. The first status character is a hexa-decimal number, indicating the highest selected element for average product temperature calculation. This can be judged, on basis of the product level, and with the items U0 – UF (calculated spot positions), item MO (temperature element offset), item MP (product immersion depth) and item MI (switch hysteresis). Refer to figure 4.2: A spot element will be used in the average product temperature calculation if its position is below the actual level minus the product immersion depth. A spot element won’t be used in the average product temperature calculation if it is above the actual level minus the product immersion depth plus the switch hysteresis. • Verify the average product temperature by manual measurement: Refer to Appendix C for the procedure to verify the average product temperature reading by using a portable electronic thermometer. Instruction manual VITO Page 31
Page 1: Instruction manual VITO interface a
Page 4 and 5: ___________________________________
Page 6 and 7: ___________________________________
Page 8 and 9: Introduction VITO Interface and ave
Page 10 and 11: Average temperature measurement wit
Page 38 and 39: Water bottom measurement __________
Page 46 and 47: Appendix __________________________
Page 48 and 49: Appendix __________________________
Page 50 and 51: Notes _____________________________
Page 52: Honeywell Enraf Delftechpark 39 262

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