罗斯蒙特5300雷达液位计中 PEP功能设置部分

Advanced Configuration May 2016Reference Manual00809-0100-4530, Rev DD C.5Probe End Projection Probe End Projection is used for two purposes:⏹Use the probe end echo as reference, in case the surface echo is lost, to calculate the surface echo position.⏹Use the probe end echo as reference when the surface echo is close to the probe end to enhance accuracy of the surface echo position.By using the Probe End Projection function, the device is capable of measuring the product level even if the surface echo is lost. The Probe End Projection is suited for challenging applications with very poor reflectivity (low dielectric constant). Due to the poor reflectivity of the product, situations may occur where the surface pulse is invisible to the transmitter at long measuring ranges.If the surface becomes invisible, the device will revert to use the probe end, and the most recently estimated value of the dielectric constant to calculate the surface. Once the surface reappears, the device will immediately use direct measurement on the surface again. The calculated surface value is less accurate than the value with direct measurement.When the microwaves emitted by the Rosemount 5300 Transmitter propagate through the product in the tank, the probe end echo appears to be located below the actual probe end. The apparent displacement of the probe end echo peak is a consequence of the reduced propagation speed of the measurement signal through the product compared to the speed through air. The displacement of the probe end pulse can be observed by using the Echo Curve Analyzer in the Rosemount Radar Master (see “Using the echo curve analyzer” on page 153).For products with very low dielectric constants the product surface level can be determined by comparing the actual probe end position as given by the Probe Length value, with the apparent position of the probe end echo peak. The difference is related to the properties of the product, i.e. the Dielectric Constant , and the distance D travelled by the measurement signal through the product, see Figure C-10.Advanced ConfigurationMay 2016Reference Manual 00809-0100-4530, Rev DDFigure C-10. The Probe End Projection FunctionNote It is important that the Probe Length and product Dielectric Constant are given with high accuracy.NoteThis function is only available for Liquid/solid product level measurement modes (i.e. not available for interface or fully submerged interface measurement modes) and a well defined probe end echo (i.e. ensure that the probe end/centering disc/weight is either always in contact with the tank wall or never in contact with the tank wall).C.5.1Guided Probe End Projection setupNote Assure that the Mounting Type, Probe Type, and Probe Length have been assigned correct values before configuring the Probe End Projection.Probe End Projection can be configured using a guide. When the tank is empty, the guided setup will be able to accurately calibrate probe end offset and probe end pulse polarity. You will be asked to insert an initial value for the Product DC. This is the value for the product dielectric constant that the device uses as a start point for estimation. This value must be as accurate to the actual value of the dielectric constant as possible.When the tank is filled, the guided setup will be able to estimate the Product DC. This valueis used as an initial value for future estimation of the Product DC.Apparent Probe End positionActual Probe End position∆, theAdvanced Configuration May 2016Reference Manual 00809-0100-4530, Rev DD For best performance, complete the guided setup with an empty tank and then a second time with a filled tank, but do not overwrite the empty tank calibration.Probe End Projection can be configured in RRM. This function can be reached from the Device Specific Configuration in the Guided Setup (if the configuration is recommended) or from the Advanced Configuration window, Probe End Projection tab. Click Guided Probe End Projection Setup to start the configuration.Figure C-11. Probe End Projection SetupIn a Field Communicator, the Device Specific Configuration is reached with sequence [2, 1, 7, 2] (if the configuration is recommended) or from the sequence: [2, 7, 2].Optional configurations DC Estimation Limit: This is a limit for the product dielectric constant estimation. The limit is a percentage, saying how much the estimated product DC is allowed to differ from the initial product DC value. If the estimation goes outside this limit, a warning will be ed Product DC: This is the estimated product dielectric constant that the device will use for Probe End Projection.Reset DC Estimation: Resets DC estimation to the configured initial value, forcing the device to start over estimating the product e Static Product DC: Check this setting if you do not want the device to estimate the product DC. This will force the device to use the configured initial product DC.。