Emerson Process Management rosemount 3300 series manual 0HDVXUHPHQW 0RGH, Lhohfwulfv

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00809-0100-4811, Rev AA October 2002

Rosemount 3300 Series

0HDVXUHPHQW 0RGH

Normally the Measurement Mode does not need to be changed. The transmitter is pre-configured according to the specified model:

Table 4-2. Measurement Mode

567@￿￿￿￿￿￿￿￿￿￿￿￿￿3301 ￿￿￿￿￿!￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿(1),￿￿￿￿￿￿￿￿￿￿￿￿￿￿￿

3302 (1), ￿￿￿￿￿￿￿￿￿￿￿￿￿

,QWHUIDFH￿,PPHUVHG￿3UREH is used for applications where the probe is fully

immersed in liquid. In this mode the transmitter ignores the upper product level. See “6HFWLRQ￿￿￿￿,QWHUIDFH￿PHDVXUHPHQWV￿ZLWK￿IXOO\￿LPPHUVHG￿SUREHV” for

more information.

127(￿

Only use ,QWHUIDFH￿,PPHUVHG￿3UREH for applications where interface is measured for a fully immersed probe.

'LHOHFWULFV

In some applications there is heavy vapor above the product surface having a

significant influence on the level measurement. In such cases the 9DSRU￿ 'LHOHFWULF can be entered to compensate for this effect.

The default value is equal to 1 which corresponds to the dielectric constant of vacuum. Normally this value does not need to be changed since the effect on measurement performance is very small for most vapors.

For interface measurements the dielectric constant of the upper product is

essential for calculating interface level and the upper product thickness. By default the 8SSHU 3URGXFW￿'LHOHFWULF parameter is about 2.

If the dielectric constant of the lower product is significantly smaller than the

dielectric constant of water, you may need to make special adjustments. See section ³,QWHUIDFH￿0HDVXUHPHQWV￿IRU￿6HPL￿7UDQVSDUHQW￿%RWWRP￿3URGXFWV´￿RQ￿

SDJH ￿￿￿ for further information.

The dielectric constant of the product is used for setting the appropriate signal amplitude thresholds, see 6HFWLRQ￿￿￿￿6HUYLFH￿DQG￿7URXEOHVKRRWLQJ for more

information on amplitude threshold settings. Normally this parameter does not need to be changed for level measurements. However, for some products measurement performance can be optimized by setting the proper product dielectric constant.

RCT contains tools to estimate the dielectric constant of the current product:

•The 'LHOHFWULF￿&KDUW lists the dielectric constant of a large number of products. Use one of the two following methods to view the Dielectric Chart:

-Choose the View>Dielectric>Dielectric Chart menu option.

-Click the Dielectric Chart icon in the Project Bar Advanced section.

•The 'LHOHFWULF￿&DOFXODWRU lets you calculate the dielectric constant of the Upper Product based on the following input:

-actual upper product thickness,

-the dielectric constant value stored in the transmitter, and

-the upper product thickness presented by the transmitter.

4-21