Endress+Hauser Prosonic S FMU90 - The Rake Control Submenu

The "relays/controls" menu
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5.4 The "rake control" submenu
!
Note!
The "rake control" submenus is only present if "rake control" has been selected in "device
properties/operating parameters/controls".
5.4.1 Basics
In order to detect clogging of a rake, the Prosonic S measures the upstream level L1 and the
downstream leve L2. Rake clogging causes L2 to become much lower than L1. Therefore, the rake
control function evaluates either the difference L1 - L2 or the ratio L2/L1.
L00-FMU90xxx-19-00-00-yy-058
Rake clogging is indicated by a relay, which can be used, for example, to trigger a rake cleaning
device.
5.4.2 Overview
!
Note!
In the "output/calculations" and "calibrate display" menus it is possible to define that the difference
L1-L2 or the ratio L2/L1 is displayed by the analog output and/or the display.
L1
L2
Step Parameter set or submenu Parameter Remarks see section
1 "relay/controls" menu Select "rake control"
2 rake control upstream water Select the upstream water level signal (L1) 5.4.3
downstream water Select the downstream water level signal (L2)
function Select the criterion for rake clogging:
•difference: L1 - L2
•ratio: L2/L1
3 rake control switch on point Define the switch on point 5.4.4
switch off point Define the switch off point
4 rake control switch delay Define the switch delay. 5.4.5
error handling Define the error handling
5 relay allocation Select the relay for rake control 5.4.6
6relay N
(N = 1 - 6)
function Select "rake control" 5.4.7
invert Select if the switching delay is to be inverted (default: no)