Cleaning Functionality - ABB AW400 Series Instruction Manual

4.4.1.3

Cleaning functionality

The cleaning functionality implemented in the AW400 supports a sequence of operations necessary to
perform a periodical cleaning of the sensors. This function is always present in the software and can be
enabled or disabled by a YES/NO selection in the configuration menu (default setting is NO).
When the selection is set to "YES", the instruments activates the cleaning sequence and operates the output
contact relays associated to CCO5 and CCO6 to drive the solenoid valves for the washing and rinsing lines
(see Fig. 10). Each phase of the cleaning sequence requires a different timing, and this can be freely
configured in parameters T1, T2, T3 and T4 (see table 2 below for details). During the cleaning sequence
active phases, the measure is frozen to the last valid value, and when instrument is operating as a Controller,
the latter is automatically forced in manual mode.
The cleaning sequence can be started locally with a manual command by pressing Key 8 / WASHING, or it
can be triggered automatically by setting proper values in the timers T1–T4.
There are two cleaning sequences designed to work in conjunction with optional ABB devices: sequence "A"
(Water Analytic Unit) and sequence "B" (Sequential Cleaning Unit). If the hydraulic cleaning system used is
different from the a above specified devices, then select "B" option and use the output contacts as directed in
Figure 10 to drive the solenoid valves.
The cleaning sequence consists of the following four phases:
T1 - Analysis: Normal operation phase of the sensor, that is the time period between the end of a
cleaning sequence and the start of the next one in automatic mode. Allowed time values
are 1 sec. to 30 hours. Typical value is 23,5 hours.
T2 – Washing: Phase to be used to wash the sensor with chemical detergent. Allowed values are 0–30
minutes. Typical value is 10 min.
T3 – Rinsing: Phase to be used to rinse the sensor with pressurized clean water. Allowed values are 0–
30 minutes. Typical value is 10 min.
T4 – Pause: Pause period usually allowed to consent the sensor to recover sensibility before starting a
new measure. Allowed values are 0–30 minutes. Typical value is 10 min.
PHASES TIME
T1 Analysis
T2 Washing
T3 Rinsing
T4 Pause
T1 Analysis
Table 2 - Sequence of cleaning phases
9 10 11 12
CCO 5
NC
Fig. 10 - Connection of solenoid valves
28
1
CCO5
•
T1
T2 O
•
T3
•
T4
•
T1
Digital I/O board
CCO 6 NC
Power supply
Power supply
1
CCO6 MESSAGE
•
•
WASH!
O WASH!
•
WASH!
•
Legend
O = open
• = closed