Related information
8.1 Basic functions
The display shows the options in this menu.
A series of basic functions must be set in this menu before the
system can operate.
Path:
Settings > Basic functions
4-1_BASIC_FUNCTIONS_103
Basic functions
Related information
8.1.1 Primary settings
The key system functions are set in this display.
Number of pumps
The number of pumps in the system is entered under "Number of
pumps".
Level control
Under "Level control", it can be set how the level in the pit should be
measured.
Options:
•
Float switches
: When only float switches are used, the total
number of float switches used must be given. For details about
setting the float switches, see section about analog sensor with
safety float switches.
•
Pressure sensor
: When an analog pressure sensor is used,
special attention must be given to the sensor setting. See
section about analog inputs.
Float switches can be used as safety high-level and dry-
running float switches.
•
Ultrasonic sensor
: When an ultrasonic sensor is used, special
attention must be given to the sensor setting. See section about
analog inputs. The user must state whether the measuring
signal is for water depth or distance from the top of the pump pit
to the water level. When the distance to the water level is being
measured, the user must enter an "Offset". This offset gives the
distance from the ultrasonic sensor to the top of the pit.
Furthermore, the "Inverted" function must be selected (it is
shown if an ultrasonic sensor is selected).
Backup battery installed
CU 362 can be supplied with a backup battery.
If fitted, tick "Backup battery installed" to enable the function.
Installation name
Enter the wastewater pit name under "Installation name".
The installation name is used when communicating with the SCADA
system or PC Tools.
Example
The number of pumps in the system is two. The level is controlled
by an analog pressure sensor.
The system does not have a backup battery (UPS) installed.
The installation name is GRUNDFOS.
Path:
Settings > Basic functions > Primary settings
4-1-1_PRIMAR
Y_SETTINGS_107
Primary settings
Related information
8.1.4.7 Analog sensor with safety float switches
8.1.2 Pit configuration and flow calculation
In this menu, flow calculation is configured and enabled or disabled.
Flow calculation requires an analog level sensor. We recommend
using a submersible level sensor. There are other types of analog
sensors, like Ultra Sonic and Radar, but these types of
sensors have a relatively slow reaction time to level changes in the
pit, and consequently the flow calculation can become unstable as it
requires a precise and quick detection of level changes.
When flow calculation is enabled, it detects which measurement
data are available. The following are checked:
•
Type of level sensor. An analog sensor is required and if it is not
present, flow calculation is not available.
•
Discharge pressure sensor. It is used to determine the Delta P
(pressure difference between suction and discharge). Not
mandatory, but it increases the precision of flow estimation and
enables the controller to calculate the specific energy
(kW usage measurement is also needed).
•
kW usage. This can come from an MP 204 or a VFD. Both
Grundfos CUE and third-party VFDs are supported. Not
mandatory, but it increases the precision of flow estimation and
enables the controller to calculate the specific energy (discharge
pressure measurement is also needed).
Basically the more measurement values are available, the more
precise the flow calculation is. If there is only an analog level sensor
available, the precision is around ± 30 %, but if a discharge
pressure sensor and kW usage are also available, a precision of ±
10 % can be expected. It is actually not so important how
precisely the flow is calculated, it is more important that it is
consistent.
Another thing that has an impact on accuracy is variations of the
inflow to the pit. Changes in the inflow when pumps are running are
detected by the software and influence the calculations, but
variations during an empty situation can influence the precision.
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