Low-Flow Operation; Functions For Tank-Filling Systems; Cascade Control; Standby Pumps - Grundfos Hydro Multi-B Instrucciones De Instalación Y Funcionamiento

11.2.4 Low-flow operation

When only one pump is operating due to cascade,
the Hydro Multi-B will regularly check for low flow by decreasing
the pump speed.
When low flow is detected, the Hydro Multi-B will change its mode
of operation to "low-flow operation" and run in on/off mode as
described below.
In on/off mode, the system has two phases:
• Off phase
Water is drawn from the diaphragm tank until the pressure of
the system reaches the lower limit of the on/off band
(P - 0.5 x on/off band).
set
• Boosting phase
The pump runs at 100 % speed until the pressure reaches the
upper limit of the on/off band (P
H [m]
A B C
Stop
Start
Stop = H + 0.5 x on/off band
set
Start = H - 0.5 x on/off band
set
On/off operation
Fig. 9
11.2.5 S-system mode (start/stop band)
S-system mode is only auto-enabled in an ES-system
if the CME pump is out of operation due to a fault.
H [m]
Pump stops
Start/stop band
H
set
Pump starts
Time [sec.]
Fig. 10 Start/stop band
18
+ 0.5 x on/off band).
set
A: Normal operation
B: Pressure boosting
C: Stop
B C
Time
[sec.]

11.3 Functions for tank-filling systems

11.3.1 Cascade control

The cascade control function for tank-filling systems is designed
to fill the tank with focus on protecting the piping and preventing
water hammer. The cascade is time-dependent and starts and
stops the pumps in a pre-defined sequence. See fig. 3 on page 8.

11.3.2 Standby pumps

Systems with more than two pumps will as default set one pump
as standby pump.
The status as standby pump alternates to ensure that all pumps
have equal numbers of operating hours.
In ES-systems, the CME pump cannot be a standby pump.

11.3.3 Maximum level exceeded

This function protects against the risk of overfilling the tank.
The level is monitored and if the level is higher than 95 % of the
height of the tank, the pumps are stopped, and the display
H.L
indicates high limit , and the

12. Data communication

The CU 323 must have a CIM module (Communication Interface
Module) fitted to be able to transfer data to the SCADA system or
to a mobile phone.
Various CIM modules are available, depending on the type of
network. See the Hydro Multi-B data booklet or contact Grundfos
for further information regarding CIM modules.
PT indicator light illuminates.