Grundfos Hydro Multi-B CM, Инструкция по установке и эксплуатации

Страница: 15 / 24

English (GB)
15
11. Functions
The booster systems include application-optimised software.
11.1 General functions
11.1.1 Dry-running protection (optional)
To protect the pumps against damage from dry running, the
booster system incorporates a water shortage function.
This function is based on the monitoring of the inlet pressure or
the level in a possible tank on the suction side.
The pressure or level can be monitored by one of the following:
• pressure switch
• float switch
• level switch
• external electrode relay
• analog sensor.
Dry-running protection with pressure switch, float switch,
level switch or external electrode relay
Set the monitoring device to the desired limit.
If water shortage is detected for more than 5 seconds, the system
will stop, and the
indicator light illuminates.
When the water supply has been reestablished, the dry-running
fault is automatically reset.
Dry-running protection with analog sensor
The limit for the minimum inlet pressure in the suction manifold is
a factory-set value which can only be changed by a Grundfos
service engineer.
If the sensor output is below the limit for minimum inlet pressure
for more than 5 seconds, the system will stop, and the
indicator light illuminates.
When the water supply has been reestablished, the dry-running
fault is automatically reset.
11.1.2 Automatic pump changeover
The automatic pump changeover function ensures an equal
number of operating hours of the pumps, but it also ensures that,
in case of an alarm on one pump, another pump is automatically
started.
There are three types of automatic pump changeover:
• operation-dependent pump change
• alarm-dependent pump change
• time-dependent pump change.
Operation-dependent pump change
In an ES-system, the speed-controlled pump has higher priority
than the mains-operated pumps and will always be the first pump
to start and the last to stop. The mains-operated pumps in an
ES-system will operate alternately as described above.
At increasing demand, the pump with the lowest number of
operating hours will be started first.
At decreasing demand, the pump with the highest number of
operating hours will be stopped first.
Alarm-dependent pump change
If a pump stops due to an alarm, the CU 323 will send a stop
command to the pump to prevent auto-restarting and start
another pump which is ready to start and which has the lowest
number of operating hours.
Time-dependent pump change
In certain applications, the demand remains constant for long
periods and does not require all pumps to run. In such situations,
pump changeover does not take place naturally, and forced pump
changeover may thus be required.
Once every 24 hours, the CU 323 checks if any of the running
pumps has a higher number of operating hours than the pumps
that are stopped. If this is the case, the pump will be stopped, and
a pump with a lower number of operating hours will start.
11.1.3 Minimum time between start and stop
This function ensures a delay between the start/stop of one pump
and the start/stop of another pump. The purpose is to prevent
hunting when pumps start and stop continuously.
Caution
When a pump is running in manual mode, it is not
protected against dry running.
WS
WS
Note
If the speed-controlled pump in an ES-system is
stopped due to an alarm, the system will function
as an S-system.
See section 11.2.5 S-system mode (start/stop
band) .
Note
If the system is stopped due to an alarm, the
minimum time between start and stop will be
ignored, and the pumps will be stopped
immediately.