Power Supply Failure; Functions; Auto-Reset; Anti-Cycling - Grundfos PM 2 Montage- Und Betriebsanleitung

7.2.1 Starting and stopping conditions
The conditions described below require that DIP
switch 5 has been set to "ON".
Starting conditions
The unit starts the pump when the pressure is lower
than p .
start
The default start pressure is 1.5 bar and can be
increased in steps of 0.5 bar. See section 5.1 DIP
switches.
Stopping conditions
The unit stops the pump when the pressure is higher
than p .
stop
p = p + 1 bar.
stop start

7.3 Power supply failure

In case of a power supply failure, the pump restarts
automatically when power returns and runs for at
least 10 seconds.

8. Functions

8.1 Auto-reset

When the auto-reset function is enabled, cycling and
dry-running alarms will be automatically reset.
To enable the function, set DIP switch 6 to "ON".
See section 5.1 DIP switches.
The auto-reset function should NOT be
enabled on pumps which cannot self-
Caution
prime when water returns after dry-
running.

8.2 Anti-cycling

To avoid inadvertent starts and stops of the pump in
case of a failure in the installation, the anti-cycling
function can be enabled.
The function will detect cycling if it occurs and stop
the pump with an alarm.
When the PM 2 has been set to start/stop according
to water consumption, cycling may occur in the
following situations:
• In case of a minor leakage.
• If a tap has not been entirely closed.
When the PM 2 has been set to start/stop with 1 bar
differential pressure, cycling may occur in the
following situations:
• If the pressure tank has lost its precharge
pressure.
• If the size of the pressure tank is insufficient.
If the cycling alarm has been activated, the pump
can be restarted manually by pressing [Reset].
When the auto-reset function is enabled, the pump
will be restarted automatically after 12 hours in alarm
condition.
To enable the function, set DIP switch 7 to "ON". See
section 5.1 DIP switches.
12
In case of a very small consumption,
the anti-cycling function may register
this as a minor leakage and stop the
Note
pump inadvertently. If this occurs, the
function can be disabled.
8.3 Maximum continuous operating time
(30 minutes)
When this function is enabled, the pump will be
stopped when the pump has been running
continuously for 30 minutes.
Restart the pump by pressing [Reset].
The purpose of this function is to avoid unnecessary
water and current consumption, e.g. in case of pipe
fracture or considerable leakages.
When the function is enabled, any
consumption exceeding 30 minutes will
cause an alarm, and the pump will be
Note
stopped.
If enabled, the auto-reset function will
not restart the pump.
To enable the function, set DIP switch 8 to "ON".
See section 5.1 DIP switches.

8.4 Dry-running protection

The unit incorporates dry-running protection that
automatically stops the pump in case of dry running.
The dry-running protection functions differently
during priming and operation.
If a dry-running alarm has been
activated, the cause should be found
Caution
before the pump is restarted in order to
prevent damage to the pump.
8.4.1 Dry running during priming
If the unit detects no pressure and no flow within
5 minutes after it has been connected to a power
supply and the pump has started, the dry-running
alarm is activated.
8.4.2 Dry running during operation
If the unit detects no pressure and no flow within
40 seconds during normal operation, the dry-running
alarm is activated.
8.4.3 Resetting of dry-running alarm
Manual resetting
If a dry-running alarm has been activated, the pump
can be restarted manually by pressing [Reset]. If the
unit detects no pressure and no flow within
40 seconds after restarting, the dry-running alarm is
re-activated.
Auto-reset
When the auto-reset function is enabled, the pump
will be restarted automatically after 30 minutes in
alarm condition. If, after restarting, the pump has not
been primed within 5 minutes of operation, the dry-
running alarm will reappear. The auto-reset function
will attempt to restart the pump every 30 minutes
during the first 24 hours. Then there will be 24 hours
between the restarting attempts.