Buttons On Pump; Pump Number; Digital Input; Stop Function - Grundfos CRE Installation And Operating Instructions Manual

9.3.5 Buttons on pump

The operating buttons and
to these values:
• Active
• Not active.
When set to Not active (locked), the buttons do not function. Set
the buttons to Not active if the pump should be controlled via an
external control system.

9.3.6 Pump number

A number between 1 and 64 can be allocated to the pump. In the
case of bus communication, a number must be allocated to each
pump.

9.3.7 Digital input

The digital input of the pump (terminal 1, fig. 4, 7 or 12) can be
set to different functions.
Select one of the following functions:
• Min. (min. curve)
• Max. (max. curve)
• External fault
• Flow switch
• Dry running (from external sensor) (only 11-22 kW).
The selected function is activated by closing the contact between
terminals 1 and 9. See figs. 4, 7 and 12.
See also section 12.2 Digital input.
Min.:
When the input is activated, the pump will operate according to
the min. curve.
Max.:
When the input is activated, the pump will operate according to
the max. curve.
External fault:
When the input is activated, a timer will be started. If the input is
activated for more than 5 seconds, the pump will be stopped and
a fault will be indicated. If the input is deactivated for more than 5
seconds, the fault condition will cease and the pump can only be
restarted manually by resetting the fault indication.
Flow switch:
When this function is selected, the pump will be stopped when a
connected flow switch detects low flow.
It is only possible to use this function if the pump is connected to
a pressure sensor.
If the input is activated for more than 5 seconds, the stop function
incorporated in the pump will take over. See section 9.3.8 Stop
function.
on the control panel can be set
Dry running (only 11-22 kW):
When this function is selected, lack of inlet pressure or water
shortage can be detected. This requires the use of an accessory,
such as:
®
• a Grundfos Liqtec dry-running sensor
• a pressure switch installed on the suction side of a pump
• a float switch installed on the suction side of a pump.
When lack of inlet pressure or water shortage (Dry running) is
detected, the pump will be stopped. The pump cannot restart as
long as the input is activated.

9.3.8 Stop function

The stop function can be set to these values:
• Active
• Not active.
When the stop function is active, the pump will be stopped at very
low flows. The causes are the following:
• avoid unnecessary heating of the pumped liquid
• reduce wear of the shaft seals
• reduce noise from operation.
H
Stop pressure
ΔH
Start pressure
Fig. 27 Difference between start and stop pressures (ΔH)
ΔH is factory-set to 10 % of actual setpoint.
ΔH can be set within the range from 5 % to 30 % of actual
setpoint.
Low flow can be detected in two different ways:
1. a built-in "low-flow detection function" which functions if the
digital input is not set up for flow switch
2. a flow switch connected to the digital input.
1. Low-flow detection function
The pump will check the flow regularly by reducing the speed for
a short time. If there is no or only a small change in pressure, this
means that there is low flow. The speed will be increased until the
stop pressure (actual setpoint +0.5 x ΔH) is reached and the
pump will stop. When the pressure has fallen to the start pressure
(actual setpoint –0.5 x ΔH), the pump will restart.
When restarting, the pumps will react differently according to
pump type:
0.37 - 7.5 kW pumps:
The pump will return to continuous operation at constant
pressure and the pump will continue checking the flow
regularly by reducing the speed for a short time.
11-22 kW pumps:
1.If the flow is higher than the low-flow limit, the pump will
return to continuous operation at constant pressure.
2.If the flow is still lower than the low-flow limit, the pump will
continue in start/stop operation. It will continue in start/stop
operation until the flow is higher than the low-flow limit;
when the flow is higher than the low-flow limit, the pump will
return to continuous operation.
Q
21