Grundfos CRE Instrucciones De Instalación Y Funcionamiento página 16

How to set the PI controller
For most applications, the factory setting of the controller
constants K and T will ensure optimum pump operation.
p i
However, in some applications an adjustment of the controller
may be needed.
Proceed as follows:
1. Increase the gain (K ) until the motor becomes unstable.
p
Instability can be seen by observing if the measured value
starts to fluctuate. Furthermore, instability is audible as the
motor starts hunting up and down.
Some systems, such as temperature controls, are slow-
reacting, meaning that it may be several minutes before the
motor becomes unstable.
2. Set the gain (K ) to half of the value which made the motor
p
unstable. This is the correct setting of the gain.
3. Reduce the integral time (T ) until the motor becomes
i
unstable.
4. Set the integral time (T ) to twice the value which made the
i
motor unstable. This is the correct setting of the integral time.
General rules of thumb:
• If the controller is too slow-reacting, increase K
• If the controller is hunting or unstable, dampen the system by
reducing K or increasing T .
p i
4.4.3 External setpoint
The input for external setpoint signal can be set to different signal
types.
Select one of the following types:
• 0-10 V
• 0-20 mA
• 4-20 mA
• Not active.
If Not active is selected, the setpoint set by means of the R100 or
on the control panel will apply.
If one of the signal types is selected, the actual setpoint is
influenced by the signal connected to the external setpoint input.
See section 4.8 External setpoint signal
16
4.4.4 Signal relay
Pumps of 20-30 hp have two signal relays. Signal relay 1 is
factory set to Alarm and signal relay 2 to Warning.
In one of the displays below, select in which one of three or six
operating situations the signal relay should be activated.
• Ready
• Alarm
• Operation
• Pump running
• Warning
• Relubricate.
.
p
For further information, see section
signal relay.
4.4.5 Buttons on pump
The operating buttons
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.
4.4.6 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.
20-30 hp
• Ready
• Alarm
• Operation
• Pump running
• Warning
• Relubricate.
Fault and Alarm cover faults resulting in Alarm.
Warning covers faults resulting in Warning.
Relubricate covers only that one individual event. For
distinction between alarm and warning, see section
4.2.3 Fault indications.
4.11 Indicator lights and
and on the control panel can be set
20-30 hp