Grundfos ALPHA 26-99 - Control Functions; Internal Control Principles; External Control Principles

11
English (US)
6. Control functions
6.1 Internal control principles
ALPHA2 26-99 circulator pumps automatically
control the differential pressure by adjusting the
pump performance to the actual heat demand,
without the use of external components.
Two different control modes are available:
6.1.1 GRUNDFOS AUTOADAPT
The Grundfos AUTOADAPT function enables
the circulator to control the pump performance
automatically within a defined performance
range.
• Adjusting the pump performance to the size
of the system.
• Adjusting the pump performance to the
variations in load over time.
Two different control modes are available for
Grundfos AUTOADAPT:
6.2 External control principles
6.2.1 0-10 VDC
ALPHA1 26-99 circulators are externally speed-
controlled by an analog 0-10 V DC signal.
The pump requires a 0-10 V signal on the signal
port to control the speed of the pump. The pump
will run at its minimum speed if the signal fails
(cable break).
Profile R
Fig. 6 Profile R
Proportional Pressure
The differential pressure increases at
increased flow.
Constant Pressure
The differential pressure is constant.
Proportional Pressure
AUTOADAPT
In proportional pressure
AUTOADAPT, the circulator is set to
proportional-pressure control.
Constant Pressure AUTOADAPT
In constant pressure AUTOADAPT,
the circulator is set to constant-
pressure control.
TM07 0439 5017
TM07 0784 0518
U [V] Pump status
0.5 < U ≤ 1 Standby (Stop)
1 < U ≤ 2 Hysteresis
2 < U ≤ 3 Min. speed
3 < U ≤ 10 Speed between Min. and Max.
470 R
36 V
0-10 V
PWM
Signal input
Signal output
Signal ref.
0.5 4 5
U[V]
123 9678 10
Max.
Min.
Stop