21.4.9 Minimum flow rate
Due to the risk of overheating, the pumps must not be used at flow
rates below 10 % of the rated flow rate of one pump.
The pumps must not run against a closed outlet valve.
21.4.10 Maximum starts and stops
The system must not be started and stopped via the power supply
more than four times per hour.
When the system is switched on via the power supply, it will start
after approximately 5 seconds.
If a higher number of starts and stops is desired, use the input for
external start-stop when starting/stopping the system.
When started via an external on/off switch, the system starts
immediately.
21.4.11 Diaphragm tank
The diaphragm tank precharge pressure must be set to 0.7 x
setpoint.
If the setpoint is changed, the diaphragm tank precharge pressure
must be changed accordingly to ensure optimum operation.
Measure the precharge pressure while the system is
pressureless.
We recommend that you use nitrogen gas for precharging.
21.5 Inputs and outputs
Ground reference (GND)
All voltages refer to GND.
All currents return to GND.
Absolute maximum voltage and current limits
Exceeding the following electrical limits may result in severely
reduced operating reliability and motor life:
Relay 1:
Maximum contact load: 250 VAC, 2 A or 30 VDC, 2 A.
Relay 2:
Maximum contact load: 30 VDC, 2 A.
GENI terminals: -5.5 to 9.0 VDC or less than 25 mADC.
Other input/output terminals: -0.5 to 26 VDC or less than 15 mADC.
Digital inputs (DI)
Internal pull-up current greater than 10 mA at Vi equal to 0 VDC.
Internal pull-up to 5 VDC (currentless for Vi greater than 5 VDC).
Certain low logic level: Vi less than 1.5 VDC.
Certain high logic level: Vi greater than 3.0 VDC.
Hysteresis: No.
Screened cable: 0.5 - 1.5 mm
2
/ 28-16 AWG.
Maximum cable length: 500 m.
Open-collector digital outputs (OC)
Current sinking capability: 75 mADC, no current sourcing.
Load types: Resistive and/or inductive.
Low-state output voltage at 75 mADC: Max. 1.2 VDC.
Low-state output voltage at 10 mADC: Max. 0.6 VDC.
Overcurrent protection: Yes.
Screened cable: 0.5 - 1.5 mm
2
/ 28-16 AWG.
Maximum cable length: 500 m.
Analog inputs (AI)
Voltage signal ranges:
• 0.5 - 3.5 VDC, AL AU
• 0-5 VDC, AU
• 0-10 VDC, AU.
Voltage signal: Ri is greater than 100 kΩ at +25 °C.
Leak currents may occur at high operating temperatures. Keep the
source impedance low.
Current signal ranges:
• 0-20 mADC, AU
• 4-20 mADC, AL AU.
Current signal: Ri is equal to 292 Ω.
Current overload protection: Yes. Change to voltage signal.
Measurement tolerance: - 0/+ 3 % of full scale (max.-point
coverage).
Screened cable: 0.5 - 1.5 mm
2
/ 28-16 AWG.
Maximum cable length: 500 m (exclusive of potentiometer).
Potentiometer connected to +5 V, GND, any AI:
Use maximum 10 kΩ.
Maximum cable length: 100 m.
Analog output (AO)
Current sourcing capability only.
Voltage signal:
• Range: 0-10 VDC.
• Minimum load between AO and GND: 1 kΩ.
• Short-circuit protection: Yes.
Current signal:
• Ranges: 0-20 and 4-20 mADC.
• Maximum load between AO and GND: 500 Ω.
• Open-circuit protection: Yes.
Tolerance: - 0/+ 4 % of full scale (max-point coverage).
Screened cable: 0.5 - 1.5 mm
2
/ 28-16 AWG.
Maximum cable length: 500 m.
Pt100/1000 inputs (PT)
Temperature range:
• Minimum -30 °C (88/882 Ω).
• Maximum +180 °C (168/1685 Ω).
Measurement tolerance: ± 1.5 °C.
Measurement resolution: Less than 0.3 °C.
Automatic range detection (Pt100 or Pt1000): Yes.
Sensor fault alarm: Yes.
Screened cable: 0.5 - 1.5 mm
2
/ 28-16 AWG.
Use Pt100 for short wires.
Use Pt1000 for long wires.
LiqTec sensor inputs
Use Grundfos LiqTec sensor only.
Screened cable: 0.5 - 1.5 mm
2
/ 28-16 AWG.
Grundfos Digital Sensor input and output (GDS)
Use Grundfos Digital Sensor only.
Power supplies (+5 V, +24 V)
+5 V:
• Output voltage: 5 VDC ± 5 %.
• Maximum current: 50 mADC (sourcing only).
• Overload protection: Yes.
+24 V:
• Output voltage: 24 VDC ± 5 %.
• Maximum current: 60 mADC (sourcing only).
• Overload protection: Yes.
Digital outputs (relays)
Potential-free changeover contacts.
Minimum contact load when in use: 5 VDC, 10 mA.
Screened cable: 0.5 - 2.5 mm
2
/ 28-12 AWG.
Maximum cable length: 500 m.
Bus input
Grundfos GENIbus protocol, RS-485.
Screened 3-core cable: 0.5 - 1.5 mm
2
/ 28-16 AWG.
Maximum cable length: 500 m.
45
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