The Grundfos CUE 120 is a variable frequency drive (VFD) that controls the speed of Grundfos pumps that do not have a drive built into the motor. Grundfos designed and developed it in India for Indian conditions, and introduced it at Plumbex India 2025 in New Delhi. It covers motors up to 22 kW, which includes most booster sets, cooling-tower pumps and transfer pumps in buildings and small plants.
This guide explains what the CUE 120 does, its ratings and features, and where it makes sense to fit one.
Why Grundfos built the CUE 120
Grundfos says that about 70% of VFDs in the field run on their default factory settings. A drive left on defaults often runs the pump faster than the system needs, or switches it on and off when it could simply slow down. The CUE 120 is meant to be easy to set up for the actual application, so the pump runs only as fast as the job requires.
CUE 120 ratings at a glance
| Item | CUE 120 |
|---|---|
| Motor power ratings | 1.5, 2.2, 4.0, 5.5, 7.5, 11, 15, 18.5 and 22 kW |
| Supply voltage | 380–440 V class ("4T"), working range 304–456 V AC |
| Enclosure | IP20 (mount inside a panel) |
| Overload | 180% current for 20 seconds |
| Control modes | V/f, sensorless vector, closed-loop vector with encoder |
| Low-speed torque | 150% torque at 0.5 Hz (open-loop vector) |
| Braking | Built-in brake unit across the range |
| Communication | RS-485 Modbus RTU built in; Ethernet, Profibus and Profinet cards optional |
Reading the model code
A typical code is CUE 120 4T 0015 N B -IP20. "4T" is the 380–440 V class, "0015" is the 1.5 kW rating, "N" means normal duty, "B" means the brake unit is included and "IP20" is the enclosure rating. Choose the rating from the motor nameplate, not the pump's catalogue number.
Inputs, outputs and communication
- 5 digital inputs for start/stop, a dry-run or low-level switch, fault reset and preset speeds.
- 2 analog inputs: AI1 takes 0–10 V; AI2 takes 0–10 V, 0–20 mA or 4–20 mA, which suits a standard pressure transmitter.
- 1 analog output (0–10 V, 0–20 mA or 4–20 mA) to send speed or load to a panel meter or PLC.
- 1 digital output and 1 relay output for run and fault signals.
- RS-485 with Modbus RTU for SCADA or BMS monitoring and for synchronising several drives.
Features that matter on a pump
- Built-in PID control with two sets of PI parameters and an adjustable output range. With a pressure transmitter, the drive holds a constant pressure without a separate controller.
- Sleep mode: when demand drops, for example in an apartment at night, the pump stops instead of running at a useless low speed, and wakes when pressure falls.
- Soft start and stop, which reduces water hammer and mechanical stress on the pump, pipes and valves.
- Automatic energy-saving function that trims motor voltage at light load.
- Multiple preset frequencies, useful for day and night duty or summer and winter cooling loads.
- Keypad parameter copy, so a commissioned setting can be copied to identical pumps.
- Built for site conditions: Grundfos states that the boards use conformal coating, the EMC design is optimised for immunity in electrically noisy environments, and every incoming component is inspected.
Where the CUE 120 fits
Grundfos lists water transfer, water boosting, cooling-tower pumps, process cooling, comfort cooling, industrial pumping, wastewater networks and building services. In our area, the most common uses are:
- Apartment booster sets in Coimbatore that run fixed-speed CR or CM pumps with pressure switches. Adding a CUE 120 and a pressure transmitter gives constant pressure on every floor and stops the constant on-off cycling.
- Cooling-tower and chilled-water pumps in foundries, mills and commercial buildings, where the pump was oversized and a valve was partly closed to control flow.
- RO feed and transfer pumps in Tiruppur and Erode processing units, where the drive can follow tank level or feed pressure.
CUE 120 or a pump with an integrated drive?
Grundfos E-pumps such as the CRE and CME have the drive built into the motor. They are the neat choice for a new installation. The CUE 120 is a separate drive, so it is the practical choice when you already have a good fixed-speed Grundfos pump and want variable speed without replacing it, or when the drive must sit in a panel away from a wet or hot pump room.
Read next
- How a CUE 120 cuts pump energy use, with a worked example
- Installing and commissioning a CUE 120: a practical checklist
Get a CUE 120 for your pumps
Fluid Pumps & Systems is an authorized Grundfos distributor in Coimbatore, serving Tiruppur, Erode, Salem, Namakkal and the Nilgiris. Send us the pump and motor nameplate photos on WhatsApp at +91 99655 35227 and we will recommend the right drive rating, sensor and panel.
Sources: Grundfos CUE 120 product brochure; Machinist, April 2025.