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Frequency converter for speed adjustment of DS asynchronous motors and synchronous motors, 0.75 to 800.0 kW, 380 to 480 V, 3~ protection class IP21 to IP55

BLEMO frequency converter



A perfect range of
BLEMO - for all applications





Version 2 IP54 - switch disconnector
K IP21 - switch cabinet installation
Better pump protection with ER41
ER41 Plain text display
Version 2 IP54 - switch disconnector
K IP21 - switch cabinet installation
Better pump protection with ER41
ER41 Plain text display


This new product line replaces the ER40. The programmable and optional features of the ER41 are virtually unlimited. It can be used for all applications in machine and plant construction, both variable and constant torque applications. It has been developed in accordance with the latest aspects of relevant standards and international regulations, including EMC and environmental compatibility, e.g. RoHs, WEEE.

Standard features

  • Multilingual operating terminal with real-time clock and USB connection
  • built-in PID controller
  • Integration of the real pump curve
  • Integrated Modbus/TCP, serial Modbus interface, Ethernet
  • Integrated EMC filter, line choke
  • Output filter up to 300m motor cable length, shielded
  • PTC thermistor input PTC, PT100, PT1000, KTY84
  • Integrated STO function, SIL3/Ple, two-channel
  • RoHs, WEEE compliant (recycling rate 88%)
  • Field buses: Ethernet/IP and Modbus/TCP with two ports, CANopen, Profibus DPV1, Profinet, DeviceNet


  • Version 1: Basic device without built-in load disconnecting switch IP55
  • Version 2: Basic unit with built-in switch disconnector IP54
  • Version K: For control cabinet IP21

Device versions

The ER41 is available in two versions ER41-...K, protection class IP21/23 and ER41-...G, protection class IP54/55 with(-V2) and without(-V1) switch-disconnectors. The devices are supplied ex works with painted circuit boards. Units from 90 kW upwards are also supplied with tinned copper busbars (optional for smaller ratings), for aggressive air.      

Application areas

  • Pumps and fans
  • Networked applications
  • Safety related applications
  • Building services engineering HKL
  • IoT / Industry 4.0 Ready
  • Mechanical and plant engineering
  • Conveying technology
  • Lifting technology

Your benefits

  • Sustainable cost savings thanks to predictable maintenance based on condition
  • Pump characteristic curve for the optimum operating range
  • Optimum operation saves energy and increases service life
  • Reduction of downtime without additional investment
  • Optimal process monitoring and control
  • Simple parameterization


Questions about the product

How do I set the start command on the ER41?

1. a connection must be established between +24 and DI1 (clockwise rotation)

Guidelines for the operation of frequency converters

  1. To achieve electromagnetic compatibility, the inverter must be operated with a built-in or external radio interference filter.

  2. If shielded cables are used between the inverter and the motor, the shield must be connected to earth at both ends. Cable interruptions should be avoided if possible. If it is necessary to separate the cable, e.g. to install a motor contactor, the cable shielding must be connected through as directly as possible. It is important to ensure that the lowest possible HF impedance is achieved.

  3. The shorter the cable, the lower the radio interference and leakage current. The maximum possible cable lengths must be taken into account.

  4. To avoid interference with the control inputs, control cables should always be shielded. The shield must be connected to the cable clamp provided on the inverter. If the shield is also connected to a control device, care must be taken to ensure that the ground points have the same potential.

  5. Control cables should not cross power cables if possible. Where this cannot be avoided, a right-angled crossing is recommended.

  6. Separate laying of control and power cables should be aimed for. If the cables must be laid parallel, e.g. on the same cable route, the largest possible distance (> 20 cm) should be selected.

  7. The shielding of the laid cables should have a low HF impedance if possible. Copper braiding is therefore preferable to steel braiding.

  8. The RF contact resistance at the connection points between shielding and housing must be kept as low as possible. Dirt, paint and insulation residues on the housing and shielding in the area of the connections must therefore be removed. In principle, the cable clamps or crimp connections provided for this purpose should be used to connect the shielding. It is advantageous to use earthing cable glands.

  9. The shielding should be connected to the housing as close as possible to the cable terminals. Longer, free cable ends act as antennas.

  10. With unscreened cables, the cable wires should be twisted and output filters should be used.

Where do I set the most important parameters?

1. 1. select quick start

2. there you will find some parameters, like run-up time or high speed. 

How do I specify my 0-10V setpoint?

1. +10V to AI1 and the ground to COM.

How do I set a PID controller?

1. 5. complete adjustment

2. 5.9 General functions => PID controller (Here you will find all necessary parameters for setting the PID controller)

How do I release the Local/Remote key?

1. 5. complete adjustment

2. 5.9 General functions => HMI command => Shock-free

How do I set fixed reference values on the digital inputs?

1. 5. complete Einst. 

2. 5.9 General functions => Preliminary settings Speeds => 2 Preset. Frequency = e.g. DI3                                                                                        

3. Then set the speeds in: Preset. Speed 2 => e.g. 25 Hz etc. 

4. please refer to the table on page 475 in the programming instructions. 

Start with closed enable DI1 - +24 (automatic restart)

1. 5. complete adjustment

2. 5.5 Command and Setpoint => Parameter Type 2-wire Ctrl => Set Level value.

How are the inputs and outputs of the ER41 assigned (factory setting)?

Ein- / Ausgang

Parametriert auf:



Start vorwärts

Level high



Level high


Sollwertfrequenz 1

0…10 V



0…20 mA



0…20 mA




How can the displayed speed of the ER41 be scaled / changed?

To adjust and change the motor speed display on the ER41 drive, follow these steps:

1. 8. my setting

2. 8.4 Adjustment

3. adjust parameters


5. return to 4. display

6. 4.4 Motor parameters

7. select motor speed

8. adjust parameters and click on user-defined selection

9. select engine speed with desired unit

How do I set anticlockwise rotation?

1. 5 Complete adjustment

2. 5.5 Command and setpoint

3. Zuord. Return run

4. please use DI2 for counterclockwise rotation

Is it possible to operate a motor with low power on a frequency converter with higher power?

In principle, it is possible to operate a motor with low power on a frequency inverter with higher power.
In this case, the ratio between motor and inverter power is important.
Experience shows that the ratio of 1:4 should not be exceeded.

E.g. it is not recommended to run a 0.75kW motor with a 30kW BLEMO frequency inverter.
For test purposes, this combination can be used, but the motor phase monitoring must be deactivated.


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