How to install a German frequency converter control cabinet?

The installation of a German frequency converter control cabinet needs to comply with the German electrical installation standards (VDE standards) and relevant international standards. The following are the detailed installation steps and requirements:

Preparation before Installation

Familiarize with Technical Documents: Carefully read the installation instructions, operation manuals, and relevant electrical schematic diagrams of the frequency converter control cabinet to understand its performance, parameters, installation requirements, and precautions.

Check the Integrity of the Equipment: Inspect the appearance of the control cabinet for any damage or deformation. Ensure that the cabinet door opens and closes flexibly and that the door lock works properly. Confirm that the electrical components in the cabinet, such as the frequency converter, contactors, relays, and fuses, are complete, and check for any looseness, damage, or missing parts. Also, verify that all connection wires are secure.

Prepare Installation Tools and Materials: Prepare the necessary installation tools, such as an electric drill, screwdrivers, wrenches, and a multimeter, as well as installation materials, including cables, wires, cable trays, cable bridges, grounding busbars, and expansion bolts.

Determine the Installation Location: Select an appropriate installation site that meets the requirements. The location should be dry, well-ventilated, with minimal dust and free from corrosive gases. The ambient temperature around the installation site should be within the allowable operating temperature range of the frequency converter (generally -10°C to 40°C). At the same time, ensure that the installation location is convenient for operation, maintenance, and inspection, and there should be sufficient space around it. The operation space in front of the control cabinet should be no less than 1.5 meters, and the maintenance space at the back and sides should be no less than 0.8 meters.

Foundation Installation

Fabricate the Foundation Frame: According to the size and weight of the control cabinet, fabricate a suitable foundation frame. The foundation frame is generally made of channel steel or angle steel, and it should be flat and firm enough to support the weight of the control cabinet.

Fix the Foundation Frame: Place the foundation frame at the predetermined installation location and fix it to the ground using expansion bolts. When fixing, ensure the levelness and verticality of the frame, with the deviation of levelness and verticality not exceeding 1.5‰.

Grounding Treatment: Weld a grounding terminal on the foundation frame, and the grounding terminal should be reliably connected to the building's grounding system. The grounding resistance should not be greater than 4Ω. The grounding busbar should be made of copper material, and its cross-sectional area should meet the requirements of the short-circuit current.

Installation of the Control Cabinet

Position the Control Cabinet: Place the frequency converter control cabinet steadily on the foundation frame and adjust its position to align the installation holes on the cabinet with those on the foundation frame.

Fix the Control Cabinet: Use bolts to fix the control cabinet to the foundation frame. Tighten the bolts to ensure that the control cabinet is firmly installed and prevent vibration and displacement.

Connect the Grounding: Connect the grounding terminal of the control cabinet to the grounding terminal on the foundation frame with a grounding busbar to ensure good grounding of the control cabinet.

Electrical Connections

Power Inlet Connection: Select an appropriate power cable according to the rated voltage and rated current of the frequency converter control cabinet. Introduce the power cable into the control cabinet through the inlet hole and connect it to the inlet terminal of the power switch. When connecting, pay attention to the phase sequence and polarity of the cable to ensure it matches the electrical system inside the control cabinet.

Frequency Converter Connection: According to the instructions of the frequency converter, connect the power cable from the outlet terminal of the power switch to the input terminals (R, S, T) of the frequency converter. Connect the motor cable from the output terminals (U, V, W) of the frequency converter to the motor. When connecting, ensure that the cable connections are firm and in good contact to avoid loose or poor connections.

Control Circuit Connection: Connect the control circuit of the frequency converter according to the control requirements. The control circuit includes the connection of signals such as start, stop, speed regulation, and fault alarm. Generally, use shielded cables for connection to prevent electromagnetic interference. Ground the shielding layer to ensure the stability and reliability of signal transmission.

Connection of Other Electrical Components: Connect other electrical components, such as contactors, relays, fuses, and thermal relays, according to the electrical schematic diagram of the control cabinet. When connecting, pay attention to the electrical clearance and creepage distance between each electrical component to meet the requirements of relevant standards.

Wiring and Arrangement

Cable Laying: Cables should be laid using cable trays, cable ducts, or through pipes to prevent the cables from being mechanically damaged and corroded. Cables of different voltage levels and purposes should be laid separately. For example, power cables and control cables should be laid separately to prevent mutual interference. During the cable laying process, pay attention to the bending radius of the cables to avoid excessive bending.

Wiring Arrangement: Inside the control cabinet, cables and wires should be arranged neatly and tied firmly to avoid a messy layout. Use cable trays or cable clips to fix the cables and wires to prevent them from loosening or shaking. For longer cables, fix them at regular intervals to prevent the cables from sagging.

Labeling and Marking: Paste clear and accurate labels and markings at both ends of the cables and wires and on the electrical components inside the control cabinet, indicating information such as the cable number, purpose, and the name and specifications of the electrical components, which is convenient for future maintenance and inspection.

Inspection after Installation

Electrical Connection Inspection: Use tools such as a multimeter to check the resistance value of each electrical connection point to ensure that the connections are firm and in good contact. Check the insulation resistance of the cables and wires, and the insulation resistance should meet the requirements of relevant standards.

Grounding System Inspection: Check whether the connection of the grounding system is reliable and whether the grounding resistance meets the requirements. Use a grounding resistance tester to measure the grounding resistance, and the grounding resistance should not be greater than 4Ω.

Electrical Component Inspection: Check whether the electrical components inside the control cabinet are working properly and whether the parameter settings are correct. Check whether the parameter settings of the frequency converter match the parameters of the motor, and check whether the actions of electrical components such as contactors and relays are sensitive and reliable.

Overall Appearance Inspection: Check whether the overall appearance of the control cabinet is clean and aesthetically pleasing, whether the cabinet door closes tightly, and whether the door lock is working properly. Check whether the wiring inside the control cabinet is neat and standardized, and whether the labels and markings are clear and accurate.