ACS850-04 drive modules (160 to 560 kW, 200 to 700 hp)

Arranging the grounding inside the cabinet

Arrange the grounding of the drive module by leaving the contact surfaces of the fastening points unpainted (bare metal-to-metal contact). The module frame will be grounded to the PE busbar of the cabinet via the fastening surfaces, screws and the cabinet frame. Alternatively, use a separate grounding conductor between the PE terminal of the drive module and the PE busbar of the cabinet.

Ground also the other components in the cabinet according to the principle above. 

Selecting the busbar material and preparation of the joints

If planning the use of busbars, note the following:

• Tin-plated copper is recommended but aluminium can also be used.

• The oxide layer from aluminium busbar joints must be removed and suitable antioxidant joint compound applied.

Planning the electromagnetic compatibility (EMC) of the cabinet

Note following when planning the electromagnetic compatibility of the cabinet:

• Generally, the fewer and smaller the holes in the cabinet, the better the interference attenuation. The maximum recommended diameter of a hole in galvanic metal contact in the covering cabinet structure is 100 mm. Pay special attention to the cooling air inlet and outlet gratings.

• The best galvanic connection between the steel panels is achieved by welding them together as no holes are necessary. If welding is not possible, the seams between the panels are recommended to be left unpainted and equipped with special conductive EMC strips to provide adequate galvanic connection. Usually, reliable strips are made of flexible silicon mass covered with a metal mesh. The 

non-tightened touch-contact of the metal surfaces is not sufficient, so a conductive gasket between the surfaces is required. The maximum recommended distance between assembly screws is 100 mm.

• Construct sufficient high-frequency grounding network in the cabinet to avoid voltage differences and forming of high-impedance radiator structures. A good high-frequency grounding is made with short flat copper braids for low inductance. One-point high-frequency grounding cannot be used due to the long distances inside the cabinet.

Planning the cooling

Note following guidelines when planning the cooling of the cabinet:

• Ventilate the installation site sufficiently so that the cooling air flow and ambient temperature requirements of the drive module are met, see pages 129 and 134. 

The internal cooling fan of the drive module rotates at a constant speed thus blowing constant air flow through the module. Whether the same amount of air must be replaced all the time in the facility depends on how much heat must be removed.

• Leave enough free space around the components to ensure sufficient cooling. 

Observe the minimum clearances given for each component. For the required free space around the drive module, see page 47.

• Also ventilate the heat dissipated by cables and other additional equipment. 

• Make sure that the air inlets and outlets are large enough to allow sufficient air flow in and out of the cabinet. This is critical for proper cooling of the drive module.

• Equip the air inlets and outlets with gratings that:

- guide the air flow

- protect against contact

- prevent water splashes from entering the cabinet. 

• The drawing below shows two typical cabinet cooling solutions. The air inlet is at the bottom of the cabinet, while the outlet is at the top, either on the upper part of the door or on the roof. We recommend that the air outlet is on the cabinet roof. 

Use an extra exhaust fan if the air outlet is on the cabinet door.

• The internal cooling fans of the drive modules and reactors/chokes are usually sufficient to keep the component temperatures low enough in IP22 cabinets. 

• In IP54 cabinets, thick filter mats are used to prevent water splashes from entering the cabinet. This entails the installation of additional cooling equipment, such as a hot air exhaust fan.

Preventing the recirculation of hot air

Prevent hot air circulation outside the cabinet by leading the outcoming hot air away from the area where the inlet air to the cabinet is taken. Possible solutions are listed below:

• gratings that guide air flow at the air inlet and outlet

• air inlet and outlet at different sides of the cabinet

• cool air inlet in the lower part of the front door, and an extra exhaust fan on the roof of the cabinet. 

Prevent hot air circulation inside the cabinet with, for example, leak-proof air baffles at the positions shown in the diagram below. No gaskets are usually required.