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VLT drives A4 enclosure

Compact IP55/IP66 VLT® drives down to 0.25 kW

22 February 2010
For the Danfoss frequency converter families VLT® AutomationDrive, HVAC Drive and Aqua Drive with power ratings up to 4 kW, a new and especially compact IP 55 / IP 66 enclosure with type designation A4 is now available. Compared with the existing A5 enclosures, the dimensions have been reduced by 33%. Nevertheless, the power components fulfil the most demanding requirements, even in applications with high overload torque, long motor cables, or ambient temperatures up to 50 °C.  

The new A4 enclosure is available in IP 55 (NEMA 12) and IP 66 (NEMA 4X) versions, and it extends the existing product line. Power components rated at up to 4 kW are available for input voltages of 380– 480/500 V (3 phase) and 2.2 kW 200–240 V (3 phase). The flexible power module design allows the use for machinery or conveyors requiring high over-torque. Similarly, the new unit can also address motors with normal over-torque, typically like fan or centrifugal pumps.  

Optimised design

Danfoss reached this size reduction through the use of modern components with optimized efficiency, and a completely newly developed cooling technology. All of the elements of a typical VLT® drive configuration, such as an RFI filter compliant with EN 55011 Class A1/B, a mains interference suppression choke, and the brake module, are integrated in the unit to avoid additional installation expenditures for external components.           

Time-saving installation

During development, special attention was given to accessibility and time-saving installation. For example, the mechanical fastening points are readily accessible from the front, and the fasteners can be operated using automatic tools. The terminal clamps are arranged to enable installation of the cabling with the simplest possible work sequence. The cable entry in the base is available with a choice of metric or non-metric threads. Additionally, all terminal clamps are fitted with a protective cover and the necessary fittings are included with the unit.           

Modular design for an economical solution

For optimal adaptation to individual applications, two A/B extension slots are provided. They can be used for communication interfaces such as Profibus, Profinet, Ethernet I/P or CANopen, as well as a module for additional inputs and outputs. Danfoss supplies the converter fully assembled and tested.              

Small drive, big advantages

The A4 frame size presents a more compact solution for customers that until now have used the A5 frame in the same power range.

The advantage of the new A4 frame size are :

  • Smaller mechanical size (32%)
  • Lighter weight (9.4 kg)
  • Easier mounting and installation for customers (outside fastening holes)
  • Easy line connection (45° connector) No external fan in 0.37 – 1.5 kW /380-500V and 0.25 – 0.75 kW / 200 - 240V
  • Ambient temperature: 50°C continuously (only drive on the market!)
  • Optional mains switch
  • Threaded cable entry holes for ‘metric areas’
  • Smooth cable entry holes for conduit installations
  • Easy fieldbus connection
  • Compatible with Ethernet based fieldbus options
  • Same internal hardware and software as for A5
  • All options designed for placing in A and/or B slot(s)

In contrary to the frame size A5 the new A4 frame size does not have space for C options in the drive. For application that require a C option, the A5 frame is still the best solution.