Fix VFD Problems with SAB Cables скачать в хорошем качестве

Fix VFD Problems with SAB Cables

In this video, Rick Hillmer will discuss a few of the disadvantages of VFDs and how to solve them with the proper cabling from SAB. All current IGBT based drives produce a chopped DC wave that simulates an AC sine wave to a motor. This chopped DC signal can cause some problems. Common mode current is created by common mode voltage, which is the sum of all three phases to ground. In a standard, balanced, 3 phase AC system, the sum of all three phases is equal to zero. But with this chopped DC output, this is not the case. When there is this common mode voltage, current will flow to ground, possibly through the motor shaft via the motor bearings. This will lead to bearing pitting and premature failure. EMI or electromagnetic interference is a disturbance that affects an electrical circuit due to either electromagnetic induction or radiation. While EMI is not governed or regulated here in the states, it is worldwide, and it can still cause problems with machinery and other electronics. One method to alleviate both of these problems is through proper cabling and connections. Many motor manufacturers, including ABB recommend using cables that have a symmetrical arrangement of 3 phase leads and 3 earth conductors covered by a concentric shield on large motors. To prevent EMI in VFD systems, many VFD manufacturers including ABB recommend using this same cable, but also providing a 360 degree contact for grounding at the motor and drive. This may be counter-intuitive to what we have all been taught-only ground the shield at one end-but doing this makes a faraday cage around the cable, preventing interference from entering or exiting. SAB produces cables and accessories specifically designed to solve these problems. All small cables have a concentric foil shield and braided drain. These cables can be cross linked polyethylene (XLPE) or even contain brake pair wires. For larger motors, SAB offers a 2kv rated cable with up to 500mcm conductors. Cord grips are also available to connect these cables for proper EMI protection. Cord grips not only provide a strain relief and seal, but these little metal tabs also provide a path to ground for the shield. Visit our Website: www.ramcoi.com Connect with us on social media:   / ramcoinnovations     / ramcoinnovation     / ramco-innovations   LEGAL DISCLAIMER: While we have made every attempt to ensure that the information provided is accurate and has been obtained from reliable sources, Ramco is not responsible for any errors or omissions, or for the results obtained from the use of this information. All information is provided "as is", with no guarantee of completeness, accuracy, timeliness or of the results obtained from the use of this information, and without warranty of any kind, express or implied, including, but not limited to warrantees of performance, merchantability and fitness for a particular purpose. At all times you should defer to the instructions and safety guidelines issued by the manufacturer. In no event will Ramco, its agents or employees thereof be liable to you or anyone else for any decision made or action taken in reliance on the information provided to you or for any consequential, special or similar damages, even if advised of the possibility of such damages.