SHEATH VOLTAGE LIMITER LINK BOXES -SVL, Stainless Steel

aychem Link Boxes Application Single core cables in operation carry alternating currents and induced voltages in the metallic sheath of the cable. These currents may cause, depending from the sheath bonding, circulating currents flowing in the cable sheath which reduce the transmission capacity of the cable and cause an additional heating. Link Boxes are used for earthing and bonding cable sheaths of single core cables so that the induced voltages and circulating currents are eliminateAdvanced Features •Different designs available •Stainless steel box •Different mechanical protection levels up to IP68 •Electrically and mechanically type tested •1-phase and 3-phase boxes •With or without surge arresters •With or without removable links •For concentric cables or single core cables •Cross sections up to 300 mm2 •ZnO sheath voltage limiter for up to 7kV protection levels, larger protection levels on request •Short circuit current up to Major Design Elements TE Connectivity's Raychem link boxes have reliable design and the housing (1) is made of stainless steel. The enclosure is water and dust tight type tested to fulfil the requirements of protection class IP68 for installations below ground. For other applications e.g. indoor installation, link boxes with less protection class are also available. Designs are capable to withstandings different electrical demands for several voltage classes. The link box lid is lockable (2) by a standard security deadlock. The optional sheath voltage limiters (SVL) (3) are made of zinc oxide and are designed to meet the requirements of IEC 60099-4. Link boxes with SVL's are available for different voltage classes and provide active over-voltage protection that contributes directly to improved reliability of the system. The indoor post-insulators (4) made of epoxy resin are light weight and provide reliable electrical performance. The cable entries (5) are available with different inner diameters to fit single core or concentric cables with different cross sections. For perfect sealing cable entries are protected with coated heat shrink tubes (6). Sheath bonding cables are fixed by various methods with compression lugs (7) or by using clamping rings. The tinned copper links (8) are removable and available for cross sections up to 300 mm2. 8 4 3 2Most popular cable sheath grounding options Single point earthing On relatively short cable sections the cable sheaths are solidly bonded together and earthed at one position. The sheaths of the three cable sections are connected and grounded at one point only. At all other points, there will be a voltage between sheath and ground that will be at its maximum at the farthest point from the ground bond. Since there is no closed sheath circuit, current does not flow along the sheaths and no sheath circulation current loss occurs. Cross bonding The cable route is sectionalized into equal lengths. The sections are cross connected to neutralize the induced voltages. The phase sum of the introduced voltages will be zero and hence there will be no circulating currents when the cable laying is symmetrical.Cross bonding and transposition For cable laying in unsymmetrical formations the induced voltages are not equal at each phase and therefore the phase sum of the voltages are not zero despite cross bonding. The cables are transposed at each joint position and the cable sheaths are cross connected, each cable occupies the same relative position in the cable formation. By this means the phase sum of the induced voltage sheaths