GB512789A - Improvements in or relating to the control of the harmonics in polyphase alternating current systems - Google Patents

Abstract

512,789. Transformers; inductances; supply systems. SIEMENS-SCHUCKERTWERKE AKT.- GES. March 14, 1938, No. 7923. Convention date, Jan. 8. [A Specification was laid open to inspection under Sect. 91 of the Acts, Sept. 14, 1938.] [Class 38 (ii) and 38 (iv)] In a polyphase A.C. system in which unbalanced harmonics are .produced by apparatus such as transformers or choking coils having asymmetric cores (e.g., cores with limbs in one plane) an auxiliary transformer or choking coil having a saturated core is associated with a selected phase or phases to form such an unbalanced harmonic load as to restore balance to the harmonics of the system. For exsample, a saturated, single phase choke 3, Fig. 1, may be connected in parallel with the centre limb winding of a star, delta, or zig-zag connected transformer or choke, the figure showing the delta arrangement. In the case of a starconnected transformer or choke winding 5, Fig 2, in which the neutral point is inaccessible, a saturated single phase choke 3 is inductively associated through a coupling winding 4 with the centre limb winding. Fig. 4 shows an arrangement in which the auxiliary harmonic loading device is in the form of a single phase auto-transformer 3, 8 associated with the main transformer or choke 7. The auxiliary transformer or choke may in all cases be regulated by tappings or displaceable core parts.