Patent ID: 11942254
Assignee: HITACHI ENERGY LTD
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A three-phase transformer comprising:
a shell-form five-limb transformer core having three main limbs, a first side limb, and a second side limb, the main limbs comprising a first outer main limb, a second outer main limb, and a middle main limb; and
three coil arrangements comprising a first outer coil arrangement arranged around the first outer main limb, a second outer coil arrangement arranged around the second outer main limb, and a middle coil arrangement arranged around the middle main limb, wherein the first outer coil arrangement includes a first coil cover insulation and the second outer coil arrangement includes a second coil cover insulation;
wherein the first coil cover insulation surrounds the first outer coil arrangement and the first outer main limb such that the first coil cover insulation separates the first outer coil arrangement from the first side limb to mitigate an electrical field strength between the first side limb and high voltage windings of the first outer coil arrangement,
wherein the second coil cover insulation surrounds the second outer coil arrangement and the second outer main limb such that the second coil cover insulation separates the second outer coil arrangement from the second side limb to mitigate an electrical field strength between the second side limb and high voltage windings of the second outer coil arrangement,
wherein each of the first and second coil cover insulation is configured to electrically insulate the coil arrangements from a transformer housing and the core and from the respective other ones of the coil arrangements, and
wherein the middle coil arrangement is not surrounded by a coil cover insulation.