{"id":2727,"date":"2026-11-10T16:23:44","date_gmt":"2026-11-10T08:23:44","guid":{"rendered":"https:\/\/www.zishengelectric.com\/?post_type=product&p=2727"},"modified":"2026-11-10T18:30:41","modified_gmt":"2026-11-10T10:30:41","slug":"66kv-69kv-power-transformer","status":"publish","type":"product","link":"https:\/\/www.zishengelectric.com\/fr\/product\/66kv-69kv-power-transformer","title":{"rendered":"66kV 69kV Power Transformer"},"content":{"rendered":"

66kV 69kV Power Transformer for Substation Duty<\/h2>\n

The 66kV \/ 69kV Power Transformer is a high-voltage transformer designed for power transmission, utility substations, industrial power systems and renewable energy applications. It provides voltage conversion between high-voltage networks and medium-voltage distribution systems.<\/p>\n

The transformer combines a silicon steel core, insulated windings and an oil-filled tank. Electrical, thermal and mechanical requirements are coordinated with the project duty and approved technical specification.<\/p>\n

\"Rear<\/p>\n

Core, Windings and Insulation<\/h3>\n

The grain-oriented silicon steel core forms the magnetic circuit. Copper or aluminum windings, insulated leads, clamping and bracing are selected for the specified losses, temperature rise and short-circuit duty. Oil-paper insulation provides dielectric separation and transfers heat to the cooling surfaces. Material grades and final construction follow the approved design.<\/p>\n

Tank, Bushings and Cooling<\/h3>\n

High- and medium-voltage bushings provide the external winding connections. Radiators transfer heat from the oil to ambient air. ONAN means Oil Natural Air Natural; ONAF means Oil Natural Air Forced and uses fans. Agree the rating at each cooling stage and the fan supply and control logic. ONAF does not create an unrestricted overload allowance.<\/p>\n

The tank arrangement, conservator, tap changer, oil-level indication, temperature instruments, pressure-relief device and current transformers follow the agreed accessory schedule. A Buchholz relay applies to suitable conservator arrangements. Online monitoring and additional sensors are optional unless included in the order.<\/p>\n

Selection and Purchase Information<\/h2>\n

A 66kV transformer and a 69kV transformer are separate nominal-voltage options. Tap adjustment alone does not establish interchangeability. Review maximum system voltage, insulation coordination, terminal clearances, grounding and the utility specification before selecting the design.<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
RFQ information<\/th>\nWhy it matters<\/th>\n<\/tr>\n<\/thead>\n
Rated MVA, load profile and power factor<\/td>\nDefine continuous demand, starting duty, overload duration and expansion or contingency requirements.<\/td>\n<\/tr>\n
HV\/MV voltage, frequency and single-line diagram<\/td>\nConfirm every winding rating, the highest voltage for equipment and the actual step-up or step-down duty.<\/td>\n<\/tr>\n
Insulation and grounding<\/td>\nSpecify impulse and AC withstand levels, neutral arrangement and site pollution requirements.<\/td>\n<\/tr>\n
Fault duty and parallel operation<\/td>\nProvide available fault current, clearing time and existing ratio, vector group, impedance and tap data.<\/td>\n<\/tr>\n
Voltage regulation<\/td>\nSelect OLTC or off-circuit taps; agree range, step size, drive supply and local\/remote control.<\/td>\n<\/tr>\n
Site and layout<\/td>\nProvide ambient temperatures, altitude, corrosion exposure, terminal orientation, clearances and foundation limits.<\/td>\n<\/tr>\n
Acceptance and delivery<\/td>\nState contractual standards and editions, witness points, document requirements and transport restrictions.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\"Oil-immersed<\/p>\n

Case 1: 66\/11kV Industrial Estate Intake Substation<\/h2>\n

The intake duty combines continuous factory demand with intermittent motor starting and changing feeder loads. The engineering requirement is to supply the 11kV distribution bus from a 66kV utility connection while keeping voltage regulation, fault duty and future expansion within the approved limits.<\/p>\n

\"Aerial<\/p>\n

Selection starts with the diversified load schedule rather than adding installed motor nameplates. Convert demand from kW to kVA using the agreed power factor, then assess starting events and the required contingency duty separately. The MVA rating is finalized after the load-flow, motor-starting and short-circuit studies; no fixed capacity is inferred from the voltage ratio.<\/p>\n\n\n\n\n\n\n\n\n\n\n
Project interface<\/th>\nEngineering and acceptance requirement<\/th>\n<\/tr>\n<\/thead>\n
Voltage conversion<\/td>\n66\/11kV, with frequency, insulation levels and neutral arrangement confirmed by the utility.<\/td>\n<\/tr>\n
Load characteristics<\/td>\nProduction feeders, pumps, ventilation and other motor loads; assess the largest starting event and nonlinear loads.<\/td>\n<\/tr>\n
Configuration<\/td>\nThree-phase oil-immersed design; ONAN\/ONAF stage ratings, winding material and OLTC or off-circuit taps to the approved schedule.<\/td>\n<\/tr>\n
Site restrictions<\/td>\nCoordinate bushing orientation, cable routes, radiator access, oil containment and the heavy-haul path to the foundation.<\/td>\n<\/tr>\n
Key engineering issue<\/td>\nBalance starting voltage drop, impedance, fault current and voltage regulation; check parallel compatibility if an existing unit remains.<\/td>\n<\/tr>\n
Acceptance<\/td>\nApprove drawings and the ITP; review serial-number test reports and complete site phasing, earthing and protection checks before energization.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\"Rear<\/p>\n

The procurement package should define transformer supply, utility interfaces, civil works, protection settings and site assembly responsibilities. Any requested outage or staged cutover must be reflected in the installation sequence and acceptance plan.<\/p>\n

Case 2: 69\/13.8kV Renewable Generation Grid Connection<\/h2>\n

The transformer connects a 13.8kV collector system to a 69kV grid. The duty includes changing generation output and reactive-power requirements at the point of connection. Selection uses the complete operating envelope, including any permitted reverse power, rather than the plant’s MW label alone.<\/p>\n

\"Gray<\/p>\n\n\n\n\n\n\n\n\n\n\n\n
Project interface<\/th>\nEngineering and acceptance requirement<\/th>\n<\/tr>\n<\/thead>\n
Voltage conversion<\/td>\n69\/13.8kV, subject to the grid connection agreement and approved winding arrangement.<\/td>\n<\/tr>\n
Load characteristics<\/td>\nVariable export, reactive-power demand and inverter-related harmonics; account for any separately specified storage charging duty.<\/td>\n<\/tr>\n
Rating and cooling<\/td>\nEstablish MVA from active and reactive duty, site temperature and cooling-stage requirements. Do not equate MW directly with MVA.<\/td>\n<\/tr>\n
Voltage control<\/td>\nCoordinate tap range and OLTC control, where specified, with plant voltage regulation and the grid operator.<\/td>\n<\/tr>\n
Site restrictions<\/td>\nReview access, terminal clearances, earthing, oil containment and separation from adjacent switchgear.<\/td>\n<\/tr>\n
Key engineering issue<\/td>\nVerify harmonic heating, fault duty, grounding and protection for every permitted switching and power-flow state.<\/td>\n<\/tr>\n
Acceptance<\/td>\nClose the FAT dossier, tap\/ratio schedule, accessory interfaces and site test records; demonstrate plant controls and protection under the approved commissioning plan.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

Confirm which tests belong to the transformer factory scope and which require the assembled plant at site. The transformer report does not by itself establish compliance of the complete generating facility with the grid connection agreement.<\/p>\n

Related Engineering Resources<\/h3>\n

Coordinate the package with our transformer site acceptance checklist<\/a> and OLTC control interface guide<\/a>.<\/p>\n

For a lower-voltage network, compare the 35kV 46kV Power Transformer<\/a>. Select the voltage class from the utility connection requirements; it is not a substitute for a 66kV or 69kV design.<\/p>","protected":false},"excerpt":{"rendered":"

The 66kV 69kV Power Transformer uses a silicon steel core and an oil-paper insulation system for utility substations, industrial power supply and renewable grid connections. Copper or aluminum windings, ONAN or ONAF cooling, tap-changing equipment and protection interfaces are selected for the project. Confirm the rated voltage, insulation level, MVA duty and agreed standard before ordering.<\/p>\n