Jinying Transformer / Technical
Construction, materials and standards. Destination voltage, frequency and certification requirements are tabulated below.
Grain-oriented silicon steel wound core, all-copper foil windings. This is where the loss figures come from.
The strip is wound continuously to shape, with no joints and no punched holes, so the magnetic path is not interrupted by cut faces. Against a stacked core this gives lower no-load loss and lower no-load current — the origin of the S11 loss level in the tables.
The secondary is wound from full-width copper foil: one turn is one layer, axial ampere-turns are evenly distributed and axial short-circuit forces are lower. Primary coils are solid copper; copper-clad aluminium is not used.
The product lines are designed to the IEC 60076 series; pad-mounted units follow IEEE/ANSI C57, and SANS 780 applies to distribution transformers for South Africa. The table below summarises what each part covers.
| IEC 60076-1 | Power transformers — General. Defines rated quantities, tolerances on guaranteed values (Table 1) and the routine/type/special test framework the other parts build on. |
| IEC 60076-2 | Power transformers — Temperature rise for liquid-immersed transformers. Sets top-oil, average-winding and hot-spot temperature-rise limits by cooling class, and how to correct them for altitude and ambient temperature. |
| IEC 60076-3 | Power transformers — Insulation levels, dielectric tests and external clearances in air. Links insulation levels to the highest voltage for equipment (Um), and sets minimum air clearances, including the correction for site altitude above 1000 m. |
| IEC 60076-5 | Power transformers — Ability to withstand short circuit. Defines the thermal and mechanical (dynamic) short-circuit withstand requirements. |
| IEC 60076-7 | Power transformers — Loading guide for mineral-oil-immersed power transformers. Covers thermal ageing and loading above the nameplate rating. |
| IEC 60076-10 | Power transformers — Determination of sound levels. Defines how a transformer's noise level is measured and stated. |
| IEC 60076-11 | Power transformers — Dry-type transformers. Requirements specific to dry-type (including cast-resin) designs, with their own insulation and temperature-rise limits. |
| IEC 60076-12 | Power transformers — Loading guide for dry-type power transformers. Companion loading guide to IEC 60076-11. |
| IEEE C57.12.00 | General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers. The IEEE/ANSI counterpart to IEC 60076-1 for markets built on that system. |
| IEEE C57.12.34 | Requirements for Pad-Mounted, Compartmental-Type, Self-Cooled, Three-Phase Distribution Transformers. Covers dead-front/live-front pad-mounted units up to 34.5 kV nominal system voltage. |
| SANS 780 | Distribution transformers. South Africa's national standard for oil-immersed distribution transformers up to 3150 kVA, Um ≤ 36 kV. |
One-line scope summaries, not a statement of certification.
IEC 60076-3 sets the rated short-duration power-frequency (AC) and lightning-impulse (LI) withstand voltages against the highest voltage for equipment, Um — the insulation class a winding is designed for, not the operating voltage itself.
| Um — highest voltage for equipment (kV) | Short-duration AC withstand (kV rms) | Lightning impulse withstand (kV peak) |
|---|---|---|
| 3.6 | 10 | 40 |
| 7.2 | 20 | 60 |
| 12 | 28 | 75 |
| 17.5 | 38 | 95 |
| 24 | 50 | 125 |
| 36 | 70 | 170 |
Source: IEC 60076-3, Table 2 (Um ≤ 245 kV). The insulation level for each order is confirmed in the technical agreement.
IEC 60076-1, Clause 10 and Table 1, set how far a routine-test measurement may differ from the guaranteed value before the transformer fails acceptance.
| Total losses | +10 % of the total losses |
| Individual (component) losses | +15 % of each component loss, provided the total-loss tolerance above is not exceeded |
| No-load current | +30 % of the design value |
| Short-circuit impedance — two-winding, principal tapping | ±7.5 % when the specified impedance is ≥ 10 %; ±10 % when it is < 10 % |
| Short-circuit impedance — two-winding, other tapping | ±10 % when the specified impedance is ≥ 10 %; ±15 % when it is < 10 % |
| Voltage ratio, principal tapping | The lower of ±0.5 % of the specified ratio or ±1/10 of the actual impedance voltage |
IEC 60076-1:2011, Table 1. Tolerances apply to a routine-test measurement against the guaranteed/design value; where the table gives only one direction, there is no restriction the other way.
IEC 60076-1, Clause 11, sets three categories of test. Which type tests and special tests apply to a given order — and any tests beyond the standard — is agreed between manufacturer and purchaser in the technical agreement; the standard does not fix a single list for every order.
Winding resistance; voltage ratio and phase-displacement check; short-circuit impedance and load loss; no-load loss and current; dielectric routine tests per IEC 60076-3; on-load tap-changer tests where fitted; leak (tightness) test under pressure for liquid-immersed transformers; check of core-and-frame insulation.
Temperature-rise type test per IEC 60076-2; dielectric type tests per IEC 60076-3; sound-level determination per IEC 60076-10 where a guaranteed sound level is specified.
Examples: short-circuit withstand test per IEC 60076-5, winding hot-spot temperature-rise measurement, zero-sequence impedance measurement, frequency response analysis (FRA), dissolved-gas analysis.
IEC 60076-1:2011, Clause 11.1.2–11.1.4. Routine testing is carried out in house — see the factory →
General guidance only — the right choice depends on the network the transformer feeds into. Confirm with the receiving utility or the project specification.
Delta HV, star LV with neutral brought out, 330° lag. Handles unbalanced single-phase loading on the LV side, and lets triplen (3rd-harmonic) currents circulate inside the delta winding instead of on the network — a common choice for 415/400 V distribution with mixed single- and three-phase loads, and where the LV side needs a path for earth-fault current.
Star HV, star LV with neutral, 0° (no phase shift). Simple to parallel with other Yyn0 units, but without a delta winding its ability to carry unbalanced LV loading and triplen-harmonic circulation is limited — better suited to loads that stay close to balanced three-phase.
Star HV, zig-zag LV with neutral, 330° lag. The zig-zag winding gives a low zero-sequence impedance, so it carries single-phase-to-earth fault current well and limits neutral displacement under unbalanced load — common on rural or pole-mounted networks with long single-phase LV runs.
General guidance, not a recommendation for any specific network — earthing arrangement, protection coordination and the utility's own connection rules decide the final choice.
IEC 60076-2 sets temperature-rise limits by cooling class, and how to reduce them for high-altitude sites.
| Transformer part | Temperature-rise limit (K) |
|---|---|
| Top oil | 60 |
| Average winding (by resistance) | 65 |
| Hot-spot winding | 78 |
IEC 60076-2:2011, Table 1 — limits for ON../OF.. (naturally or forced-air cooled, natural oil circulation) liquid-immersed transformers with 105 °C-class solid insulation, 20 °C yearly-average ambient. Oil-directed (OD..) cooling allows a higher 70 K average-winding rise.
For an installation site above 1000 m where the factory itself is at normal altitude, the top-oil, average-winding and hot-spot temperature-rise limits are reduced: for a naturally air-cooled transformer (…AN), by 1 K for every 400 m the site altitude exceeds 1000 m; for a forced-air-cooled transformer (…AF), by 1 K for every 250 m. Corrections are rounded to the nearest whole kelvin.
IEC 60076-2:2011, Clause 6.3.2 and Table 2.
Above 1000 m, IEC 60076-3 also requires external clearances in air — and, where necessary, bushings — to be selected for the site altitude, since the dielectric strength of air falls as altitude rises.
IEC 60076-3:2013, Clause 16.
HV connection voltage, LV utilization voltage and system frequency vary by market — 415 V is standard low-voltage practice across much of West Africa, 400 V is used in Tanzania, South Africa and most of Central Asia, and the Philippines runs a 60 Hz, 240/480 V system built to IEEE/ANSI C57. Confirm the exact voltage, frequency and certification regime for the destination market in the table below before specifying an order.
The fewer of these are missing from the first email, the fewer rounds of back-and-forth before a firm quotation.
Full parameter tables for every series, plus the reference above, as PDF.
Certification
| Destination | HV | LV | Frequency | Conformity scheme |
|---|---|---|---|---|
| Southeast Asia | ||||
| Indonesia | 20 kV | 400 V | 50 Hz | — |
| Philippines | 13.2 kV | 240/480 V | 60 Hz | — |
| Vietnam | 22 kV | 380 V | 50 Hz | — |
| Africa | ||||
| Nigeria | 11 / 33 kV | 415 V | 50 Hz | SONCAP |
| Kenya | 11 / 33 kV | 415 V | 50 Hz | PVoC / KEBS |
| Tanzania | 11 / 33 kV | 400 V | 50 Hz | TBS |
| South Africa | 11 / 22 kV | 400 V | 50 Hz | SABS 780 |
| Egypt | 11 / 22 kV | 400 V | 50 Hz | — |
| Ghana | 11 / 33 kV | 400 V | 50 Hz | — |
| Angola | 15 / 30 kV | 380 V | 50 Hz | — |
| Central Asia | ||||
| Kazakhstan | 6 / 10 kV | 380 V | 50 Hz | — |
| Uzbekistan | 6 / 10 kV | 380 V | 50 Hz | — |
| Latin America | ||||
| Chile | 12 / 23 kV | 380 V | 50 Hz | — |
| Mexico | 13.2 / 23 / 34.5 kV | 220Y/127 V | 60 Hz | NOM-002-SEDE/ENER |
| Colombia | 11.4 / 13.2 / 34.5 kV | 208Y/120 V | 60 Hz | RETIE |
| Peru | 10 / 22.9 kV | 380/220 V | 60 Hz | — |