Specifying a distribution transformer for Egypt
Egypt’s distribution companies buy to EEHC’s own specifications, EDMS 08-100-5 for 11 kV and EDMS 08-200-5 for 22 kV, both oil-immersed, both stepping down to 400 V. Losses, impedance and tapping are fixed by rating in those documents, and a supplier needs an EEHC approval certificate and independent type-test reports before bidding.
Medium voltage and low voltage
| Specification | Transformation ratio | Impulse / power-frequency withstand |
|---|
| EDMS 08-100-5 | 10.5–11 kV / 400 V | 75 kV / 28 kV, 1 min |
| EDMS 08-200-5 | 22 kV / 400 V | 125 kV / 50 kV, 1 min |
Both specifications are written for the networks of the Egyptian Electricity Distribution Companies, EDCs, under the Egyptian Electricity Holding Company (EEHC), with frequency 50 Hz. The low-voltage winding is 0.4 kV (400 V); low-voltage test voltage 3 kV for 1 minute.
What EEHC fixes in the specification
- Vector group Dyn11, three-phase, two-winding, oil-immersed; conventional or hermetically sealed, at the EDC’s option
- Tapping: off-load tap switch on the HV winding, seven positions from +5 % to −10 % in 2.5 % steps (+5, +2.5, 0, −2.5, −5, −7.5, −10 %)
- Short-circuit impedance at 95 °C, ±10 %: 4 % up to 630 kVA; 5 % for 800, 1000 and 1250 kVA; 6 % for 1500 to 2500 kVA; 7 % for 3000 to 5000 kVA
- Standard ratings: 25, 50, 63, 100, 160, 200, 300, 400, 500, 630, 800, 1000, 1250, 1500, 1600, 2000, 2500, 3000, 3500, 4000, 5000 kVA
- Cooling ONAN; ONAF is an option. Temperature rise limits: top oil 45 °C, winding 55 °C, hot spot 60 °C
- Site conditions: ambient −5 to +45 °C (50 °C optional), humidity up to 95 %, altitude up to 1,000 m
- Core of grain-oriented silicon steel or amorphous; copper winding; porcelain bushings with at least 4 cm/kV creepage outdoors (4.5 cm/kV optional); Buchholz relay from 500 kVA; four bi-directional wheels
- Reference standards: IEC 60076 series, IEC 60296 for the oil, IEC 60137 for bushings
Guaranteed losses
| kVA | No-load loss, silicon steel (W) | No-load loss, amorphous (W) | Load loss at 95 °C (W) |
|---|
| 100 | 272 | 74 | 1,505 |
| 200 | 456 | 103 | 2,520 |
| 400 | 638 | 160 | 4,638 |
| 630 | 825 | 250 | 6,430 |
| 1000 | 1,222 | 360 | 9,450 |
| 1600 | 1,950 | 500 | 14,900 |
| 2500 | 3,400 | 670 | 16,300 |
The specification gives one loss table for both voltages, at 400 V and 95 °C. A no-load loss is given for silicon-steel and for amorphous cores. Tenders are compared on the present worth of guaranteed losses over 20 years. A unit whose measured losses exceed the guarantee within the 10 % tolerance is penalised, one above the tolerance is rejected, and no credit is given for losses below the guarantee.
Approval, type tests and guarantee
- Tender documents must include type-test and special-test reports from an independent laboratory and an approval certificate issued by EEHC
- Type tests: full-wave lightning impulse and temperature rise. Special tests: noise level to IEC 60076-10 and short circuit
- Short-circuit test: to be done in a laboratory approved by EEHC. Without it the supplier gives a three-year guarantee and the approval is granted for one year at a time, renewed if no EDC reports a complaint
- Guarantee: 12 months from commissioning or 18 months from delivery; at least four years for a supplier delivering for the first time
- Documents, drawings and manuals in English, dimensions in centimetres
Import registration
Egypt’s General Organization for Export and Import Control (GOEIC) keeps a register of qualified factories and trademark owners under Ministerial Decree 43 of 2016, amended by Decree 195 of 2022. Goods in the categories covered by the decree are released at the port only if they come from a registered factory or trademark owner. Ask your clearing agent to check your tariff code against the current list before the order is placed.
What our published ratings cover
- Oil-immersed S11 for 11 kV: HV 6 to 11 kV, LV 380, 400, 415 and 433 V, vector group Dyn11, ONAN, IEC 60076, 50 Hz, ratings 30 to 4,500 kVA including 50, 63, 100, 160, 200, 400, 500, 630, 800, 1000, 1250, 1600, 2000 and 2500 kVA. 11 kV / 400 V and Dyn11 are both in the published list.
- Tapping: the published range is ±2 × 2.5 %. EEHC’s seven positions from +5 % to −10 % are quoted on request.
- 22 kV: the S11 20 kV class is published at 30 to 1,600 kVA with Dyn11; the YBW compact substation lists 22 kV on the high-voltage side. 22 / 0.4 kV units to EDMS 08-200-5 are quoted on request.
- 25 kVA and 300 kVA ratings, amorphous cores, EEHC impedance values, the EDMS loss table, ONAF or hermetically sealed designs: quoted on request to the specification you send.
- The EEHC approval certificate and independent type-test reports are not part of the published ratings. Ask for them in writing on the quotation.
Send with your enquiry
- Distribution company (EDC) and the tender or specification reference, EDMS 08-100-5 or 08-200-5 and the option items the EDC has selected
- Rated power (kVA), HV (11 kV or 22 kV), LV 400 V, Dyn11, tapping range
- Conventional or hermetically sealed; silicon-steel or amorphous core; ambient and altitude if above the standard conditions
- Quantity, delivery date and port of discharge, and whether the approval certificate is required for bidding