10 kV / 20 kV / 35 kV Medium-Voltage Distribution Transformers for Kazakhstan

Distribution demand in Kazakhstan runs mainly on 10 kV and 35 kV medium-voltage networks stepping down to 0.4 kV, under an extreme continental climate that can swing from about −50°C in northern winters to above +40°C in southern summers.

That range - not the kVA rating - is what drives transformer design: insulation systems, sealing, cooling and short-circuit withstand must all be specified for the real site temperature envelope.

 

 

Distribution networks form the largest equipment demand segment in Kazakhstan, supplying urban, industrial and rural loads. The backbone voltage levels follow the post-Soviet GOST practice - 110 kV sub-transmission stepping to 35 kV and 10 kV distribution, then 0.4 kV utilisation. 20 kV is a recognised standard voltage in IEC 60038 and is used in some new industrial or dedicated projects, but it is not a mainstream utility distribution level; the system voltage of any specific project must be verified from the electrical specification before transformer design starts.

 

 

 

• Temperature envelope: northern regions can approach −50°C in winter; southern regions exceed +40°C in summer. Materials must remain ductile at low temperature and insulation systems must tolerate the full range.
• Grid quality: significant voltage fluctuations require strong short-circuit withstand capability and a wide voltage regulation range (tap range).
• Logistics: long inland transport in extreme cold demands robust packaging and moisture protection from factory to site.

 

 

GNEE Electric has supplied SCB-2500/20 dry-type transformers (2500 kVA, 20 kV class) for Kazakhstan projects. The unit combines an oil-free, flame-retardant design with low noise, low partial discharge and strong overload capability under forced-air cooling.

 

Key data:

Parameter	SCB-2500/20 (Reference)
Rated capacity	2500 kVA
Primary voltage	20 kV
Secondary voltage (no-load)	400 V
Frequency	50 Hz
Cooling	ANAF (air natural / air forced)
Insulation level	LI 125 / AC 50 (20 kV class, per IEC 60076-3)
Vector group	Dyn5 / Dyn11
HV tappings	±2 × 2.5% (off-circuit)
Short-circuit impedance	6%
No-load loss	≤ 5000 W*
Load loss (120°C)	≤ 24,300 W*
Temperature rise (winding)	100 K
Thermal class	F
Sound power level	≈ 59 dB (at 1 m)
Protection	IP21 enclosure / IP21 LV cable box
Standards	IEC 60076-11:2018, GB/T 10228-2015

 

*Loss values marked with * are from the original project datasheet and should be re-verified against the current GB/T 10228-2015 / GB 20052-2020 limits for 2500 kVA (a modern SCB13 10 kV unit at level-2 sits near 1,440 W no-load; the 20 kV class increases winding losses) - request the factory type-test report for the exact unit.

 

 

The table below lists 10/0.4 kV SCB dry-type transformers at level-3 energy efficiency (SCB10 loss level), GB 20052-2020 Table 2, F class (load loss at 120°C). If your project requires SCB13 (level-2), no-load loss is typically 20–25% lower at the same rating - ask for the level-2 table.

 

Rated Capacity (kVA)	Vector Group	No-Load Loss (W)	Load Loss 120°C (W)	No-Load Current (%)	Impedance (%)	Sound Level (dB)
30	Dyn11	150	710	0.6	4.0	57
50	Dyn11	215	1000	0.6	4.0	-
80	Dyn11	295	1380	0.6	4.0	58
100	Dyn11	320	1570	0.6	4.0	-
125	Dyn11	375	1850	0.6	4.0	59
160	Dyn11	430	2130	0.6	4.0	-
200	Dyn11	495	2530	0.5	4.0	60
250	Dyn11	575	2760	0.5	4.0	-
315	Dyn11	705	3470	0.5	4.0	62
400	Dyn11	785	3990	0.4	4.0	-
500	Dyn11	930	4880	0.4	4.0	63
630	Dyn11	1070	5880	0.4	4.0	63
800	Dyn11	1215	6960	0.3	6.0	65
1000	Dyn11	1415	8130	0.3	6.0	-
1250	Dyn11	1670	9690	0.25	6.0	67
1600	Dyn11	1960	11700	0.25	6.0	-
2000	Dyn11	2440	14400	0.20	6.0	69
2500	Dyn11	2880	17100	0.20	6.0	-

Values per GB 20052-2020 Table 2, level 3 (SCB10 loss level), 10/0.4 kV, Dyn11. "-" = value not listed in the source table. Confirm final values with the manufacturer's type-test report.

 

 

• Confirm the real system voltage (10 kV, 20 kV or 35 kV) and vector group with the project electrical design - do not assume from region alone.
• State the site ambient range (e.g. −45°C to +40°C) so insulation and sealing are designed for it.
• Demand current-standard compliance: IEC 60076-11:2018, GB/T 10228-2015, GB 20052-2020 (or the applicable local standard). Reject certificates citing withdrawn editions.
• Request the type-test report with no-load loss, load loss, partial discharge and sound level measurements.
• For 20 kV units, confirm insulation level (LI 125 / AC 50) and tap range against the network's actual regulation needs.

 

 

What voltage levels are used for distribution in Kazakhstan?

Kazakhstan's grid follows the former Soviet GOST system: 110 kV sub-transmission, with 35 kV and 10 kV as the dominant medium-voltage distribution levels and 0.4 kV low voltage. 20 kV is a standard voltage in IEC 60038 and appears in some new or dedicated projects, but it is not a mainstream utility distribution level in Kazakhstan - always confirm the actual system voltage with the project specification.

 

Why do transformers for Kazakhstan need special design?

Kazakhstan has an extreme continental climate: winter temperatures can reach about −50°C in the north while summers exceed +40°C in the south, with strong grid voltage fluctuations. Transformer insulation, sealing, cooling and short-circuit withstand must therefore be specified for the actual site temperature range and network conditions, per IEC 60076 and the project's local codes.

 

What standards apply to dry-type transformers supplied to Kazakhstan?

The current reference standards are IEC 60076-11:2018 (dry-type transformers) and, for Chinese-manufactured units, GB/T 10228-2015 and GB 20052-2020 efficiency levels. Older references such as IEC 726 (withdrawn in the 1990s) or GB/T 10228-1997 must not be used in specifications - verify that any certificate or datasheet cites the current editions.

 

What is the difference between SCB13 and older SCB10/SCB12 dry-type transformers?

SCB10, SCB12 and SCB13 are loss-level designations: SCB10 corresponds to level-3 energy efficiency (GB 20052-2020), while SCB13 corresponds to level-2, with no-load loss typically about 20–25% lower than SCB10 at the same rating and load loss also reduced. A 630 kVA SCB13 unit, for example, has no-load loss ≤ 910 W versus ≤ 1,070 W for SCB10.

 

References

1. IEC 60076-11:2018 - Power transformers, Part 11: Dry-type transformers. 
2. IEC 60038 - IEC standard voltages (including the 20 kV level). 
3. GB/T 10228-2015 -  (Technical parameters and requirements for dry-type power transformers).
4. GB 20052-2020 -(Minimum allowable values of energy efficiency and the energy efficiency grades for power transformers).
5. KEGOC (Kazakhstan Electricity Grid Operating Company) - grid structure and voltage practice. 
6. GNEE Electric - Dry Type Transformer range. 

 

Standards and figures above were verified against the cited sources as of the publication date. The SCB loss table reflects level-3 (SCB10) limits; project datasheet values marked with * should be re-verified against current standards. If you spot an error, contact us so we can correct it.

 

Supplying Distribution Transformers for Kazakhstan or CIS Projects?

Send your system voltage, site temperature range and load data - we will return a compliant specification with verified loss data and delivery plan.

Contact Our Engineering Team

 

Or email ：sales@gneeelectric.com 

WhatsApp： +86 158 2468 7445

 

Disclaimer: This article is provided for general information and does not constitute engineering advice or a product warranty. Voltage practice and standards should be confirmed against the applicable project specification and local codes. Henan GNEE Electric Co., Ltd. makes no representation regarding the accuracy of third-party references.