A capacity-regulating transformer is a distribution transformer with two rated capacities in one tank. It runs at the high rating while demand is high and changes to the low rating when demand stays low, which cuts the no-load loss during light-load periods. The ETENZ unit is the on-load type: a controller decides when to change and an on-load capacity switch makes the change without an outage. It comes in seven rating pairs from 160(50) kVA to 630(200) kVA.
On-Load Capacity-Regulating Distribution Transformer
For utilities and rural network contractors: one transformer, two ratings, switched automatically under load — supplied alone or in an E-House.
Distributed Node Power SupplyPackage Substation
Key Metrics
160(50)–630(200)kVA
Rating pairs
10–11kV
HV
400V
LV
815–2230kg
Total mass
Product Features
Two ratings per unit
Every unit carries a high and a low rating, from 160(50) kVA to 630(200) kVA, so the peak and the long light-load periods are served by one transformer.
Two ratings per unit
Every unit carries a high and a low rating, from 160(50) kVA to 630(200) kVA, so the peak and the long light-load periods are served by one transformer.
Switches under load
The rating changes automatically while the transformer stays energised, so there is no planned outage and nobody has to switch it by hand.
Lower no-load loss
Light-load periods run on the low rating, where no-load loss is 240 W rather than 570 W on the 630(200) kVA unit, and 100 W rather than 200 W on the 160(50) kVA unit.
On-load voltage taps
The ±5 % HV tapping range is adjusted on load, so the 0.4 kV supply can be corrected without taking the transformer out of service.
Three HV options
HV is 10, 10.5 or 11 kV with 0.4 kV LV, so the same design serves 10 kV and 11 kV distribution networks.
Product Details
S stands for three-phase and 13 for the loss level; M marks the sealed tank and ZT on-load capacity and voltage regulation. After the hyphen that follows ZT comes the high rating with the low rating in brackets, both in kVA, and after the slash the system nominal voltage in kV. S13-M·ZT-630(200)/10 is therefore a three-phase sealed unit at loss level 13, rated 630 kVA and 200 kVA, for a 10 kV system.
The capacity controller follows the load and decides which rating the transformer should run at; the on-load capacity switch then makes the change. The switch changes the connection of the HV winding, delta at the high rating (Dyn11) and star at the low rating (Yyn0), while the transformer stays energised, so supply continues through the change. Switching points and time delays are confirmed with the order.
No-load loss at the high and the low rating: 200 W and 100 W for 160(50) kVA, 340 W and 150 W for 315(100) kVA, and 570 W and 240 W for 630(200) kVA. Load loss at the two ratings runs from 2310 W and 870 W on the smallest pair to 6200 W and 2600 W on the largest. Short-circuit impedance is 4.0 % on both ratings up to 500(160) kVA; the 630(200) kVA unit has 4.5 % at 630 kVA and 4.0 % at 200 kVA.
Delivery Scope Options
Scope 1
Single Unit or Complete Package Supply
Scope 1Single Unit or Complete Package Supply
Transformers are supplied as single units against the order schedule, or as a complete package together with the protective enclosure, the temperature controller and the cooling fans. The active part is wound, assembled and routine-tested at the works and shipped as a complete unit; the assembly interface for the accessories follows the transport conditions. Where the transformer is to arrive together with a prefabricated power module, the E-House line takes on the enclosure, the internal arrangement and the foundation fixing, and the transformer is delivered as equipment housed within it.
Scope Includes:
Single unit or complete package
Complete-unit shipment and assembly interface
Foundation and fixing interface
In-cabin delivery handled by the E-House line
Technical Specifications
Product form
Three-phase, sealed, oil-immersed distribution transformer with two rated capacities and on-load capacity switching
Type designation
S13-M·ZT-□(□)/□: high rating (low rating), kVA / system voltage, kV
Rating pairs, high (low)
160(50), 200(63), 250(80), 315(100), 400(125), 500(160), 630(200)
kVA
Capacity switching
Automatic: capacity controller with on-load capacity switch; transformer stays energised
HV system voltage
10, 10.5 or 11
kV
HV tapping range, on load
±5
%
LV
0.4
kV
Vector group
Dyn11 at the high rating; Yyn0 at the low rating
No-load loss, high (low) rating
160(50) kVA: 200 (100); 200(63) kVA: 240 (110); 250(80) kVA: 290 (130); 315(100) kVA: 340 (150); 400(125) kVA: 410 (170); 500(160) kVA: 480 (200); 630(200) kVA: 570 (240)
W
Load loss, high / low rating
160(50) kVA: 2310 / 870; 200(63) kVA: 2730 / 1040; 250(80) kVA: 3200 / 1250; 315(100) kVA: 3830 / 1500; 400(125) kVA: 4520 / 1800; 500(160) kVA: 5410 / 2200; 630(200) kVA: 6200 / 2600
W
No-load current, high (low) rating
0.6–1.0 (1.0–1.3)
%
Short-circuit impedance, high (low) rating
4.0 (4.0) up to 500(160) kVA; 4.5 (4.0) at 630(200) kVA
%
Total mass
160(50) kVA: 815; 200(63) kVA: 965; 250(80) kVA: 1095; 315(100) kVA: 1330; 400(125) kVA: 1655; 500(160) kVA: 1990; 630(200) kVA: 2230
kg
Rated frequency, insulation level, temperature rise, dimensions
Confirmed for the selected rating pair and site conditions
Switching points, time delays, tap positions
Confirmed with the order
| Parameter | Specification |
|---|---|
| Product form | Three-phase, sealed, oil-immersed distribution transformer with two rated capacities and on-load capacity switching |
| Type designation | S13-M·ZT-□(□)/□: high rating (low rating), kVA / system voltage, kV |
| Rating pairs, high (low) | 160(50), 200(63), 250(80), 315(100), 400(125), 500(160), 630(200) kVA |
| Capacity switching | Automatic: capacity controller with on-load capacity switch; transformer stays energised |
| HV system voltage | 10, 10.5 or 11 kV |
| HV tapping range, on load | ±5 % |
| LV | 0.4 kV |
| Vector group | Dyn11 at the high rating; Yyn0 at the low rating |
| No-load loss, high (low) rating | 160(50) kVA: 200 (100); 200(63) kVA: 240 (110); 250(80) kVA: 290 (130); 315(100) kVA: 340 (150); 400(125) kVA: 410 (170); 500(160) kVA: 480 (200); 630(200) kVA: 570 (240) W |
| Load loss, high / low rating | 160(50) kVA: 2310 / 870; 200(63) kVA: 2730 / 1040; 250(80) kVA: 3200 / 1250; 315(100) kVA: 3830 / 1500; 400(125) kVA: 4520 / 1800; 500(160) kVA: 5410 / 2200; 630(200) kVA: 6200 / 2600 W |
| No-load current, high (low) rating | 0.6–1.0 (1.0–1.3) % |
| Short-circuit impedance, high (low) rating | 4.0 (4.0) up to 500(160) kVA; 4.5 (4.0) at 630(200) kVA % |
| Total mass | 160(50) kVA: 815; 200(63) kVA: 965; 250(80) kVA: 1095; 315(100) kVA: 1330; 400(125) kVA: 1655; 500(160) kVA: 1990; 630(200) kVA: 2230 kg |
| Rated frequency, insulation level, temperature rise, dimensions | Confirmed for the selected rating pair and site conditions |
| Switching points, time delays, tap positions | Confirmed with the order |
Product FAQs
No. The controller and the on-load capacity switch make the change on their own, and the transformer stays energised throughout, so supply is not interrupted and nobody has to operate anything on site. Switching points and delays are confirmed with the order.
When the peak needs the high rating but the load stays within the low rating for long periods, for example in a rural distribution area with a short seasonal peak. On the low rating, the 630(200) kVA unit has a no-load loss of 240 W instead of 570 W. The trade-off is the capacity switch and controller that a single-rating unit does not need; where the load stays near the high rating most of the year, the ETENZ Oil-Immersed Distribution Transformer is the simpler choice.
Take the high rating from the peak demand, then check that the load in the long light-load periods fits within the low rating of the same pair; the seven pairs run from 160(50) kVA to 630(200) kVA. A load profile showing the peak and the light-load level is also used to set the controller’s switching points.
Yes. The transformer can be supplied on its own, or installed with MV switchgear and LV distribution in an ETENZ E-House such as the Integrated E-House or the MV Switchgear E-House. The E-House line supplies the enclosure, the internal layout and the base fixing, and the transformer arrives as installed equipment.
The HV system voltage (10, 10.5 or 11 kV), the rating pair or the peak and light-load demand, the required switching behaviour, the site temperature range and altitude, the grid frequency, and the documents required in the destination country.
Yes. HV options are 10, 10.5 and 11 kV, with 0.4 kV LV. State the grid frequency, the HV and LV voltages and the document language with the order; drawings, test records, the packing list and installation and maintenance instructions are prepared for the destination country.
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