Substations
Compact substations
One prefabricated enclosure carrying the medium voltage switchgear, the transformer and the low voltage distribution, delivered as a unit and set on a prepared foundation.
At a glance
- Standard
- IEC 62271-202AC prefabricated substations, operating voltage up to 52 kV
- Operation
- from outside, or walk inthe standard covers both
- Transformer
- commonly in the distribution rangerating set by the load
- Medium voltage
- commonly a ring main unitconfiguration set by the network
- Enclosure
- concrete, steel or compositeset by site and specification
A compact substation arrives complete, which moves the site work before delivery rather than after it. A prepared foundation, cable ducts in the right positions and access for the delivery vehicle and the lifting equipment are the three items that decide whether a delivery date is real.
Because the enclosure is type tested with its contents, changing the equipment inside later is not free. The rating, the ring main unit configuration and the low voltage schedule are worth fixing before the order rather than during manufacture.
What gets specified
| Parameter | Typical options | What decides it |
|---|---|---|
| Transformer | Rating, voltage pair and construction | The load and the network |
| Medium voltage switchgear | Ring main unit, commonly two ring switches and a transformer feeder | The network arrangement at the site |
| Low voltage distribution | Incomer rating, number and rating of outgoing ways | The loads supplied |
| Enclosure material | Precast concrete, steel or composite | Site, transport and specification |
| Operation | From outside through doors, or walk in | Operating practice and climate |
| Internal arc classification | As tested for the station | Where people can be when the station is energised |
| Metering and auxiliaries | Metering position, auxiliary supply, remote signalling | The network operator and the owner |
Typical options are the ones buyers most often specify. They are not a list of what is available, which is confirmed per enquiry.
Applicable standards
| Standard | What it covers |
|---|---|
| IEC 62271-202 | AC prefabricated substations, cable connected, operating voltage up to and including 52 kV, operated from inside or outside |
| IEC 62271-200 | AC metal enclosed switchgear above 1 kV up to and including 52 kV, for the medium voltage equipment |
| IEC 61439-1 and IEC 61439-2 | Low voltage switchgear assemblies, for the low voltage board |
| IEC 60076-1 | Power transformers, general requirements |
The standard that applies is set by the specification and the destination market. Editions change, so the edition cited in a specification is confirmed in the quotation.
Documents normally requested
| Document | What it evidences |
|---|---|
| Technical datasheet and single line diagram | Ratings, panel functions and the arrangement offered |
| General arrangement drawing | Footprint, height, cable entry and floor fixings |
| Type test report | The design has passed the type tests of its standard, including internal arc where claimed |
| Routine test report | The individual assembly's tests before dispatch |
| Schematic and wiring diagrams | Control, protection and interlocking circuits |
| Operating and maintenance manual | Operation, interlocks and maintenance |
An internal arc classification is only as good as the type test behind it, and it applies to the tested configuration. Ask for the report that matches the arrangement offered.
What we need to quote accurately
| 01 | Transformer rating and the primary and secondary voltage |
| 02 | Medium voltage configuration: ring main unit functions or panel schedule |
| 03 | Low voltage distribution: incomer rating, number and size of outgoing ways |
| 04 | Enclosure type and whether it is operated from outside or from an internal aisle |
| 05 | Site access for delivery and lifting, and the foundation arrangement |
| 06 | Metering position and any network operator requirement |
| 07 | Quantity, destination, required delivery date and acceptable condition |
Delivery and logistics
Distribution equipment is heavy, and a delivery date is only real once the site is ready for it. The dimensions and weight of the unit offered decide the vehicle, the lifting equipment and the route to the foundation, and they come from the manufacturer's drawing rather than from the rating.
Liquid immersed transformers are usually shipped filled, which affects transport rules and the handling on arrival. Anything crossing a border also carries customs documentation, and where the destination applies its own conformity or energy efficiency rules the paperwork has to match that market rather than the country of manufacture.
Lead times vary widely with rating, specification and manufacturer loading. We state a delivery basis in each quotation for the specific unit offered and do not publish a general lead time we cannot hold.
Common questions
Can the transformer inside a compact station be changed later?
Physically, sometimes. But the type test covers the station with the equipment it was tested with, so a change can affect what the test evidence proves. It is cheaper to settle the rating before the order.
Related
Request a quote for this equipment
Send the rating, the voltage and the destination, or submit the specification, drawing or nameplate. Anything missing is raised before it reaches a supplier.