Substation rehabilitation, testing and maintenance
Primary and secondary equipment across the substation, not only the transformer.
Who substation rehabilitation and maintenance is for
Substation rehabilitation and maintenance covers the equipment around the transformer: circuit breakers and disconnectors, current and voltage transformers, protection relays, earthing, cables, and the secondary systems that supply and control them. Each item is tested to a published method and serviced, and where the survey shows it is needed, the work is brought together as a rehabilitation package for the substation.
TSOs, DSOs and utilities with ageing substations
Reliability targets to meet with ageing primary and secondary equipment, and each intervention to be justified with test evidence, item by item.
Network rehabilitation programmes
Substation rehabilitation funded through a regulated investment plan or a development-bank programme, scoped per substation and documented item by item.
Industrial operators with their own MV networks
Plants and industrial zones that operate their own medium-voltage substations, such as the organised industrial zones in Türkiye.
Renewable and storage collector substations
Collector substations at solar, wind and battery storage sites, frequently remote, with switchgear and protection that the plant's availability depends on.
Primary and secondary substation equipment the programme covers
The work on each item is testing, adjustment, cleaning, parts replacement and recommissioning, as the survey finds it needed.
HV switchgear and circuit breakers
Service and timing of circuit breakers: operating times and main-circuit resistance measured to IEC 62271-100, and the mechanism adjusted where the results call for it.
Disconnectors and earthing switches
Main-circuit resistance measured to IEC 62271-102, with mechanical adjustment and parts replacement where the results or the inspection call for it.
Current and voltage transformers
Current transformers tested to IEC 61869-2 and capacitive voltage transformers to IEC 61869-5: accuracy, capacitance and dissipation factor, and for current transformers the knee point and the secondary winding resistance.
Busbars, arresters, insulators and panels
Busbars, surge arresters, insulators, capacitors, busducts and MV switchgear panels: mechanical adjustment, cleaning and parts replacement, and silicone (RTV) coating of insulators.
Protection relays, tested by secondary injection
Protection relays tested by secondary injection to IEC 60255-1, and configured where the scheme calls for it.
Secondary systems
AC and DC supplies, battery banks, LV switchgear, control and SCADA systems, compensation, UPS and communications. Valve-regulated station batteries are tested for capacity to IEC 60896-21.
Earthing and ground-grid testing
Earth electrode and ground-grid resistance measured to IEEE 81, and soil resistivity where it is needed.
MV cable testing
Very-low-frequency (VLF) AC withstand testing to IEEE 400.2 after installation or repair, and the test after installation that IEC 60502-2 sets for extruded cables.
Thermographic surveys
Thermal imaging of energised plant under load to ISO 18434-1, which finds hot connections and contacts without an outage.
Substation rehabilitation packages
Scoped per substation from the survey: retrofit of breakers and relays in LV and MV switchboards, redrawing of secondary schemes where drawings are missing or out of date, and recommissioning.
How substation maintenance runs around your outage windows
Phases, in order, inside the eight stages every programme follows. Work that needs a bay or a circuit switched out is planned into the outage windows your network allows.
Survey
What is installed, its condition, its drawings and the outages available, established on site.
Test and inspect
Each item tested to its method and inspected, and energised plant surveyed thermally under load.
Service, adjust and replace
Mechanisms adjusted, contacts and parts replaced, insulators cleaned and relays configured, as the findings set.
Re-test
The same tests repeated after the work, so that each item returns to service with a result.
Records
Results filed per item, each with its method, ready for the next outage plan.
What you provide
The assets and the site
The organisation, the site, the number of transformers with their rating and voltage ranges, the situation and your timeline: what the enquiry form asks for.
Existing records
DGA results, oil analysis and test reports, sent as a reply to our acknowledgement. A result means more when it is read against the same unit's history.
Outage windows
When each unit can be switched off, whether a regulated outage plan or a load-shedding rota sets it. Tests and work that need a de-energised unit are planned into those windows.
Access to the site
Access, ground conditions, crane availability and supply, confirmed at the site survey before a price is fixed.
What you receive for each substation
Test records per item
Operating times, contact resistance, relay tests, earth resistance and thermal images, each with the method it was carried out to.
A scoped rehabilitation package
Where the survey shows it is needed: what to retrofit, which schemes to redraw and what to recommission, substation by substation.
Recommissioned equipment
Items serviced, tested again and returned to service, with the result that shows it.
Circuit breaker, relay, earthing and cable test standards
Each test follows a published method, and the method is recorded with the result. Citing a method says how the work is done and what it is measured against.
| Standard | What it governs here |
|---|---|
| IEC 62271-100 | Circuit-breaker operating times and main-circuit resistance |
| IEC 62271-102 | Main-circuit resistance of disconnectors and earthing switches |
| IEC 61869-2 | Current transformer tests |
| IEC 61869-5 | Capacitive voltage transformer tests |
| IEC 60255-1 | Protection relay tests, including secondary injection |
| IEC 60896-21 | Capacity of valve-regulated station batteries |
| IEEE 81 | Earth resistance and soil resistivity |
| IEEE 400.2 | VLF AC withstand testing of cables |
| IEC 60502-2 | Voltage test on extruded cables after installation |
| ISO 18434-1 | Thermography of energised plant |
The detail on the capabilities page
Substation rehabilitation and maintenance: common questions
What does the programme cover beyond the transformer?
Primary equipment — circuit breakers, disconnectors, current and voltage transformers, busbars, surge arresters, insulators, capacitors, busducts, cables and MV switchgear panels — and secondary equipment: protection and control relays, AC and DC supplies, battery banks, LV switchgear, control and SCADA systems, compensation, UPS and communications. The work is testing, adjustment, cleaning, parts replacement and commissioning.
How are circuit breakers tested?
The opening and closing times are measured, and so is the resistance of the main circuit across the contacts, to the methods in IEC 62271-100. The results are compared with the manufacturer's values and with the breaker's earlier results, so that a slowing mechanism or worn contacts are found before the breaker is asked to clear a fault.
What is secondary injection testing?
It tests a protection relay by feeding currents and voltages from a test set into the relay's inputs to simulate fault conditions, and recording whether and when the relay operates. It proves the settings and the relay's response without a fault on the primary system. Relay tests are carried out to IEC 60255-1.
How is a substation earthing system tested?
The resistance of the earth electrode or grid is measured, together with soil resistivity where a design or a rehabilitation needs it, to the methods in IEEE 81. The result is compared with the design value and with earlier measurements, because corrosion and changing ground conditions move it over the years.
Why carry out thermographic surveys?
A thermal image taken under load finds connections, bushing terminals and contacts that are running hot, which marks where energy is being lost and where a fault may be developing. The plant stays energised, so the survey needs no outage, and it tells the next outage plan where to look first. Surveys follow ISO 18434-1.
How are medium-voltage cables tested after installation or repair?
After installation or repair, cable insulation is proved with a very-low-frequency AC withstand test to IEEE 400.2. For extruded cables, IEC 60502-2 sets the test after installation. The test voltage and duration follow the cable's rating and the standard, and the results are recorded with the method for the owner's cable records.
Scope this programme for your site
Tell us the assets, the site and the situation. The enquiry form opens with this programme already selected.