# Operations and Maintenance

Maintenance and fault response for operational plant.

Source: https://crestwatt.com/services/operations-maintenance/
Publisher: CrestWatt — Electrical contracting for utility-scale solar, storage and grid connections.
Contact: info@crestwatt.com
Language: en-GB

CrestWatt maintains the electrical systems it commissions, and takes on operational plant built by others. Maintenance is delivered against a defined visit schedule with structured records, so that the asset owner can evidence compliance and track condition over time.

**Standards and methods cited:** BS 7671, ENA TS 41-24, Thermographic survey, HV authorised person

## Planned preventive maintenance

- HV switchgear inspection, contact resistance and operational checks
- Transformer inspection, oil sampling and protection device function testing
- Protection relay re-verification and settings audit against the current relay schedule
- Thermographic survey of switchgear, transformer stations, combiner boxes and DC connectors under load
- Earthing system continuity and electrode resistance re-testing
- LV distribution periodic inspection and testing to BS 7671
- String level performance verification and DC re-testing on a sample plan
- Communications and SCADA link verification

## Corrective maintenance and fault response

- HV cable fault location by TDR and thumper, excavation coordination, joint repair and re-testing
- DC string fault finding, connector replacement and re-certification
- Protection and control fault diagnosis, relay replacement and re-commissioning
- Inverter and transformer station electrical fault support to OEM procedure
- Communications and fibre fault location, re-splicing and re-certification

## Operational support

- HV authorised person and senior authorised person cover for switching and permits
- Annual condition reporting against the asset register
- Support to asset managers on warranty claims and OEM interface

## Contract forms

Fixed-term PPM contracts with defined visit schedules and reporting, call-off corrective maintenance, and combined commissioning plus first-year O&M for new plants.

## Next step

Send the asset register and the current O&M schedule. We will propose a maintenance programme and a fixed annual price.

## Common questions

**What does planned preventive maintenance cover?**

HV switchgear inspection and contact resistance, transformer inspection, oil sampling and protection device testing, protection relay re-verification against the current relay schedule, thermographic survey under load, earthing continuity and electrode resistance re-testing, LV periodic inspection to BS 7671, sample DC re-testing and communications verification.

**Does CrestWatt maintain plant it did not build?**

Yes. CrestWatt maintains the systems it commissions and takes on operational plant built by others, working from the asset register and the existing O&M schedule.

**Is HV fault response available?**

Yes. HV cable fault location by TDR and thumper with excavation coordination, joint repair and re-testing; DC string fault finding and connector replacement; protection and control fault diagnosis and re-commissioning; and fibre fault location, re-splicing and re-certification.

**What contract forms are available?**

Fixed-term PPM contracts with defined visit schedules and reporting, call-off corrective maintenance, and combined commissioning plus first-year O&M for new plants.

## Related scopes

- [Testing and Commissioning](https://crestwatt.com/services/testing-commissioning/): IEC 62446-1 DC commissioning; AC, LV and HV pre-energisation testing; protection commissioning; SCADA point to point; witness testing; FAC compilation.
- [Protection, Control and Switchgear](https://crestwatt.com/services/protection-control-switchgear/): Relay, CT and VT supply; panel design, build and wiring; IEC 61850 configuration; settings; secondary and primary injection; site acceptance.
- [Cable Termination and Testing](https://crestwatt.com/services/cable-termination-testing/): LV, MV and HV terminations to 132 kV; DC crimping and MC4 assembly; fibre fusion splicing; Modbus RS-485 termination. IR, VLF, sheath, TDR, OTDR and certification.