Wind energy · Repair
Wind Turbine Circuit Breaker Repair
The generator, converter and grid-side breakers in a turbine base — 690 V ACBs and large MCCBs from ABB, Schneider, Siemens and Eaton — stripped, rebuilt and injection-tested at our Pontefract workshop. Current ranges and the first-generation units nobody else will touch.
- Frames800 – 4000 A
- Typical turnaround24–48 hrs once quoted
- Warranty12 months
- TestingSecondary injection, certified
Equipment
The breakers we see in the turbine base
A doubly-fed or full-converter turbine has a short list of LV breakers, and most of the fleet runs the same few families. The main breaker between the generator, converter and step-up transformer is usually a drawout or fixed ACB rated 1000 to 2500 A at 690 V, with an electronic trip unit and motorised charging so the controller can open and close it remotely. Around it sit the converter-side and auxiliary MCCBs — Tmax, Compact NS and NSX, 3VL, NZM — and on larger machines a second ACB on the grid side.
Each family has its own failure pattern. Emax units of the first generation lose charging motors and PR112/PR113 trip electronics. Masterpact NW mechanisms stiffen once the factory grease hardens; their Micrologic units hold up better but the closing coils and MCH gear motors don't. Siemens 3WL units suffer secondary-connector and auxiliary-switch wear from repeated racking. None of these is a reason to scrap a breaker with a sound frame and sound arc chutes.
We rebuild them. Every unit is fully stripped, every wearing component measured against the manufacturer's published limits, and the breaker rebuilt with new or re-manufactured parts where the measurement says so — not where a parts list says so.
| ABB SACE Emax E1–E3 (gen. 1) | Charging motor, closing/opening coils, PR11x trip unit electronics, auxiliary contacts |
| ABB Emax 2 / E2.2–E4.2 | Contact erosion from high operation counts, Ekip trip unit connectors, racking gear |
| Schneider Masterpact NW / NT | Hardened mechanism grease, MCH gear motor, XF/MX coils, main-contact wear, secondary disconnect |
| Siemens 3WL | Secondary connector wear, auxiliary switch blocks, motor operator, ETU trip unit faults |
| Eaton IZM / Moeller IZM | Mechanism latches, motor operator, contact carriers |
| MCCBs — Tmax, NSX, 3VL, NZM | Trip unit drift, terminal overheating, mechanism fatigue — repaired where economic, replacement advised where not |
Scope
What a turbine breaker overhaul includes
This is the full scope. A repair addresses the reported fault plus anything the strip-down finds; an overhaul does all of it regardless.
Mechanism
Complete strip, degrease, inspection of latches, pivots, springs and linkages against wear limits. Re-lubricated with the correct grade — not the general-purpose grease that stiffens in a cold tower. Closing and opening times verified afterwards.
Contacts & arc chutes
Main and arcing contacts measured for erosion and pressure; replaced as sets where worn. Arc chutes checked for splitter erosion, cracking and carbon tracking. Contact resistance measured per pole and recorded.
Motors, coils & auxiliaries
Charging motor and gearbox tested for current draw and charge time. Closing, shunt and undervoltage coils tested at rated and minimum voltage. Auxiliary contacts, ready-to-close and position switches proved — these drive the turbine controller's interlocks.
Trip unit
Secondary injection across every enabled protection element — long-time, short-time, instantaneous, ground fault — against the published curve. Dead or drifting electronics on obsolete units are replaced with a modern trip unit engineered into the frame.
Terminations & secondary wiring
Vibration finds every loose connection. Main terminals inspected for heat damage and re-plated where needed; secondary disconnects and wiring looms checked for fretting and replaced where insulation has worn through.
Certification
Strip-down report with photographs, parts replaced, measurements taken, and the full test record. Written for the owner's engineer and the ISP's QA file. 12-month warranty on the work.
Obsolescence
The first-generation problem
Turbines commissioned between roughly 2000 and 2012 are running breakers whose production ended years ago. The OEM's proposal is usually a current-generation unit — different depth, different secondary connector, different trip unit — which means a cabinet modification, a control-wiring change and a commissioning visit on every affected turbine. Across a fleet that is a project, not a spare.
Repairing the original avoids the project. Donor breakers supply serviceable mechanisms and contact carriers; components that can't be sourced are re-machined to pattern; trip electronics that are dead get a modern unit fitted inside the original frame so the cell, the busbars and the controller wiring are untouched. The breaker's published characteristics are proven by injection test before it leaves.
| Cabinet modification | Repair: none · Replace: adapter plates, busbar work, possibly a new cradle |
| Control wiring | Repair: unchanged · Replace: new secondary connector pin-out, controller I/O re-mapped |
| Commissioning | Repair: refit and function test · Replace: full protection and interlock commissioning |
| Lead time | Repair: days · Replace: weeks to months for the unit, plus engineering |
| Fleet consistency | Repair: one breaker type across the fleet · Replace: mixed types, mixed spares |
FAQs
Frequently asked
Do we need to send the cradle as well as the breaker?
Usually not. Send the moving portion; photograph the cradle, the secondary disconnect and the cell interior and email them with the nameplate. If the strip-down suggests a cradle fault — worn cluster contacts, damaged racking gear — we'll ask for it or attend site.
The breaker nuisance-trips on start-up. Is that a breaker fault?
Sometimes. Converter start-up current is harmonic-rich and an older trip unit with a true-RMS sensing limitation, or one that has drifted, will see it as a fault. Injection testing tells us whether the unit is out of tolerance. If it isn't, the fix is a settings review or a trip unit with better harmonic handling — and we say so rather than rebuild a breaker that didn't need it.
Can you match the OEM's settings and parameters?
Yes. Send the protection settings from the turbine documentation or the existing unit and the breaker comes back set to them, with the injection test recorded at those settings. Where a modern trip unit replaces an obsolete one, we set it to reproduce the original characteristic.
Do you offer a fixed price?
After diagnosis, yes — a fixed price for the defined scope. Strip-down and diagnosis is quoted up front. Where the unit is beyond economic repair we tell you and quote the alternative: a tested replacement via our sister company, or a repair of a donor unit.
Get started
Tell us about the breaker
Make, model and rating from the nameplate, plus a description of the fault. We'll come back with a clear recommendation and a fixed price — usually the same working day.
- Workshop & office01977 253063
- Out of hours07496 013884
- Email & photosinfo@circuitbreakerrepair.co.uk
- WorkshopUnit 13–17 Dale Court, Pontefract, West Yorkshire WF9 3FL