Contactors
Contactor Repair & Overhaul
High-current contactors — Schneider TeSys LC1F, ABB AF and A-series, Siemens 3RT and 3TF, Eaton DIL — rebuilt with new contact sets, coils and auxiliaries and tested for pick-up, drop-out and contact resistance. A fraction of the price of a new frame, and back in days rather than the OEM's weeks.
- Frames115 – 2100 A
- Typical turnaround2–5 working days
- TestingPick-up · drop-out · mΩ per pole
- Warranty12 months
Can a contactor be repaired?
Yes — above about 100 A it's usually the right call
A contactor is a handful of wearing parts on a frame that doesn't wear: main contacts, contact springs, a coil, a magnet and some auxiliary blocks. On small frames a new contactor costs less than the labour to rebuild one. Above about 100 A that reverses. A new LC1F630 or AF750 is a four-figure item on a lead time, and the frame you have already fits the enclosure, the busbar drilling and the control wiring.
The faults are predictable. Contacts erode and pit until the poles run hot or weld. Springs lose pressure. Coils overheat in a warm cabinet or die on a control-supply transient — the AF-series electronic coils especially. Magnet faces pick up debris and the contactor chatters. Auxiliary blocks, which the controller depends on for feedback, go intermittent long before the main poles fail.
We strip the contactor, replace every wearing part as a set, clean and check the magnet, and test it as a unit before it goes back. Generator, compressor, pump, mill, crusher, wind-turbine stator and crowbar contactors — same process.
| Main contacts | Replaced as complete sets, fixed and moving, with new contact springs; pressure and gap verified |
| Pole carriers | Inspected for heat distortion and cracking; replaced from donor stock where needed |
| Arc chutes | Cleaned; replaced where cracked, eroded or tracked |
| Coil & magnet | Coil resistance and insulation tested; magnet faces cleaned; shading rings checked; coil replaced where marginal |
| Auxiliaries | Auxiliary contact blocks and interlocks proved in every position; replaced where intermittent |
| Terminations | Inspected for heat damage; re-plated or replaced |
| Test | Pick-up and drop-out voltage, contact resistance per pole, insulation resistance, coil current, mechanical operation |
Ranges
Contactors we overhaul
Schneider TeSys LC1F
The 115 to 2100 A frames on generators, compressors and wind-turbine converters. Contact kits, LX1F coils, pole carriers and LA1/LADN auxiliary blocks. A range we overhaul continuously, including for US customers.
LC1F115 · F150 · F185 · F225 · F265 · F330 · F400 · F500 · F630 · F780 · F800 · F1250 · F1700 · F2100
LC1F repairABB AF and A-series
AF-series electronically controlled coils fail on supply transients; the older A-series frames suffer classic magnet and shading-ring wear. Both are rebuilt with contact sets and coils to the frame size.
AF116 – AF2650 · A110 – A300 · EK / EH series
Siemens 3RT / 3TF · Eaton DIL
3RT1 and 3RT2 on newer plant, 3TF6 on the older fleet, plus the 3RH auxiliary blocks. Eaton and Moeller DIL M frames on drives and MCCs.
3RT1075 – 3RT1476 · 3TF68 / 3TF69 · DILM115 – DILM2600
Testing
What "tested" means for a contactor
A contactor that closes when you press it is not a tested contactor. Every overhauled unit is proved on the bench for the things that actually stop plant: pick-up voltage at the bottom of the coil's tolerance band, so it closes reliably when the control supply sags; drop-out voltage, so it releases when commanded; contact resistance measured per pole with a micro-ohmmeter, so the poles run cool at full current; coil current and insulation resistance; and mechanical operation for chatter and bounce. Auxiliary contacts are proved in every position.
The results go on the certificate against the unit's serial number, with the parts fitted. Fit it, connect it, and the controller sees exactly what it saw with the original.
| Pick-up voltage | Must close at or below the lower coil tolerance limit |
| Drop-out voltage | Must release within the manufacturer's band |
| Contact resistance | μΩ / mΩ per pole at test current; balanced across poles |
| Insulation resistance | Pole-to-pole and pole-to-earth |
| Coil | Resistance and operating current at rated voltage |
| Auxiliaries | Every NO/NC block proved in both positions |
FAQs
Frequently asked
How much does contactor repair cost?
It depends on frame size and what the strip-down finds, so we quote after inspection — but the working rule is a third to a half of a new contactor for the large frames, and less again where only contacts and coil are needed. Strip-down and diagnosis is quoted up front. Below about 100 A we'll usually tell you to buy new.
The contactor chatters or hums. Repairable?
Almost always. Chatter comes from debris or corrosion on the magnet faces, a damaged shading ring, a weak coil or a low control supply. The first three are overhaul items; the last is a site fault the pick-up voltage measurement will point to.
The contacts have welded. Is the contactor scrap?
Not usually. Welded contacts are replaced as a set; what matters is whether the heat has distorted the pole carriers or damaged the arc chutes. We check both on strip-down and tell you before quoting. Repeated welding on the same duty points to an application problem — undersized frame, wrong utilisation category, or a coil supply dropping out under load — and we'll say so.
Can you supply just the contact kit or coil?
Yes, where we hold it. But a contact kit on a contactor with tired springs, a marginal coil and worn auxiliaries is a short-term fix. We'd rather overhaul the unit and certify it — the labour difference is small.
Do you repair contactors for wind turbines?
Yes — generator, rotor and crowbar contactors from turbine converter cabinets are a large part of the LC1F and AF work we do. See generator contactor overhaul for the turbine-specific detail and service exchange for fleets.
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