Load Tap Changer Repair
Contact replacement through full LTC rebuild. Disassembly, in-house machined replacement contacts, diverter and selector switch reconditioning, drive mechanism overhaul, oil service, test, and documentation. GE, McGraw-Edison, Allis-Chalmers, Westinghouse, Moloney, Reinhausen, Federal Pacific, Siemens, and Waukesha.
LTC repair scope: contact replacement vs. full rebuild.
Contact replacement gets most LTCs back in service. The main moving contacts, arcing contacts, and reversing switch contacts wear on a predictable schedule, and swapping them at the right interval prevents the failure modes that cause transformer outages.
A full rebuild is the right call when the unit has accumulated significant switching operations and mechanism wear is visible beyond the contacts, when oil analysis shows contamination consistent with internal arcing rather than normal contact erosion, or when the drive mechanism shows binding, irregular motion, or fatigue in the spring or cam hardware.
The distinction matters because a contact kit that goes into a mechanism with worn diverter switch hardware or degraded spring tension will not last its rated service interval. You are replacing the cheap part and leaving the failure mode in place.
We evaluate each unit on arrival and tell you what we find before we proceed. If contact replacement is all the unit needs, that is what we quote. If the mechanism needs more, we show you why.
Full rebuild scope.
Full teardown of the LTC compartment. Every component inspected and photographed. Wear measurements documented against OEM tolerances before any parts are replaced.
Main moving, main stationary, arcing, reversing, and neutral contacts replaced with new parts machined in our Palm Harbor shop. No third-party sourcing delays, we make them here.
Diverter switch contacts and transition resistors inspected and replaced as needed. Housing cleaned and inspected for pitting or erosion beyond contact surfaces.
Switching device reconditioning: selector switch contacts inspected, cleaned, and replaced where worn. Mechanical motion verified through full tap range. Locking hardware and latching verified.
Spring mechanism, motor drive, cams, and position indicators serviced. Worn hardware replaced. Timing verified against OEM spec.
Oil drained, compartment cleaned, new insulating oil to spec. Final contact resistance measurement, operational cycling through full tap range, and documentation package with before/after readings.
Makes we repair and rebuild.
We carry replacement contacts in stock or machine them to order for every major LTC family. Because we make the parts ourselves, we are not dependent on a third-party supplier's lead time when your transformer is out of service.
One of the most common LTC families in US distribution and transmission transformers. Full contact sets in stock.
The 550 series is installed in a significant portion of the US transformer fleet. Cooper dropped support; we kept making the parts.
Full contact sets for all major Allis-Chalmers reactor-type LTCs, including the complete TLH-21 isolated reversing kit.
Reactance-type LTCs. Eaton discontinued support; the contact geometry is documented in our shop archive.
Transfer switch and selector switch contacts for Moloney transformers. A discontinued St. Louis manufacturer whose units remain common in cooperative fleets.
FPE was discontinued decades ago. Reinhausen RMV-1 parts machined to original drawing dimensions.
We make the parts. We do the work.
Most LTC rebuild shops source their replacement contacts from an aftermarket supplier and wait on that supplier's lead time before the rebuild can start. We machine the contacts in our own shop in Palm Harbor. When your transformer is out of service, that difference matters.
We also operate field crews across Florida and the Southeast. If you need the LTC pulled from the transformer, transported to the shop, rebuilt, and reinstalled, that is one crew, one company, one call. No coordinating between a parts supplier, a rebuild shop, and a field contractor.
No third-party sourcing. We machine replacement contacts to OEM dimensions in our own shop, in stock or to order.
Pull it, rebuild it, reinstall it. FL and Southeast coverage. One point of accountability from the field to the finished unit.
Before and after contact resistance readings, operational test results, parts replaced, and oil test report. Delivered with the unit.
Maintenance and repair guides by model.
Every LTC family we repair has its own maintenance guide: contact wear limits, inspection intervals, known failure modes, and what we find when these units come into the shop. Find your model below.
LR65 & LRT65 · LRT-200 · ML-32 & MLT-32 · Type VR-1 regulator
GE replacement parts →
URT · UTT & UTTA · UTTB · UVT-2000
Westinghouse replacement parts →
Moloney MA/MB & MA2/MB2 · Federal Pacific TC-525 & TC-546 · Reinhausen RMV-1 · Waukesha UZD
Contact sets →
Failure symptoms · Maintenance schedule · LTC vs DETC · What is an LTC?
Load tap changer repair questions.
Can a load tap changer be repaired, or does it have to be replaced?
Almost every LTC we see is repairable. The wear items are contacts, transition resistors, and drive mechanism hardware, all of which are replaceable. Replacement of the whole tap changer is normally driven by a cracked housing, a failed barrier board, or an insulation failure in the winding leads, not by contact wear. Send us photos and a model number and we will tell you which case you are in.
How do I know if my LTC needs repair?
The common signals are sticking or hesitating taps, a rising contact resistance reading, dissolved gas analysis showing acetylene or ethylene consistent with internal arcing rather than normal contact erosion, carbon accumulation in the compartment oil, and audible irregularity in the drive mechanism through the tap range. Any one of those justifies pulling the unit for inspection.
Do you repair obsolete tap changers the OEM no longer supports?
That is most of what we do. McGraw-Edison, Federal Pacific, Moloney, Allis-Chalmers, and older Westinghouse families are all discontinued. We machine the replacement contacts in our own shop in Palm Harbor from archived drawings or from a sample part, so support ending at the OEM does not end support for your transformer.
Can you pull and reinstall the tap changer, or is it shop-only?
Both. We run field crews across Florida and the Southeast, so we can pull the unit, transport it, repair it in the shop, and reinstall it as one scope with one point of accountability. If your own crew is doing the removal, we can also take the unit shipped in and return it tested and documented.
What comes back with the repaired unit?
Before and after contact resistance readings, the operational test record through the full tap range, and an itemized list of parts replaced. Wear measurements against OEM tolerance are documented at teardown and photographed.
Related services.
Full catalog of replacement LTC contacts for all major OEM families. Order parts for your own maintenance crew.
On-site LTC inspection, contact resistance testing, oil sampling, and field maintenance. FL and Southeast coverage.
Full shop rebuild of circuit breakers, air, vacuum, oil, and SF6. Same shop, same crew.
Part no longer available? We reverse-engineer from a sample, a print, or a model number and machine to OEM spec.
We respond within one business day with a clear scope and timeline. If you have oil analysis results or tap position history, include them, they help us scope the job accurately.