Motor circuits, starters, overloads, contactors and variable-frequency drives — diagnosed, repaired, replaced and set up. When a motor keeps tripping or a drive keeps faulting, the answer is rarely the part that is showing the symptom.
Single-phase and three-phase motors on shop equipment, pumps, fans, compressors, conveyors, augers, hoists and process machinery.
Won’t start, hums and trips, starts cold but not hot, runs hot, draws high current, or drops out under load. Insulation and winding checks, running current on all legs, supply voltage under load, and mechanical load ruled in or out.
Magnetic and combination starters, contactors that chatter or weld, coils that have failed, burnt or pitted contacts, and starters that are simply undersized for what they are now switching.
Overloads that trip early, overloads that no longer protect, and overloads set to the wrong value after a motor was changed. Sizing checked against the motor nameplate, not the previous setting.
Overcurrent, overvoltage, undervoltage, ground-fault, overtemperature and acceleration/deceleration faults. The fault code narrows where to look — motor, cable, load, parameters or supply.
Drive replacement when a unit is beyond repair or obsolete, with nameplate data, motor parameters, accel and decel times, current limits and control wiring set up for the machine it is running.
Motors turning backwards after a service change, a panel swap or a new supply. Rotation confirmed and corrected — important on pumps, augers and anything with a one-way load.
Single-phasing and voltage imbalance quietly destroy three-phase motors. Both are worth measuring before a motor is condemned, and again after it is replaced.
Motor leads, junction boxes, flexible connections, cord-connected equipment, disconnects and the connections that loosen from vibration and heat cycling.
Start-stop stations, remote controls, interlocks, e-stops, float and pressure switches, and the control voltage that feeds them. See electrical controls.
A motor that trips its overload is doing what it is supposed to do — something is drawing more current than the setting allows. The useful question is why. The common causes, roughly in the order they turn up:
Replacing a motor without answering that question usually means replacing it twice. The troubleshooting process is built around finding which of those it actually is.
A drive fault code is a starting point, not a diagnosis. An overcurrent fault on acceleration can be an accel ramp that is too aggressive for the load, a current limit set too low, a blocked or stiff load, a motor cable problem, or a failing motor. An overvoltage fault on deceleration usually points at a regenerating load with nowhere to put the energy — ramp times, braking, or the absence of a brake resistor. Ground-fault codes are worth taking literally and testing for.
When a drive is replaced, the parameters matter as much as the hardware: motor nameplate data, current limits, ramp times, control method, and the control wiring it needs to see. A drive that has been dropped in with default settings will often run, then fault under real production conditions.
Manufacturer experience includes drives such as Schneider Altivar, TECO and Lenze. Grasse Electric is an independent electrical service contractor, not an authorized distributor or factory service provider.
The service request form takes photos for exactly this reason. A nameplate photo and a fault-code photo often shorten the call by an hour.
Depends on size, availability and what failed. Small, common motors are usually replaced — a rewind costs more than a new one. Larger or specialised motors are often worth sending out for repair. Either way the cause gets found first, so the replacement does not fail the same way.
Either works. If you have a preferred supplier or a spare on the shelf, that is fine. If not, a suitable drive can be sourced — sized to the motor and the load, not just matched to the old part number.
Usually yes. Temperature, a shift change, a different product run, or a building-wide load that rises later in the day all show up that way. It is worth noting when it happens, because that pattern is often the fastest route to the cause.
Bucket-level troubleshooting, starter and overload replacement, and control wiring, yes. Large MCC replacement or new-build installation is outside what an owner-operated shop takes on.
Sometimes, safely — for example bypassing a failed control device while a part is on order, where that can be done without defeating a safety function. Where it cannot be done safely, you will be told that rather than given a workaround that creates a hazard.
Call for service, or send the nameplate and fault-code photos through the request form.
