Medium- and High-Voltage Mining Motor Repair
Industrial motor repair and rewind for mines and motor repair shops. We accept motors above 1,000 V only, subject to nameplate and technical scope review.
In short
TEMISA assesses medium- and high-voltage mining motors for repair, rewind and testing. Send the motor nameplate voltage and failure details. Low-voltage motors, including the 550 V and 950 V Joy models documented below, are outside our current service scope. Those pages are technical references and a historical March 2026 job, not current offers.
- Medium and high voltage only; nameplate review required.
- Class H form-wound stator rewind.
- Bearing fits restored to ANSI/EASA AR100.
- Acceptance tests defined for the specific motor and agreed scope.
- No new service for motors rated at 1,000 V or less.
Archive · outside current service scope
Joy motor references and a historical repair
Joy 600128-716
235 HP · 950 V
View reference detailsJoy 600128-1574
210 HP · 550 / 950 V
View reference detailsJoy 600128-0735
250 HP · 950 V · job completed by TEMISA
View reference detailsThese 550 V and 950 V motors are outside our current scope. The original ratings and historical test results are retained for reference; they are not an invitation to request a low-voltage repair.
Motor repair shops
Enquiries for medium- and high-voltage motors only. Each scope, test plan and shipping arrangement is evaluated from the nameplate and diagnosis.
Industrial mines
Assessment of medium- and high-voltage motors used in mining processes. Check the motor voltage itself, not the supply voltage of the mine or its transformer.
The process and test tables below describe the documented historical Joy repair. The test plan for a new medium- or high-voltage motor is defined separately after technical review.
Scope of work
Documented repair process: winding and enclosure
| What we upgrade | What we never change |
|---|---|
| Stator rewound with new form-wound coils | Explosion-proof enclosure |
| Class H insulation system | Flame-path surfaces and their dimensions |
| Varnish treatment with dehydration and controlled oven cure | Lead entrances |
| Bearing fits restored to ANSI/EASA AR100 tolerances | Mounting and shaft dimensions |
| New bearings, induction-mounted, and new seals | Nameplate rating: HP, voltage and speed stay as built |
| Rotor dynamically balanced | |
| Temperature sensors (RTDs) tested |
Enclosure dimensions are not modified. Before a rebuilt explosion-proof motor goes back underground, the mine's qualified electrical person inspects it, as MSHA regulations require.
In our shop
What happens to your motor at TEMISA
1Teardown and diagnosis
The failed winding is exposed and documented before anything is quoted.
2Form-wound coils
New coils are formed and taped in the shop; the core is checked first.
3Varnish and oven cure
The winding is dehydrated, varnished and cured in a controlled oven.
4Dynamic balance
The rotor is balanced and the residual unbalance is recorded.
5Release tests
Static and dynamic tests are recorded before the motor ships.
Photos taken at the TEMISA shop. They show the process, not a specific customer motor.
Release tests
Tests recorded for the historical Joy repair
| Test | Standard | Acceptance |
|---|---|---|
| Winding resistance, phase to phase | IEEE Std 1415 | Unbalance < 3% |
| Insulation resistance, 1 min | IEEE Std 43 | > 100 MΩ |
| Polarization index and dielectric absorption | IEEE Std 43 | PI > 2.0 · DAR > 1.5 |
| Step-voltage DC high-potential | IEEE Std 95 | > 100 MΩ, leakage < 1 mA |
| Surge comparison (turn-to-turn) | IEEE Std 522 | EAR L-L < 3% · P-P < 10% |
| Core loop test with thermography | Shop procedure | Uniform core temperature |
| Rotor growler test | Shop procedure | No open bars |
| Dynamic balance of rotor | ISO 21940 | Residual unbalance recorded |
| 60-minute run test: current, temperature, vibration | Shop procedure | Vibration < 0.11 in/s |
Reference job · March 2026
Joy 600128-0735, 250 HP 950 V: grounded winding to 6,700 MΩ
A cutter motor from an underground mine in Mexico arrived with its winding grounded at 0.03 MΩ and both bearings damaged. It left with a new Class H form-wound winding, restored bearing fits, a balanced rotor, 6,700 MΩ insulation resistance, PI 7.94 and 0% surge unbalance.
Credentials
Who does the work
- CFE LAPEM qualification
- Current qualification under specification W6000-20 (motors), certificate 053/26, valid through May 20, 2027. Scope: service to electric motors from 150 to 15,000 HP at rated voltage up to 1.5 kV. This certificate scope is distinct from the current commercial policy: no motors rated at 1,000 V or less are accepted.
- Repair process standard
- Repair processes follow ANSI/EASA AR100 (a process standard, not a certification).
- Plant
- 5,600 m² shop in Tlajomulco de Zúñiga, Jalisco, Mexico, with overhead cranes up to 60 t. Founded 1954.
FAQ
Frequently asked questions
Other questions: write to ventas@temisa.mx and an engineer will answer.
Which motor voltages do you accept?
Medium and high voltage only, subject to nameplate review. Motors rated at 1,000 V or less, including 550 V and 950 V Joy cutter motors, are outside our current commercial scope regardless of power or urgency.
Why are 950 V Joy motors still documented here?
The pages preserve technical references and a real March 2026 repair with its original results. They do not offer new service for those low-voltage motors.
What information is needed for an enquiry?
Provide the motor type, rated nameplate voltage in volts, company and contact details. A nameplate photo and the failure description help us define the technical scope. If voltage is unknown, check the nameplate before submitting.
Do you modify an explosion-proof enclosure?
The documented historical repair did not modify the enclosure. No new explosion-proof repair or approval is promised by these reference pages. Any applicable inspection and acceptance requirements must be established for the specific equipment.
What warranty and shipping terms apply?
For eligible motors, scope, warranty, freight, customs arrangements and turnaround are stated in the individual quotation after technical review.
Are you a Joy or Komatsu dealer?
No. TEMISA is an independent motor repair shop founded in 1954. The brand names identify equipment in the technical references; they do not imply OEM authorization.
Request for quotation
Medium- and high-voltage enquiries
Provide the motor type and nameplate voltage above 1,000 V. Low-voltage models shown in the reference archive are not accepted. A nameplate photo and failure details help define the scope.
- Answered by an engineer, in English.
- Every motor returns with its recorded test data.
Or email ventas@temisa.mx or call +52 33 3614 2460 (Mexico, Central Time).
Mining motor enquiries in Spanish: motores industriales para minería.