High Voltage

What is High Voltage and Electrical Substations?

In the industrial context, the infrastructure of High Voltage (HV) y Medium Voltage (MV) comprises the set of equipment, conduits, transformers, protection systems, and distribution lines responsible for receiving electrical energy from the Comisión Federal de Electricidad (CFE) at elevated voltage levels (typically from 13.8 kV, 23 kV, 34.5 kV up to 115 kV) to reduce it to internal utilization voltages (480 V, 220 V, 127 V).

Critical components that make up these systems and require specialized attention include:

• Power and Distribution Transformers: Substation, pad-mounted, or pole-mounted type equipment, whether dry-type or oil-immersed dielectric.
• Fuse Cutouts and Disconnect Switches: Switching and physical protection devices.
• Power Circuit Breakers (SF6, Vacuum, or Oil): Load interruption and overcurrent protection elements.
• Surge Arresters: Protection devices against transient overvoltages caused by atmospheric discharges or grid switching operations.
• Grounding Systems and Lightning Rods: Network of electrodes and conductors that dissipate fault currents and atmospheric discharges to protect personnel and equipment.
• Distribution and Transfer Panels: Load control and coupling centers with emergency generators.

When is this service needed?

A plant or maintenance manager should immediately schedule a high-voltage diagnostic or maintenance service if any of the following operational signs are detected:

1. Annual maintenance period expired: More than one year has passed since the last dielectric and physicochemical tests on the transformer.
2. Unexplained protection trips: Main circuit breakers or cutouts opening without an obvious overload cause on low-voltage lines.
3. Strange noises or vibrations in the transformer: Presence of excessive humming (altered magnetostriction effect) or internal arcing.
4. Thermography results with hot spots: Detection of elevated temperatures in terminals, bushings, or switch connections.
5. Low power factor or penalties on the CFE bill: Recurring charges for a power factor below 95% or presence of harmonic distortion outside the Grid Code limits.
6. Oil leaks or low levels: Presence of dielectric oil stains in the containment pit or level indicator below the minimum in the transformer's conservator tank.

Problems that SINE México's service solves

• Avoids unscheduled plant shutdowns: A failure in the main transformer stops 100% of production, generating millions in losses per hour.
• Prevents explosions and fires: Oil monitoring and insulation tests prevent catastrophic failures due to internal short circuits.
• Eliminates CRE fines: Ensures technical compliance with the energy quality parameters required by the Grid Code, avoiding penalties of up to 10% of annual revenue.
• Reduces electricity billing cost: By correcting the power factor using well-calculated and tuned capacitor banks, penalties are eliminated, and bonuses from CFE are obtained.
• Protects personnel life: The correct functioning of grounding systems and the calibration of protections ensure that ground faults are cleared in milliseconds, preventing fatal accidents due to step or touch voltages.

Benefits for your plant

• 99.9% Operational Continuity: Minimization of the risk of unforeseen interruptions in the main electrical supply.
• Extension of transformer lifespan: A well-maintained transformer can operate efficiently for more than 30 years; lack of maintenance reduces this expectation to less than half.
• Total Regulatory Compliance: Technical folders ready for audits by STPS, Civil Protection, insurance companies, and inspection units (UIIE).
• Direct Return on Investment (ROI): Preventing a single catastrophic failure event pays the cost of preventive substation maintenance for the next 15 years.

Applications and industries we serve

We offer high-voltage solutions throughout the northeast of the country (Coahuila, Nuevo León, Durango, Chihuahua) for demanding sectors:

• Automotive and Auto Parts Industry: Assembly and foundry plants with high load demands and sensitivity to voltage variations.
• Metallurgical and Foundry Industry: Operation of electric arc furnaces requiring large capacity substations and harmonic filters.
• Distribution Centers (CEDIS) and Logistics: Pad-mounted substations to keep refrigeration networks and automated systems operational.
• Food and Beverage Industry: Continuous processes where a power outage compromises safety and spoils entire batches of raw material.
• Industrial Parks: Maintenance of overhead and underground medium voltage distribution networks.

Available Tests and Diagnostics

Applicable Regulations and Standards

Our services and procedures strictly align with current national and international regulations:

• NOM-001-SEDE-2012: Electrical Installations (utilization), which governs the design and safety conditions of substations.
• Grid Code (CRE): General Administrative Provisions that establish the criteria for efficiency, quality, reliability, continuity, and safety of the National Electrical System.
• NOM-022-STPS-2015: Static electricity in workplaces, safety conditions (grounding systems).
• IEEE C57 / ANSI / NETA MTS: International standards for performing maintenance tests on electrical power equipment and systems.
• NFPA 70B: Standard for the maintenance of electrical equipment.

Our work process (SINE México)

1. Initial Diagnosis and Survey: We visit your plant free of charge to physically evaluate the substation, review maintenance history, and define the required technical scope.
2. Planning and Outage Management: We coordinate with the client and process the outage request with CFE to schedule the power cut safely and during the time of least operational impact.
3. Safety and Lockout (LOTO): Before entering the area, we apply strict lockout/tagout protocols, verify the absence of potential, and install temporary safety grounds.
4. Execution of Physical and Electrical Tests: We perform general cleaning with biodegradable dielectric solvents, retighten connections with a torque wrench, maintain operating mechanisms, and conduct a complete battery of electrical tests (Megger, TTR, Ground Resistance).
5. Oil Treatment (if applicable): We perform filtering and dehydration of the dielectric oil using thermo-vacuum to remove moisture and suspended particles.
6. Delivery of Technical Folder and Release: System energization under supervision, delivery of a detailed technical report with trend graphs, interpretation of laboratory analyses signed by a specialist engineer, and recommendations for corrective actions.

Common mistakes when contracting substation maintenance

• Hiring companies without certified personnel: Working with high voltage requires specific technical competencies and Category 4 personal protective equipment (PPE) (arc flash). Unqualified personnel put their lives and the plant's infrastructure at risk.
• Omitting dielectric oil tests: Cleaning the substation externally is useless if the transformer's internal oil is degraded or contaminated with water. Physicochemical and dissolved gas analysis is the equivalent of a blood test for the equipment.
• Not verifying the calibration of test equipment: Performing tests with Megger or TTR equipment without a valid calibration certificate generates erroneous readings that can hide serious faults or suggest unnecessary component changes.
• Not following up on hot spots detected by thermography: Ignoring a connection with high temperature guarantees a conductor fusion failure in the short term.

SINE Mexico Warranty

All our preventive and corrective high-voltage maintenance services include written warranty, backed by detailed technical reports and signed by mechanical electrical engineers with a valid professional license. We use measuring equipment from world-leading brands (Megger, Doble, Fluke) calibrated by laboratories accredited by EMA (Entidad Mexicana de Acreditación).

Frequently Asked Questions

How often should an industrial electrical substation be maintained?

According to NFPA 70B and NOM-022-STPS recommendations, major preventive maintenance should be performed annually. This includes physicochemical tests of transformer oil, insulation tests (Megger, TTR), insulator cleaning, connection retightening, and operational tests of grounding systems and lightning arresters.

What consequences does non-compliance with the CRE Grid Code have for my plant?

Non-compliance with the Grid Code can result in severe economic sanctions from the CRE, ranging from 2% to 10% of the previous year's gross income, in addition to the possibility that CFE may order the disconnection of the load center if severe disturbances (harmonics, low power factor) affecting the National Electrical System are detected.

What is the dielectric strength test of oil and why is it critical?

It is a test that measures the ability of transformer mineral oil to withstand electrical stress without breaking down (arc puncture). A low value (less than 30 kV in standard ASTM D-877 cups) indicates the presence of moisture, conductive particles, or sludge, which puts the transformer at imminent risk of short circuit and explosion.

How do you coordinate an outage with CFE for maintenance?

At SINE México, we handle the entire technical-administrative process with CFE. We submit the formal outage request with due anticipation, justifying the work and coordinating schedules (usually weekends or night shifts) to minimize the impact on your plant's production, ensuring physical lockout and grounding before intervention.

Request your free quote and technical visit

Do not risk the continuity of your plant. Protect your high-voltage assets with the team of specialist engineers from SINE México. We serve in Torreón, Saltillo, Piedras Negras and throughout the northeast of the country.

• Phone / WhatsApp: +52 871 228 3838
• Email: ventas@sinemantenimiento.com
• Offices and technical support: Torreón, Coahuila, México.