Medium-Voltage Surge Protection Products

Overview / Key Function

VarStec designs and manufactures three types of medium-voltage surge protection equipment: RC Snubbers for transformer protection, Motor Surge Protection (MSP) systems for motors and generators, and Medium-Voltage Transient Voltage Surge Suppressors (MV-TVSS) for phase-to-phase and phase-to-ground transient protection. Equipment is available for 50/60 Hz systems from 2.5 kV through 38 kV, with common insulation levels through 200 kV BIL. Each package is custom-engineered and manufactured for the project voltage, equipment being protected, switching conditions, insulation requirements, and required protection, control, and mounting configuration.

Industry Applications & Specialized Solutions

Surge-protection requirements vary by industry, application, equipment type, cable length, switching device, insulation level, and system configuration. VarStec selects and configures the protection equipment based on these application conditions, project specifications, and, where available, transient study results. Typical industry applications include:

• Mission-Critical Infrastructure & Data Centers:
  RC Snubbers are commonly applied in data centers and other facilities where medium-voltage transformers are frequently switched. They are particularly applicable to dry-type transformers and installations with short cable distances between the circuit breaker and transformer, typically 60 meters (200 feet) or less, where high-frequency switching transients can produce significant terminal over-voltages and ringing.
• Heavy Industrial, Mining & Manufacturing:
  Motor Surge Protection (MSP) systems are applied to medium-voltage motors and generators to limit the crest voltage and rate of rise of incoming surges, protecting motor end turns and winding-to-core insulation from switching and other power-system transients. By reducing insulation stress, MSP systems help reduce motor failures and the associated downtime.
• Commercial & Industrial Power Systems:
  Our Medium Voltage Transient Surge Suppressors (MV-TVSS) serve as the first line of defense from lightning and utility switching transients for service entrances and loads operating between 2.4 kV to 38 kV.

Technical Details & Product Scope

Technical details and product scope vary by surge protection application and project requirements. VarStec systems are available for medium-voltage applications from 2.4 kV through 38 kV and are configured for the system voltage, frequency, protected equipment, site conditions, and customer specifications. Equipment is supplied in metal-enclosed assemblies and may include disconnecting means, fusing, blown-fuse indication, protection, controls, and other features required by the application.

RC Snubbers for Transformer Protection

Designed to protect medium-voltage transformer primary windings from high-frequency voltage transients. RC Snubbers reduce transient over-voltages during switching and improve breaker performance by reducing the rate of rise of recovery voltage (RRRV) and transient recovery voltage (TRV). They feature surge capacitance ratings from 0.125 µF to 2 µF or as specific, and resistor ratings from 20 ohms to 200 ohms or as specified. Like our capacitor and harmonic filter products, RC Snubbers are system-fit to the project requirements and can be supplied with required switching, protection, and control features.

Motor Surge Protection (MSP)

This product fundamentally operates by decreasing the crest voltage and the rate of rise of impending surges, preventing damage to motor end turns and winding-to-core insulation. These units can be custom-designed for direct mounting to generators, motors, and compressor housings (pecker-head mounting) and can be equipped with differential current transformers to afford the highest level of protection for both the motor and motor surge protector.

Medium Voltage Transient Voltage Surge Suppressors (MV-TVSS)

The MV-TVSS provides transient voltage protection by shunting surges to ground or across phases before they can enter the low voltage system. It features phase-to-phase and phase-to-ground metal oxide varistors (MOVs), with optional heavy-duty distribution class or station class lightning arresters.

Strategic Benefits & Value Engineering

Reduced Equipment Failure & Extended Lifespan

By limiting the magnitude and rate-of-rise of voltage transients and damping resonant and ringing transients, VarStec surge protection products extend the life of transformers, motors, and generators by protecting against inter-turn insulation failure.

System-Fit Performance with Custom Integration

VarStec surge protection equipment is configured for the specific application and project requirements. Units are supplied fully assembled, tested, and ready for interconnection, with available air-disconnect and grounding switches, current-limiting fuses, blown-fuse detection, and other required protection, control, and switching functions.

(Disclaimer: Every surge protection unit is engineered and configured to the specific electrical system, site conditions, and project specification. The ratings, construction features, and accessories listed are provided as system-fit, application-specific selections rather than fixed catalog limitations.)