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Station service voltage transformer for step-down service (69 - 145 kV)

Outdoor oil-filled station service voltage transformer for HV to MV for remote power needs

SSMV inductive voltage transformers consist of a single-phase design intended for connection between phase and ground on 69 kV- 145kV HV grounded neutral networks to supply power to panels at medium voltage levels. The design allows for convenient siting with simple mount on single phase support stand near HV transmission lines, when combined with user supplied primary and secondary side protective devices.

The primary and secondary side of the SSMV are protected from over-voltages by integrally mounted surge arresters, sized for the system voltage ratings, that are cantilever mounted at the factory on the SSMV. This arrangement can supply a distribution feeder for remote power needs within 30kM. SSMV offers output voltages from 2.4kV to 15kV levels (contact factory for specific output voltage needs) for either 50 or 60Hz application. Power levels available up to 200kVA single phase that can be banked for 600kVA three phase supply.  

Hermetic sealing of the design is accomplished using a gas cushion above the oil to prevent free-breathing outside moisture-laden air. ANSI 70 gray insulators are supplied with high creep and high strike designs. Porcelain insulators are normally standard with Polymer offered as an option.


  • Rural electrification for reducing the cost of first power
  • Railway applications for small power needs
  • Mountain-top or other remote site power needs for small commercial, industrial or mining sites loads

Why Hitachi Energy?

Hitachi Energy developed the market for station service voltage transformers in North America and remains an innovator in this field with this new SSMV design. Our product offering is more diverse and covers most application specific needs for our global users in order to provide optimal service in a compact size package. Hitachi Energy has product bundling capability to offer a complete mini-substation package in order to lessen the first cost of rural power requirements if user want Hitachi Energy to coordinate the entire mini-substation package.

  • Our experts can assist you with advice for finding the optimum solutions
  • Designed for easy siting within very small spaces from polar to desert climates
  • Low loss design is one of the most efficient station service solutions available on the market today as compared to power transformers, tertiary windings on power transformers, distribution lines, or MV supply from other sources
  • This product provides high reliability and power availability for any critical load need up to as high as 200kVA per phase

Brief performance data

Installation Outdoor
Design Station service voltage transformer type
Insulation Oil-Paper
Highest voltage for equipment 69 – 145 kV
Voltage factor (Vf) Up to 1.25
Insulators Porcelain standard insulators *
Creepage distance ≥ 25 mm/kV (Longer on request)
Service condition  
  • Ambient temperature
-40ºC to +40ºC (Standard) **
  • Design altitude
1000 m (Standard) **
Power Ratings 100 kVA, 167 kVA , 200 kVA
Over-voltage protection Station class arrester on HV side and distribution class arrester on MV side


*  On request silicon rubber (SIR)
** Others temperatures and altitudes are possible

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