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Power Voltage Transformers / Station Service Transformers

Power voltage transformers (Power VTs) combine the attributes of an inductive voltage transformer with the application of a small power transformer. Therefore, they are the perfect solution wherever low voltage is needed and high voltage is available.

Power VTs only have to be connected to the high voltage overhead line to provide power at low voltage. Due to this direct connection to the transmission line, the reliability of Power VTs is very high, as they are not dependent on distribution lines that are more susceptible to outages. Trench Power VTs are designed as single-phase line to ground transformers. By using three devices a “three-phase power supply” with accumulated output power is also possible.


Up to kVa

power output

for Trench Power VTs in a three phase operation.


The Trench Power VT portfolio covers the high voltage range up to 550 kV. The maximum continuous output power in single phase operation is 167kVA. Therefore, the maximum power performance in three phase operation is up to 500kVA.

Trench Power VTs are providing a reliable source of power and high insulation performances for many application such as:

  • control power supply for an utility substation, switching station, power generating station, hibernating power stations
  • construction power near a high voltage transmission line
  • reliable standby power for critical loads
  • remote oil / gas pumping stations
  • flood control pumping stations
  • desalinization stations
  • hard to access locations with an overhead / underground high voltage transmission line
  • micro substations for sites with limited floor space
  • portable / easily relocatable low power substation for short -term or long-term power supply
  • powering high voltage tower mounted line switches
  • mobile phone / relay stations
  • refurbishing old substations, adding redundancy to control power supply
  • transmission line hazard lighting
  • powering refrigeration and air-conditioning plants in remote food processing/ storage facilities
  • remote railroad signaling
  • a portable testing station

Standard Features

  • Combination of Inductive Voltage Transformer and Power Transformer
  • Low cost alternative to small power transformers or distribution feeders
  • Available with windings for metering and protection purpose
  • Accuracy classes according to international standards
  • Output power up to 125 kVA in single phase operation
  • Clean Air, Oil or SF6-insulated, composite insulator
  • Design and dimensions based on proven Trench Inductive Voltage Transformers (SVS, field experience since 1978)
    and Trench Test Transformers (TES, field experience since 1975)
  • Compact size and weight as compared to conventional power transformers
  • Excellent control of internal and external insulation stresses through the use of a proprietary finely graded bushing system
  • Exclusive use of corrosion resistant material
  • Easy transportation and handling due to light weight
  • Output power and voltage customizable to needs of application site
  • Single phase unit
  • Maintenance free
  • Explosion proof design due to the compressible insulation medium SF6 and rupture disk
  • No insulation ageing
  • Remote supervision of insulation condition by monitoring inter nal gas density

Special Features

  • Adjustment of the secondary voltage in defined fixed taps by ad ditional transformer
    (up to three steps in positive and negative direction)
  • 30kV lightning impulse withstand for the secondary side – also for the neutral
  • Short circuit protection on the secondary side by fuse
  • BIL up to 1800kV (chopped wave 2070kV)
  • IP 55 qualified
  • NEMA 4X qualified
  • Overload capability – cycle operation
  • Seismic performance tested up to 0.5g
  • Cable discharge capability
  • Online monitoring via optical sensors inside the coils
  • Mobile solution on trailer

Trench power voltage transformers are the ideal solution for various applications, combining the economy of an inductive voltage transformer and the versatility of a small power transformer, with the safety and reliability features expected from Trench products.


Mechanical and electrical data

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