Bushing instrument transformers

Current transformers moulded in self extinguishing resin for the measurement of AC currents from 50 to 60 000A.

With inner diameters between 106 and 500 mm, these transformers are often used on bushings of power transformers or on generator bushing insulators. 

2 versions, indoor or outdoor, are available. The outdoor version is equipped with a weatherproof terminal box fitted with 2 cable glands.

These ring type current transformers are available for indoor (ORF) or outdoor use (ORFE). They have been designed to meet the requirements for metering and protection duties of:
- power transformers and auto-transformers
- HV or MV wall bushings
- GIS substation
- IPB
- Homopolar detection in neutral connections

The secondary terminals are accessible either directly in the case of indoor equipment (ORF) or through a watertight terminal box in the case of outdoor application (ORFE).

As per customer’s requirement, secondary windings can integrate time constant constraints.

English version coming soon!

These Current Transformers have been designed and developed in close collaboration with RTE, the French Electricity Transmission Network, to match the most stringent requirements of outdoor substations.

- Their « window type » design makes it possible to install them under Extra High Voltage (EHV) environment taking advantage of the insulation of primary (cable, GIS busducts, wall bushing, …)

- They can also be equipped with a filter capacitor to limit the high frequency voltage peaks showing during connect/disconnect cycles, or in case of fault on the network.

- CT’s of 1A secondary for outgoing line protection are equipped with a voltage limiter protecting CT against overvoltage in case of secondary open circuit.

These ring type current transformers are available for indoor (ORX) or outdoor use (OREX). They have been designed to meet the requirements for measuring:
- line currents
- zero-sequence currents in the neutral of power transformers
- earth fault currents in power transformers.

The secondary terminals are accessible, either directly in the case of indoor equipment (ORX), or through a watertight terminal box in the case of outdoor application (OREX). Several types of terminal boxes are available depending on the required characteristics.