Instrument transformers are high accuracy class electrical devices used to isolate or transform voltage or current levels to low and easily measured values. When used for revenue metering purposes, instrument transformers provide voltage or current signals that very accurately represent magnitude and phase transmission line values.

When used for protection purposes, the instrument transformer outputs must accurately represent the transmission line values during both steady-state and transient conditions. These critical signals provide the basis for circuit-breaker operation under fault conditions, and as such are fundamental to network reliability and security.

Instrument transformers used for network control supply important information for determining the state of the operating conditions of the network.

Chase Power are the exclusive Australian representative of RS Isolsec, specialists in tailor-made instrument transformers since 1954. They manufacture and supply instrument transformers, current transformers (CT’s), voltage or potential transformers (VT’s or PT’s), protection transformers, measuring transformers, Rogowski coils, current and voltage sensors, insulating parts in cast resin for low voltage (LV), medium voltage (MV) and high voltage (HV) applications.

  • LV Current Transformers – main applications include substation earth leakage protection, thermal relays, summation CT, DC transducer, tariff metering. Retrofits or maintenance programs might require use of split core current transformers
  • LV Current Transformers on HV – These ring core or split core transformers are installed in Very High Voltage (VHV) environments using the insulation of the existing primary conductor (cable, busbar, busduct,…) for nominal voltages of 20kV – 63kV – 75kV – 225kV – 400kV – 800kV
  • LV Voltage Transformers – Single phase and three phase low voltage voltage transformers (LV VT’s) and potential transformers (LV PT’s), for the measurement of AC voltages up to 2000V
  • MV Current Transformers – bushing and wound primary current transformers for medium voltage current transformer applications
  • MV Voltage Transformers – medium voltage (MV) voltage transformer and potential transformer (PT) products, vacuum moulded in self-extinguishing resin.  Select from single-pole, double-pole, integrated fuse, three-phase, outdoor,  low induction and thermal output MV voltage transformers
  • MV Series or damping reactors that can be installed in capacitor banks for cos phi regulation. They limit the current transients to acceptable values for the capacitor units and reduce surge currents to acceptable values for the corresponding control devices

How to select a current transformer?

How to select a voltage transformer?

Instrument Burdens

Lead Burdens

To view a selection of the instrument transformers we have supplied, please visit our photo gallery.

Contact us to discuss your current or voltage transformer requirements or to request a quotation.