Instrument transformers are often undervalued in transmission systems. However, acting as a power system’s eyes and ears, these components are indispensable for grid protection and energy billing. Even the best circuit breaker simply won’t trip as required in an emergency unless it receives a signal via an instrument transformer. Moreover accurate measurement of voltage, current and power factor under all possible load conditions is essential for the correct billing of delivered / consumed energy.
Hence the consequences of a faulty or inaccurate instrument transformer can be disastrous in terms of personal safety, damage to the grid and business success. As a result, most national utilities require traceable and internationally recognised calibration certificates for the metering capabilities of instrument transformers. Instrument transformers must also comply with the quality requirements of the system in which they are installed – the transformers themselves should not initiate network failures.
Independent, standards-based testing
DNV GL offers complete testing and calibration packages for most instrument transformer types from medium- to ultra-high system voltages (MV to UHV). Completely impartial, our testing is carried out according to relevant and internationally recognised standards such as the IEC 61869 series and the ANSI/IEEE Std. C57.13.
A full range of tests is available including:
- Metering calibration
- Dielectric tests
- Temperature rise tests
- Short-circuit withstand tests
- Mechanical tests
Customer-specific tests are also available on request.
World-class facilities and global reputation
Instrument transformer calibration and testing is available at our KEMA Laboratories in the Netherlands, USA and Czech Republic . Each of these facilities is capable of simulating the normal operation and fault conditions that instrument transformers face in the field, including the highest short-circuit powers. Transformers that successfully compete the full testing protocol specified in the relevant standard receive a KEMA Type Test Certificate – globally recognised as the hallmark of a quality component.